Why Are Black Skimmers Dying on Marco?

Black Skimmers (Rynchops niger) inhabit coastal areas in Florida such as estuaries, beaches, and sandbars. Marco Island has had the largest Black Skimmer nesting colony in Southwest Florida since 2017. They face many threats and habitat loss due to coastal development as their main threat. The Black Skimmer is protected by the U.S. Migratory Bird Treaty Act. It is also protected as a state threatened by Florida’s Endangered and Threatened Species Rule.

On Friday, July 30, 2021, I visited the Black Skimmer nesting colony, and saw chicks that are almost flight capable (fledged) by the water’s edge cooling off and others testing their flight feathers. I also saw deteriorated bodies of dead chicks scattered all over.

On July 21 and 22, 2021, Black Skimmer chicks on Sand Dollar Island were observed limping with swollen joints. Stewards brought several sick and dying chicks to the von Arx Wildlife Hospital. Birds were eventually sent to FWC for testing.

On July 22, 2021, Audubon, Florida issued a statement saying that they are actively monitoring the situation with both DEP and FWC.

On Wednesday, July 28, 2021, The Clinic for the Rehabilitation of Wildlife (CROW) on Sanibel Island issued this statement.

“Today, Sanibel-Captiva Conservation Foundation (SCCF) brought in eight Black Skimmer nestlings after they were found covered in sand spurs and displaying symptoms of septic arthritis. Sepsis in these birds affected multiple joints which led to bone destruction, severe swelling, pain, and redness. Since the beginning of July, we have admitted 14 Black Skimmer chicks with septic arthritis. 

All of the Black Skimmers treated so far this year have been admitted from the Fort Myers Beach area. Although it's a grave prognosis for these eight chicks, we are hopeful to continue collaboration with FWC and local area biologists to find out why these cases of sepsis are plaguing the Black Skimmer colonies.”

The presence of sand spurs in both Marco and San Carlos Point (SCP) on Fort Myers Beach location was also being scrutinized, but birds have had puncture wounds from sand spurs for many years. Adam Dinuovo responded that on Marco he handled skimmers with sand spurs from 2017 to 2019 while banding the birds, and most had wounds from sand spurs but no septicemia. Sand spurs are collected manually in each location while at SCP they also use a 30% vinegar solution to spot treat for sandspurs without the use of broadcast herbicide.

What are the similarities between Marco Island and San Carlos Point in Fort Myers Beach? SCP is managed by FWC with a full-time biologist monitoring the nesting colony.  SCP’s nesting colony is much smaller than those at Marco and had its first case of septic arthritis during the first week of July. Sand Carlos Point is posted just like Sand Dollar Island. It is a plugged salt water marsh (not free flowing) while Tigertail Lagoon is free flowing and has outfalls emptying into the lagoon.

On Friday, July 30, 2021, I had a conversation with Marianne Korosy, Director of Bird Conservation at Audubon, Florida with questions on water testing, tissue testing and timetable of testing results.

Korosy confirmed that on Marco, water samples have been collected by DEP, and FWC has contracted with the Southeastern Cooperative Wildlife Disease Study at the University of Georgia for the tissue analysis of dead Black Skimmers.

She also confirmed that the first step is figuring out if the same bacteria that’s in the water is also present in the dead chicks. The DNA analysis is very expensive, and they will need to identify who is going to do the DNA testing and who will pay for it.

DNA testing: Could this new approach be a game changer of enterococci testing and become part of beach and other recreational water monitoring programs? DNA testing will distinguish the source of the bacteria (whether it is from human feces) or harmless enterococci, or non-enterococci bacteria.

Last year on Marco, the birds died in late July and early August. FWC did not release the names of the bacteria till December 4, 2020. Dr. Korosy is hopeful that we will have the results much sooner.

While the public is concentrating on “what’s in the water that is killing the birds,” bacteria also may cause serious health issues in humans while in recreational waters around Marco Island. Is DNA sequencing the future of water quality testing and could it save the Black Skimmer colony on Sand Dollar Island?