Working at a bird banding station in Louisiana catching birds coming across the Gulf of Mexico, Jaclyn Smolinsky remembers one day leaving a site where they caught 300 to 400 birds and looking up at a tree where birds had chosen to rest and thinking that it looked like a Christmas tree.
“There was a red bird in it, a blue bird, a yellow bird, a green bird – all these different colored birds – and I just thought, ‘This is so cool that these birds just arrived from a flight that probably took about 17 to 37 hours. This is so amazing.’ From that point on, I wanted to study migratory birds in any capacity,” said Smolinsky.
Now a research associate in the aeroecology laboratory of Jeff Buler, assistant professor in the University of Delaware’s Department of Entomology and Wildlife Ecology (ENWC), Smolinsky has gone from tracking migratory songbirds at stopover sites in the field to following their activity and departures at stopover sites using weather radar.
“It’s staying with the same birds and using the radar technology so it’s really related to what I used to do except I don’t see the birds and put little tags on them any more, I just use the radar to study them. It’s sort of transitioned from actual birds to dots on a screen. But they’re still birds,” said Smolinsky. “I’m drawn to this side of it because there are so many cool technologies available now.”
In Buler’s lab, Smolinsky explained that they are using weather radar to identify areas that birds are consistently using – areas in high densities during their migration that would be targets for conservation.
“We’re trying to identify these areas that birds are consistently using in to be able to say, ‘Hey, this is an important place,’” said Smolinsky.
Sometimes on their migration south, however, birds will just take what they can get with regard to habitat, as evidenced by an area like Central Park in New York City.
“Whether or not it’s necessarily good habitat is a whole other story. In New York City, there’s a ton of birds that use Central Park. That might not necessarily be because it’s such great habitat but because all around it there’s nothing else for them to use. There can be these sorts of migrant traps, so to speak, that concentrate birds but don’t really provide great resources,” said Smolinsky.
This leads to an interesting phenomena of birds that are flying south for the winter actually making detours north and inland, which Smolinsky said could be to look for better foraging grounds.
Interestingly, Smolinsky said, a bird departing southern Alabama might head north on Oct. 1 but be found in the Yucatan six days later.
One bird in particular that has been tracked doing this is the red-eyed vireo, which will go north to a bottomland hardwood forest location to forage and then fly south.
The red-eyed vireo research was featured in a recent paper on which Smolinsky was a co-author published in the Proceedings of the National Academy of Sciences. The paper was titled “How Fat, Weather and Date Affect Migratory Songbirds’ Departure Decisions, Routes, and the Time It Takes to Cross the Gulf of Mexico.”
The research was led by Jill Deppe, associate professor in the Department of Biological Sciences at Eastern Illinois University, and Smolinsky’s role in the study came when she did her master’s work at the University of Southern Mississippi with Robb Diehl and was a part of Frank Moore’s Migratory Bird Research Group.
Looking at three species of songbirds – red-eyed vireo, Swainson’s thrush and wood thrush – the research team used automated radio telemetry to track the species from coastal Alabama to the north Yucatan Peninsula during their fall migration to investigate the birds’ decisions made when navigating the Gulf of Mexico and the consequences, which had been virtually unknown to that point.
The results of the paper determined that large fat reserves built up in the birds and low humidity, which indicates beneficial weather patterns, made for a more favorable journey southward across the Gulf of Mexico.
Smolinsky said that the fat reserves are hugely important for birds to make a successful crossing.
“There’s no island oasis in the Gulf of Mexico to refuel so once they fly south and they’re doing it, they kind of have no choice and it’s a risk. If they hit a rainstorm or something like that, a lot of birds will land on oil or natural gas platforms that are out there, and they use them to rest. Sometimes they don’t make it if they don’t have enough fat,” said Smolinsky.
The researchers also found that age was not related to departure behavior, arrival or travel time and that vireos negotiated the Gulf of Mexico differently than thrushes, which the paper noted could be attributed to defense of wintering territories by thrushes and not by foraging habits.
Article by Adam Thomas