Shed

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Digger’s most recent shed (Western Hognose Snake)

Both of our snakes, Digger and Emory, have shed recently and it is fun to inspect the tissue paper-like skin. Snakes have a clear scale that covers each eye, and you can see how that scale sloughs off with the rest of the skin. There is even a hardened scale that covers Digger’s “hog nose” that sheds.

Snakes shed their tough outer skin so they can grow and I wondered how quickly our snakes have grown. I found that it is incredibly difficult to keep a live snake straight enough to measure its length, so measuring the shed skin is much easier. Digger’s most recent shed was 30.5 inches; he has grown 4 inches over the last 10 months! Emory has shed even more often and has grown nearly a foot longer since last September. At 52 inches long, she is nearing the typical length of adult Great Plains Rat Snakes, so I expect her growth spurt to slow down soon.

Molting in the Rain

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Aldo the American Kestrel enjoyed a rain shower on Thursday morning. As he spread his wings to soak in the rain, his molting flight feathers were visible. He has short primary feathers growing on his left wing and new rectrices, or tail feathers. About two weeks ago, I found most of his tail feathers on the ground in his mew. Now, new feathers are starting to grow in and give the appearance of a diamond-shaped tail almost like a raven. Aldo’s tail will keep growing, though, until the feathers are all the same length.

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Unlikely Relatives

Rainbow Lorikeet and American Kestrel (Source: birdnote.org)

In a raptor program last week, a young man asked why Aldo looks more like a parrot than a hawk. It seemed like an odd question and I wasn’t sure how to answer it.  Later that night I put Google to work and found that his observation was actually very astute.

 

Falcons have long been grouped with hawks and eagles due to their similar predatory lifestyles. On the outside, just about the only thing they share with parrots is a sharp, curved beak. This tool is used for very different purposes: parrots crack hard seeds with their beak while a raptor’s hook is used for tearing meat. But researchers recently made a surprising discovery by studying what we can’t see with the naked eye: DNA. By comparing these building blocks in a variety of birds, they found that falcons actually share more genes with parrots than they do with hawks. Falcons and parrots are, in a way, long-lost relatives.

Al Batt, birder and storyteller, said last week at his evening lecture that he learns the most when he answers questions. That seemed a little backwards to me, but I realized exactly what he meant when I thought of this question about parrots. The inquisitive visitor saw similarities between species that I wouldn’t have noticed. It forced me to look at Aldo from a new point of view, trigger new questions in my mind, and learn something new along the way.

 

 

 

 

Mobbing

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When Aldo the American Kestrel was perched outside in the backyard last week, he instantly made a few enemies. Our local robin pair swooped down low over Aldo’s head. They flew back and forth, chattering and flicking their tails along the perimeter of the yard. What did poor Aldo do to deserve such an attack? His crime was being a bird-eater too close to the robin nest.

Many songbirds are known to mob, or dive-bomb, raptors. Sometimes they will even come close enough to knock the bigger bird on the head or nip at their tail feathers as they fly away. It seems like a dangerous game, but they do it to protect themselves and their families. They take the risk in order to chase off a dangerous predator from the neighborhood.

Aldo’s charm and cute face could not fool the robins. He was a threat to their babies that recently fledged out of the nest so they were very persistent in their assault. I soon brought Aldo back inside for some peace and quiet.

 

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Humidity Control

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Emory’s cloudy eyes indicate she is preparing to shed her skin.

When Emory, the Great Plains Rat Snake, had cloudy eyes last week, I set up a sort of spa to help with her upcoming shed. She had trouble shedding her skin last time and I suspect humidity was to blame. In dry conditions, the skin cracks and breaks off in many little pieces. It can even be more difficult to peel off and some skin might get stuck on. This can be a problem especially for the clear scale covering the eyes. If the eye caps stay on, layers build up during each shed and will eventually damage the eye.

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To avoid these problems I installed a simple “fogger” in Emory’s enclosure. An ultrasonic fog generator (visible as the red glow in the photo) sits in a bowl of water and produces a fine mist. Just a 20-minute session with the fogger is enough to raise the humidity from 35% to 50%. With this daily burst of humid air, Emory was able to shed her skin overnight all in one piece.

Uropygial Gland

Do you ever see something so odd that you just can’t look away? I recently had that experience with a Barred Owl’s uropygial gland. This owl was unfortunately the victim of a car collision. When Curator Kaylee brought the bird back to the Museum, I took the opportunity to look at the gland that is very rare to catch a glimpse of on a live bird. This uropygial gland, also known as the preen gland, is hidden under layers of feathers on the bird’s back, just above the tail. It secretes an oil that keeps the feathers strong and waterproof. The bird spreads the oil by rubbing its beak near the gland and then preening the rest of its feathers.

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A Barred Owl’s uropygial gland.

Most birds have a uropygial gland, but owls have a particularly conspicuous one. After parting the feathers you could see the gland on a hawk as a bump on the skin, but an owl’s gland projects out like a bulging flap. I haven’t been able to find an explanation for this difference, but it is interesting to ponder and quite a strange thing to see!