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Birds with Big Brains Best at Resisting Climate Change

New research shows that birds with big brains are better at resisting climate change-induced shrinking than birds with smaller brains. Such loss of body volume has become prevalent across most bird species over the last 40 years, a phenomenon nearly all researchers in this field believe is a direct result of a warming planet.


Birds are shrinking. It’s a trend that has been going on for decades. This loss of avian body volume has occurred across a range of species, but researchers have noted that the changes are particularly significant in one type; songbirds.

“The body size changes in songbirds are small but significant, affecting familiar species of sparrows, warblers, and thrushes,” explains a press release announcing the new study. “In fact, the size changes are so pervasive that some scientists have suggested that reductions are a universal response to warming.”

Now, researchers from Washington University in St. Louis have taken a closer look at the phenomenon of shrinking birds. And what they found seems to indicate that one particular characteristic appears to have helped birds from a number of these vulnerable species resist the shrinking without completely avoiding it altogether. That characteristic is brain size.


“As temperatures warm, body sizes are decreasing,” said Justin Baldwin, a Ph.D. candidate in the laboratory of Carlos Botero, assistant professor of biology in Arts & Sciences at Washington University, and lead author on the study. “But larger-brained species are declining less strongly than small-brained species.”

To conduct their analysis, Baldwin and his fellow study authors looked at a database of over 70,000 dead birds collected by researchers at the University of Michigan. All of the birds in the database had died in building collisions in Chicago between 1978 and 2016.

The Washington University researchers calculated brain volume and lifespan data for 49 of the 52 North American migratory species included in the original database. And their results were definitive. For the migratory birds with bigger brains, their overall body size was the closest to their size four decades earlier. In contrast, the birds with smaller brains showed significantly more loss of overall body size over those four decades.

“This doesn’t mean that climate change is not affecting brainy birds,” cautioned Botero, “or that brainy birds are going to do just fine. What our findings suggest is that climate change can have a much stronger effect on the less-brainy birds.”

Furthermore, the study authors note that this ability to resist the effects of climate change-induced shrinking didn’t require the avian equivalent of Albert Einstein.

“The species we studied only spanned a two-fold difference in relative brain size, which was enough to reduce the effects of increases in breeding temperature by 70 percent,” Baldwin said. “This tells us that even small differences in cognition matter.”

When explaining how this increased brain size may be helping the birds resist shrinkage, the researchers point to a few benefits birds with larger brains enjoy.

“{In bird species} relative brain size correlates with increased learning ability, increased memory, longer lifespans, and more stable population dynamics,” said Baldwin. “In this case, a bigger-brained species of bird might be able to reduce its exposure to warming temperatures by seeking out microhabitats with cooler temperatures, for example.”

“Rapid changes in the environment often produce a few winners and a whole lot of losers, which is really unfortunate,” he added. “Many wildlife populations have moved toward colder places as the planet has warmed. Selection forces those that don’t move to adapt, for example, by changing their body size.”


As far as practical applications of their study, the researchers note that climate change and its effects on animal populations will need to be understood if we have any hopes of helping the most vulnerable species survive an ever-warming habitat. And, they caution, if their same results show up across other types of animals, smaller-brained species may be the ones that need more help than the larger-brained ones.

“When it comes to climate change mitigation and planning, a major goal is to maintain population-level connectivity,” said Baldwin. “We want to allow species to move toward the poles or upslope in elevation to keep up with warming climates. Our findings suggest that this type of intervention could be especially important for smaller-brained species.”

You read it here first, people. Those with bigger brains must help those with smaller brains survive climate change. I didn’t say it. The bird people did.

Follow and connect with author Christopher Plain on Twitter: @plain_fiction