Ranging from South America north to southern Texas, the Groove-billed Ani has a fascinating breeding system known as joint nesting. Small groups of pairs rather than single pairs are formed for nesting, and all females lay their eggs in the same nest and care for the eggs and young. Aggressive displays are used to keep Groove-billed Anis from rival groups out of the territory.
The most detailed studies of Groove-billed Anis have taken place in Costa Rica, where a major source of predation on adult birds was carnivorous bats. Recently fledged anis had very low survival rates in their first month, but survival rates improved after that.
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Description of the Groove-billed Ani
The Groove-billed Ani is a black bird with a long tail and a very large black bill with a series of grooves in each side. Length: 14 in. Wingspan: 17 in.
Seasonal change in appearance
Similar to adults but browner and with either none or less distinct grooves in bill.
Insects and berries.
Forages on the ground and in bushes.
Breeds in south Texas, and is resident from Mexico to South America. Occasionally winters along the Gulf Coast states of the U.S.
Groove-billed Ani nests with up to 20 eggs are the result of multiple females laying eggs in the same nest.
The call consists of two syllables, with the accent on the first.
- The Smooth-billed Ani has a more pronounced gonydeal angle on the lower mandible, and has a smoother bill. Range generally limited to southern Florida, populations declining rapidly.Great-tailed Grackle
The Ani can be overlooked when hanging out with grackles. Grackles have smaller bills. The tail of the ani sometimes looks like it is about to fall off. Grackles may appear irridescent or all black, depending on the lighting. Anis are a duller black.
The nest is a bowl of twigs lined with leaves and is placed in a small tree.
Incubation and fledging:
– Young hatch at 13-14 days.
– Young fledge (leave the nest) in 6-10 days after hatching but remain with the adults for some time.
Bent Life History of the Groove-billed Ani
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 Groove-billed Ani – the common name and sub-species reflect the nomenclature in use at the time the description was written.
CROTOPHAGA SULCIROSTRIS SULCIROSTRIS Swainson
This Central and South American species was added to our fauna by George B. Sennett (1879), who secured a fine, male on May 19, 1878, near Lomita, Tex., while it was “flying about the low bushes in open chaparral. It was very shy, flying in and about the bushes, and was shot on the wing.” The only one I have ever seen did not seem at all shy. I was sitting down, quietly watching some Texas sparrows that were hopping around on the ground near me, in some thick brush bordering a resaca near Brownsville, Tex., when one of these curious -birds appeared. It seemed more curious than shy, as it moved about slowly in the bushes, looking me, over; it remained in my vicinity for some time and I could have, shot it easily. It is said to show a preference for thick underbrush in the vicinity of water, or for lightly wooded swamps.
In his proposed work on the birds of the Caribbean lowlands, Alexander F. Skutch devotes two long and very interesting chapters to the home life of the groove-billed ani. He has kindly placed at my disposal his unpublished manuscript and allowed me to quote freely from it. As to its haunts, lie writes: “The variety of the habitat of the anis is enormous and their only restriction seems to be that they do not tolerate the forest and are never seen there,. They are birds of open country but seen nearly indifferent to its type. In the inhabited districts of the humid coastal regions they are one of the most conspicuous species. Their favorite haunts are, bushy pastures, orchards, the lighter second growth, and even lawns and clearings about the native huts. Marshland is as acceptable to them as a well-drained hillside, and they are numerous in such extensive stands of sawgrass as that surrounding the Toloa Lagoon in Honduras, although it is probable that they do not venture far from some outstanding hummock or ridge which supports a few low bushes in which they can roost and nest, In the semidesert recrions of the interior, where their associates of the coast lands, if present at all, are as a. rule rare and restricted to the moist thickets along the rivers, they are among the most ilumerous of birds, and live among scattered cacti and acacias as successfully as amid the rankest vegetation of the districts watered by 12 feet of rainfall in the year. In altitude they range upward to 5,000 feet, but are not nearly so numerous in the elevated districts as in the lowlands.”
