Saturday, March 19, 2005

THE VALUE OF RAPTOR RESEARCH

At the end of John Blakeman's interesting essay about hawk and falconry terminology , he noted that he had had two captive redtails that he kept for purposes of raptor research. I asked him to explain what might be learned from such research. He promptly sent me a letter answering my question. [You might want to read his essay first, before reading his explanation, to understand some of the terminology].

Marie,

I understand your concerns regarding the removal of breeding adults from the wild, a concern of mine, too. Falconers never, ever do this to use haggards in the sport, so that is not a concern here. Scientific researchers do this only for good purposes, and I think mine were such.

One bird borrowed from the wild, for a season, was a gigantic old female. I trapped her to determine food requirements at various temperatures. She was kept in a large temperature-controlled environmental chamber where we could change light and temperature exactly as those changed in the wild in both summer and winter. The amount of food the hawk consumed in cold winter was compared to the reduced amount of food consumed in warm summer weather. At the time, 37 years ago, there was very little published data on the actual caloric requirements of raptors in general, and specifically the red-tail. There was a question of whether mature, experienced adults required more or fewer calories each day than inexperienced, inefficient immature hawks do. My data showed that they were very similar, and the bird was then released back to the wild, where it was seen nesting the following year in the same territory. The bird was trapped in the autumn and released in the following May. Not much was known then about the daily food requirements of wild raptors, and my data confirmed the data of some others regarding the common red-tail.

Today, this information would be taken (and has been) from the hundreds of adult hawks held in raptor rehabilitation centers. In the 1960s, these didn't exist. At the time, there was even a question if wild raptors could be successfully kept in captivity, especially for breeding. And how much food would captive raptors require? Would this vary by age and sex?

Bald eagles, Cooper’s hawks, peregrines, and several other species were rapidly declining and their extinction was on the horizon. A number of raptor researchers scrambled to collect data on how these birds might be rescued. The place to start was with common species such as the red-tail. We could have just sat there and bemoaned the rapid declines of our beloved wild raptors. Conversely, we could have devised scientific trials and procedures that would yield real data that could be used to restore declining populations. Had raptor researchers (most of whom were also falconers) not taken decided actions with captive hawks, the peregrine falcon most likely would have become extinct or extirpated here. Virtually all of the breeding peregrines in the East and Midwest descend from peregrines breed in captivity and released for re-introduction. With the peregrine, it was a hands-on approach, one that yielded great successes.

I, and others, were initiating the same things with red-tails, on the outside chance that this great species might someday become endangered like the peregrine. Fortunately, that day never arrived. The red-tail is safe. But in the 60s, our knowledge of the physiology and reproductive biology of even the common red-tail was abysmal. We can't save something that we don't understand, and in the 60s we didn't understand either red-tails or peregrines. Simple, baseline data such I collected on this single wild adult bird were required. The rest is history, thankfully now with red-tails and peregrines gracing our skies across the continent. We weren't so sure that would be the case in 1969.

My breeding trials of red-tailed hawks proceeded from this, but I never used a wild-caught adult for these, as it was very clear early on that wild-caught adults would not breed in captivity. I'll give an account of my red-tail breeding experiences sometime later, as they are rather detailed and lengthy. It was from them that I saw red-tail nesting activities first hand, activities that all will be seeing once again as Pale Male and Lola do their thing up there at 927 Fifth Ave.

The second adult red-tail that I trapped from the wild was the part of another, somewhat lengthy story. But in summary, she was a remarkable white, albinistic female that I discovered in mid-winter 1970. I watched her build a nest and breed with a normal male. The pair raised a normally colored tiercel eyass, which we banded. But because the mother was so blazingly prominent in her glistening white, she was seen everywhere that she went within her two square miles of territory. After asking residents of the area about the bird, I learned that many people were familiar with her, and I was warned that several locals had taken gunshots at her. I had state scientific collecting permits that allowed me to trap the bird, and for her own safety I did, in August, long after the breeding season. We kept her for two molts, as her plumage coloration changed during the first molt, something that had never been seen in “albino” red-tails before. After the second molt the bird was released in Nevada, away from all humans.

For a decade after that, I trapped many adult red-tails, but only to attach ID bands. Each was immediately released back to the wild.

I'm a certain that many readers disagree with the necessary interventions wildlife researchers often take to learn about, restore, and protect wild animals. But these are necessary. Wildlife management must be evidence-based, moving on the sound findings of dedicated and knowledgeable individuals. An example of this has occurred here. The restoration of the 927 nest support structure was based on design suggestions derived from understandings of red-tailed hawk nest requirements, both in the wild and in captivity. Pale Male, Lola, and their progeny will benefit from past experiments with captive red-tails. I'm glad that my experiences can be put to good purposes here, along with those of other professionals.

Sincerely,

John A. Blakeman