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.
Following is her second set of responses.
As I was watching the other day, I’m pretty sure I saw Pip raise his/her butt and shoot a stream of Pip poop from one side of the nest to the other. Is that how nestlings handle their nature calls?
— Posted by rbk
It is truly amazing that we are talking about raptor poop in The New York Times.
Yes, baby birds of many types instinctively avoid messing up their living area by directing their waste out (or at least over the side) of the nest — so Washington Square citizens, look out below. Raptor chicks like red-tails really have the ability to take this to the extreme, often painting vertical surfaces with a substance that will harden like cement very quickly. Cleaning up after these birds at animal hospitals is no small task.
Pip has decorated the wall and the window of his nest area over the past week or so; those are the spots that you see through the nest cam (and the windows cannot be scrubbed at this point). The falconry folks have their own descriptive term for it: slicing. Another unique thing about birds (and reptiles, too) is that their droppings have three components: fecal matter, urine and urates, which give it the white color. Urates are really a concentrated alternative to urine, possibly an adaptation to developing in the limited space of the egg. There is only a single opening where the droppings, as well as the eggs, exit the body, called the cloaca, instead of the standard mammalian design of having 2 separate openings for urine and feces. This is also why the “male or female” question is something of a mystery for many birds: both males and females have the same exterior design, and the reproductive organs are entirely internal.
Pip seems to spend much of his/her time in the nest on his haunches instead of on his feet. Does this have to do with his/her center of gravity? Pip also spent quite a bit of time just now flexing his/her feet out in front of him/her. What’s that about?
— Posted by Laura
Many readers had questions about Pip’s coordination, or seeming lack of it. His/her remarkable ability to fall asleep with a full stomach almost instantly, usually flat on his face, is enviable. In the case of some bird species, the young are ready to walk and feed themselves almost instantly right out of the egg, just as baby chickens and ducks can. We call these birds “precocial.” But other bird species are “altricial,” which means they are in need of more parental care.
Red-tails are considered “semi-altricial” — not as helpless as naked and blind songbird nestlings, but not ready for prime time, either. Pip is a normal altricial chick at this point — the lack of coordination and muscle development means that he has difficulty holding his head up, sleeping upright like mom and even getting his legs to support his weight so that he can stand. You will gradually see these perfectly normal issues improve over the next few weeks as he learns to walk around, tear food and feed himself. For more on the developmental biology of birds, visit the Cornell Laboratory of Ornithology to see the online encyclopedia Birds of North America and check out some of the great science projects that you can participate in by recording your observations of wild birds.
How long do baby hawks typically stay in the nest? Also, at what age will Pip lose his downy coat and grow feathers?
— Posted by Annalyse
This may make some human parents envious, but the red-tail babies, also known as nestlings, only spend about 45 days in the nest. So Pip has about four more weeks to go. Once out of the nest, Pip is officially considered a fledgling, but Violet and Bobby are not done yet. The fledgling period is a vulnerable time for a bird. They can be easily injured on the ground by roaming dogs, cats or even automobiles, and sometimes “bird napped,” rescued by well-meaning citizens convinced that they are lost or separated from the adults. In most cases, the parents are watching closely from nearby perches much as human parents keep track of their preschoolers at the playground. Violet and Bobby will still feed and care for Pip for some weeks (about 10) around the park as he gradually hones his flying and hunting skills. Although there are not true “lessons,” per se, he will have to pick things up on his own. They will start to wean him off food deliveries later in the summer, ignoring him as he calls for food to encourage him to fend for himself.
For a preview of what Pip will look like as his feathers grow in, check out the Franklin Institute nest camera and the Urban Hawks blog, which also has some great pictures taken of other red-tail nests around New York City. These young Philadelphia hawks are about 10 days ahead of Pip, and their parents show similar great taste in real estate. Their nest is on the board room window of the Institute’s building with a great view of downtown Philadelphia.