Nesting: Dr. Charles W. Richmond, drawing on his experience with it near Bluefields, Nicaragua, sent some elaborate notes on the groovebilled ani to Major Bendire (1895), from which I quote as follows:
It appears to breed at various times during the year, as I have found fresh eggs July 6, 1892, and young birds, recently from the nest, November 29, the breeding reason spreading over seven months of the year at least, as it begins nesting earlier than the date of taking my first eggs. Nests are frequently built in the heart of a thick, thorny orange or lemon tree, and this appears to be a favorite situation. In this case the nest is from 4 to 7 feet from the ground, and, besides being difficult to get at, is somewhat protected from invasion the wasps which almost invariably take up their abode in the same tree. In going through a small lemon grove I found an old nest of this species. In the cavity there were no eggs, but on poking the nest to pieces six badly decayed eggs rolled out
One nest containing three eggs in the proper place and two others at the bottom, under the lining of green leaves, was located in a bamboo about 12 feet from the ground. The eggs were fresh, and more would probably have been deposited; the leaves forming the lining were still green. The parent birds were away at the time. Another nest was situated in some vines which bad over-run an old tree stub, and was about 15 feet from the ground.
It may be that where numerous eggs are deposited in one nest only those eggs that are deposited In the proper place and directly influenced by the incubating bird are hatched, while those placed among the sticks forming the bulky exterior are left unhatched. It would be Interesting to watch the progress of a large nestful of eggs and note results. The nests found by me were all composed of dead black twigs, rather loosely put together, very bulky and conspicuous structures, lined with green leaves, or, if old nests, with leaves that bad the appearance of having been picked green.
One of Dr. Richmond’s nests is described by Major Bendire (1895) as “a rather loose structure, about 10 inches in diameter and 4 inches in height. The inner cup measures 4 inches in diameter by 21/2 inches in depth.”
According to George K. Cherrie (1892) Sefior Don Anastasio Alfaro says of the nests he collected in Costa Rica:
The structure is voluminous, composed chiefly of coarse dead twigs,, but presents one peculiarity not observed in any other bird, namely the nest being lined with fresh green leaves. My three specimens were all placed in low trees, and neither was found at a greater height than three meters. One had been built above an old nest of one of the larger Tyrannidae.
It will not be without interest, I think, to insert my observations relative to one of these nests. On the 20th of May I noticed a Zopilotillo with a dry stick in its bill, which was immediately carried to a point in the hedge-row where it was deposited with three others. After assuring myself that the bird was building its nest there, I retired, with the intention of returning at a more opportune moment. And when one week later I returned to the same spot, what was my surprise to see Dot only the nest completed and containing six eggs, but more than this: In the thorns and leaves about it were scattered seven more eggs! As a consequence, if that collection was not the work of the Zopilotillos collectively, the poor owner would have had to deposit three eggs daily! In the finding of some of the eggs scattered in the leaves was revealed one of the architect’s peculiarities. A hole had been left in the centre of the nest and only recently filled with leaves whose fresh green color testified that they had been cut and placed there later than the others forming the carpeting to the bottom of this common incubator.
Alden H. Miller (1932) writes of his experience with the nesting habits of the groove-billed ani in El Salvador:
Several nests were watched from the time there was one egg until there were nine, or in one case eleven, eggs. The eggs were deposited regularly at one day intervals and there was no certain indication in any of the sets, of two females contributing to the same nest as has been claimed by other observers. My findings, however, do not. prove conclusively that community nests may not exist, at least occasionally. Incubation is uniform within a set and, correspondingly, birds were found to be incubating regularly only after the sets were completed. In the set of thirteen the eggs were resting in three layers in the necessarily ample cup of the nest.
