A medium sized falcon of the dry, open habitats of western North America, the Prairie Falcon consumes both mammals and birds. Only a small territory around the nest is defended from other Prairie Falcons, and large areas can be used for foraging by more than one pair. Cliffs are the most commonly used nests sites.
Male Prairie Falcons do most hunting for the young birds, although it is the female that usually feeds the young the prey brought by the male. Prairie Falcons can live to be over ten years old in the wild.
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Description of the Prairie Falcon
The Prairie Falcon is sandy brown above and pale below, with dark wing linings evident in flight. They have a white patch and a dark stripe below the eyes.
Seasonal change in appearance
Juveniles have heavy brown streaking on the breast.
Prairie Falcons inhabit prairie and dry, open country.
Prairie Falcons eat small birds and mammals.
Prairie Falcons forage by flying low over the ground to surprise prey, or by pursuing prey in flight.
Prairie Falcons are resident across much of the western U.S. and Mexico, and also winter a bit farther east. The population has increased in recent decades.
Male Prairie Falcons perform a variety of aerial acrobatics during courtship.
The male Prairie Falcon brings food to the nest, but the female feeds the young.
The call consists of a raucous scold.
- Peregrine Falcons have darker upperparts and more uniformly colored underwings.
The Prairie Falcon’s nest usually consists of a scrape on a cliff ledge
Number: Usually lay 3-5 eggs.
Color: Whitish with darker markings.
Incubation and fledging:
The young hatch at about 31 days, and fledge at about 35-42 days, though remaining dependent on the adults for some time.
Bent Life History of the Prairie Falcon
Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.
Bent Life History for the Prairie Falcon – the common name and sub-species reflect the nomenclature in use at the time the description was written.
FALCO MEXICANUS Schlegel
The prairie falcon is a close counterpart of the lanner falcon (F. biarmicus feldeggii) of Europe. It is also the prairie and desert cousin of the duck hawk, which it closely resembles with its pointed wings and its dash and courage, although it preys more on small mammals. Possibly this mammal-catching is due to the falcon’s marked preference for the open spaces where the rodents live. In certain sections both the prairie falcon and the duck hawk occur, and there the two can be distinguished from each other by the uniformly lighter color of the falcons, The falcon is the same size as the duck hawk and larger than the American sparrow hawk, which it resembles in seine of its habits. It ranges, normally, east to the Missouri River, occasionally to Minnesota and even to Illinois. It is particularly abundant in eastern Washington and Oregon and in the coast ranges that lie west of the great central Californian valleys. Yet, in California, it is seldom out over these level valleys but prefers the rough, broken foothills. This is easily understood when we find that the prairie falcon markedly prefers a nesting site in a cavity, or in a crevice, in the face of a cliff. Its range reaches only a little over the international boundaries into British Columbia and Alberta on the north and into the Mexican highlands on the south. At the present time it is rather rare over much of the range east of the Rocky Mountains, and it is steadily growing rarer everywhere.
Spring: Throughout the more northern and colder parts of its range the prairie falcon is migratory, generally retiring toward the south to escape the coldest weather, especially in the Rocky Mountains and east. In the Yellowstone National Park I found them passing through on migration, appearing after March 25. Farther east, in northeastern Wyoming, they are rare, arriving usually about April 10 or 12, according to Peabody (1907). In Colorado, they are common in the warm months but all leave the mountains during winter. Still farther east they are seen occasionally in Kansas, Missouri, and the Dakotas; but south of these States prairie falcons are resident, except perhaps on the highest mountains.
Courtship: Dawson (1923) gives an interesting account of the courtship of this falcon:
About the brink of the precipice a dozen Falcons are at play. It is courting time and the birds are showing off. The females are the larger birds, but it is their turn to sit in the boxes while the aspirants perform. The doughty males are not really contending: only renewing their vows as they come hurtling out of the heavens, screaming like all possessed and cutting parabolas whose acuteness is a marvel of the unexpected. The female croaks in wild approval, or takes a turn herself because she cannot contain her fierce emotions. The rock walls resound with boisterous music, and the observer feels as though he were witnessing the play of elemental forces: riotous, exultant, unrestrained, the very passion of freedom and conquest.
Nesting: Although the discovery of a prairie falcon nest is an event to be cherished, it is still more rare to see a pair hunting for a site. Harry S. Swarth (1904) tells us: “On April 6, 1902, Mr. Howard and I watched a pair flying about a rocky cliff in Ramsey Canyon. They were apparently in search of a nesting site for they flew into quite a number of caves and crevices in the rock, screaming shrilly the while, but on a later visit to the place we failed to find them.
In the open, rough sagebush country of California, Oregon, and Washington, prairie falcons choose for their nesting sites outcroppings of rocks, or cliffs, 50 to 400 feet in height and usually perpendicular. The sites chosen are generally 30 feat or more above ground and inaccessible to man, except by ropes from above. In the northeastern part of their range falcons are known to nest in the badlands of Montana, Wyoming, and western North and South Dakota, although rarely in eastern North and South Dakota. There are only a few records of occurrence in Minnesota and none of nesting sites (Roberts, 1932). A preferred site faces out over open country, and a southern exposure is often chosen, for the bright hot sun seems to cause no discomfort. ‘Where there are neither cliffs nor crevices these birds will nest in all sorts of niches in any kind of wall, even in dirt banks. Consequently, while the average site is very characteristic, nests may be found almost anywhere. Decker and Bowles (1930) say that in one nest we took a handsome set of five eggs after no more of an effort than simply walking to it and picking up the eggs, while others are placed under an ‘overhang’ of rock at such dizzy heights that we simply wished them good luck. In Washington they are, as a rule, less than sixty feet above the ground, forty feet being perhaps a fair average.” In most cases the shelves or crevices used are natural, but in the soft material of dirt banks the birds may excavate a hollow of their own. Where they have a choice of sites falcons place their nests in recesses, or “pot-holes”, varying from a few inches to several feet in width and penetrating into the walls from a foot to as much as 5 feet. Generally there is a projection above, protecting the nest. Although the species, as the name indicates, is prairie-loving, falcons are sometimes found where the mountains are quite heavily wooded. On the other hand, they do not nest on cliffs over the ocean as the duck hawks sometimes do. As a rule there is no nesting material whatever, the eggs being laid on clear sand or gravel, or amid bones, bits of fur, and feathers. Although falcons often use ravens’ nests that are placed in niches in the rocks, they less often make use of ones placed on rock pinnacles, but Sclater (1912) says of Colorado birds: “Dille found a nest on the top of a chimney of sandstone in some buttes in the north of Weld county, on May 5th; it was an immense pile of rubbish, with skeletons and dead animals scattered round. * * * Gale took four eggs of this species from an old eagle’s nest on April 24th, in a cliff on the Little Thompson River, the situation was about fifty feet from the bottom, and thirty feet from the top of the cliff, * * * another nest in a similar position on the St. Vram.” There is only one well-authenticated record of a falcon nest in a tree, even on the prairies, where cliffs are rare. Goss (1891) says: “At Marysville, Mo., [was] a nest in a tree, thirty-five feet from the ground; notes fail to show whether the nest was in the forks of the branches or in a hole in the tree, but doubtless in the latter.” Since that record no further instances of tree-nesting have come to light. Mr. Bent noted a nest in a cliff at the top of a rocky hill in the Mojave Desert, San Bernardino County, Calif., saying: “When we yelled or clapped our hands the bird flew out from a little shelf on the side of a vertical crevice in the rocks. The eggs were in the remains of an old nest of a raven which had crumbled almost to dust, only a few pieces of sticks remaining, the eggs lying on the dirt in the center. Later, while I was at the nest the female made several close swoops at me within ten or fifteen feet; she was flying and cackling all the time.” Generally these swoops are vicious in appearance and very trying to the collector’s nerves, but almost always the falcon will, when within a few feet of the intruder, suddenly swerve to one side or the other. She does not have quite the nerve required for an actual attack, but Mr. Dawson (1923) says: The assaults of an angry Falcon are really dangerous. Even when the earliest efforts are discouraged by a show of sticks or stones, it is decidedly disconcerting to feel the rush of air from a passing falcon-wing, upon your hatless pate, or to mark the instant change in pitch from the shrill uproar of impending doom to the guttural notes of baffled retreat. The Falcon has a nasty temper at best, and if she dare not vent her spite on you, she will fall upon the first sight who crosses her path. Woe betide the luckless Barn Owl who flaps forth from his den to learn the cause of the disturbance. I have seen such bowled into the sage in a trice. * * At such times also the Raven is put on trial for his life. In spite of their close association, there is evidently an ancient grudge between these birds. * * * The Raven is an adept at wing-play himself, and the Falcon’s thunderbolt is met with a deft evasion. * * * But the Raven takes no pleasure in it. His eyes start with terror, and while he has no time for utterance himself, the distressed cries of his mate proclaim the danger he is in.
