Florida veterinarians manage migratory mortality
It’s a long, hard journey from South Africa to Canada. By plane the trip on South African Airlines from Cape Town, South Africa, to Halifax, Nova Scotia, takes three flights, all day and costs more than $2,000 a seat. The greater shearwater--an Atlantic sea bird--makes the more-than-9,000-mile trip every year. But some birds don’t make it. Last week, the Florida Fish and Wildlife Conservation Commission reported 254 recorded deaths as the colonies of birds made their way north over the Atlantic Ocean.
“They’re migratory; they don’t even stop here,” says Dan Wolf, DVM, a veterinarian with the Florida Fish and Wildlife Conservation Commission. “They fly north to Canada and basically do a figure eight in the Atlantic staying off shore the whole time.”
Last week some of these birds--both deceased and in an extremely weakened state--began washing up on Florida’s eastern shoreline. St. John’s Veterinary Hospital in St. Augustine, Fla., started seeing birds on Tuesday; by Thursday the practice had taken in 14.
“Most of them were brought in alive, but none of them made it,” says Kathleen Deckard, DVM. “They just didn’t have enough left in them.”
Deckard treated the birds by placing them in incubators, rehydrated them with fluids and gave them food with a stomach tube. But some didn’t even survive long enough to receive treatment.
“This time every year we see a normal mortality,” Wolf said. “(They’re) immature, first-year birds that just don’t have enough gas to get back up to Canada.”
Wolf had 18 dozen birds shipped to his office in Tallahassee, Fla. He examined half the birds; every one was an immature bird.
“They don’t have any stores of energy to start with,” Deckard says of the young birds. “They’re getting hypoglycemic, which makes them feel weak and tired. They’re fighting wind and heavy seas ... mostly what they’re experiencing is fatigue. They just completely run out of any fat in their body to survive. There’s no place to rest.”
Wolf says the majority of the colony does make it north, but if a bird isn’t an effective hunter or if there’s a storm, those factors can mean life or death, especially for young birds. Both veterinarians suspect the mortality rate from such a journey is fairly high. Whether they see the birds weakened or deceased on shore depends largely on weather patterns.
“This is actually a smaller amount than we’ve had in previous years,” Wolf said. “We had around 1,000 wash up in 2007.”