This week, Dr. Elizabeth Bunting, a wildlife veterinarian at the Animal Health Diagnostic Center at Cornell College of Veterinary Medicine, and other experts will be responding to readers’ questions about Pip, the red-tailed hawk hatchling, or eyas, who emerged from the egg on May 6 in a nest on a 12th-floor ledge at New York University — and about Pip’s mother, Violet, about whose injured leg many of you have expressed concern.
Following is her first set of responses.
Who would have tagged [Violet]? Is there any database of tagged red-tails? I can see the point of tagging out in the wilderness where you are trying to keep track of populations, but surely the hawks in N.Y.C. are pretty easy to monitor?
— Posted by happy looker
The urban hawks are easy to monitor when they are attached to the nest, but, as with most birds, they can be hard to tell apart because they all pretty much look the same: the feather patterns and sizes are generally consistent within a species. (Pale Male is an exception because of his coloring).
And while the adults may stick around their territory year round, the juveniles will leave in the fall and have to find their own digs in the spring. So having a way to identify individuals is critical in learning all sorts of information about birds — like how long they live, how far they travel, what kind of territories they have, and even how their feather patterns change over time as they age — exactly the kinds of questions that people are asking about this red-tailed hawk family. Wildlife agencies also need this kind of information to estimate bird population numbers and monitor endangered species in order to make good management decisions.
The Bird Banding Laboratory, or B.B.L., a cooperative program between the United States and Canada to maintain a database of banding data, has written a brief history on the practice. Bands are inexpensive, easy to place and generally cause few problems. The bands are individually numbered and come in many sizes appropriate for different species, and they are placed by licensed researchers, rehabilitators, state or federal agencies interested in bird movements. When the band is used, the number and some basic information about the bird are recorded. If a bird is recaptured or dies, the finder calls the B.B.L. to report the number.
We were able to see only some of the numbers from Violet’s band, but the B.B.L. determined that she was banded in 2006 around the Delaware Water Gap area in New Jersey (she’s a Jersey girl). [See City Room post on the history of Violet’s band.]
My question is, was the decision about whether or not to capture Violet affected at all by her fame? And the fact that there was a live nestcam going? I can imagine that even if there were only a 1 percent chance of something going wrong when capturing her (say, she knocks Pip out of the nest or something), the potential P.R. catastrophe could be so enormous that it could have affected the decision about whether or not to treat her.
— Posted by Ridley
It is great to see the public engaged and interested in wildlife, and to have this opportunity through the nest camera to observe wild animals doing what they do every day. Watching the hawks on camera, when they are most relaxed, gives the impression that it would be straightforward to capture the bird, removal of the band and return her to the nest. But in reality, wild animals can be incredibly unpredictable when they are approached by people, particularly with their young nearby.
While it is human (and veterinary) nature to want to dive in and help an injured animal, we really made the effort to get an objective assessment of the bird, keeping in mind that her long-term welfare, the welfare of her nestling, and the safety of the personnel involved were our priorities.
So, how do you cleanly pluck a fully operational adult raptor from a windowsill on the 12th floor of an office building, with her chick only inches away and her mate bearing down on you? We considered a number of options.
It became quickly apparent that the nest was not at all sturdy, and was in an extremely precarious position on a slanted window ledge. There were no locations to secure a safety harness for personnel, either on the roof or by the adjacent window. We had very real concerns that any approach, if it resulted in any kind of struggle or commotion by the adults, would send the nest over the ledge. We thought it would be unlikely that Violet would approach a trap (she had plenty of food available), and we all agreed that we had to have a plan to rescue the hatchling, in the event that Violet’s leg could not be treated on site. Once we determined that capturing her would be very risky and there was a high likelihood that at least one of the birds could be seriously injured, we also had to take seriously the possibility that the entire thing would play out in front of thousands of concerned viewers, including schoolchildren. Because we felt that her leg was not in immediate danger, we made the difficult decision to monitor instead of trying to treat her. There is a basic principle of medicine that sums this up very well : First, do no harm.
A full report of the day-long analysis is available on the Department of Environmental Conservation Web site.
Is the leg better or no change? Is there an infection? At what point if ever would there be an intervention to take care of the leg?
