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In September we wrote about a study that revealed that bird populations have declined nearly 30 percent — a loss of 3 billion birds — in the last fifty years. While scientists don’t quite know what’s caused this decline, new evidence shows that in addition to species decline, North American migratory bids have been getting smaller over the past four decades, and their wingspan wider. The changes appear to be a response to a warming climate.
The Stats:Dave Willard, a collections manager emeritus at the Field Museum has collected the dead birds (since 1978!) who have flown into skyscrapers and explained that this has yielded important scientific data.
For the analysis, the biologists used 70,716 dead birds representing 52 species — including thrushes, sparrows and warblers — that Willard had logged between 1978 and 2016. Of those species, 49 saw statistically significant declines in body size. In particular, the length of the tarsus or lower leg bone, shrank by 2.4%.
Meanwhile, wing length showed a mean increase of 1.3%, with the species showing the fastest declines in tarsus length also showing the most rapid gains in wing length.
The bird’s wingspans may have increased to compensate for smaller bodies that produce less energy for the incredibly long distances the birds travel during their migrations.
Why This Matters: One of the scariest things about climate change is that we truly have no way of knowing the breadth of effects it will have on our planet. Because of our activity, we’re forcing animals to try and adapt to a rapidly warming planet–which means that some will be successful and others will perish.
While scientists don’t fully know why birds are shrinking in size they’ve speculated that hot temperatures during their breeding season stresses young birds and don’t allow them to grow as large. Regardless, we don’t know what sort of reverberations smaller birds have across ecosystems, e.g. what it might mean for their predators.
by Ashira Morris, ODP Staff Writer As the world warms, it’s not just people who are feeling the heat. Bats are also susceptible to extreme heat, and overheated bat boxes can be “a death trap,” the Guardian reports. In the wild, bats move between rock and tree crevices in search of a perfectly moderated temperature. […]
by Natasha Lasky, ODP Staff Writer A new report entitled The World’s Forgotten Fishes from the World Wildlife Fund has found that there has been a “catastrophic” decline in freshwater fish, with nearly a third of all freshwater fish species coming perilously close to extinction. The statistics paint a sobering picture: 26% of all critically […]
by Amy Lupica, ODP Staff Writer Move over Dolly, there’s a new clone in town and her name is Elizabeth Ann the Black-Footed ferret. You read that right; the U.S. Fish and Wildlife Service (USFWS) announced on Thursday that it had successfully cloned the first U.S. endangered species. Elizabeth Ann was born on December 10, […]
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