Weights

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Animals are amazing actors with the ability to mask injuries and illness. They want to hide any weakness from potential predators or competitors, while still finding their basic needs to survive. Raptors will keep hunting for food even with extreme injuries. When our Great Horned Owl, Theo, was rescued, he appeared to be well fed. The rehabilitators believed he was actually running down mice despite having a broken wing. Since their behaviors rarely show signs of illness, their weight is often the first sign of a problem. We take daily or weekly weights to track our birds’ health. The key is knowing what is normal for each bird.

I chart each bird’s weight to keep an eye on patterns. Aldo’s chart, for example, shows daily fluctuations and seasonal changes. His weight last summer hovered around 108 grams (3.8 oz) and increased in November. The higher weight gives him a little extra buffer against cold temperatures through the winter. As spring approaches, he has begun shedding weight in preparation for breeding season and warmer weather. With a baseline of these normal weight patterns, I can identify abnormalities and keep him at healthy weight.

Beak Styles

It had been three months since Aldo’s beak was last trimmed and it was clear he needed another touch-up. The tip of the beak had grown long and his tomial tooth extended far below his bottom bill.

Birds don’t have teeth, so this unique feature of falcon beaks is poorly named. The tomial tooth is not a tooth at all; it is simply a notch in the corner of the hook. Compare that shape to the smooth line on the inside edge of the hawk beak. While this small notch gives me a challenge to shape when trimming Aldo’s beak, it helps falcons quickly dispatch their prey. The notch fits into the vertebrae of their bird or mouse meal and snaps the neck quickly, allowing the falcon to fly off without struggling with its prey. It must be a useful tool, especially considering falcons’ long, slender toes that might not have the power needed to kill prey with their feet alone. Another small meat-eater (one that has no talons at all) takes advantage of having tomial teeth: northern shrikes!

I carefully studied photos of the shape and position of the tomial tooth before trimming Aldo’s beak. I was reassured by knowing that the notches will grow back on their own if I don’t shape them properly, but I wanted to give him a proper falcon beak. Since I had worked on his beak two times before, I felt more confident as I dremeled away the excess keratin. This time he ended up with two intact, correctly-positioned tomial teeth, ready to slice through his mouse reward.

Plumage

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Last time Aldo was inside due to cold temperatures, he spent some quality time in my office. He kept busy by watching visitors pass by in the hallway, listening to the strange noises emanating from my computer, and, apparently, mimicking the artwork on the wall. The watercolor prints were done by a naturalist that I worked with a few years ago. She painted a variety of animals, but my favorite piece is the male kestrel, shown at the perfect angle to highlight his handsome plumage. The solid block of rusty-brown on the tail and slate-blue wings contrast with the female’s rather plain brown wings and tail.

Such a striking difference is rare in raptors. In most species, there is no difference in plumage. The only way to tell male from female is by size: if you see them sitting right next to each other, the female is the larger one of the pair. With individual birds, it’s a bit of a guessing game. Our Red-Tailed Hawk, Carson, weighs just over 3 pounds. That falls in the upper range of Red-Tailed Hawk weights, so she is likely a female. With Aldo we don’t have to guess: his colors tell us without a doubt that he is male.

Steps Toward Flight

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To prepare for a training session, I closed the blinds in the classroom and set out a step stool – just in case. I brought Aldo into the room and carefully closed the doors behind me. I removed the metal swivel and leash that normally keep him secure on the glove if he tries to fly away. He needs this level of freedom – in a controlled room like the classroom where he cannot escape or hurt himself – to accomplish his new training goal: to fly!

I let Aldo step onto the perch and take in his surroundings. He has seen the classroom many times before, but he was curious as he looked around the room, his head bobbing up and down. After a moment, I raised the glove to his feet once again. He looked down at it and stepped up with both feet. I bridged and gave him a few mouse tidbits, then set him back on the perch to try again. While not very exciting yet, this is the first step in flight training. I will gradually move the glove farther and farther away so he has to take a big step, then hop, then finally fly to the glove. Eventually, he will fly across the room during raptor programs to demonstrate falcon speed for audiences!

Identity

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In the spring of 2014, a young kestrel’s life was upended when he fell out of his nest and broke both wings. Luckily he was found and admitted to the Carolina Raptor Center in North Carolina. As his wings healed, the veterinarians realized that his recovery would not be perfect and he would never fly well enough to survive on his own. Rehabilitators continued to raise him and coincidentally influenced his sense of identity. This baby bird was at a critical stage of his life where he would learn who he is by carefully observing his parents. The kestrel looked up each day to see a human bringing food and a human speaking to him. He essentially learned that he is, by extension, a human. Learning to recognize humans as his own kind was a lesson he could never unlearn. If released, he would seek humans to socialize with, to breed with, and defend his territory against. He would be either too friendly or too aggressive toward people to stay safe in the wild. His perceived identity might be a liability in the wild, but it gave him a pleasant temperament for life in captivity where he would interact with people on a daily basis. This bird was placed at the Cable Natural History Museum where he was given a new identity: Aldo, Education Ambassador. With his background, he excels at bridging the gap between humans and wild kestrels, the two species he is caught between.