I want to begin this post by stating that falcons do not usually eat penguins. I choose the title to grab your attention and promote my upcoming blog series on penguins. I also wanted to see if my blog could become the #1 Google hit for the search term “falcons eat penguins”. Hold on a sec . . . Falcons eat penguins. Falcons eat penguins. Falcons eat penguins.
This post is part 3 of a series on American Kestrels. I’ve been writing about kestrels because I think they’re cool and I will be studying them for my master’s research. If you’ve been keeping up, so far we’ve learned that kestrels generally live in open habitats, are colorful, can “hover” while they hunt, and nest in cavities. Kestrels also engage in a behavior called tail-pumping, which is not fully understood. My goal is to determine what functions tail-pumping may have for kestrels. There are 4 hypotheses I will be testing in my research. Hopefully I will be catching and banding kestrels (for individual identification) soon.
Idea #1 – American Kestrels pump their tails to help maintain balance on a perch. This concept is pretty straightforward. As previously mentioned, kestrels spend a lot of time in open habitats. Much of their time is spent hunting from a perch, which is often a powerline or bare tree branch. Some of these perches are more stable than others, so the thought is that kestrels pump their tails up and down to keep their balance on unstable substrates. There is also the fact that open perches are more susceptible to high winds, which may make it more difficult for a kestrel to stay on its perch. In my field work, I will be observing kestrels on perches and recording their behavior. I will be calculating tail-pumps per min and estimating the stability of a perch. If the kestrels do not stay on a perch long enough for me to measure tail-pumping, I will shoot them. I’m predicting that kestrels will pump their tails at higher rates in windier conditions or when perched on unstable branches. Unfortunately, my advisor told me I could not watch kestrels tail-pump during a tornado. Wow! 300 tail pumps per minute! A new record!
Is this a stable perch?
Idea #2 – American Kestrels pump their tails to communicate with other kestrels. Some bird species, such as moorhens and Elegant Trogons, appear to flick their tails when communicating with each others. Trogons seem to tail-flick during courtship and aggressive interactions. I will be presenting my kestrels with a kestrel model and using playback of kestrel calls (klee klee klee klee klee klee klee klee!) to determine whether the presence of other kestrels affects tail-pumping rates. Do males interacting with other males pump their tails more frequently as a signal of aggression? Does one of the sexes act submissively to the other? Or does tail-pumping lead to this?
Idea #3 – American Kestrels tail-pump as a pre-attack signal. This idea is based on the fact that several researchers have mentioned seeing kestrels pump their tails before attacking prey. One researcher actually raised juvenile kestrels and presented them with real and fake mice to observe their reactions. He even named his kestrels after characters from Lord of the Rings! The researcher noted that kestrels pumped their tails at much higher rates when presented with real mice. Anyway, tail-pumping may be an excited response that signals an impending attack, so I will be recording hunting behavior and comparing it to tail-pumping rates in the period before the kestrel left his/her perch.
Idea #4 – American Kestrels pump their tails to deter pursuit from predators. This idea is based on the fact that previous studies on birds (such as moorhens, motmots, and phoebes) have revealed that tail movements may be used to signal vigilance. In other words, by pumping their tails, these birds are showing that they are aware of the presence of a predator. If you’re familiar with White-tailed Deer, you know that they flick their tails in moments of danger. The same mechanism may be at work in kestrels. By pumping their tails, they may discourage predators who prefer to ambush their prey. Also, predators may learn to associate the tail-pumping with the agility and sharp talons of the kestrel. Thus, a kestrel may be seen as a difficult to capture prey item. I will be using models of a potential predator (Cooper’s Hawk) to see if kestrels increase their tail-pumping in the presence of a predator. I will also be using other bird models which probably do not represent a threat to kestrels to compare tail-pumping rates.
Please don’t eat me!
Hopefully you’ve come away with an appreciation for kestrels and a basic understanding of why they may pump their tails. I started observing a few kestrels recently and have decided to name them based on nearby landmarks. The first male I found was across from Dunkin Donuts, so I named him Duncan. There’s also another male named Dodge and a Female named Eastside. I’ve already seen them hover hunt and catch prey, which is pretty cool! Remember that American Kestrels often perch on power lines, so be sure to keep an eye out when in the country or even in urban areas! These are the falcons you are looking for. Falcons eat penguins. Falcons eat penguins. Okay, I’m done now. Falcon out!