TIL amazing new information about cuckoos which I really want to share, but I’m guessing most of you don’t know much about them in the first place so I’m going to infodump for a minute to bring you up to speed. Buckle up!
Cuckoos are brood parasites- they don’t raise their own young. Instead, the hen lays a single egg in the nest of a target species (usually one that is significantly smaller), and that species raises the cuckoo. This leads to comically disproportionate parenting:
“Ma, the nest is too small!”
The larger birds in all these photos is the cuckoo chick. As you can imagine, such a big ass baby needs a lot of food, which means they don’t want competition from the foster parents’ actual babies. Cuckoos have a couple adaptations to deal with this.
1. Their eggs develop super fast, ensuring that the cuckoo chick probably hatches first (TIL they even pre-incubate the egg internally a little prior to laying, which helps speed up the process).
2. The cuckoo chick has special back muscles and a groove on the back so they can push the other eggs/chicks out of the nest. https://youtu.be/SO1WccH2_YM
Cuckoo chick pushing egg out of nest.
Cuckoo chick pushing other chicks out of the nest. “Bye suckas!”
This parasitism is bad for the host species, who wastes valuable resources tending to a chick that isn’t theirs, so there’s an evolutionary arms race against the cuckoo. Host species started developing more extravagant eggs in an attempt to be able to distinguish them from the cuckoo egg. The cuckoo, in turn, started developing eggs that closely mimicked their host.
Ok, now that you know how utterly fucked up neat this all is, let me tell you what I learned today. Apparently scientists have been trying to figure out how the hell the cuckoo convinces the host parents to feed it enough food. Remember, these are big ass birds that need like 4x the amount of food that the host chick would eat. I always figured the host parents fed it because it was begging, and because it was a larger bird with a bigger appetite, it begged more. Not so!
Scientists analyzed the begging call of the cuckoo chick and found that it imitated the call of FOUR host chicks. So while the parents only see one chick in the nest, they hear four. Even neater, one species of cuckoo developed a fleshy colored area on the wing joint that mimicked the color of a chick’s open mouth. See, a lot of passerine chicks, while drab in color, have a really brightly colored mouths to help the parents know where to stick food:
This one species of cuckoo developed a simulation of that on its wing. So the host parents would see a real mouth and two fake “mouths.”
This has been your daily reminder that nature is not a Disney film.
jacobvanloon
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