Do choosy cuckoos choose well-matched hosts?

A reed warbler feeds a cuckoo chick

Brood parasitism, the reproductive strategy of choice for cuckoos and cowbirds, sounds like a lazy approach to parenting: lay your eggs in another bird’s nest, and let the unwilling adoptive parents take the trouble to raise your chicks. But contracting out parental care like this comes with many of its own complications. Chicks raised by parents of a different species have to eliminate competition from their adoptive nestmates, and may grow up a bit confused; reluctant host birds may need to be told, and reminded, that raising cuckoo chicks is an offer they can’t refuse.

ResearchBlogging.orgBut before crossing all those hurdles, a brood parasite’s first task is to lay eggs in the nest of a host who won’t immediately recognize and reject them. The strong natural selection imposed by host rejection has led cuckoos to evolve “host races” that lay eggs whose color and spotting pattern matched to those of their preferred host species. This kind of broad-scale pattern could arise without much direct effort by female cuckoos—those who lay eggs in the nest of the best matching host species would simply be the ones most likely to have chicks that survive to the next generation. But is it possible that cuckoos do take an active role in matching up to their hosts, seeking out host nests containing eggs that look like their own?

The answer, according to a series of studies over the last several years, is yes—probably.

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Friday coffee break

Experimental coffee

NiB does not endorse drinking coffee at your lab bench. No, sir.

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

From Noah: A newly described family of amphibians looks like earthworms, and apparently spend their entire lives underground.

“The complete life cycle, everything, is happening under the soil,” said S. D. Biju, an environmental scientist at theUniversity of Delhi who led the research. “So far we don’t have much information about feeding; we think they eat earthworms.” [Links sic.]

From Sarah: The single biggest factor behind the underrepresentation of women in “math intensive fields” may be the difficulties of balancing an academic career with motherhood.

 Women deal with all the other challenges of being academic scientists as well as men do. Childless women are paid, promoted and rewarded equivalently to their male peers (and in some analyses at even higher rates). Children completely change the landscape for women—but do not appear to have the same effect on the careers of men.

From Jeremy: A widely-cited study linking attractiveness and immune system responsiveness doesn’t hold up under scrutiny.

So the conclusion is that high testosterone, low levels of cortisol, and a high immune response to a vaccine correlate with physical attractiveness ratings. But there are several things here which bring the potential impact of this study down a bit. First, the correlation between testosterone and vaccine response disappeared when they took out the people who had NO response to the vaccine. This was a large number of people.

And from Devin: A palm-sized walking stick species, thought to be extinct, has been rediscovered on a tiny volcanic island.

Some climbers scaling Ball’s Pyramid in the 1960s said they’d seen a few stick insect corpses lying on the rocks that looked “recently dead.” But the species is nocturnal, and nobody wanted to scale the spire hunting for bugs in the dark.

That last piece comes with this amazing video, of a giant walking stick hatching from an improbably small egg.

Lord Howe Island Stick Insect hatching from Zoos Victoria on Vimeo.