FWC identifies sickness that killed threatened black skimmers on Marco Island
This summer, more than 100 young seabirds were found sick and dying from an unknown illness on Marco Island, and a state agency finally has some answers.
The juvenile black skimmers, a state threatened species, were displaying swollen leg joints and were unable to walk or fly, Florida Fish and Wildlife Conservation Commission spokeswoman Michelle Kerr wrote in an email.
“Any skimmers found alive but sick in the colony were taken to licensed and permitted wildlife rehabilitation facilities,” she wrote. “Veterinary staff diagnosed bacterial arthritis in several of the admitted birds.”
Skimmers are named for the species’ unique feeding technique. The birds fly low and skim the water’s surface with their lower bill, catching bait fish along the way.
The birds generally nest in colonies along beaches with the largest colony in Florida residing on Marco Island.
FWC sent some specimens to the Southeastern Cooperative Wildlife Disease Study at the University of Georgia for examination. Veterinarians there diagnosed the birds with bacterial dermatitis, tendinitis and osteomyelitis, Kerr wrote.
Bacterial dermatitis is a skin infection, tendinitis is an inflammation of the tendons, and osteomyelitis is an inflammation of bones.
The vets also found a suite of bacteria in the birds including: Staphylococcus aureus, which is typically found in the upper respiratory tract and skin of humans that can cause osteomyelitis; Serratia marcescens, which is commonly found in the respiratory and urinary tracts of humans; Escherichia coli, which is found in the lower intestines of warm-blooded animals; and Pseudomonas aeruginosa, which is found widely outdoors.
FWC confirmed that adult black skimmers did not display the same symptoms as the chicks and fledglings.
“While these tests confirmed the cause of mortality in the young skimmers, the source of the pathogens is presently unknown,” Kerr wrote.
During a Nov. 18 Marco Island Beach and Coastal Resources Advisory Committee meeting, Adam DiNuovo, a seabird biologist with Audubon Florida, spoke about the black skimmer deaths.
DiNuovo said he started seeing birds with swollen ankle joints. He estimated two-thirds of the colony's chicks were affected.
"We did some tests on those birds and the necropsy showed septic arthritis in the joints," he told the committee.
Due to funding limitations, he said, the genetic testing needed to determine where the bacteria came from is not feasible. He also said that more robust water quality testing in the area could help determine the bacteria source.
"It could be a leaky pipe somewhere that nobody knows about," he said.
Brad Cornell, policy director with the Audubon of the Western Everglades, said the mortality event this past summer is an important conservation issue.
“Coastal birds are threatened for lots of reasons from sea level rise to erosion. It’s tough raising babies around the beach,” he said. “Marco is one of the biggest colonies in the whole state. To have that kind of a die off is a real hit.”
Cornell said the dead birds were found thorughout the summer, so the more than 100 dead were not found all at once.
Cornell likened the bacteria findings to harmful algal blooms, saying wildlife can act like the canary in the coal mine — alerting of potential risks to people.
“Anytime bacteria are killing wildlife or in the water where humans are, we should be paying attention and doing what we can to diagnose the problem,” he said. “I think this is taking a little too long, but FWC is working hard and we appreciate that.”
Karl Schneider is an environment reporter. Send tips and comments to firstname.lastname@example.org. Follow on Twitter @karlstartswithk