Nest sites were from two feet to twenty-five feet above ground in almost any kind of bush or tree. Usually they were located between six and twelve feet above ground in thorny tangles or close twiggery. One nest was found, however, in an open crotch of a fan of a royal palm. Adult birds are not much in evidence around nests which are being built or around sets of incomplete eggs. When flushed from sets of complete eggs, they may approach within five feet of the intruder and utter their feeble, squeaking Dotes of protest.
A. J. van Rossem (1938) found several nests, on July 29, 1925, “in the mimosa, scrub in the marsh along the north shore of Lake Olomega,” in El Salvador. “These nests were all in similar situations, that is, they were rather conspicuously placed in mimosa. bushes and more than six feet above the mud or water.”
Mr. Skutch devoted considerable time to studying the communal nesting habits of the groove-billed ani. He found them to be among the latest birds to breed, remaining together in small flocks from February to May while the other birds of the region were raising their broods. During June he watched the construction of a communal nest, on which three pairs worked in perfect harmony, operating in pairs and not as a unit. One of the pair remained on the nest while its mate brought in the material. There was not the least jealousy between the pairs, and “two or more pairs often perched quietly in the same bush. Each pair preferred to -work alone at the nest, and if a second pair flew into the nesting tree, the first often quietly withdrew. This was not always their conduct, and sometimes one of the second pair (probably the female) took a place on the nest beside one of the first pair, -while their two mates perched near by, or else brought them sticks.
“The normal set of eggs for each female is three, or more commonly four. Nests belonging to a single pair generally contain this number, and the nests belonging to two pairs, which I encountered, contained a maximum of eight. Once I found a nest with 12 eggs, which covered the bottom two layers deep, and six birds were interested in them. * * * Of ten nests which I found in Honduras and Guatemala and was able to watch for an adequate period, four were the property of single pairs, five of two pairs together, and one belonged to three pairs in common.”
All the birds of both sexes took turns in incubating the eggs, but their shifts on the nest bad no regular order and no fixed duration. “Just as the parents cooperate in incubating the eggs, they all join in the care of the nestlings. I have watched three nests, each belonging to two pairs, during the time they contained young. Two of them, I made quite sure, were attended by four adults, but at the other I could not convince myself that there were more than three attendants. Possibly some calamity had befallen the fourth bird, or possibly also I failed to recognize it, since the anis at this nest were unmarked and indistinguishable.”
Eggs: The groove-billed ani lays 4 to 13 eggs, the smaller numbers being apparently commoner. The eggs vary in shape from oval to elliptical-oval, or rarely to elliptical-ovate or rounded-ovate. The ground color, when visible, varies from “glaucous-blue” to “Nile blue” or “pale Nile blue”; when first laid, the ground color is completely covered with a thin layer of dull white, chalky deposit, which eventually becomes somewhat discolored; as incubation progresses this chalky covering becomes more or less scratched, by contact with the twigs in the nest or by the action of the bird’s feet in turning the eggs, or in relining the nest, so that ultimately much or nearly all of the blue ground color is visible; even then the shell is not glossy. The measurements of 51 eggs average 30.93 by 24.06 millimeters; the eggs showing the four extremes measure 35 by 25, 32 by 26, and 27.68 by 21.84 millimeters.
Young: Mr. Skutch determined, by close observation of marked birds and by noting which individual of a marked pair laid the eggs, that both sexes share in the duties of incubation. They were very impatient sitters, constantly changing about; 30 minutes was the longest time that he saw one incubate, during the early stages, and they sometimes left the nest unguarded for 10 or 20 minutes, while they enjoyed each other’s company; during the last two days of incubation they lengthened their periods on the eggs to from 30 to 45 minutes to an hour. He describes the hatching process in detail:
“Fourteen days after the last egg had been laid, I held one in my hand while the birdling worked its way out of it. When I first took it up there was a gap in the larger end, which extended about a third of the way around the circumference. The little bird’s short, thick bill was in this gap, and so pressed out of position that the lower mandible overshot the upper, only a temporary condition.
