The vampire strikes again!
Photo by Ian White*
In honor of Halloween, let’s talk about vampire birds.
I am using “vampire” loosely here, the same way people do when they talk about “vampire” bats. These vampire birds are hematophagic (blood-eating!), but do not follow other items of vampire lore: they have reflections in mirrors, can enter your house without an invitation, do not shape-shift, are mortal, and do not sparkle in the sunlight.
Sharp-beaked Ground Finch, Geospiza difficilus
This is one of the famous Darwin’s Finches of the Galápagos Islands. This species is a vampire only on two of the islands, Wolf and Darwin; everywhere else it eats bugs and seeds like a regular finch. Even on Wolf and Darwin, it mostly eats bugs and seeds, but sometimes it craves something a little… richer…
(Sharp-beaked Ground Finch. Photo by budgora*)
I’ve been meaning to write about this topic for a while—now xkcd has beaten me to it:
Oh, well. Since the comic doesn’t actually answer the question, I’m hoping you’re all still interested! (Also, at the end there will be a bonus discussion of ant rain. Yes, ant rain. You won’t find that on xkcd!)
There is a thing that happens a lot in biology, especially in animal behavior: one set of researchers finds an interesting relationship, like, say, “Birds prefer to eat bugs off of cows with lots of spots, and don’t like to eat bugs off of cows with no spots.” (This is a made-up example.)
Blackbirds flying near a cow, Pt Reyes, CA.
Then, some other researchers do a study and say, “Hey, our birds prefer to eat bugs off of cows with no spots! That’s the opposite!”
Then still different researchers do another study and say, “Our birds don’t care at all about the number of spots, they just care whether the spots make a shape like a smiley face. You guys must all have made a mistake. The Smiley Face Rule is the new Lek Paradox! #nobelplease”
To put it less ridiculously: scientists get different results sometimes, and it can be hard to figure out why. Did someone make a mistake? Who is right? Today’s featured paper takes an example of this confusing scientific disagreement and elegantly makes sense of everything, with the help of this handsome little bird:
Common Yellowthroat (male).
Photo by Dan Pancamo*
Today I submitted the Big Grant Proposal that I’ve been working on for a while. To celebrate this, because I am a normal person, I dissected some owl pellets.
Now that’s what I call a party.
These particular owl pellets were from Great Horned Owls—these ones, in fact:
When an owl eats something, it doesn’t digest the whole thing. The hard-to-digest parts—bones, fur, exoskeleton—get smooshed into a pellet in the gizzard and then regurgitated. These pellets are a record of what the bird has eaten.
This is my “How is it your business what I’ve eaten?” look.