Collared puffbird
True to its name, the collared puffbird has a black band of feathers around its neck and an oddly bulbous head. The bird is, frankly, a little comical, but its situation is not: The average puffbird body has decreased in mass by nearly 4% since 1980, according to the team’s results.
“The broad result is that climate is changing at our study site,” and “at the same time, the morphology of birds exposed to those conditions is changing,” said Vitek Jirinec, an ecologist at Louisiana State University and lead author of the study, in an email to Gizmodo.
“Variation in mass, wing, and mass:wing is also linked to temperature and rainfall in the shorter-term (seasonal) interval,” Jirinec added. “That means more evidence that bird body size and shape is related to temperature and rainfall. If these change over time, it makes sense to see the morphological shifts we report. As for how exactly mass is related to climate, we are not sure.”
One hypothesis proposes that animal body sizes get smaller when the weather gets warmer. Another is that climate change has reduced the amount of food available to these birds. In either case, it appears the climate is driving the reduction in bird mass, with the birds species in this study losing about 2% of their body mass per decade on average.