The close association of Falcon and Raven at nesting time is the strangest element in the lives of both of them. To be sure, their requirements of nesting sites are similar; but it is more than that which induces the birds to nest within a hundred yards of each other in the same canyon, when neighboring or distant canyons offering as excellent sites are empty. So constant indeed is this association that when one finds the Raven’s nest, he says, “Well, now, where is the Falcon’s?” Of the entire number of Ravens’ nests which came under my observation in one year, seven were thus associated with nests of the Falcon in the same canyon, and the remaining three were within a quarter of a mile of Falcons~ in neighboring canyons separated by a single ridge. And it is impossible to tell from the stage of incubation which bird is the follower. * * * The only guess we dare hazard is that both birds reap advantages of warning in case of hostile approach. Concurrent with this association is the annual, or at least occasional, shifting of sites on the part of both species.
* * * This shifting is of course quickened by persecution. If unsuccessful in raising a brood one year the bird will try another situation, but always, except in extreme instances, in the same canyon or general locality. In this way the Falcon appropriates the site once occupied by Ravens (and so gets credited with a “stick” nest, though I am satisfied that the Falcon never lifts a twig); and the Ravens, in turn, without opposition are allowed to rear their pile in a niche just previously occupied by the Falcons.
Decker and Bowles (1930) write that while potholes: are perhaps the favorite nesting sites of these birds, they are by no means the only kind selected. In many cliffs there are no potholes at all, but on some projecting ledge of rock a Western Red-tail or a Raven will have built its nest during some past season, and it is the old nests of these two species that are very commonly used by the Falcons. In fact, in many localities the abundance of the Falcons as breeding birds depends entirely upon the presence of the old nests of these other birds. An instance by way of proving this statement occurred to us in the past spring when we visited a cliff where the year before we had found a Falcon using an old Raven’s nest. The nest had been dislodged by the winter storms and, as there were neither old nests nor potholes, there were no signs of the Falcons to be found anywhere in the vicinity. This is only one case in several that we have noticed. In our experience the Falcons will always return to the old nest, even though the rightful owners wish to take possession themselves. A very interesting example of this was given us in the past spring of 1928, a somewhat detailed account of which may be permissible. The nest in question was that of a Western Redtail, which was situated on a ledge about twenty-five feet from the ground and some forty feet below the top of the cliff. We had taken a set of three eggs of the Hawk from this nest in 1926, and in 1927 we had found it occupied by a Falcon with five eggs. Going to it in 1928 we at first thought it deserted as no bird could be seen, but, upon going directly beneath it and shouting, the Falcon flushed with her customary fierce challenge. Much to our pleasure the nest contained five eggs of the Falcon and, to our great surprise, one egg of the Red-tail, all of which were perfectly fresh. The poor Hawks had been through a very hard spring, as they had built a nest about half a mile distant across the river and had their eggs eaten by Ravens. Of course we had no means of ascertaining the course of events, but it would have been most interesting to know if the hawk had laid its egg before or after the Falcons had taken possession of the nest. It is highly probable that the Falcons could and would drive away the rightful owner, if they wished to do so, even though the Hawks had taken possession first. However, on the other hand, it seems highly possible that the Ravens had destroyed an incomplete set in the new nest and the Hawk had then taken advantage of a temporary absence of the Falcons and laid the egg to complete her set in her nest of a former year.
The friendly relationship existing between Falcons and Ravens, that are both nesting in the same cliff, is nothing short of astounding, especially when we consider that a Raven is perhaps the most “dyed-in-the-wool” egg eater in the animal kingdom. It is fairly safe to say that in seven cases out of ten a pair of Ravens will be nesting in the same cliff that is occupied by a pair of Falcons, the nests in many cases being only a few hundred feet apart. Yet strangely enough we have never seen a sign of friction of any kind existing between the two species. When we first commenced our studies of these birds we always were fearful that the Ravens would eat the Falcon eggs before the set was complete. However, this has never occurred in all the many instances that have come under our observation, the Falcons paying little or no attention to the Ravens at any time. The reason for this may, perhaps, date back to some past generations of the Ravens who learned through hitter experience that it was far the wisest thing to make the contents of a Falcon nest the exception to their general rule of eating eggs and baby birds. Perhaps this knowledge has been inherited by the present generations. One thing absolutely certain is that the Falcons “rule the roost” and do exactly as they please in the selection of nests, the poor Ravens simply taking what the Falcons do not want and making the best of things. As a rule the Ravens lay their eggs about a week earlier than the Falcons, but the latter have apparently already selected the nest they want and the Ravens usually build a new nest for their first set. If the contents of the nests of both species are removed they will usually lay again in the same nests, but they occasionally trade nests * * *~ Yet in all this switching around we have never seen any signs of discord between the two species, trying as it must be on their tempers.
John G. Tyler (1923) says:
In the region where my observations have been made the north end of the ridges breaks off abruptly into cliffs and for that reason most of the nests I have examined have had a northern exposure. A few have been on west-facing cliffs and one faced the east or northeast, but none has been on ledges with an outlook to the south. Of seventeen nests personally examined during the past few years nine have been in pot holes of various sizes, where the eggs rested on the gravel and small loose rocks which lined the cavity. Six sets were laid on the tops of nests built by ravens and these nests were utilized without any alterations whatever. In one case, the nest was newly built and freshly lined with wool, while the other five were in various stages of disrepair. One pair of falcons used, during three seasons, a hole in which a pair of ravens had evidently built a nest many years before. The female does the brooding, although the male will sometimes take her place under unusual conditions. Usually the male, unless hunting, will perch on a tree somewhere near the nest. Decker and Bowles (1930) say that for some reason she will remain with the eggs when in an open nest almost to the lest extremity, “while in one of the pot hole nests she may flush at some little distance.” They continue: The period of incubation does net seem to influence her actions in this respect to any great extent so far as we have seen. We had one most fascinating exhibition of n close sitting bird at one site where an old nest of the Raven was used. One of us was walking along the top of the cliff, while the other walked along at the base, the man at the top being considerably further in advance. Presently a nest was sighted at very close range with the bird crouched upon it and most intently watching the man below her. The man at the top made very little noise and she had not seen him, so ha had a perfect opportunity to study her. She flattened herself down into the nest so far as to be completely out of sight from any direction excepting directly above and remained in that position until the man below was almost up to her. Then she stood up in the nest and commenced her battle cry that gives such a never failing thrill to the bird lover, not leaving until she knew it was useless to remain any longer.
In its action around the nest we have never known a Falcon to actually strike a human being.
Between the “close sitters” and the wary birds there are all gradations. After the female has been driven from her nest, she will seldom return to her eggs while the enemy remains in sight. Should the intruder suspend activities and remain quiet, she may perch more or less nervously on a tree not too far away; but renewed movement will often bring her back to scream and swoop. She is evidently the more aggressive and the more concerned over the eggs. The male usually contents himself with circling high overhead.
