Climate change is altering birds’ internal clocks, expert says
When birds sing outside your window at dawn, they’re responding to internal clocks set to daily and annual rhythms.
But what happens when climate change interferes with these clocks, putting the survival of species, potentially even humans, at risk?
“Biological clocks — daily and annual timing — is found in every organism, from gut bacteria to worms, algae, plants, and all of the animals,” said Vincent Cassone, a professor and chairman of the department of biology at the University of Kentucky.
All have an “internal biological timing system” that is approximately timed to 24-hour and 365day cycles, he said. These rhythms are synchronized largely with the daily rise and fall of the sun, with light and temperature influencing changes throughout the year. Birds are the clearest manifestations of these changes, he said.
“We know that the time of morning is punctuated by the singing of birds,” he said. “We talk about the first robin of spring. We know it’s fall because the Canada geese are starting to migrate. The annual clock of birds is a bellwether for the timing systems of all organisms.”
Cassone is speaking this week in Vancouver at the International Ornithological Congress, which coincides with the public Vancouver International Bird Festival. Visit iocongress2018.com and vanbirdfest.com for more information.
Climate change has the potential to fiddle with these clocks, with the outcomes varying by species.
“There’ll be winners and losers,” said Cassone, noting this is also a cautionary tale for human survival. “Climatic changes that we may see in the migratory patterns of birds ... those are canaries in a coal mine. When those start changing, we need to know what’s changing for us.”
Examples could include reduced productivity in agricultural harvests or commercial fishing catches, he said.
If the photoperiod suggests spring is coming, and the temperature suggests spring is here because it’s warmer, it’s possible that flowering plants and insects may emerge earlier, causing birds to breed earlier, and perhaps starting to sing in February, Cassone continued.
In Kentucky, introduced house sparrows are taking advantage of a warming planet to breed three to four times per year compared with about twice in the past, while species such as wood thrushes and bluebirds are in decline due to shrinking food sources, he said.
“Generalists do very well, they ’ll eat anything. Specialists in environmental times tend to do poorly or have to move to different latitudes or altitudes.”
Birds that travel on vast northern migrations with short breeding periods could be at risk. For ocean-ranging pelagic birds, their food sources might have moved to another location.
Another threat is the spread of avian malaria from tropical areas under a climate-change scenario, “marching to the poles, away from the equatorial regions,” Cassone said.