At intervals the struggling prisoner drew its bill farther into the egg then suddenly pushed it outward, bringing the keeled upper edge, armed with a rather insignificant egg -tooth or ‘pip,’ against the edge, of the shell at one end of the hole, and breaking off a small fragment at the outward thrust. In its squirmings the bird, impelling itself in some manner I could not determine, rotated imperceptibly slowly in the shell, in such a way that the head, turned under one wing, moved backward and the upper edge of the bill was constantly brought to bear upon a fresh portion of the shell, which was chipped off at the next outward thrust. Occasionally the strugling birdling emitted a weak cry. Thus bit by bit the ragged-margined aperture was lengthened until it extended about two-thirds of the way around the egg, when the struggles of the bird succeeded in cracking the remainder, and the large end of the shell fell off as a cap. Then the naked creature wormed its way out into my palm, where it lay exhausted by its continued effort.”
In another nest the last egg to be laid hatched in 13 days. The young, when first hatched, “were blind, black-skinned, and without, any trace of feathers.” When the nestlings were 6 days old they were “both bristling with long pinfeathers. The plumes of the one, that was the older by a few hours were already beginning to peep through the tips of these pinfeathers.” Later in the day, the feathers had burst their sheaths with amazing rapidity, and the young bird “was already well covered. The back and belly, save for a naked line down the middle of the latter, bore a soft, downy black plumage. Broad ends of the flight feathers of both wings and tail now showed.”
From this time on, the young birds became more lively and left. the nest when approached, climbing about among the branches or down onto the, ground to hide in the grass. They were brooded by one of the parents until they were a week old, returning to the nest at night. But “the following two nights they remained in the nesting tree but did not return to the nest to sleep. They could not yet fly and had entered a half scansorial, half terrestrial stage of existence. – When they were 10 days old I tried to catch them for a photograph, but they hopped from limb to limb with such agility that, protected as they were by the sharp thorns, I was unable to secure them. When they were 10 days old they could make short flights from branch to branch of the same bush. Their bills were smooth, without any grooves, and their cheeks were bare of feathers.”
All through his account Mr. Skutch emphasizes the affection that is shown by all the members of the ani family for one another. While he was watching the second nest of the pair on which the above observations were made, something very unusual, if not entirely unique, happened. One of the young from the previous brood, now nearly fully grown, “was the constant companion of his parents during the period in which they were busy with their second brood.” He frequently perched on the rim of the nest while one of his parents was incubating, and twice he was seen to offer food to the parent on the nest. After the young had hatched, “the youngster fed the nestlings regularly, but not so often as his parents.” During four hours and a quarter, he saw the male, always the more attentive parent, bring food to the nestlings 29 times, the female 14, and the young assistant 8 times. “The young bird not only fed the nestlings but was ardent in protecting them, flying up close to me and uttering an angry gr”-rr-rr whenever I came near them. In the absence of the parents he attempted to defend them alone.”
Plumages: The young nestling and the development of its first plumage are described above. In this juvenal plumage the contour feathers are short and soft, “bone brown” below and darker above; the wings and tail are much like those of the adult; the bill is less specialized and not grooved.
Van Rossem. (1938) says:
The postjuvenal plumage, attained by a complete body and tail and a partial wing molt, is not different from that of the adults except that the rectrices are noticeably narrower. An irregular molt of the primaries takes place at this time, although some of the juvenal quills (though their number and location varies) are held over till the following spring. In March and April of the next year there is a partial body, tail, and wing molt in which an irregular number of rectrices are renewed and such juvenile remiges as have been held over from the previous fall are replaced by new ones. The adult plumage with wide rectrices follows in the second fall, that is, at the first annual molt. The time of the annual molt extends from the middle of July to the first of October, the younger (one-year-old) birds molting earlier than the older ones. The spring molt of the adults includes some of the rectrices and secondaries.