Throughout most of its range this falcon is a valley or foothill bird, so that it conies as a surprise to hear of its hunting, and even breeding, far above timberline. Merriam (1890) says: “A pair of these Falcons had their nest on a high cliff in the crater of the main peak of San Francisco Mountain, and another pair had possession of a similar ledge on Kendriek Peak.” Both of these locations were at least 11,000 feet above sea level. Bergtold (1928) says that in Colorado the prairie falcon “breeds up to 10,000 feet.” Lowe (1895) says that “one was shot at 10,000” in the Wet Mountains, Huerfano County, Cob. Dr. E. A. Mearns (1890) saw one on June 4,1887, at the very tip of Humphreys Peak, Ariz., at 12,562 feet, and writes: “These only braved the wind and cold at the summit. The name of ‘Prairie’ Falcon scarce accords with my recollection of that scene.~~
Eggs: Usually there are four or five eggs to a set in California, Oregon, and Washington. Records of just 100 sets collected in these States show 7 percent contained three eggs, 21 percent four eggs, 70 percent five eggs, and 2 percent six eggs. But four sets obtained farther east in Wyoming and Colorado showed one set of two eggs, one of three eggs, one of four eggs, and one of five eggs. Therefore it is presumed that eastern nests have fewer eggs. Additional sets of two eggs have been taken, even in California; hut in these cases the sets were incomplete or second sets. Bendire (1892) says that the “eggs are laid at intervals of a day or two.”
Tyler (1923) says:
The eggs from any one pair of birds bear a close resemblance from year to year and it is always possible to tell, by the eggs alone, when a new female takes possession of a nest.
I have never made a practice of taking second sets, but I have determined that a second set is nearly always laid within a period of from twenty to twenty-five days after the first set has been removed. Usually the same nest is used, although sometimes the birds move to another site which, as a rule, is in the same cliff or in one not far away. * * * Undisturbed birds raise but one brood of young each season. Moreover, I am inclined to believe that certain pairs occasionally pass a season without nesting, as I have, on two different occasions, found both birds present at a nest site, yet their actions did not indicate that they were nesting and on subsequent visits they showed no active interest in the neighborhood.
Prairie falcon eggs are somewhat smaller than those of the duck hawk and average lighter in color than the eggs of any falcon except the American sparrow hawk. The eggs are very handsome and, since they vary a good deal in color, are attractive to collectors. According to Mr. Bent’s notes they are ovate to nearly oval, finely granulated to smooth, and often pimpled. The ground color is white, creamy white, or pinkish white. About half the surface is finely and evenly sprinkled with minute dots, nearly or quite concealing the ground color; the other half is more openly spotted with larger spots that are sometimes concentrated at one end; sometimes there is a broad wash of color at one end, and sometimes the overlying color even obscures the ground color so that the whole seems “vinaceous-cinnatnon.” The markings are “burnt sienna”, “amber-brown”, “tawny~~, or “cinnamon.” These three ground colors and the four overlying ones are capable of many combinations. Since the markings also differ in shape and distribution, prairie falcon eggs are subject to a wide variation in appearance. Very rarely an egg will show a uniform color all over. One beautiful tint is a purplish shade noted by Coues (1874) and by Dawson (1923) but even better described by Truesdale (1910).
The measurements of 331 eggs, from all sections, average 52.3 by 40.5 millimeters; eggs showing the four extremes measuring 57.9 by 42.7 and 47.1 by 36.0. The largest egg came from Sweetwater County, Wyo., but one only a trifle smaller was collected in the State of Washington.
Young: Bailey and Niedrach (1933) reached a nest in Colorado just as the eggs were hatching. They tell us that they used a photographer’s tent as a blind, and, although the female falcon was suspicious of the blind, especially of the bright lens, she came back to her nest again and again. The last time, the motion-picture camera was started as she approached, “and in a few moments she alighted as before. Motionless, with wings dropped, she looked at the blind, and finally, apparently satisfied that all was well in spite of the whirring noise, settled down upon her eggs.” On the following day two downy young sprawled on the rocky shelf. The mother returned in half an hour to cover the falconets and the other two eggs.
When the young falcons first leave their eggs they are as helpless and ill-formed as any birds could be. During the following five weeks they are carefully looked after and fed by the female parent. They grow rapidly, and at the end of this period they leave the nest and are soon able to care for themselves. Taverner (1919a), however, distinctly noted that the young, after leaving the nest, “while full-fledged and apparently strong on the wing, were under parental care.”
Although we have many accounts of finding the nests and of securing the eggs, with whatever habits could be noted at the time, only one scientist, that I know of, has had the time and patience to make a detailed study of the brooding, care, and growth of the young. F. II. Fowler (1931) made this study in 1928 in the canyons of the eastern side of the Mount Hamilton range of mountains in California. The nest that he designates as Nest no. 1 on April 29 “was found to contain five young falcons, about nine days old, according to subsequent weight comparisons. [Full set of eggs was found April 1.] Nest number 2, which could not be visited until May 6, then contained four very young birds, believed, after much subsequent study and figuring, to average about three days old. [Full set of five eggs was found April 1.]” Mr. Fowler continues:
They were weak, had a marked tendency to capsize, and when they did roll over immediately curled up as if still in the shell. Only the most advanced had their eyes part way open, and the others showed very marked and extensive granulation around the unopened eyelids. No remnants of the fifth egg, nor of a chick hatched from it, could be found.
The young in nest number 1 were systematically weighed and photographed in the nest, until the family took to wing some time between May 23 and the next visit on May 30. Those in nest number 2 were weighed, and a selected bird photographed to scale, until they appeared ready to leave the nest when last visited June 6.
The weights of a typical young falcon are as follows (condensed from Fowler’s diagram): May 6,1928 3 days old weighed 234 ounces May 13, 1928 10 days old weighed 7Y2 ounces May 20, 1928 17 days old weighed 14 ounces May 30, 1928 27 days old weighed 20 ounces June 3,1928 31 days old weighed 19 ounces June 6, 1928 34 days old weighed 18 ounces
Weights taken at neat number 1, when adjusted to compensate for age, and for full or empty crop, correspond closely with the longer and more complete record taken at nest number 2, and are therefore not here included.
* * * This pair (nest no. 2] were mighty hunters, remarkable for the variety of their quarry. They also had the habit of bringing in their game intact to the nest, or to a small shelf near the base of the cliff, and there plucking the birds and leaving the remains, after satisfying the ravenous family and their own appetites.
This habit is rare, I believe. Usually the mammals are torn into and partly eaten before being brought to the nest to feed to the young. When the feeding is about completed, the parent lifts the remains in its beak, makes a running start, and on the instant of taking wing shifts the remains to its talons. On some rocky point in the vicinity it then probably cleans off and eats the scraps of meat from the skin and bones, and leaves them where they are never found for record. The larger birds are ordinarily partially plucked before being brought to the nest, and the fag ends are probably carried away at the end of the feast. Smaller birds disappear on the spot as if by magic. This habit of carrying remains away was observed from the blind in 1930 * * *
It is difficult or impossible to estimate definitely the number of animals represented by a given numbers of pellets from a nest. All the young may receive a full crop of fur from a single large ground squirrel. In a family of five, such as that at nest number I, this meal might result in five pellets available for analysis from the death of one animal. On the other hand, five pellets found at the roosting place of a mature bird would almost certainly have meant at least five animals killed. * * *
After the photograph and movie campaign of 1930 had been completed, four pellets were found on the edge of the mesa, just behind the old bird’s lookout rock across the canyon; none was found at the base of the rock. These pellets measured 2.00 x 0.80 in.; 2.12 x 0.88 in.; 1.82 x 0.90 in.; and 2.10 x 0.90 in.; they are notably more compact and symmetrical than those of the young.
Observation of falcons in captivity coupled with the fact that these wild birds deserted their lookout point for the firmer footing of the flat mesa shows that the process of casting up a pellet is a serious and sea-sick business. When the symptoms of “casting” first attack a falcon it draws its feathers down flat, stands up full height, sticks its head and neck outward and upward, and for a few moments looks bereft of its senses. It then starts to duck its head in a series of quick jerks, at the same time contorting its neck violently from side to side. This muscular action appears to force the relatively large pellet from the bird’s interior upward into the crop. The sidewise contortions then cease, and the pellet is cast by a series of up and down pumpings of the head and neck. The bird then stands for a few moments seemingly with the sad question in its mind: “Would a good dose of Mothersills have obviated all of this?” It then shakes itself, resumes its interest in life, and begins to wonder where the next supply of fur and feathers is available. * * *
Probably a definite weight of meat (with comparatively little variation one way or the other) is required to develop a young falcon from the egg to the day of flight. Whether this food supply consists of tender birds or tougher rodents probably makes little difference in the total weight consumed. However, toward the end of the nest life the demands of the family are so tremendous that an endless stream of mammals and fair sized birds seems to be the only recourse of the hard-working parents. Small birds could hardly be caught fast enough.
