Bird calls may just serve a purpose beyond what scientists have speculated, because according to a new study in Science, birdsong may just help prepare zebra finch eggs for global warming.
Zebra finch parents sing certain songs to their eggs just days before they hatch, and this alters their growth and behaviors once they break out.
These results will likely surprise a good number of scientists, as zebra finches are very well-studied—in fact, they serve as the model organism for researchers looking to examine the behavior, endocrinology, and neurobiology of all birds. But prior to now, no one had picked up on the significance of this so-called “incubation calling”, until lead author and Deakin University post-doc Mylene Mariette decided to investigate under the tutelage of Dr. Katherine L. Buchanan.
Changing the Growth of the Chicks
They hypothesized the calls given by parents in the three to five day period before hatching helped the unborn zebra finches prepare for their new environment. To test this, they recorded the incubation calls of 61 female and 61 male wild-caught zebra finches, who were nesting in outdoor aviaries.
As temperatures fluctuated, the researchers noticed a trend: When the maximum temperature rose above 78 degrees Fahrenheit (26 degrees Celsius) during the incubation period, the parents sang the special incubation calls. Taking this further, the researchers then isolated the eggs from the parents (leaving fake eggs in their place, so as not to stress them out). Half the eggs were exposed to recorded incubation calls, while the rest were played regular parent contact calls.
And when the eggs hatched, a significant difference was seen between the sizes of the two groups: The ones exposed to the incubation calls (and thus were theoretically prepared for higher temperatures) weighed less.
But why would weighing less be an advantage?
As it turns out, the authors believe that smaller birds regulate their internal temperatures more efficiently. As temperatures peak, they seem to take less oxidative damage throughout their bodies, meaning they take much less stress overall.
To compound this fascinating discovery, the researchers discovered that the incubation calls seem to lead not only to a difference in physical size, but also a difference in reproduction and lifetime behaviors. The incubation-called offspring went on to produce more fledglings in their first breeding season, and the males showed a predilection for nesting in higher-temperature areas.
All in all, it seems to be somewhat good news for zebra finches; for the time being, at least, they will likely be able to acclimatize fairly simply to a warming planet, thanks to a little bit of heads up while they’re still in the egg.
—–
Image credit: Thinkstock
Comments