Study: Keys ospreys may not merit special status

Florida Keys ospreys, the winged raptors that thrill visitors and terrify shallow-water fish, could lose a special state protective status.

Monroe County’s population of ospreys has been designated as a Species of Special Concern since 2011 based on the possibility that Florida Bay and Keys ospreys may be a distinct subspecies that choose not to migrate and tend to have a mating and breeding cycle earlier in the year.

Florida Fish and Wildlife Conservation Commission board members, meeting Monday and Tuesday at Orlando’s Orange County Convention Center, will vote on whether to start a review process “to determine whether it is appropriate to remove the [Monroe County] osprey from the list of Species of Special Concern.”

A 2016 study by FWC biologists “concluded that ospreys in southern Florida are not genetically distinct from ospreys elsewhere in the state,” wrote Craig Faulhaber, the FWC’s avian conservation coordinator.　

“Although the osprey population in Monroe County continues to decline, the overall Florida population is stable or increasing,” Faulhaber wrote. “Based on new genetic analyses, a re-evaluation of the listing status of the osprey in Monroe County is warranted.”

The Special Concern designation applie to species that may merit endangered or threatened status but that have not been studied extensively enough to ascertain whether they qualify. Killing or harming a Special Concern animal could be prosecuted as a third-degree felony under state law.

“We would be concerned about this de-listing,” said Pete Frezza, Everglades Region research manager for Audubon of Florida. “We have a unique sub-population of osprey living in the Keys. They have characteristics and traits of ospreys found nowhere else in North America.”

Frezza said, “Large fish-eating water birds such as herons, brown pelican, eagles and osprey have all experienced population decline in recent years. This is almost certainly due to an inability to find adequate prey during nesting time.”

If removed from the Special Concern status, ospreys will remain among 800 species listed under the federal Migratory Bird Treaty Act, which imposes a misdemeanor count for harming them with penalties up to a $15,000 fine and six months in jail.

Osprey numbers in Florida and nationwide generally have “increased significantly” from a worrisome low population in the early 1980s to an estimated 310,000 individual birds in the United States and Canada. “Ospreys are widespread in Florida, and the state contains two of the densest breeding colonies in the world,” the FWC report says.

“In contrast, the resident southern coastal osprey subpopulation has declined steadily since the early 1970s,” it continues. “The number of breeding pairs in Florida Bay declined 58 percent from 1973 to the early 1980s.... More recently, osprey in Florida Bay declined from 136 pairs in 1980 to 60 pairs in 2007, a 56 percent decline.”

Overall, there now may be 100 to 150 osprey mating pairs in the Keys and Florida Bay, according to the FWC.

“The decline is not well understood but is likely tied to the health of the Everglades ecosystem,” the report says. “It is possible that the observed decline in Florida Bay is due to food stress.... Hypersalinity from reduced freshwater inflow into Florida Bay may be responsible for reduced availability of prey.”

Biologists also expressed “concern regarding exposure to heavy metals” due to eating contaminated prey fish. A 2017 statewide study “found that mercury concentrations in nestlings were highest in coastal areas of Collier and Monroe counties.”

The biological review recommendation currently is listed for the FWC’s consent agenda.

This story was originally published July 8, 2017 at 8:29 AM with the headline "Study: Keys ospreys may not merit special status."