Food: Mr. Skutch writes (MS.) : “The food of the anis consists largely of insects, which they secure both from the ground and among the foliage of bushes, and to a smaller extent of fruit and berries. Often they hunt grasshoppers and other creatures among the long grass or tall weeds, where they are completely hidden from view except when occasionally they leap a foot or so above the herbage to snatch up an insect -which has tried to escape by flight. Perhaps their favorite method of foraging is beside a grazing cow or mule. Several together remain close to the head of the beast, moving along by awkward hops as it moves and just managing to escape its jaws and forefeet, ever on the alert to snatch up the insects frightened from their retreat in the grass by the passage of the herbivore. It is frequently stated in books, and affirmed by the residents of the countries where the anis live, that they alight upon cattle and pluck ticks and other vermin from their skin-hence the name garrapatero (tick-eater) given them in Costa Rica.
“While this is doubtless true in certain parts Of the ani’s range, I have watched them in the neighborhood of cattle from Panama to Guatemala and only once in three years have I seen an ani alight on a cow. Since the ani associates so much with cattle without alighting upon them, and the giant cowbird, another black bird of approximately the same size, does frequently perch upon them and relieve them of their vermin, it seems likely that the ani may be often credited with the acts of the cowbird especially since the latter is shier and less known. I have occasionally questioned one who informed me that the ani plucks ticks from the grazing animals, only to find that he was unaware of the existence of the giant cowbird. At a little distance such a person might easily suppose that the birds upon the animal’s back were the same as those about its feet, and since his closer approach would leave only the latter, the illusion would probably persist.”
He has also seen a group of anis excitedly following a battalion of army ants, probably not to feed on such fiery morsels as the ants, but to pick up “the cockroaches, spiders, and other small creatures driven from their retreat among the dead leaves by the relentless hordes.” Again Tie says: “After the first heavy rain of the season has sent the winged brood of the termites forth from their nests in countless millions, one can watch the anis everywhere feeding like flycatchers, making ungraceful darts, not exceeding a few feet, from low twigs and fences; but the insects are so numerous on these occasions that they can catch many without quitting their perches.”
Major Bendire (1895) quotes Dr. Richmond as saying: “The food of those examined by me on banana plantations consisted almost entirely of small grasshoppers, the stomachs being much distended with these insects. From the fresh earth found on the bill and feet of these birds, I should judge they also feed on the ground.”
Prof. A. L. Herrara, of the City of Mexico, wrote to Bendire that “it is a social bird, being usually. found in small companies of from six to fifteen individuals, absolutely monogamous, sedentary, and of semi domesticated habits, frequenting the haciendas and the fields and pastures in their vicinity, and as it is considered very useful because of its habit of destroying large numbers of parasites infesting the cattle, it is not molested by the inhabitants, and becomes very tame. It extracts the Ixodes and other Acaridam with remarkable skill, without causing ulcerations which might result from the proboscis or sucker remaining in the fibres of the skin, and it must be regarded as one of the most useful birds of Mexico, especially in warm regions, so abounding in parasites of all kinds.”
Behavior: Dr. Richmond (Bendire, 1895) says:
At Mr. Haymond’s plantation, on the Escondido River, above Bluefields, this species was unusually plentiful, owing, no doubt, to a large number of cattle kept there. The birds follow these animals as they meander over the pastures, hopping along on each side of an animal, catching grasshoppers and other insects which the cow disturbs as it moves along. Frequently the cow moves too rapidly and the birds lag behind, when they make short flights to the front again, passing over one another after the manner of the Grackles when feeding in a field. Only half a dozen birds or so follow a cow usually, and not many congregate in a flock, except when roosting. On this plantation, where the species Is more abundant than usual, the birds appear to roost in numbers.