The food actually secured probably depends to a large extent on the locality, the season, and the individual hunting ability of the parents. In the general locality of these studies ground squirrels and meadowlarks (being the most readily available source) probably form a large part of the normal supply of the average falcon family. Here, and elsewhere, it is probably more difficult for the parents to raise a brood hatched a month late than one hatched at the normal time. The hunting ability of the parents is a prime factor in at least the variety of the food supply.
Only by observing a large number of families can a true estimate of the falcon’s economic status be established.
Mr. Fowler (1931) also gives the following data in detailed tables: At Nest no. 1 a partial tabulation showed that 1 California horned lark, 8 western meadowlarks, and 9 California ground squirrels were eaten between April 29 and May 20, 1928. At Nest no. 2 it was possible to make much fuller tabulations, showing 2 mourning doves, 8 burrowing owls, 3 California horned larks, 9 California jays, 15 western meadowlarks, 3 Brewer’s blackbirds, 2 California shrikes, 1 rock wren, 1 poultry, 1 unidentified bird, 1 California pocket gopher, 7 California ground squirrels, and 1 Nelson spermophile eaten by four young between May 6 and June 6, 1928. The poultry item was “one small white wing about the size and shape of a meadowlark; probably a Leghorn chick from a neighboring ranch”, but a detached wing might have been picked up so far as data show.
Speaking of a nest in Montana, Cameron (1907) says that a pair of Say’s phoebes that built a nest “in a hole near the Prairie Falcons’ eyrie were killed by the latter for their young.”
Plumages: Falconets just out of the egg, or at least as soon as they are dry, are covered with fine white down. When the birds are about two weeks old the darker feathers of the tail and wings become noticeable, and a few days later various feather tracts on the body outline themselves. At about four weeks of age, the feathers are well started. During the following week the feathers grow so fast that the bird actually loses some of its body weight, although ample food may be greedily swallowed. The changes in color are rapid, so that a young bird five or six weeks old is really darker above than the adults. Although this coloration is rich, it is still obscured until the shedding of the last down at some two months of age. The final growth of plumage and the last shedding of down take place after the young are on the wing. The young falcons out of the nest are buffier and more striped than the adults, with a more reddish tinge to the upper parts; the iris is brown; the feet and legs are slate color; the claws, black; the bill, bluish black, with the base of the under mandible yellow. It is not known just when the changes are completed, but gradually the juvenile plumage becomes lighter, clearer, and more like the adult. The feet and legs become yellow, while the mandibles and iris change little, if any. Bailey and Niedrach (1933) write:
Out came the female falcon. And, what a bird! Niedrach had promised a surprise, but such a beautiful hawk was not expected. Instead of the natural brown plumage of the species, this bird was cream white, with occasional markings of the natural dark color. She hovered overhead, shrieking her displeasure at the invasion, and, even at that distance, her black eyes contrasted with her light-colored feathers. Niedrach has known that particular bird for nine years. She had nested in the vicinity each year, but he bad never been able to reach her nest to photograph it, and, in that time, he had never seen other light-colored falcons, with the exception of one young bird, which had a white feather in the center of the back. Apparently, the young were usually of normal plumage. [PL 10.]
Like most hawks, the adult prairie falcons may exhibit either light or dark phases of plumage, with all gradations between the two extremes. Although it is probable that this species molts at least once a year, nothing is known about the time or the manner. Neither is it known positively whether there is only one molt each year or more.
Food: While I was examining reports on the food habits of this falcon, from various sections of its wide range, two things became very evident: First, no adequate study of the subject has ever been made, and we are therefore mostly dependent upon various items picked up incidental to oological, or other, studies; and second, these incidental notes show great diversity of food, possibly due to difference in range, availability of certain victims, opportunities of the observer, and changing conditions as affected by man. All agree that this falcon is bold and enterprising and fully capable of easily killing prey even larger than itself. No doubt the ease and certainty of securing a stated prey are responsible for a seeming preference for that prey in that locality; otherwise, food is normally quite varied.
In places where there are large flocks of these small birds, the prairie falcon preys on sparrows and Brewer’s blackbirds, more or less harrying the flocks as long as they remain in the vicinity. Its powers of flight are great enough to permit of the successful chase and capture of mourning doves; and in places it takes meadowlarks in numbers. Speaking of central California, Tyler (1923) says: “My personal observations have convinced me that small birds are preferred at all times * * *ï From the time the falcons return to their nest cliffs in early spring through the egg laying and incubation periods the Gambel Sparrows (Zonotrichia 1euicophrys gambeli) are very abundant in the regions where falcons abound and a very heavy toll of sparrows is taken. But, by the time the young falcons have appeared, these sparrow hosts have practically all migrated and the falcon turns his attention to Western Meadowlarks, Valley Quail, and Western Mourning Doves.” Most of the falcon’s hunting is done early in the morning and late in the afternoon, even in cloudy or comparatively cool weather. Dawson (1923) says:
The bird makes little fuss over the capture of small game. It simply materializes out of the empty blue and picks up a gopher or a blackbird as quietly as you would pluck a flower. The approach has doubtless been nicely calculated. The thunderbolt, launched from the height of half a mile, has been checked every few hundred feet by a slight opening of the wings, that the Falcon might gauge the caliber and the intent of the victim; and the final plunge has, therefore, the speed and accuracy of fate. In case of larger game the quarry is knocked headlong by a crashing blow, after which the assailant turns to try conclusions as to weight. But the Falcon prefers always to snatch, and when small game is abundant, the bird is less likely to disturb rabbits or poultry.
* * * While his visits to the poultry yard are by no means rare, and his offenses, judged from this narrow human angle, are serious, we shall not stop to plead the thousands of destructive squirrels which this bird accounts for.
Henninger and Jones (1909) say: “They seem to prefer bird flesh, but during a scarcity of such diet may be driven to any of the smaller animals.” On the other hand, Decker and Bowles (1930) say that during the nesting season young rabbits are preferred, probably because of abundance; but stomach examination indicates change of diet in winter. Mr. Ridgway (1877) says: “Latein November, of the same year 11867], it was noticed again among the marshes along the Carson River, near Genoa, where it was observed to watch and follow the Marsh Hawks (Oireus hudsonius), compelling them to give up their game, which was caught by the Falcon before it reached the ground; this piracy being not an occasional, but a systematic habit.” But Cameron (1907) says that a golden eagle in Montana seemed to play a somewhat similar trick on a prairie falcon: “On September 21, 1904, at our ranch in Dawson County, my wife and I watched a Prairie Falcon in the act of carrying off a Meadowlark which was screaming and struggling in its talons. As the falcon rose level with the hill-tops, a Golden Eagle sailed majestically over in close proximity to it, thereby appearing to fluster the other which allowed its victim to escape.”
