Spring Cleaning

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In spring, I love to find wildflowers blooming, to wait for migrating birds to return, and (perhaps most of all) to connect the outdoor hose. Winter makes a frozen mess in the raptor mews that we try to clean with buckets of hot water, but we can’t get everything. The birds don’t seem to mind since they spend their time on perches, elevated above the muck. But it was clear to us they required a heavy spring cleaning. We spent a full morning this week rinsing, washing, scrubbing, raking, and disinfecting every surface of the mews. With the help of above-freezing temperatures and a little elbow grease, the mews are practically sparkling!

Sticks

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Carson holding on to one of her sticks.

Even through the ice and snow last week, birds can sense that it’s spring. There seem to be more osprey than we’ve seen in recent years in the Cable area and they are busy nesting. Over the course of two or three days I watched one pair’s nest-building progress on my daily commute. What started as a few tree branches dangling precariously from a utility pole quickly became a sturdy mass of sticks. It is similar in structure to bald eagle and red-tailed hawk nests. In red-tailed hawks, the male and female work together to collect sticks and weave them together into a nest lined with strips of bark, fresh plants, or dried vegetation.

Our red-tailed hawk, Carson, has also sensed the springtime urge to build. Noticing an uptick in her activity this spring, I decided to test her interest in nest building. I placed 5 sticks around her mew one night and wondered if she would touch them. I was surprised to see each stick had moved the next morning. Since then, she moves the sticks around nearly every day, and occasionally she gathers them on top of her platform as if waiting for more sticks to appear so she can make a decent-sized nest.

Bath time

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Last Saturday was finally warm enough for the birds to take a bath outside. When I gave Carson a pan of water, she hopped in as soon as I left the mew. I watched from the door for a moment, but she just looked back at me. I went back to my office to give her some privacy. An hour later I returned to check on her, expecting to see a dripping hawk after splashing and playing in the water. Instead I found Carson still standing in her water, completely dry except for her feet.

I continued to check on her throughout the morning and nothing changed. She simply stood in the water pan for three hours straight. I guess she decided that all she needed was a nice foot soak!

Enrichment

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To maintain healthy birds in captivity, we encourage natural behaviors to keep their minds and bodies active. Most of a wild raptor’s day is spent simply sitting on a perch and watching their surroundings. That is easy to replicate in the mews: our birds sit and watch the Museum’s backyard daily.

For the rest of their time, we place new objects in the mew for them to look at or toys to play with. Carson recently received a phone book that Jayme (Living Collections Assistant) carefully folded like a fan. After a few weeks, Carson had ripped up nearly half of the book! Shredding is a natural behavior that wild raptors do when they catch a large meal, like a rabbit. This kind of enrichment keeps Carson busy and gives her an opportunity to rip and tear something for fun.

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.

Insulation

 

The floor of the classroom was covered in tiny white feathers after Carson’s sojourn there last week during the cold weather. As I tried to clean, the fluffy feathers caught every wisp of air movement from my broom, sailed past my neatly-swept pile of dirt, and floated down on the other side of the room. I decided to find out why these feathers are so difficult to collect and placed one under the microscope. The branches, or barbs, of these downy feathers are very fine and delicate. Each barb sways independently to make a globe of loose fluff. That’s why birds like Carson have a base layer of thousands of downy feathers to stay warm. When puffed out, she literally has her own down comforter for the winter. The power lies in the air trapped inside the fluff, making dry conditions essential to maintain the insulation; a wet downy feather simply clumps together in a soggy mess.

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To protect this warm, fluffy layer, she has an outer layer of contour feathers. These body feathers are highly structured with each barb hooking tightly to its neighbor like Velcro. The interlocking barbs create a strong and waterproof layer. While Carson needs her insulation dry now that she is back outside, I find that sweeping the classroom can be made a bit easier by misting those pesky downy feathers to subdue their airborne tendencies.

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