An orange tree near the house was a favorite place where thirty or forty birds came to pass the night, flying in from the surrounding pasture about dusk, and after a few short flights from one tree to another, passed into the roost one or two at a time, hopping about as if seeking a favorable perch, uttering their peculiar note meanwhile. Out of this roost I shot seventeen birds one evening, and the males greatly predominated; there were only five females in the lot. The note of this species reminds one somewhat of the Flicker, Colaptes auratus, but may be better represented by the combination “plee-co,” rapidly repeated, with the accent usually on the first syllable, but sometimes on the last. I have frequently found one of the small flocks resting on a bush or bamboo along the water’s edge, perfectly silent, until my near approach started them off, one or two at a time, scolding as they went. Their flight is even, slow, as short as possible, and consists of a few flaps of the wings, followed by a short sail, then a few more flaps, etc.
Mr. Skutch writes (MS.) : “Their flight is as perfectly characteristic of the birds as any other of their peculiar habits. A long journey, say anything much in excess of a hundred yards, is seldom made by a continuous flight, but the bird advances with frequent pauses in conveniently situated trees and bushes. As he alights on one of the lower branches, the momentum of the long tail carries it forward above the head with an abrupt jerk. Recovering his balance, he remains here for some moments, looking around with caution and calling in his high-pitched voice. Then, satisfied that the path ahead is clear, with a tue tue tue, pihuy pihuy pihuy, he launches himself upon the next stage of his journey. A few rapid beats of his short wings serve to impart the requisite momentum, and he sets them for a, long glide. In this manner he can cover surprisingly long distances, on a slightly descending course, without further muscular effort. If his ultimate destination is a certain perch in a tree or bush, he will often arrest his flight on another considerably below it. By a few queer, rapid, sideways hops along the branch, and some bounds, or better bounces, from limb to limb, be gains the desired position where, as likely as not, he spreads his wings to the morning sun.”
Mr. van Rossem (1938) says: “They feed side by side with never a sign of friction or argument over the choicer insects, and at night roost in low trees or bushes, pressed shoulder to shoulder to the limit of available space. We not infrequently found them thus when hunting at night. During the time just preceding nesting it was noticeable that they were inclined to roost two and two instead of in a long line. In some cases the pair was sitting in close contact, even thouoh there might be plenty of room to perch comfortably.”
Voice: Dr. Richmond’s impression of the note of the groove billed ani is mentioned above. Seflor Alfaro says, in his notes given Mr. Cherrie (1892), that, in Costa Rica, it is “known as ‘Tijo, tijo, in imitation of its peculiar notes which seem to repeat the word tijo over and over again.” Dr. Chapman (1896) says: “Its note is a prolonged chee-wyyaa, easily distinguishable from the single whining whistle of C. ani.” Mr. van Rossem (1938) says: “The ordinary or ‘conversational notes tire , a series of very liquid and what can best. be described as ‘contented’ bubblings and cluckings. The louder, often repeated is the alarm note.”
Range: Lower Rio Grande Valley ofTexas and Baja California, south to northern South America. The range of the groove-billed ani extends north to southern Baja California (San Pedro aiid Santiago) ; southern Sinaloa (Mazatlan) ; southern Texas (Lomita and Corpus Christi) ; aiid Yucatan (Progreso and Chicbeii-Itza). East to Yucatan (Chichen-Itza) ; British Honduras (Cavo); Honduras (La Ceiba ‘ ) ; Colombia (Santa Marta ‘ ); and Venezuela (Altagracia, Curacao, and Caicara). South to Venezuela (Caicara) ; and Peru (Chachapoyas aud Luna). West to Peru (Lima and Cutervo) ; Ecuador (Tumbez) ; Costa Rica (San Jose and La Palma) , El Salvador (Sousonate) ; western Guatemala (Lake Amatitlan) ; southwestern Cl)lapas (Tapaeliula) ; Nayarit (San Blas) and southern Baja California (San Jose dol Cabo and San Pedro)
The birds found in the cape district of Baja California have been separated subspecifically and are known as the San Lucas ani, C. s. pallidula.
