How climate change is impacting this iconic Florida bird species

Global warming is impacting a one-of-a-kind bird species in Florida in a way that is surprising ornithologists, a study found.

Populations of the Florida scrub-jay, the only bird found solely in the state, have been declining significantly since researchers began studying them in 1969 due to habitat loss from rapid housing development in the last half-century, John W. Fitzpatrick, emeritus director of the Cornell Lab of Ornithology at Cornell University, told ABC News. But climate change is further complicating the survival of the threatened species.

Florida scrub-jays are now nesting one week earlier than they did in 1981, according to a study published recently in the journal Ornithological Advances. While longer breeding times typically lead to higher populations of birds, the number of offspring of the Florida scrub-jay has decreased by 25% since 1981, according to the paper.

"The intriguing thing about what's going on with the Florida scrub-jay is that for most birds, breeding earlier in the breeding season is an advantage," Fitzpatrick said.

Researchers hypothesize that the warmer temperatures are making the jays' nests more susceptible to predation by snakes for a longer period of the Florida spring than in the past. The birds are building nests and laying more eggs after nests are lost to predators, "until they finally give up," said Fitzpatrick, co-author of the paper.

From 1981 to 2018, the average winter temperature at Archbold Biological Station near Lake Placid, Florida, increased by 2.5 degrees Fahrenheit, the researchers found.

The scrub-jays used to nest in mid-March, but the nesting period has shifted to late February, giving snakes a longer amount of time during the spring season to feed on the nests.

So while warm winters are leading to an increase in reproductive efforts, they are having lower reproductive success, the study found.

An estimated 100,000 to 150,000 scrub-jays were distributed all over the state before widespread housing development, Fitzpatrick said. That number has dwindled to about 5,000 to 6,000 individual scrub-jays scattered throughout the state, mainly in the Ocala National Forest in central Florida, he added.

The birds nest in the stunted oak vegetation that sprouts in spots where old sand dunes have left large sand deposits, Fitzpatrick said.

"Today, those sand dunes are mainly covered with people and houses and orange groves and theme parks and golf courses," Fitzpatrick said, adding that being low to the ground makes them a prime target for Florida's plentiful snake population.

The species, federally protected under the Endangered Species Act, is considered one of the most intelligent among birds, and scrub-jays have "exceptional" spatial memory, Fitzpatrick said. They live in family groups and help defend the territory, and are a prized viewing for avid birdwatchers, he added.

But climate change could dampen the success of conservation efforts for the species.

"Even in permanently protected areas like Archbold [Biological Station], jay populations face ever-worsening odds of persistence," Sahas Barve, lead author and director of avian ecology at Archbold, said in a statement. "We've spent decades managing habitat for the Florida scrub-jay, but there is one thing we can't control and that is climate."