— Posted by Mom
I don’t think we will ever know for sure what caused the injury to Violet’s foot — there are no witnesses, and Violet isn’t talking.
The two most serious problems that I wanted to rule out were an infection in her foot, also called “bumblefoot,” or a constriction from either the metal band or other string that could be cutting off her circulation. When I arrived at N.Y.U., I was able to get an excellent view of Violet’s leg, and she had pretty good, although imperfect, use of her toes, which showed there was still good nerve and tendon function, and there was no sign that she had damaged circulation, which would have appeared as discolored or dead tissue.
We were also able to read part of the band number, and found out from the banding database that the band had been on her leg for almost five years.
Loss of circulation would severely damage her leg in a fairly short time frame (days to weeks), so it seemed unlikely that the current swelling was entirely due to the band being too small or restrictive.
Later in the day, we were able to see high quality video and pictures that showed that even with the swelling, there was some space between the band and her leg, ensuring room for circulation, and that there were no strings around it. Watching her over the course of the day, I noticed that she occasionally stretched her foot, or took a rest standing on her other leg, but generally was willing to stand on it, use it to eat and come in to land — things that she wouldn’t do if she had a painful bone infection or loss of circulation.
While she has trouble navigating the nest sometimes, she is walking around on uneven sticks in the equivalent of a pair of stilettos — not really what her feet were designed to do since hawks are usually flying or perched in trees. And finally, because the New York hawk watchers are very good at documenting the red-tail nests from year to year, I was able to locate pictures that were taken of her in 2010, showing that she had an abnormal right foot even then. At that point, the possibility that she was in immediate danger of losing her leg from a serious condition seemed far less likely.
Red-tailed hawks and other raptors often get prey bites (those squirrels and rats don’t always go quietly) and traumatic damage to their feet that is really the hawk equivalent of the old football injury. It is possible that she had an injury to her foot some time ago, and that it has mostly healed, but occasionally her foot becomes puffier when she is lying down, as she was while brooding her eggs. She looks pretty comfortable most of the time lately, preening her feathers (generally people and birds don’t worry about their hair when they are in a lot of pain) and standing on both her feet more and more.
The 2010 photos also gave us the timeline evidence that she made it through the winter-the toughest time for hawks- with this foot problem. Since the menfolk help out with the grocery shopping only during nesting season, she must be capable of hunting for herself and hopefully will continue doing well.
I’d like to know what you consider to be the biggest dangers to Pip, and other wild birds in urban environments, and what actions we city-dwellers can take to protect urban birds.
— Posted by Lucy
As many wildlife rehabilitators will tell you, they see a constant stream of animals that have come up on the short end of things after an interaction with human development. The most common injuries and problems vary somewhat with the species and where they live. Small songbirds are often unfortunate victims of free roaming house cats. Birds in the city environment contend with collisions from cars, buses, and trains (yes trains) and many, many windows (for information on how to prevent window collisions, check out the Audubon society’s Web site).
There are toxins as well. Raptors often pick up lead from being out and about, or play roulette if they eat prey that has died from exposure to pesticides or rat poison. As people have seen from the nest cam, they can also have trouble getting tangled in our discarded plastic (Easter grass!) and fishing line. The important point is to learn how those things we do routinely every day can impact wildlife — and come up with safer alternatives.
It seems like I read that hawks like to eat pigeons and other birds, but I’ve only seen Bobby and Violet feeding mice, rats and squirrels to Pip. Did I miss something, or is fowl not on the menu?
— Posted by Jean
It certainly seems, with the pigeon population being what it is on the streets of Manhattan, that it would be pigeons at breakfast, lunch and dinner. But red-tails are not primarily bird eaters, so to speak. They are fairly large and heavy bodied raptors, not what you need to pick off quickly scattering birds in midair. Other raptors, like Peregrine falcons and the Accipiters (sharp-shinned and Cooper’s hawks) feast primarily on birds. In fact, the “Sharpies” are the ones that routinely swoop down and grab the little songbirds at your bird feeder. I have seen Bobby and Violet feeding bird parts to Pip (there were starling and pigeon remains in the nest when I was there), but the rats and young squirrels are easier to catch. And dining preferences appear to vary from uptown to downtown; Pale Male has had great success catching pigeons.