LOWER KEYS — The population of federally-protected Key deer spread out between 11 different islands is roughly 875 following an outbreak of the flesh-eating New World screwworm, according to a study completed last week.
Roel Lopez, director of Texas A&M’s Institute of Renewable Natural Resources, was behind the research to determine the herd’s current size. He has been studying Key deer for almost two decades. What he found in the data left him optimistic.
“This looks promising from a population perspective,” Lopez said last week.
According to the study, the Key deer population has been increasing by roughly 3.5 percent annually since data was first collected on the herd in the early 1970s. Lopez noted, however, that that percent will drop for 2016 due to deaths related to the outbreak.
As of Friday, according to U.S. Fish and Wildlife Service, the number of Key deer either euthanized or found dead due to screwworm infestation was 132 — with 121 being adult males. This spans back to July when the suspected, and later confirmed, parasite was first discovered in the Keys, after no sightings of it in the U.S. had happened for over 30 years.
But the Lower Keys herd, diminutive cousins of America’s white-tailed deer, will more than likely bounce back, according to Lopez.
“The timing couldn’t have been better,” Lopez said. “Males are the most expendable.”
Lopez referenced the fact that the outbreak occurred during the peak of mating season, during which adult males fight with each other to determine dominance over a territory occupied by an adult female. This causes the antlered males to suffer wounds, which creates openings where screwworm larvae like to burrow. If the outbreak would have occurred during the peak of birthing season, typically April through June, Lopez said that could have had a devastating impact on the population by killing female deer and their fawns.
“Emphasis is always placed on the females,” Lopez said.
Duke University wildlife extinction ecologist Stuart Pimm and University of Wisconsin-Madison wildlife ecology professor Timothy Van Deelen both previously offered the Free Press similar views on the importance of females over males in maintaining a healthy deer population.
In his study, Lopez determined the number of mating females on Big Pine and No Name keys — where the majority of the herd lives — as well as how many males would be required for the population of the endangered species to remain sustainable.
For Big Pine, only 34 males are needed for the 342 breeding females. For No Name, of the 36 breeding females, only four males are needed. These numbers assume that one male will mate with 10 females, which Lopez said isn’t a stretch.
Lopez also said in the study that the current female-to-male population ratio is 4-to-1. Before the outbreak, it was closer to 2.5-to-1.
“From a viability perspective, this is all OK,” Lopez said.
Previous estimates by the U.S. Fish and Wildlife Service had the Key deer population at somewhere between 1,000 to 1,200. That data dates back to around 2005, according to Lopez. The most recent population study was done due to the outbreak die-offs. Lopez said before this most recent event there wasn’t a need to know specific numbers as the population had been steadily rising.