Pip right now is working hard to put in a full set of flight feathers. This is the only time in his life that all his feathers will come in at once, and it is an enormous job for the young bird. Adult raptors lose or “molt” only a few flight feathers at a time, because they cannot afford to be grounded. On the nest cam, you can see the dark spots that are the ends of the largest feathers emerging from the back of his wing and tip of his tail. As they push out from the follicles, the feathers, called pinfeathers or blood feathers, have large blood vessels within the shaft and are protected within tubes of light flaky keratin, the same stuff that your fingernails are made of. Counting from the outside tip of the wing, the first 10 feathers are the largest and are called the “primary” feathers, the ones that are most essential for flying. Once Pip has a full set of flight feathers he will be ready go, although, as you can see from his classmates, the downy remnants will give him a comical look for a while longer.
This is a two-part question:
- What are Pip and Violet doing exactly when they are running their beaks on their feathers and bodies? Do they have parasites (say, fleas) that they are trying to catch? Does it help Pip grow his feathers? Is this social grooming behavior when Violet does it to Pip? I have never seen Bobby do it to Pip, only Violet.
- Is the nest super smelly now that it’s been so well used? If Violet and Bobby use the nest next year, will they do anything to house-keep before hand?
— Posted by PPL
And a two-part response:
- Certainly wild birds, like the rest of the animal world, can have their problems with lice, mites and other itch inducing joy riders, although not fleas, and they routinely groom their feathers to remove them, in a process called “preening.” In fully feathered birds, preening smooths the delicate interlocking weave of the feathers, which, along with a special oil from the preen gland that birds spread over their body, sheds rain and keeps them dry and warm; thus the proverbial saying “like water off a duck’s back.” Raptors are not particularly social in their habits, which may explain why Bobby appears to be coolly detached from preening duty. A majority of the preening in Pip’s case involves removing the protective keratin covering from all the new “pin” feathers that are coming in. This allows the feathers to spread out and take on the proper shape for flying.
Juvenile raptors often have somewhat different coloration than the adults, making them easy to age. Red-tailed hawks in their first year will have only a plain brown striped tail. It is not until the second summer that they replace their first set of feathers and graduate to the beautiful orange-red color that gives them their name.
- Is the nest smelly? You bet!! But fortunately for John Sexton, the president of New York University, outside whose office the nest sits, there is a large pane of solid glass in the way. What with the leftover lunch and dinner entrails, the bird waste and the assorted trash, the nest can become quite aromatic as time goes on. However, it is hard to know if the hawks really notice — sense of smell is tough to evaluate in wild animals (you can’t just ask) and the research is conflicting. There is some evidence that turkey vultures have a great sense of smell, allowing them to pick up the location of those nice ripe carcasses that they feed on. Newer studies looking at the genes behind olfaction show that some birds do have a very well developed olfactory bulb — the part of the brain that processes smell. This suggests that they can smell, but good or bad smells are in the nose of the beholder, so who knows what might smell bad to an animal that eats dead rats for a living?
Does the occasional eyas fall from its nest? What are the odds Pip will fall? If the odds are good that he will, is there any way at all to prevent this happening?
Can you tell us, please, if Pip has a Hawkish instinct for danger; if he “knows” not to stray too close to the edge before he can fly?
— Posted by Rea Tarr
The short answer here is, unfortunately, yes, it is possible for a baby bird to venture too close to the edge and topple from the nest, so it is very nerve-wracking for the viewers to watch Pip wander around a window ledge high above the ground. To say a young raptor “knows” or understands the risks would be going further than most scientists would agree with — can we say that birds are capable of that level of analysis? It may be small comfort to say that nest falls do not happen frequently — after all, there are plenty of adult red-tailed hawks who make it through the process. But strictly from an evolutionary point of view, this instinct must be highly conserved. Those reckless risk takers or poor uncoordinated individuals who suffer from accidents do not survive to pass on their genes — ensuring that those with the strongest urge to stay safe and sound until the flight feathers come in are the ones in the gene pool the next time around.