In the Yellowstone National Park I once saw a prairie falcon make several swoops at a flock of 44 Brewer’s blackbirds, although on that occasion they all escaped into the thick foliage of some big pines. Ellsworth D. Lumley writes me in a letter: “On November 16, 1932, I witnessed a prairie falcon eating an English sparrow in this city [Great Falls]. Another falcon sat in a nearby tree and gave its piercing cry.” But Lumley also writes that on October 18, 1932, a falcon stomach was found to contain a pellet of hair and some small bones, indicating rodent diet. Goss (1891) says that he saw a prairie falcon “dart from a telegraph pole into a flock of chesnut-collared Longspurs, and knock down four of the birds at a single dash, killing three and winging the other.” Fuertes (1920) adds “jays” to the list of falcon prey. Mrs. Bailey (1928) writes that the prairie falcons were “about the alfalfa fields at Carlsbad [N. Mex.] in September, apparently looking for game among the flocks of waders that followed the irrigation of the fields. When the waders were quietly feeding, the appearance of this dark, short-necked hunter would send a big flock of the silvery birds into the sky, or if he dashed in among them, would put them to disorderly flight.” Mrs. Bailey, quoting Dr. Wetmore, also says that “they harried the Yellow-headed Blackbirds so mercilessly that they set up an outcry whenever a bird of any size appeared on the skyline.” Strange, indeed, seems the incident witnessed by Pemberton and Carriger. They (1915) write that a prairie falcon was seen on May 27, 1909, “to sail into a flock of sea gulls flying near the beach and strike one of them to the sand. After performing the trick the bird flew away, evidently not caring to eat his prey.”
We have already spoken of the prairie falcon taking doves and valley quail, but it also preys upon many other game birds as well. Willard (1916) says that they take considerable toll from the flocks of band-tailed pigeons. “These terrors of the air will dash into a tree and grab a pigeon off a branch, rarely making an unsuccessful raid.” Still, because this falcon prefers open country, its raids fall more severely on game birds of the open, such as valley quail and Gambel’s quail, and it has found the newly established European partridge a choice morsel. Munro (1929) says: “The present relative abundance (the species is by no means common) is perhaps due to a recent increase of European Gray Partridge which these falcons hunt persistently. When a Prairie Falcon passes along one of the open hillsides frequented by these birds coveys rise in every direction. No better aid in estimating the partridge population of a hillside could be devised.”
Even the sharp-tailed grouse is not too large a quarry. Bendire (1892) says that he found “the remains of a Columbian Sharp-tailed Grouse in the crop of one specimen.” E. S. Cameron (1907) and Henninger and Jones (1909) mention this grouse as prairie falcon prey, without giving further particulars. Goss (1891) cites both ducks and prairie chickens as victims. When the boldness and audacity of this falcon are considered, it does not sound strange to bear that it will catch ring-necked pheasants at a game farm. Jewctt (1926) says: “On November 24, 1925, at the Oregon State Game Farm at Corvallis, Oregon, one of the farm employees shot an adult female Falco meneanus that was in pursuit of a female Ring-neck Pheasant. * * * This is the first Prairie Falcon to be seen there, and only the second record of the species in the Humid Coast Belt of western Oregon of which I have knowledge.” Mrs. Bailey (1928) also speaks of this habit: “A Ring-necked that was once attacked by one was so terrified that, at each swoop of the Falcon, it would flatten itself against the ground.”
In addition to the upland game birds, prairie falcons sometimes attack water birds. Decker and Bowles (1930) say: “A large female at Santa Barbara, California, had killed a Coot (Fulica americana) with which it tried to fly across the road.” E. S. Cameron has known the prairie falcon to prey upon mallards and both kinds of teals. He (1907) says: “At the time of their migration Green-winged
Teal seem to be a favorite quarry and Mr. J. H. Price has twice shot one of these ducks from a flock pursued by a Prairie Falcon before it had made its stoop. This dashing marauder attends upon the Teal as they move up and down the creeks.” From such a list as this, with so many game species upon it, it would seem that the prairie falcon is a great destroyer of birds. The fact is that all the incidents given here are exceptional, although interesting because they illustrate the prowess of some individual prairie falcons. Grinnell, Dixon, and Linsdale (1930) actually say: “Feeding ducks and coots at Eagle Lake appeared to pay no attention to hunting Falcons. It was thought that in that vicinity this species hunted for meadowlarks and flickers.”
I believe, also, that prairie-falcon attacks on poultry are unusual occurrences. Although I have searched the literature about this species, I find only the following records, and these include both specific instances and general statements based upon evidence unknown to me. Baird, Brewer, and Ridgway (1905) say: “Dr. Suckley procured a specimen at Ft. Dalles in the beginning of winter, 1854: 5, caught in the act of carrying off a barn-yard fowl of about its own weight, and which it had just seized near the door of a dwelling-house.” Ridgway (1877) notes: “In the Truckee Valley we saw one snatch a young chicken from a door-yard, in the presence of several spectators.” Merriam (1891) records one shot while “in the act of chasing a chicken in the lower part of Birch Creek [Idaho], August 7 11890]; its stomach contained a Horn Lark (Otocoris). But they “were often seen chasing Teal up and down the creek.” Cohen (1903) adds: “One attacked a band of half grown turkeys early in the fall and the other flew from an oak at some pigeons inside their enclosures and struck the wire netting.” Peabody (1907) says: “As is well-known, this Falcon is a terror to poultry.” Cameron (1907) notes: “The Prairie Falcon is very bold in its attacks upon game birds and poultry * * “‘. In attacking full grown hens the falcon suddenly checks its stoop about a yard above the victim over which it hovers before making the final dash. Meanwhile the shrieking fowl runs wildly about and there is often time to scare away the freebooter which then mounts with incredible rapidity.” Truesdale (1910) writes: “Their food consists chiefly of small mammals, birds and occasionally chickens which they catch. * * * I have seen this falcon fly into a flock of chickens and strike one * * * returning again and get another one in the same manner, until they have killed off nine chickens.” Vernon Bailey (in Florence Merriam Bailey, 1902) says: “The falcons are bold freebooters when a farmyard happens to lie in the valley below and their hungry young are calling, but ordinarily ground squirrels and other small rodents supply most of their food. The few birds they get are mostly caught on the wing. One that shot past me in pursuit of a flock of Gambel quails in southern
Utah struck a quail from the flock with such force as to knock it to the ground amid a cloud of feathers, but fortunately for the quail it landed in the brush, where it escaped.” H. S. Swarth (1924) records: “Once observed in pursuit of domestic pigeons in Flagstaff, and several times after poultry about ranch houses. The one specimen preserved was shot while making off with a chicken.” Tyler (1923) adds: “October 24, 1912, near Fresno I saw, at close range, a falcon which was circling overhead suddenly fold his wings and swoop at a small white chicken in a barnyard. The chicken escaped by quickly diving under a clump of shrubbery.” Finally, Ellsworth D. Luniley writes us: “On the May 13, 1933, trip I came into possession of a prairie falcon that a woman had killed the day before. It was in the chicken yard with a chicken in its talons and when approached allowed the woman to come close enough to knock it out with a rock.” But, on the other hand, Bendire (1892) bears contrary testimony for the prairie falcon: “Poultry was rarely molested; and although one of these Falcons would sometimes make a dash at some of the fowls, it seemed to me that it was done more to scare and to see them run than to capture them. Not a single instance came under my observation where a chicken was actually struck by one of them. I have no doubt whatever that they are fully capable of killing a fullgrown hen and of carrying her off, but they do not seem to care for poultry, and I have more than once seen chickens feeding under a tree in which one of these birds was sitting.” In many ways I consider Mr. Tyler’s article (1913) particularly illuminating when he writes: “A farmer living near New Hope once told me of a longwinged ‘bullet-hawk’ that made regular visits to his place in quest of young chickens, which it seized and bore away so rapidly that he could never prevent the loss. Finally he resolved to wait for the robber, as it always appeared about the same time each day, coming from the foothills of the Coast Range mountains, fully twenty-five miles away, and returning toward the same place. * * * At the shot the bird dropped its victim [a squawking young fowl] but continued its flight, although apparently much weakened. It was never seen again.” There are scores of falcons in these same Coast Range mountains. If chicken-killing is at all common, why did not Mr. Tyler hear of, and record, other instances? That this was simply one and the same individual that had developed a taste for chicken seems shown by the fact that it never returned after being shot at once.
