The wildlife species most often associated with the risks of climate change (loss of sea ice, warming oceans, more precipitation) are the so-called charismatic megafauna: polar bears, penguins, cranes, seals, beluga whales, sea turtles, and other well-known animals.
A less-than-six-inch-long wren that lives in dry forests of Central and South America, on the other hand, is an unlikely candidate for your “birds-affected-by-global-warming” list. Nonetheless, biologists at two Canadian universities reported in a recent scientific article that the warming climate has led to problems for Rufous-and-white Wren, a species that occurs from southern Mexico to Panama and also in Colombia and Venezuela.
The researchers studied a population of the wren in the Guanacaste Conservation Area in northwestern Costa Rica. Every year for 15 years, they captured birds in mist nets, gave each a distinctive combination of colored leg bands, and then surveyed the population to see which birds were still alive and which had perished.
They found that as temperatures rose, more wrens died. For example, during the 15-year period, wren survival was 15 percent lower in the hottest April than in the coldest April. The research, by Brad Woodworth of the University of Guelph (now at the University of Queensland) and Dan Mennill of the University of Windsor, is the first to document temperature-induced mortality in a tropical insect-eating bird.
The findings suggest that climate change is putting many tropical wildlife species at risk, even those that already live in warm environments. The authors, writing in the journal Proceedings of the Royal Society B: Biological Sciences, say: “Although declines of tropical bird species have primarily been attributed to direct habitat loss and degradation caused by humans, the observed negative effects of increased temperature on survival in an undisturbed habitat reveals a mechanism by which climate change could drive future population declines in the tropics independent of habitat loss.”
A version of this article was published in “Birding Briefs” in the July/August 2018 issue of BirdWatching. Subscribe
“The Other Guys”
In 2006, Dan Mennill was one of a group of ornithologists who reported finding evidence of Ivory-billed Woodpeckers living in Florida. Auburn professor Geoff Hill, the group’s leader, described their efforts in this article.