Casual records: In Louisiana a specimen was collected uear New Orleans about 1890; another ani taken at Ostrica during the winter of 1919; a third was obtained without late of collection near Houma, a fourth was taken at Cottonport oil December 11, 1932; while a fifth was collected on Grand Isle on April 23, 1935. A specimen was taken at Huachucas, Ariz., 10 miles from the Mexican border, in May 1888, and it was noted at a point 20 miles Dorth of Tucson on August 21, 1932. About Nvember 1, 1904, a specimen, was taken near Emporia, Kans., and on Octobcer 12, 1913, one was killed on an island about 9 miles north of Red Wing, Minn. A specimen was obtained at Jupiter Inlet, Fla. 1891, and there is also a somewhat indefinite record of its occurrence in the early part of January in the vicinity of Kingston, Jamaica.
Egg dates: Central America: 4 records, May 27 to July 29. Baja California- 6 Tecords, April 1 to September 3. Mexico: 40 records, March 20 to August 14; 20 records, May 16 to June 30, indicating the height of the season. Texas: 7 records, March 17 to July 15.
SAN LUCAS ANI
CROTOPHAGA SULCIROSTRIS PALLIDULA Bangs and Penard
The groove-billed ani of the Cape region of Lower California, Mexico, was described and given the above name by Bangs and Penard (1921), based on a series of 18 specimens from San Jose del Cabo. It is said to be similar to Crotophaga sulcirostris sulcirostris Swainson of Mexico, and of about the same size, but much paler and with less purplish iridescence; the U-shaped Iridescent markings of the back and breast paler and duller greenish, not so brilliant; the dull purplish bronze of the head and neck of true SULCIROSTRIS replaced by paler, more grayish bronze; the lusterless parts of the body-feathers grayish brownish black instead of dull black.
Eighteen adults of this new form, laid out beside a series of nearly double that number from various points in Mexico and Central America, are strikingly different; the pale, dull colors of the Lower California bird cannot be matched by any specimen in our series of true SULCIROSTRIS. The difference is noticeable at a glance but rather difficult to describe. Brewster (19092), in his account of the birds of the Cape Region of Lower California, states that the Groove-billed Ani is not known to occur in central and northern Lower California, and that the colonies which have become established in the Cape region were probably originated by birds which came from western Mexico. However this may be, the isolated colony of Cape St. Lucas has developed into a very distinct form, worthy of recognition.
Griffing Bancroft writes to me, on August 6, 1937, that he is “as nearly satisfied as it is possible to be from negative evidence” that. this form of the groove-billed ani is extinct.
Nesting: Lyman Belding (1883) writes: “The 1st of April I discovered four of these birds in a marsh, in which was a rank growth of tule, flags, and reeds. Having shot one of them, and the others were not molested, they remained in the marsh until May 15, or later. A nest found April 29 contained eight eggs. It was fastened to upright reeds, and was composed of coarse weed stalks and mesquite twigs, lined with green leaves. The female, while incubating, was very wary, slipping quietly away from the nest and returning to it very stealthily, below the tops of the reeds.”
William Brewster (1902) says that the nest “taken by Mr. Frazar was in a willow about twenty feet above the ground. It is a flat,loose, but withal rather neat structure, formed outwardly of dead twigs and very substantially lined with cottonwood and willow leaves, which look as if they must, have been dry when gathered.
This nest measures about six inches across the top, and the cavity is nearly an inch in depth. * * * Mr. Frazar met with the Groove-billed Ani only at San Jose del Cabo, where a flock of about thirty frequented some thick brush about pools of water near the mouth of the river.”
Eggs: The eggs of this race are apparently Just like those of the species elsewhere. The measurements of 9 eggs average 31.99 by 24.00 millimeters; the eggs showing the, four extremes measure 33.5 by 23, 31.8 by 24.9, and 30.5 by 23 millimeters.