1:10 A.M. — Wildlife researchers recovered the carcass of a Florida panther Thursday in Collier County, bringing this week’s body count for the endangered species to three.
The panther recovered Thursday, a 1 1/2-year-old female, is the 23rd documented death this year, two short of the record set in 2007.
This year, 16 panthers have been killed by vehicles; six, including the most recent cat, have been killed by other panthers; the cause of one death is unknown.
Panther mortality has been high over the past four years: After the 2007 record, which included 15 roadkills, there were 23 documented deaths in 2008 (10 roadkill), and 24 in 2009 (a record 17 roadkill).
Biologists estimate the panther population at 100 to 120, so about 20 percent of the population is dying every year.
Over the same time period, however, researchers have documented the births of 96 panther kittens — this number only includes kittens from females wearing radio collars.
“You have to take into account recruitment,” said Dave Onorato, a research scientist with the Florida Fish and Wildlife Conservation Commission’s panther section. “There are a lot of uncollared panthers, and some of those are producing kittens. The counts we do every year show the population is hovering around 100. It’s stable. We’re not seeing anything in the counts that show the population is crashing.”
The story of the Florida panther population is one of collapse and rebound.
A subspecies of the cougar, Florida panthers once ranged through South Carolina, Tennessee, Georgia, Mississippi, Alabama, Arkansas, Louisiana and Texas.
Over the years, development destroyed panther habitat, and the whole population was forced into South Florida.
As population and range shrank, panthers started inbreeding, and subsequent generations developed genetic abnormalities, including reproductive problems and heart defects.
By the early 1990s, the population was 20 to 30.
To beef up numbers and improve the gene pool, in 1995, eight female Texas cougars were introduced into South Florida to breed with Florida panthers.
Since then, the population has more than tripled and genetic defects have largely disappeared.
More panthers, logically, means more panther deaths every year.
It also means more panther roadkill: From 1972 through 1999, 30 panthers were killed by vehicles; since 2000, vehicles have killed 148 panthers.
“There’s a correlation with the number of cars: How many people were in Florida in 1972?” Onorato asked. “And panthers are moving. Because the population has increased since 1995, they’re moving into areas where there are more roads.”
The one proven way to limit vehicle-related deaths is to build wildlife crossings under roads.
“It’s tough because of how expensive crossings are,” Onorato said. “We’re always going to have problems with roads and panthers. Florida is highly developed, and we can’t fence every road.”
South Florida has reached its carrying capacity: The area can’t support any more of the species.
A few male Florida panthers have crossed the Caloosahatchee River, but for the population to increase, females must cross the river, too — no female panther has been documented north of the river since 1972.
“The limiting factor is for females to get antsy and swim across the ditch to establish a breeding population,” Onorato said. “We hear people say there are lots of panthers up there, and they’re producing kittens. But the data says, if they’re reproducing, there would be dead kittens on the road. We haven’t seen that.”
State and federal agencies, along with environmental groups and landowners are working on a panther conservation plan that would be a framework for protecting panthers on 200,000 acres in eastern Collier County, said Paul Souza, field supervisor of the U.S. Fish and Wildlife Service’s South Florida office.
“It’s important for people to understand how endangered this animal is,” Souza said. “We saw the population increase after 1995. That was the first step. Many steps — wildlife crossings, partnerships with landowners, science — are essential for the conservation of this species.”
FLORIDA PANTHER FACTS
• Scientific name: Puma concolor coryi
• Taxonomy: The Florida panther is a subspecies of the cougar, also known as mountain lion, puma and catamount.
• Status: Endangered
• Population: 100-120
• Distribution: South Florida
• Habitat: Hardwood hammock, pine flatwoods, saw palmetto and cabbage palm thickets, cypress forests, mangrove forests and freshwater marshes.
• Home ranges: Male panthers have home ranges of 150 to 200 square miles; a female’s home range is typically about 80 square miles.
• Size: Males average 130 pounds and measure 6 to 8 feet from nose to tip of tail; shoulder height is 2.6 feet. Females average 80 pounds and measure 5 to 7 feet with a shoulder height of 2.2 feet. Kittens weigh 4 to 8 ounces at birth.
• Diet: Whitetail deer, feral hogs, raccoons, armadillos and small alligators.
• Reproduction: Males reach maturity at 3 years. Females reach maturity at 11?2 years and breed throughout the year, with peak breeding in the spring. Gestation is three months. Typical litter size is two kittens, which leave the den at 2 months and are fully independent at 11?2 years.
• Life span: 8 to 15 years in the wild, 10 to 20 years in captivity.
• Threats: Habitat loss is the main threat to the subspecies. The leading cause of death is collisions with cars; other causes of death are one panther killing another and disease.