Like most mornings, I asked Aldo the American Kestrel to step onto the scale. I adjusted his leather equipment, glanced at the numbers on the screen, and had to do a double take. The scale read 122 grams, much higher than yesterday's weigh-in.
Puzzling over how he gained 10 grams in one day, we returned to the classroom where I tied his tether to his favorite perch. It was too cold for this migratory bird to be outside, so he would spend the day watching the backyard from a warmer perspective.
I started to leave the room when I heard something hit the newspaper under his perch. I turned just in time to see Aldo shake his head and spit out another pellet. As I picked up the pellet, I felt something hard underneath the compressed mouse fur. What could it be if kestrels have strong stomach acid that digests bones? I split the pellet and excavated a piece of gravel that matched the type in Aldo's outdoor enclosure. He shook his beak again and two more small stones plopped onto the newspaper.
Before I could clean up the pellets, Aldo leaned forward and raised his tail. A very large mute was ejected and the white liquid started to run off the edge of the newspaper. The only time I see a mute this big is when it's the first one of the morning.
After voiding significant amounts of rocks and waste, I wondered what Aldo's weight would read now. We went back to the scale and found a weight of 115 grams, much closer to what I expected. When he weighs less than a baseball, small changes in weight - even 7 grams - can make a big difference. I was glad to find that today's sudden weight gain was quickly erased by Aldo's morning routine of pellet casting and muting.
Comments