While all ornithologists are naturally more interested in falcon attacks on birds than on mammals and are more likely to note such instances, there are many notes of mammal destruction by prairie falcons. Goss (1891) says that they kill “mice”; Bendire (1892) and Henninger and Jones (1909) list “rodents”; Bryant (1918) adds “pocket gopher”; Coues (1874), Goss (1891), Fisher (1907), Tyler (1923), Dawson (1923), and lix (no date) all record “ground squirrels” of various species; Cooper (1870), Ridgway (1877), Goss (1891), Bendire (1892), Henninger and Jones (1909), and Sciater (1912) specify “hares” or “jack rabbits”; Decker and Bowles (1930) say that their food during the nesting season, “so far as we have seen, consists almost entirely of cotton-tail rabbits and young jack rabbits”; while Sciater (1912) adds “prairie dogs” to the mammal list. Bailey and Niedrach (1933), operating in Colorado, give us more details: “A few minutes later, we saw the falcon darting low over the homes of the prairie dogs. He dipped close to the earth and struck one of the rodents scurrying for cover, and, with scarcely slackening speed, mounted into the sky with a young prairie dog dangling from his talons. He circled higher, as though to look us over, and then flew to a pinnacle of rock where we could see him tearing at his prey.” As said before these falcons can kill prey larger than themselves, and this is particularly true of the jack rabbits that are fully twice as heavy as their destroyers.
So it seems evident that many of us know only a part of the story. Unfortunately, only one study of the food of the prairie falcon has been made, so far as I know, and the details of that are given under subheading “Young” (p. 24). It is a good account, but it shows us that there is much more to be learned about the food of these birds. Strange to say, when we consider the prowess and strength of the prairie falcons, there are several records of lizard and insect eating. Fisher (1893b) says: “Lizards are occasionally taken, and, among the insects, the large crickets and grasshoppers which are so abundant in some sections of the West are also eaten.” Goss (1891), also, lists lizards as one of the items of food, but does not speak of insects. Taverner (1926) says: “On occasions it even turns seriously to grasshoppers and the crop of at least one specimen examined by the writer was filled with these insects. Of eight other stomachs examined, 3 contained game birds; 5, other birds; 2, mammals; and 2, insects.” Tyler gives an interesting account of a prairie falcon hunting on the ground. He speaks of the probability that it was after a jack rabbit; but, to me, it seems very likely that it was after rodents or insects. I have personally seen them hunting grasshoppers in just that way. Tyler (1923) says:
That this species sometimes seeks its food in much more lowly manner than one would expect is evidenced by an incident which came to my notice on January 13, 1920, near Hugbson, Stanislaus County. I was sitting in an automobile talking with an acquaintance when I noticed a Prairie Falcon on the ground in a large grain field. * * * He was hopping over the ground and seemed to be carefully looking at the many small bunches of stubble which had accumulated as a result of the recent plowing of the field. The falcon was repeatedly seen to hop up onto small clumps of this straw, and scrutinize them carefully as if in search of any small bird which might be concealed therein. After satisfying itself that no prey was to be found, other straw heaps, in turn, were visited. Fully half an acre of ground was covered, but the falcon was not seen to capture anything. * * * As I left the field, * * * it sprang into the air and beat away on strong wings. As the falcon began to gain speed a jack rabbit sprang from its place of concealment, whereupon the falcon made a very swift and graceful swoop toward the rabbit but did not appear to endeavor to strike it.
Giving due consideration to all the cross currents noted in the lives of various prairie falcons, we begin to wonder just what their economic value to man may be. The most serious complaint against them is not that they kill chickens, but that they destroy tame pigeons. Often a single falcon will hang around a grain elevator to catch the tame pigeons coining there for waste grain. At times, a falcon will locate a pigeon coot and visit it more or less regularly until it has taken every bird. But, even this pigeon hunting seems to be more or less individual, and is not at all a general habit.
Probably the destruction of poultry, pigeons, and wild birds by prairie falcons is pretty well balanced by the good the falcons do in destroying so many noxious rodents. Dr. A. K. Fisher (189Th) writes: “At present the data we have on the food of this Hawk is not enough to decide whether the species should be protected or persecuted.” Later, although still undecided, Dr. Fisher (1907) sums up the evidence well, saying:
Throughout a large portion of the country inhabited by this species, poultry is scarce, as most ranchers do not yet attempt to raise it. Although this falcon feeds extensively upon waterfowl, quail, prairie chickens, and other game, it attacks also various kinds of injurious mammals, notably the smaller ground squirrels, such as the striped, Franklin, Richardson, Harris, and the allied species, which abound in many sections of its range. In this respect it is of considerable service to the agriculturist, and probably offsets the injury done by destroying game; but, unfortunately, the data at hand are insufficient to show just how extensively it preys on these animals; hence the benefit done cannot be correctly estimated.
Richard M. Bond (1936b) says: “At an eyrie in southwestern San Luis Obispo County was found a fresh half-eaten wild cat (Lymz rufus californicus) kitten, the estimated live weight of which was slightly over 2 pounds, or about the load limit of a female Prairie Falcon. There is no proof that the kitten was killed by a falcon (it was on a ledge about 30 feet from the nest), but a rather extensive exploration of the cliff disclosed no signs of other large birds of prey.”
Behavior: To use the wording of the hawking brotherhood, this is a noble bird, met with far out over the wild, lonely foothills, over the unsettled plains and prairies, and even over the deserts of the Southwest. It is strong, bold, and a fearless fighter, but wary, shy, and secretive where it has been subjected to molestation. Like most other hawks it likes to sit on dead trees and other conspicuous perches that will give it a wide outlook over the domain that it considers its own. Although it is normally a resident of the Sonoran Life Zone, some individuals nest, as in Colorado, almost up to the tops of the mountains; and many of the lowland birds climb to the highest altitudes as soon as the nesting season is over.
While individuals vary, most nesting prairie falcons react as Mr. Bent records: “While I was at the nest the female made several close swoops at me within 10 or 15 feet. She was flying around and ‘cackling’ all the time. Meanwhile, the male was flying around at a safe distance.” S. F. Rathbun writes that when he approached a nest “the falcon flushed from the nest and gave three shrill cries, and immediately its mate came to the scene. Meanwhile my friend was working his way up the side of the crevice in the wall. The pair of falcons dashed back and forth, the one that flushed diving at me repeatedly, at times coming within 10 feet of my head, and both gave their cries so loud I think they could be heard nearly half a mile.”
Bailey and Niedrach (1933) tell us:
As we walk along the edge of the dog town, near the steep escarpment, a great winged eagle sails out into space from a spot of shadow, where he had been resting unobserved, and flies leisurely along, and then while we admire the beauty of his flight we are attracted by a shrill scream of displeasure overhead, as a medium sized falcon darts with the speed of an arrow at the slow moving eagle. The latter’s movements are no longer leisurely, however. He immediately puts on all speed, and with the unwelcome falcon swooping in vicious onslaughts from the rear, much as a small terrier would snap at the heels of a lion, the great bird makes an undignified and hurried exit from the vicinity.
Decker and Bowles (1930) had a still more entertaining experience:
While examining the location, a cliff with one nest of Prairie Falcon and one nest of western red tail, we found that someone had shot a bird from each pair, oddly enough it being the male Red-tail and the female Falcon, their bodies lying on the ground close to their respective nests. The remaining parents had continued to ‘carry on,’ however, and the young that both nests contained seemed to be in excellent condition. When we appeared upon the scene and worked around close to the cliffs we started a very interesting disturbance between the two birds, both of which showed the greatest solicitude. Their previous unfortunate experiences with mankind had evidently taught them to keep well out of gunshot range of human beings, but the Falcon was apparently so angry that he had to give vent to his feelings on something, the nearest available object being the poor female Red-tail. Consequently we were treated to a most marvelous exhibition of what can be done by two trained experts in the art of flying, and the unusual and graceful movements of the Hawk were as thrilling to us an they were unexpected. The Falcon would mount high in air over her and then drop down upon her like a meteor until so close that it seemed inevitable he must tear her to pieces. Then, just as he seemed upon the point of Etriking her, the Hawk would turn gracefully back downward and thrust her great talons up at the approaching Falcon. Then there seemed no possible chance of avoiding a collision that would have meant almost certain death to them both, but always the Falcon would swerve in the very nick of time, missing by the merest fraction of an inch. This most interesting performance kept up until we left.
