Greater flamingo, one of a small group of birds, along with pigeons, that produces a milk-like substance that they feed to chicks. (Photo by Michael Nichols)

This starts out somewhat convoluted. Last fall during a field trip, my camera was left in the car of a couple who live on the north side of Chicago. They further indicated that there was no place they could leave the camera at their residence so that I could pick it up during the day. One of them works at the Field Museum. I then thought of Doug Stotz, an ornithologist at the museum who does not live far from me. He was willing to be the go between: he would obtain the camera, take it home, and leave it behind some plants on his front porch. When I went to pick it up, a car in the driveway revealed that either Doug or his wife, Francie Muraski-Stotz, was home. I had met Francie a few times but did not really know her. I saw the camera but decided to knock on the door to say hello. Francie answered and we started chatting. It is rare for me to go very many minutes into a conversation without bringing up ppigeons. I told her that I was hoping to get the Field Museum interested in featuring an exhibit on the bird as the century anniversary of the species’ extinction approaches. She told me that she used to work in the museum’s exhibit department and she liked the passenger pigeon idea. And thus began our collaboration on a proposal to the museum. After several get-togethers and various delays, we were ready to present our proposal. People were out of town over the holidays, and we cancelled one appointment due to bad weather, so last Thursday was the day we were to meet with the exhibit people.

Francie must know a million people at the museum. From the minute we entered the building she was encountering friends she had not seen for awhile. But we deliberately arrived early in part to say hello to folks (I never did get to see friends in the fish and herps departments) and wound up having lunch with folks from the bird department. (Doug is in Peru) I find such gatherings to be inspiring- it is a great privilege to listen to world class ornithologists talk about birds. I am thankful that I live in a region that can support institutions like the Field Museum.

The group Francie and I had lunch with consisted of people I have known for a long while. There was Dave Willard (collection manager), John Bates (head of zoology department), Jason Wechstein (an authority on bird parasites), Josh Engle (new employee of the museum although he still leads occasional bird tours), and Nick Block (graduate student at U of Chicago, studying evolution of Madagascar birds). Passenger pigeons came up (duh!) and it was a great opportunity for me to ask some questions. Pigeons produce a substance known as pigeon milk (aka “esophageal fluids.”). This is a viscous material resembling loose rice pudding or cottage cheese that originates in the crop of the bird. The crop is a pouch-like growth near the throat that holds food. In pigeons, the lining sloughs off to produce the highly nutritious milk that spurs rapid growth of the young over the first several days of life. Later, the milk is mixed with adult food. (With respect to passenger pigeons, if the milk-laden squabs should fall or get pushed by the myriad of hunters seeking them, they would often splat upon impact with the ground). My question was: are pigeons the only birds that produce that milk? It turns out that emperor penguins and flamingoes also produce this kind of milk.

A more difficult issue involves how birds communicate with each other. How could all or most of the continent’s passenger pigeons gather in the same handful of places to nest? How did birds wintering in Kentucky know that the big mast year was in Pennsylvania this year and Michigan the next? The Old Timers thought the pigeons sent scouts in expeditions up to several hundred birds to find where the mast was in early spring and then would return with the information to pigeons on wintering territory. A.W. Schorger (author of the 1955 book Passenger Pigeon: Its Natural History and Extinction) rejected this, believing instead that in the fall movements south some flocks would encounter mast-rich areas and convey that information in the course of interacting with other migrating or wintering flocks. Even how that mechanism would work is not clear to me except birds headed to a specific destination might move in a more deliberate way that would prompt other birds to follow. But that leaves questions too (enough mast for one flock might not be for five). The Field Museum folks did not really have an answer but noted other examples of where the sudden appearance of food would soon draw lots of birds. John Bates cited a particular species in Costa Rica that was thought to be very rare. He arrived at an area within their range at a time when bamboo was in bloom and the birds were abundant. Later, nests were found. They did give me some names of people studying these questions.

After the prolonged and pleasant conversation, Francie and I headed towards our meeting with the exhibition staff. Although Francie was familiar with the dynamics, I learned a lot. Large exhibits of any kind are risky ventures because they are very expensive to produce or even display and thus have to draw patrons willing to pay extra to see them. And even if an exhibit is successful in one city doesn’t mean it will be in another (The Darwin exhibit was a hit in London but proved much less popular in Chicago). The exhibit people indicated that they would be much more likely to host a smaller exhibit should one be available. They provided us with contacts and other information to help make that possible. I will keep you posted.