Drone surveys Caloosahatchee River wading bird rookeries for Audubon, estuary program
Members of the Charlotte Harbor National Estuary Program were testing a drone camera to improve the nesting bird counts on rookery islands.
It rises vertically, buzzing like a beehive.
But before long, you can’t hear the quadcopter drone: The sound of hundreds of nesting birds it’s surveilling is more powerful.
The drone, piloted by Fort Myers ecologist Church Roberts, is photographing and videoing nests and breeding pairs on the Caloosahatchee River.
He recently surveyed the rookery on little Lenore Island, two miles downstream from Interstate 75 on the Caloosahatchee River.
Ecologist Church Roberts is piloting a drone to survey wading bird nests and breeding pairs on Lenore Island in the Caloosahatchee River, near Fort Myers, Florida. This is a video clip from the survey. His consulting firm, Church Environmental, earned a grant from the Charlotte Harbor National Estuary Program to do this work. CHURCH ROBERTS/CHNEP
Roberts, who’s also an FAA-licensed operator, got a grant from the Charlotte Harbor National Estuary Program for the survey and to fly its drone, which ultimately will yield counts for use in wildlife education and policy proposals.
He’s partnering with Audubon of the Western Everglades, which is providing a boat and a skipper, free of charge.
“Surveying nesting activity is important not only for protecting the birds and their habitat but also for the fish and waters they rely upon,” said Jennifer Hecker, CHNEP executive director.
“We’re looking for trendlines,” said Pete Quasius, the Lee-County-based Audubon lobbyist who’s ferrying Roberts and the drone to the rookery islands.
Wildlife scientists are increasingly using drones to gather data.
Traditionally, ecologists have looked for good vantage points to observe a flock, and use binoculars and other basic tools to estimate its size.
It's often easier to get a good count by airplane, perhaps even using aerial photos. But this can be costly.
Drones seem a good compromise. They provide a better view than a land- or boat-based observer. They can capture photos and videos for later analysis.
Unlike airplanes, drones are relatively small and quiet, reducing the risk of spooking the birds.
And, at least one study suggests drone-based counts are more accurate than traditional methods.
In February, a study published in the journal Methods in Ecology and Evolution was dubbed #EpicDuckChallenge, and grabbed mainstream media attention,
Researchers in 2016 spread a few thousand rubber ducks on a beach in south Australia, organized in colonies. They had one group of veteran wildlife-spotters count birds using binoculars and another group count birds in aerial photographs captured by drones.
The drone-human approach yielded the more-accurate counts.
It's possible drones could disturb birds; however, if used responsibly “they are far less intrusive and less likely to cause disturbance” than boat-based surveys where spotters must fight the temptation to get too close, Hecker said.
In the Caloosahatchee surveys, Quasius checks bird behavior when Roberts is piloting the drone over a rookery island.
“The birds just ignore it,” Quasius said after two drone-survey outings to Lenore Island.
If a bird should flush – meaning it abruptly flies away – chances are good the nest-spotters are too close.
There’s still a lot of coming and going on a rookery island, however.
“The parents are hard-working. They constantly bring food to their young, and then turn around and go back to get more,” Hecker said. She recently accompanied Roberts and Quasius on their first Caloosahatchee survey trip using the drone.
The drone produces movie-grade video that allows scientists to zoom-in via computer – allowing the drone to be used from a greater distance than in a boat-based survey in which surveyors employ binoculars and spotting scopes.
The drones also can view areas and features not accessible by boat.
On his second drone-based survey of Lenore, Roberts photographed wood storks, roseate spoonbills and great egrets.
He got photos of spoonbill nests – some near a pond nestled inside mangroves or tucked into trees – that were too low to be visible from Quasius’ pontoon boat.
Lenore Island first gained prominence 23 years ago, when The News-Press reported that, for the first time on record, endangered wood storks were using this island as a nesting site.
Bird experts rejoiced over the nests spotted on Lenore Island in the summer of 1995. The news wasn’t so good at Corkscrew Swamp Sanctuary in Collier County, where heavy rains slashed the number of active wood stork nests.
Fast-forward to the present.
“What we saw this year was pretty phenomenal, compared with years past,” Quasius said.
After a string of bad nesting seasons, great egrets, white ibis, wood storks and other wading birds in the heart of the Everglades started to rebound in 2017.
Many of the birds produced some of their healthiest nests in a decade, fledging tens of thousands of chicks. That’s according to South Florida Water Management District's annual wading bird report that came out this month.
However, the same report showed wading birds still struggling to breed in the disappearing shallow wetlands near the Big Corkscrew Swamp and coasts of southern Florida.
The district studies the nesting success of wading birds because ecologists believe the species are among the best indicators of the health of the water system.
The birds rely on natural patterns of rain and drought, needing long wet seasons for prey fish to multiply and grow in the swamps, followed by dry spells that concentrate those fish into smaller pools to make them easier to catch.
Drone data from Lenore Island has yet to be analyzed. The results will go into a report that's part of the estuary program-funded study. Ultimately, the estuary program will keep the databases, which will be public records.
The estuary program is a nonregulatory, public-private partnership working to protect estuaries and water resources in Lee, Charlotte, Sarasota, Manatee, Polk, Hardee and DeSoto counties.
Monitoring bird nesting is one small sliver of the activities it supports.
Hecker said her organization is working with staff at Charlotte Harbor Aquatic Preserve to explore conducting a similar study of rookeries there that would also use drones.
“If we don’t know the ecological health of an estuary,” Hecker said, “we can’t provide information to resource managers and policymakers, to protect it."