Category Archives: Terrestrial Mammal Research

Floods, Fires and Hurricanes

By Elina Garrison

In 2015, FWC and other agencies partnered with the University of Georgia and Joseph W. Jones Ecological Center to begin “The South Florida Deer Research Project” in Big Cypress National Preserve (BCNP) and Florida Panther National Wildlife Refuge (FPNWR). One of the main objectives of the study is to understand how hydrology, fire and predators impact deer populations in the unique South Florida system. To date, the team has captured close to 300 deer and fitted 263 adult deer with GPS radio-collars, yielding over 548,000 locations. In addition, three camera grids containing a total of 180 remote-sensing cameras were deployed to monitor deer and other species. Thus far, the team has recorded and cataloged over 360,000 photos. The study was designed to include four years of field work in an effort to capture seasonal and annual fluctuations in weather, predation, and hunting pressure. However, none of us would have expected to capture the weather extremes we have thus far!

In winter 2016, a normally dry season turned into a record-breaking high water event. By February the water stage was over 12 inches above normal and exceeded the prior winter flood record of 1995. We documented unusual deer movement activity, for example, the number of deer detections in our camera grid in FPNWR more than doubled as deer from lower elevations moved to higher ground. Luckily, the duration of the winter 2016 high water event did not last as long as it had 1995.

January in Florda is typically in the middle of the dry season. However, in 2016, an unusual amount of rain caused record flooding throughout our study area.

In March 2017, one of the largest wildfires in Florida started in BCNP. It would eventually burn over 21,000 acres, including an area that contained one of the project’s camera grids and numerous collared deer. No mortalities of collared deer occurred due to the fire and interestingly, deer stayed within their established home-ranges as the woods around them burned. Furthermore, collar data demonstrated deer in proximity to the burn moved into the burned landscape shortly after.

June 2017 brought another flooding event; more rain fell in three days (over 15 inches) than had in the previous 36 weeks, breaking another record. In some areas of BCNP, the water level rose five feet in three days.

Just two days after the large Cowbell Fire burned through much of North Addition Lands, one of the GPS-collared female deer emerges from the burn with another deer.


The most recent event, Hurricane Irma, just occurred. The eyewall of this massive hurricane came within 25 miles of our study site. None of the collared deer died during the hurricane, and preliminary data indicate some that deer moved into pine flatwoods and tropical hammocks, but overall movement rate did not decrease during the storm.

These “record-breaking” events make field work difficult, but they give us insight into impacts of weather extremes that may become more common in the future. The data gathered, both through telemetry and remote cameras, will allow us to analyze how these extreme events impact deer survival, movement, habitat use, and recruitment of fawns, and other aspects of deer ecology. In addition, although the study is focused on white-tailed deer, the cameras capture all wildlife that use these areas, allowing us to examine the effects of extreme weather at a community level.

For more information and quarterly updates, please visit the South Florida Deer project website.

Monitoring reproductive characteristics of male Florida panthers to assess genetic introgression

by Dave Onorato

sperm under microscope
Sperm abnormalities noted in Florida panthers include partial mid-piece aplasia (left) and tightly coiled tails (right).

One of the first clues that helped FWC panther researchers conclude the remnant population of Florida panthers was in peril over 30 years ago was the preponderance of so-called correlates of inbreeding depression.  Among these were several that could directly impact the fitness of individuals, hence increasing the probability of extinction of this endangered animal.  Of particular note were attributes of the male reproductive system documented in the 1980s and early 1990s that revealed panthers had the poorest sperm quality (see photo above) of any wild felid at that time. Males were also frequently unilaterally or in some cases bilaterally cryptorchid, the latter being effectively sterile.  These early findings played an important role in the decision making process to implement the genetic introgression program in 1995, which involved the temporary release of eight female pumas from Texas into the wilds of south Florida to mimic historic gene flow.


Male Florida panther in the Picayune Strand State Forest east of Naples, Florida. FWC staff and collaborators at SEZARC have examined male reproductive characteristics from >200 panthers since 2000.


Genetic introgression had a significant impact on improving male reproductive performance.  For instance, in the ensuing 15 years, only 10 percent of male panthers examined were cryptorchid in comparison to 66 percent during the pre-introgression period.  Staff continue to collaborate with Dr. Linda Penfold at the Southeast Zoo Alliance for Reproduction and Conservation (SEZARC) on male panther reproduction research.  Staff collect testicles during necropsy and ship them to Dr. Penfold’s lab where sperm quality and quantity analyses are conducted.  In some cases, sperm has been banked, something that could prove useful for genetic management of the population.  The long term data we have originate from a period when the population was undergoing a severe bottleneck through a stage of population expansion.  These data provide us with valuable information to assist with making informed decisions regarding the implementation of future genetic introgression programs should they be warranted.