Mr. Bond (1936b) says: “At an eyrie in western Kern County a female was flushed from the eggs and was joined in the air by the male. A pair of Barn Owls (Tyto alba pratincola) flew from the same cliff. The female Prairie Falcon broke the wing of the female owl, and the male falcon killed the male owl outright, each with a single stoop.”
Although I have long known that this falcon likes to chase and hector large birds, I still wonder why it chooses the great blue heron so often. Is it simply because of the size of the heron and its very evident fear of the falcon? Ellsworth D. Lumley writes us: “These birds seem to take delight in annoying the herons, for I watched one of them as he repeatedly dived toward a heron that was standing on the rock cliii, coming to what appeared to be inches of the heron’s head. The heron always ducked and lowered himself as the falcon sped by. The herons were also attacked when flying by the falcons, although I never saw one of them struck.” Like Mr. Lumley, I have never seen a great blue heron actually struck by this tormentor, but the falcons I have seen seemed to take a positive delight in seeing how closely they could sweep and in how loudly they could make the herons shriek.
In spring falcons are keen, dashing, and wary, beautiful to see as they dart across the country. But in autumn they may be seen at times hunched up, like a clod, on some hare limb or pole. If startled then they may only fly negligently a few hundred feet and may even show entire indifference to a person’s presence. Usually they catch their food by dashing, lightning like swoops that are the very essence of grace and wildness. At other times they may be seen hopping on the ground or across the grass, like small fowls after grasshoppers. They may be seen over low plains and deserts, or they may be up over snow-clad mountains. Tyler (1923) says:
A moody creature at all times, peevish and whimsical, the Prairie Falcon is a bird of extremes. One never knows just what to expect from this handsome falcon and the expected seldom happens. He may fairly dazzle us with a burst of speed as he comes in to his nest cliff from a long flight over the sage-covered ridges; but our admiration fades as we behold him stoop-shouldered and motionless, for an hour at a time, on some low mound in a pasture, a picture of listless dejection.
A pair of ravens in a nest not fifty feet from the falcons’ own pot hole may be tolerated for days at a time with no act to indicate that the falcons are even aware of the presence of their neighbors. Then a sudden outburst of anger, totally unprovoked so far as the human eye can detect, may mark the beginning of merciless and unceasing persecution. * * *
Sometimes the canyons echo with her noisy cackling as the female falcon strikes again and again at the observer who approaches her nest cliff and yet, when, upon a return visit, we expect the same thrilling demonstration, she often flaps silently away with all the cramped awkwardness of a sparrow hawk just aroused from the duties of incubation.
With a roar of wings the male sweeps along a canyon wall, dashes into a feeding flock of quail, snatches a victim and beats away like some giant swift; but when we hope to see this marvelous exhibition of flight repeated, we find him hopping around sparrow-like on the ground in some summer fallow field scrutinizing the bunches of stubble for a chance hidden meadowlark or Savannah sparrow.
A wounded falcon, or one who has changed her nesting site only to have the new location discovered, can give an exhibition of unmistakable anger which defies all attempt at description; but an overfed mid-October bird as it sits dreamily on a roadside fence post is usually too utterly lacking in spirit to attempt anything that requires more energy than a lazy flight to some more secluded perch
Because so much of the time our only view of falcons and hawks is while they are on the wing, the flight of the prairie falcon is of particular interest. It is direct and swift, with short, powerful beats of the wings. Mr. Bent says that the prairie falcon “flies with rapid strokes of its pointed wings, the strokes being more downward than upward, with frequent spells of sailing.” S. F. Rathbun writes that in eastern Washington the normal flight is strong and even with “a succession of rapid wing-strokes, then short glides”; and that “when even a strong wind is on its counter, the plane of its flight is not in the least affected. At one time a bird hovered for a space above the sage, then made a very wide sweep and returned to alight upon the surface of a freshly fallowed field. In many of its flight actions the prairie falcon resembles the sparrow hawk. Its hovering is identical and of common occurrence. But the prairie falcon’s dashing and rapid flight is what gains a person’s immediate notice and admiration.” At another time Mr. Rathbun wrote: “What tricks this bird can pull in the air! How fast it flies! When one is close to it, you have a better appreciation of its flight. I never enjoyed anything more than watching the flying of these two birds. But at the speed they flew I would hate to have one hit me.” Nor is Mr. Rathbun alone in being impressed by the swiftness of this flight. J. G. Cooper noted it as long ago as 1870, and ever since that date ornithologist after ornithologist has admired it. Its flight has often been compared to that of the swift. As a rule there is little circling except at great heights above the ground. In its descent upon prey, the speed of the bird is so great as to be “as swift as an arrow” and to earn for the bird the name of “bullet hawk.” So rapid is the swoop and so powerful the blow that the prey must often be killed before it is at all aware of the danger. Over the foothills of the Rocky Mountains I noted that the height of hunting falcons was usually only 30 or 40 feet above ground; but when they did mount into the air, over the more level valleys, they ascended very rapidly and were soon lost to sight. Not only does the prairie falcon swoop, but the speed of its flight is great enough to catch even rather swift prey by direct pursuit. When it chooses to alight upon a high perch it flies low and when close enough suddenly closes its wings and shoots gracefully up to the desired height because of the speed already attained. Naturally such marvelous fliers give graceful, wonderful exhibitions near their nests.
So far as the literature shows, Mr. Taverner was uniquely favored when he found prairie falcons bathing. He (1919a) says: “They were usually seen bathing in the shallows of the river shore.” And in a letter Mr. Taverner adds: “We saw the birds splashing in the water from afar in true bird-bathing style.”
Voice: The notes of the prairie falcon are somewhat similar to those of the American sparrow hawk but are louder, fiercer, and wilder. Bendire (1892) says: “Their alarm note was a rapidly repeated ‘k66, k66, k~6,’ and a sort of cackle.” Peabody (1907) says there are two cries “that might be written down: a rattling, ‘Kr-r-r-r,’ with rising intonation; and a peevish, whining ‘Icruic.’ This I find compared in my note book to a noise made occasionally by ffickers, or to one call of the guinea hesi.” Decker and Bowles (1930) say: “The cry may be described as a shrill yelping ‘kik-kik-kik-kik-kik,’ repeated over and over again. It strongly suggests a combination of the cackle of a Cooper’s Hawk (Accipiler ccoperi) at its nest and the alarm notes of the Greater Yellow-legs (Totanus melanoleucus).” But the best general description that we know of is that given by Tyler (1923), who writes:
The voice of the Prairie Falcon is, on the whole, rather disappointing. A series of rapidly-repeated screeching, whistling, or cackling notes of varying tone and pitch constitute the usual calls, and these are most often heard in the spring months near the nesting cliffs. Sometimes these notes are given with considerable spirit, hut often there is recognizable a sort of indifferent tone. In many cases I have been unable to detect any difference between the voices of the male and female of a pair of falcons, but some females, which may be old birds, have harsh cackling voices, while a few males with which I have come in contact have rather pleasing high-pitched whistling calls. While inspecting nests I have often found that one of the pair of birds will remain silent while the other makes all the noise, but this is not always the case. In the majority of instances it has been the male that whistled while his mate kept silence. Occasionally, both birds of a pair will become enthused and the resultant din is most thrilling.
Enemies: Such a bird as the prairie falcon is naturally let alone by most birds, and, because of its lonely life, contacts with others are rare. No doubt antagonisms between two or more pairs of these falcons are fierce and intense. Howard (1902) writes:
When we were within a few hundred feet of the cliff we were greeted by a sudden screaming, and on looking up saw three prairie falcons in an aerial combat.
Their flight was very swift and graceful; undoubtedly two of the birds were the pair nesting in the cliff and the other an intruder. One bird of the pair was following in close pursuit of the enemy while its mate would ascend high into the air and with folded wings drop like a falling stone and at the same time utter a shrill scream. Just at the second one would naturally expect to see the enemy dashed to pieces, a slight turn of the tail would carry him to one side and the would-be assassin would dart harmlessly by like a flash.
