Because of their evolutionary diversity, birds (including this satin bowerbird) provide a perfect example of the host/parasite relationship.
Parasite: The surprising role of lice, mites and ticks in the real love lives of birds
February 13, 2020 | Science
When female birds choose a mate, says Dr. Michael Stock, they’re on the lookout for any undesirable baggage that their male suitors might be hiding.
If an Australian male satin bowerbird tries to woo a mate with a flashy, “blinged-out” bower (the reedy structure pictured above) that’s too small, he might be carrying blood-feeding lice. A male black-capped chickadee with a dark black bib and bright white plumage probably has fewer feather mites. And the gentleman sage grouse with the most stamina during his mating dance is least likely to be infected with malaria. But those parasitic interlopers hitching a free ride in the skies don’t only affect mate selection.
“Much of what we know and love about birds – their colours, sizes, ecology and behaviour – is shaped, at least in part, by the parasites they are infected with,” says Michael, a parasitologist and associate professor of biological sciences at MacEwan University.
The complex relationship between birds and the parasites that live in and on them – something Michael has spent his career studying – is the topic of his new natural history book, The Flying Zoo.
“Every species of bird is a bit like an island for a parasite,” explains Michael. “And when organisms are ‘trapped’ in this way, they evolve to stay inside the animals – competing with each other and fighting for the best places to live within their ‘habitat.’”
At the same time, the birds themselves are evolving to control the parasites. The bill shape in raptors (e.g., eagles, hawks and falcons), for example, has changed over time to curve in a particular way that allows them to preen for feather lice.
It’s one part of a co-evolutionary dance that, of course, isn’t limited to birds alone. Michael is already working on his next book that explores the impact of parasites on mammals.
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