The South Florida Deer Research Project  

by Elina Garrison

deer with radio collar
Monitoring deer through wet and dry seasons allows us to better understand how annual and seasonal hydrological changes impact deer movement, habitat use and survival.

Throughout the state, white-tailed deer (Odocoileus virginianus) are one of the most valued and sought-after game species. In South Florida, deer are also the most important prey species of the endangered Florida panther (Puma concolor coryi).  In recent years, particularly in the southern portion of the Big Cypress National Preserve (BCNP) and Everglades National Park, the area has experienced deer declines. Previous deer research in the BCNP region dates back to the early 1990s. Since that time, the area has changed significantly, including hydrological changes, an increase in the panther population, and changes in other predator populations. Therefore, there was a need for up-to-date information on deer survival and causes of mortality to better understand deer ecology in South Florida. In addition, there was a need for a cost-effective monitoring methodology for more reliable deer density estimates to guide long term management.

panther on trail
The team has deployed 180 trail cameras throughout the study area. The cameras are used to develop a new survey technique for deer, but also to capture activity and other important information for a variety of wildlife species, including Florida panthers.

To address these research and management needs, FWC partnered with the University of Georgia and other agencies to begin a large-scale, multi-year study called “The South Florida Deer Research Project.” Since 2015, the team has captured and fitted over 200 deer with GPS collars in the Florida Panther National Wildlife Refuge and Bear Island and North Additional Units of BCNP. We are also using trail cameras, in combination with the marked deer, to develop a monitoring tool. In addition, cameras provide information on fawning period, recruitment, timing of antler casting, and activity patterns of deer relative to season, weather events, and human activity. The study will continue through 2018. For more information and quarterly updates, please visit the South Florida Deer project website:

Salt Marsh Mink Research

by Chris Winchester


floating camera trap
A floating camera trap used to detect Atlantic salt marsh mink

The Atlantic salt marsh mink (Neovison vison lutensis) is one of four subspecies of mink that occur in Florida. Historically, mink have been difficult to survey due to their secretive nature and affinity for remote salt marsh habitat. As a result, little information is available on mink distribution or specific habitat requirements in Florida. Current data on mink distribution and habitat use is required to evaluate population status and identify potential threats to habitat quality.

In 2014, FWC biologists evaluated the effectiveness of a floating camera trap to survey for mink in salt marsh habitat along the north Atlantic coast.  The floating camera trap, based on a design developed by University of Florida researchers, consisted of a trail camera attached to the inside of a seven-gallon bucket, which was placed onto a floating platform constructed of plywood and foam insulation.

Mink inside trap
Atlantic salt marsh mink inside of the floating camera trap

FWC biologists placed 269 floating camera traps in the salt marsh for 14 days each. Mink were detected on 50 camera traps (19%), confirming the effectiveness of the survey method. The data collected will be used to evaluate Atlantic salt marsh mink population status in Florida and determine the habitat needs of one of Florida’s most elusive mammals.

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Freeze frame – Estimating Florida panther population density via trail camera photographs

by Dave Onorato and Marc Criffield

Obtaining estimates of density or abundance for large carnivores that are rare, elusive, and inhabit remote wildlands has been a long standing challenge for scientists.  The FWC Panther Research Team, along with collaborators at the National Park Service and Conservancy of Southwest Florida, initiated a study in 2014 to estimate the density of Florida panthers in a 162 km2 section of the Big Cypress National Preserve north of I-75 (Alligator Alley).  Fifty passive infrared motion detecting cameras were deployed within a standardized grid across the study area from April to September 2014 to capture photographs of both marked (radiocollared) and unmarked panthers.  Cameras collected five photos in rapid succession when triggered by motion.  During the study period, 88,534 photos of wildlife were recorded.  The majority of photos were white-tailed deer and Osceola wild turkey.  Other species documented included river otters, feral hogs, Florida black bears, bobcats, coyotes, alligators, several species of birds, insects, herps, and panthers. Individual panthers are not reliably identifiable by their fur, unlike spotted or striped felids, hence our reliance on having a portion of the population marked.  In order to estimate density, photographs of marked and unmarked panthers will be analyzed within a spatial mark-resight (SMR) model that is based upon the framework of traditional mark-recapture analyses.  The SMR model utilizes the spatial component of marked panther encounter histories at known locations (camera sites) across the study area, counts of unmarked panthers at camera sites, and radio telemetry data from marked panthers using the study area, to derive a density estimate.  Results should help direct future research projects that utilize this study design to derive population densities across multiple study areas in order to obtain a range-wide population estimate for panthers with acceptable levels of precision.  Such estimates play a critical role in determining progress towards achieving recovery criteria established for the endangered Florida panther.