This Jay Is Evolving in a Very, Very Weird Way. As she gathered more and more data on different populations of the island scrub jays around Santa Cruz Island, Katie Langin, a biologist at Colorado State University, had a revelation: The birds, members of one single species, had split into two varieties in different habitats. Ever since Darwin and his famous finches, biologists have thought that in order for a species to diverge into two new species, the two populations had to be physically isolated. Those finches, for instance, each live on a different Galapagos island, where their special circumstances have resulted in specialized bill shapes. Yet the two varieties of island scrub jay (they haven¡¯t technically speciated¡ªyet) live on the same tiny island. If they wanted to meet each other for a brunch of acorns and/or pine nuts and perhaps later some mating, they could just fly right over.
Now, the island scrub jay has apparently said ¡°screw all that isolation.¡± This is particularly weird because birds have, you know, wings. It¡¯d be easy to see how something less mobile like a snail could split and stay isolated, but the jays are more than capable of flying between populations and mating. Yet they only very rarely do. Why that is, Langin isn¡¯t yet sure, but she has a few hypotheses. A simple explanation would be that each variety is only attracted to birds with beaks like its own. But then how did the split happen in the first place? Perhaps a population of jays long ago settled in a certain kind of forest, evolved either an acorn- or pine cone-specialized beak, and henceforth found only that trait to be wildly attractive (sexual selection is, after all, a matter of determining the fitness of your mate, and few things are more fit than being able to eat the food in your environment). ¡°Another alternate hypothesis going into this would be maybe individuals that are hatched in pine habitat just prefer to settle in pine habitat,¡± Langin says. ¡°There¡¯s actually a lot of evidence that experiences birds have immediately after they hatch come into play when they¡¯re selecting a place where they want to breed.¡± She cautions, though, that her study didn¡¯t collect the data needed to support this, and that more research is in order here.
Langin's study in Evolution, "Islands within an island: Repeated adaptive divergence in a single population."
via the Corvid Blog.
We put up a fat pack for our bird feeder last year, and the western scrub jays would come and YELL ALL THE TIME.
First they'd sit in one of our trees. HEY HERE I AM. LOOK AT ME!
Then they'd jump on the fence. YEP. STILL HERE. HOW 'BOUT THAT?
Then they would alight on the top of the feeder. WOO BABY. LOOK AT THAT FAT PACK!
Then they'd jump to the fat pack and start feeding. stab stab stab stab
Then they'd fly back to the fence, but not before cleaning their beaks on the metal of the bird feeder. WOW THAT WAS GREAT. AND I AM AWESOME.
But we had to cut down the trees (they were quite dead and leaning against the power lines) and the jays have not been back. There is a tree a couple of feet away in the neighbor's garden, but I guess it's not close enough, and they feel too exposed. :(
posted by potsmokinghippieoverlord at 6:32 PM on March 12, 2015 [3 favorites]