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Dead Palms Or Home Sweet Home? Just Ask The Woodpeckers

Maureen Tan/Fairchild Tropical Botanical Garden
Environmental ecologist Josh Diamond shows an image taken from inside a palm tree cavity made by woodpeckers.

Sometimes the best science comes from an idle, casual observation. Take Isaac Newton. Or Josh Diamond.

Diamond was finishing his doctoral degree in environmental science at Florida International University in 2017, commuting by bike, when he began noticing near-perfect round holes in dead palms. The fastidious carpenters, it turned out, were South Florida woodpeckers.

Like any good scientist, he wondered why woodpeckers would choose dead palms over pines, live oaks or other branching trees normally preferred by the birds. What he found was a gap in the science.

“We don't really know as much about the urban habitats of woodpeckers [or] the tropical part of Florida, where our tree composition gets very, very different from the rest of the lower 48,” Diamond said.

Credit Joshua Diamond/Florida International University
Macaws nesting in woodpecker holes on a dead palm.

So he started counting. In a paper published in August in the journal Urban Ecosystems, he reported that of more than 1,800 nests he found, most woodpeckers chiseled their tiny burrows in dead palms.

His conclusion? The birds had adapted to the heavy urbanization of South Florida, where the piny ridge and hardwood hammocks that separate the ocean from the Everglades have mostly been blotted out by development. Further north, the same birds nest in dead hardwoods and pine. But in South Florida, where the landscape has been dramatically altered by imported palms, the birds have found new habitat.

“Thanks to the landscaping trade, we have a tremendous number of introduced and exotic species, especially in our urban areas,” he said.

That led Diamond to his second conclusion: if South Florida can abandon its quest for perfectly manicured lawns, and leave alone dead palms that don’t pose a risk, woodpeckers could have a lot better chance at successful co-existence. And because of their role as one of the animal kingdom’s important carpenters, that could be a boon to even more animals.

Credit Joshua Diamond/Florida International University
Corn snakes find refuge in a woodpecker hole in the trunk of a dead palm.

In his surveys, Diamond discovered corn and rat snakes, opossums and squirrels. Bats, including Florida's endangered bonneted bat, can also use the holes, he said, as well as screech owls, bluebirds, nuthatches and exotic birds including macaws, starlings and mynas.

And that’s important because birds in general play an important role for ecologists looking for ways to save disappearing animals.

“They're colorful, they're noisy. They are above ground and above water, which definitely makes them easier to observe,” Diamond said. “So they lend themselves easily to questions of ecology and studying questions of how can we make our urban areas more friendly to animals.”

Florida has already lost most of its red headed woodpeckers, Diamond said. And the red-cockaded woodpeckers, which have both federal and state rules that legally require landowners to protect them, are down to 3 percent of their original population in the Northeast, with just over 1,300 clusters of the birds counted in Florida in 2000. The predominant woodpeckers that remain in South Florida include the red-bellied, pileated, downy and and the northern flicker woodpeckers.

Credit Joshua Diamond/Florida International University
Pileated woodpeckers nest in the trunk of a dead palm.

For the study, Diamond traveled from the Keys to Palm Beach, riding his bike around suburban neighborhoods and dense city streets like Biscayne Boulevard in Miami. He visited Everglades National Park, Big Cypress National Preserve and the Fakahatchee Strand.

Wherever he went, Diamond said people were usually fascinated by what he was doing.

“If I was just recording the nest for the first time, I'm on a bicycle and taking notes with a little pad of paper. So it only takes me two minutes to record a nest,” he said. “But when I come back with a 50-foot long, collapsible fiberglass pole, with a camera on top, that's when people would come up to me and ask what I was doing.”

A couple of times they invited him into their backyards to investigate a nest.

The woodpeckers chiseled holes primarily in royal palms, but also in foxtail palms, queen palms and cabbage palms, he said. It's not clear if the palms drew more woodpeckers because of their abundance or because property owners tend to leave dead palms around longer than other trees with more branches and more hazards. Lawnworkers told him they dislike cutting down dead palms because they gum up chainsaws.

Credit Joshua Diamond/Florida International University
Baby myna birds in a palm tree cavity made by woodpeckers.

Red-bellied woodpeckers inhabited most of the holes, suggesting they had best adapted to urban surroundings. But he was also surprised to see how well pileated woodpackers, the largest in North America, were doing.

"They would do well even in urban areas like Greynolds Park," he said. "I saw those making cavities on Biscayne Boulevard."

Both are generalist, meaing they can live almost anywhere. That's unlike the rare red-cockaded woodpecker that lives primarily in pinelands. Another surprising find was the Northern Flicker. Their numbers are falling nationally and Diamond found them living only in the Everglades and Homestead, along the borders of developed areas. He's not sure why they don't share the adaptability of their cousins.

Diamond, who grew up in Washington D.C. and came to South Florida for his masters degree in 2012, is hoping the study adds another layer to a growing effort in urban conservation that makes way for animals in city life. 

“If you have a dead palm, and you live in Florida, and it's in your backyard and not reducing the curb appeal of your house, I would suggest leaving it,” he said. “The birds will appreciate it.”