Most of the small birds keep out of the falcon’s way as far as possible. Still, I once saw a prairie falcon pursued across a valley by a scolding Clark’s nutcracker, although it soon escaped into the top of a dead fir. And Pierce (1915) says: “On January 9,1915,1 collected another female Prairie Falcon near Chino, California. My attention was drawn to this bird, which was sitting in a large branching willow, by the actions of some Red-winged Blackbirds (Agelaius phoeniceus neutralis) that were sitting about in the same tree with the falcon. Several of their number kept persistently flying at the falcon, who apparently cared little for their actions, as she sat quietly until I approached.”
With other raptors the contacts observed have largely been fighting ones. Brooks (1909) says that “a male Peale Falcon incessantly badgered the female Prairie Falcon of a pair nesting near, with a series of splendid stoops.” Of a nesting site known to have been used previously to 1901 by prairie falcons, Cohen (1903) writes: “In 1901, March 30, the site was tenanted by a pair of duck hawks * * * It is probable that no pair of duck hawks, or even prairie falcons dwell within a few miles of each other’s domain owing to mutual antagonism * * ‘~. In 1902 we did not arrive at the prairie falcon nest until April 15, so as to allow the usurping duck hawks ample time to pay the rent, and found things vice-versa once more.” Grinnell, Dixon, and Linsdale (1930) record that “a great horned owl was trapped at Eagle Lake on October 19, 1923. A Prairie Falcon that discovered the owl in the trap swooped and struck at the bird repeatedly.”
One strange enemy with which the prairie falcons could ill contend was the open tar pits in California, The bones of the victims have been collected and reported upon by Dr. Loye Miller. He says there were great numbers of prairie falcons, duck hawks, and an extinct falcon caught at the McKittrick pool, but not so many at the Rancho La Brea now within the western limits of Los Angeles.
We so rarely get any items on the parasitic enemies of birds that the following is particularly welcome. Ellsworth D. Lumley writes of a prairie falcon taken in the act of killing a chicken: “I found its stomach contained a pocket gopher, but more interesting than this I found its entire viscera filled with long white roundworms. These were wound through the mesentery, intestines, cardiac muscles, even into the lungs and trachea. The insides of the bird looked almost as if they had been sewed together with white thread.” These worms have since been identified as Serratospiculum tendo by Dr. John E. Guberelet, of the University of Washington, who further adds that these parasites are not uncommon in hawks in various parts of the world.
Winter: According to Decker and Bowles (1930), these birds change their diet from rabbits to birds in winter. The stomachs of the birds mentioned in the previous paragraph all contained the remains of western meadowlarks. Cameron (1907) says the Montana prairie falcon is a “relentless persecutor of the Sharp-tailed Grouse. I have even seen the falcon watching on a pine for the grouse to emerge from the snow at its foot. On February 7, 1895, an adult Prairie Falcon (now in my possession) was shot by a neighbor, J. C. Braley, at Terry, under peculiar circumstances. His wife was cooking beet root and threw out the refuse on the snow, when the falcon, passing overhead, stooped to the beet root which it probably mistook for raw meat.” That these falcons do thus pass the winters in this cold Montana climate was also noted by Bendire (1892): “I have met with them (during winter) at Fort Walla Walla, Washington, and also shot an adult male on February 19, 1885, at Fort Custer, Montana, while the weather was still intensely cold.”
Although this is a bird of the wide open spaces, it was seen inside the city limits of Denver in December 1919, at least. There it was supposed to have preyed on juncos and English sparrows. Curious to say, Dr. Fisher found these falcons under nearly the opposite conditions in winter, in Death Valley, Calif. There is additional evidence that many falcons spend at least the winters over the desert ranges of southern California and Nevada.
Prairie falcons are resident in most of the California habitat, and their winter habits are not known to differ from those of other seasons.
Range: Western United States and southern Canada east to southeastern Saskatchewan, the Dakotas, and Missouri and south to Mexico and Lower California. Accidental in Minnesota, Wisconsin, Illinois, and the Farallon Islands.
Breeding range: The breeding range of the prairie falcon extends north to northern Washington (probably Lake Chelan); southeastern British Columbia (Osoyoos Lake and probably Deer Park); southern Alberta (Elbow River, Milk River, and Little Saudhill Creek); southern Saskatchewan (Eastend and probably Last Mountain); and North Dakota (Fort Lincoln). East to North Dakota (Fort Lincoln); southeastern South Dakota (Harrison); and northwestern Missouri (Maryville). South to northwestern Missouri (Maryville); northern Texas (Blanco Canyon); New Mexico (Mesa Pajarito, Montoya, Santa Rosa, Capitan Mountains, probably Big Hachita Mountains, and Animas Mountains); southern Arizona (Tombstone and Huachuca Mountains); and Baja California (San Luis Island and San Esteban). West to Baja California (San Esteban); California (San Pasqual, Colton, probably Mount Pinos, Ssrgents, Berkeley, East Park, and probably Shasta Valley); Oregon (Fort Kiarnath, Prineville, and The Dalles); and Washington (probably Walla Walla, Cheney, and probably Lake Chelan).
Winter range: The winter range of this falcon extends north nearly to the limits of its breeding range. At this season it is found north to Washington (Walla Walla); rarely to Okanagan Landing, British Columbia; Montana (Billings); rarely southeastern Wyoming (Cheyenne); and Nebraska (Alda and rarely Omaha). East to Nebraska (rarely Omaha and Red Cloud); Kansas (Hays); Texas (Corsicana); Nueva Leon (Monterrey); Hidalgo (Real del Monte); and Gaxaca (Tehuantepec). South to Oaxaca (Tehuantepec); and Baja California (Cape San Lucas). West to Lower California (Cape San Lucas, San Jose del Cabo, Mira Flores, and San Jose); California (Chino, San Fernando, Paicines, iPetaluma, and Maryaville); Oregon (rarely Corvallis); and Washington (Walla Walla).
Spring migration: Early dates of spring arrival at points north of the winter range are: South Dakota: Harrison, February 7; Vermillion, April 4. North Dakota: Harrisburg, March 21. Saskatchewan, Osler, April 11. Alberta: Manton, March 28.
Fall migration: Late dates of fall departure are: Alberta: Brooks, October 12. Saskatchewan: Eastend, October 18. North Dakota: Red River Valley, October 2; Foster County, October 8 (once, December 6,1891). South Dakota (rarely winters): Harrison, October 30; Yankton, November 9. Southward flights of this hawk have been noted in August in New Mexico.
Some idea of the movements and (for some birds) lack of extensive travels of these falcons may be found in a few recovery records of banded birds. Three juvenile birds banded on May 18, 1930, in the Lucerne Valley, Mojave Desert, Calif., were retaken as follows: The first on October 6,1930, at Lancaster, Calif.; the second on October 28, 1930, near the point of banding; and the third on December 15, 1931, nine miles east of Calipatria, Calif. Another juvenile, banded on May 2, 1928, at Merrill, Oreg., was recaptured about August 5, 1928, at Irvine, Alberta; while still another banded at the same time and place was retaken at Arbuckle, Calif., on September 29, 1928.
Casual records: Among several records (some sight) for Minnesota, the following may be mentioned: A specimen from Traverse County on September 11, 1894; a female taken near Madison on September 24, 1895; an immature male near Pipestone, on November 1, 1930; and a somewhat doubtful record of one purported to have been taken during the winter of 1890: 91 at Benson, Swift County. There are several records for Iowa and a rather doubtful record without date or exact locality for Wisconsin (Kumlien and Hollister, 1903). In Illinois, one was taken at Rock Island sometime prior to 1872; one at Mount Carmel on September 27, 1871; and one at Bridgeport in July 1871. There also is a record of one on the Farallon Islands, Calif., on December 18, 1886.
Egg dates: California: 134 records, March 10 May 25; 67 records, April 6 to 15, indicating the height of the season.
Washington and Oregon: 16 records, March 25 to April 28; 8 records, April 5 to 14.
Alberta and Saskatchewan: 7 records, April 22 to June 14.
Montana and Wyoming: 14 records, April 25 to June 10; 7 records, May 4 to 19.
Texas and Mexico: 10 records, February 18 to May 25; 5 records, April 22 to May 10.