Category Archives: Wildlife Research

Documentation of a Neuromuscular Disorder in Florida Panthers

By Dave Onorato, Lara Cusack, and Mark Cunningham

Florida’s panther has made significant progress towards recovery during the last 25 years.  One aspect of our research that has assisted with this improved outlook for panthers is our continual monitoring for signs of any disease issues that may surface in the population, since these have the potential to impact prospects for long term persistence.  During this period, a number of significant disease events have occurred, including infections with feline leukemia virus and pseudorabies virus.  In spring 2018, via a collaboration with members of the public and Corkscrew Swamp Sanctuary (CSS) in Collier County, the FWC Panther Team identified a litter of kittens on trail camera videos that appeared to have weakness in their hind limbs.  Subsequent deployment of additional video cameras in the area by FWC further documented the difficulties one of these kittens was having when trying to keep up with the dam.  

This neuromuscular disorder (termed feline leukomyelopathy [FLM]) has now been documented via necropsies in two panthers and a bobcat.  While the total number of panthers impacted is unknown, we have evidence that <10 are affected.  FLM presents as demyelination of portions of the spinal cord, brainstem, and cerebellum.  It is suspected that this impacts locomotion in the afflicted animals.  Since the initial documentation in 2018, FWC has ramped up monitoring and capture efforts in areas where we suspect FLM is affecting wild felids.  Documented cases have so far been restricted to Collier County, although video and photos suggest FLM may be present in other counties in SW Florida.  There are still many unknowns as to what might be the root cause of FLM; is it viral? congenital? is it related to the application of herbicides or pesticides?  Analyses on samples we have collected from afflicted felids have permitted us to determine that FLM is probably not congenital, as it has been documented in two species.  A viral component has not been ruled out.  Of particular interest is the plausibility of an environmental toxicant.  Since we’ve seen most cases of FLM present themselves in panther kittens, it seems reasonable that a toxicant may be more impactful on kittens as opposed to adults.  One thing is certain; demyelination resulting from FLM is permanent, so afflicted animals can’t recover.

The outpouring of public support has been amazing with regards to sharing videos and reports of animals appearing to have the same condition in Florida and beyond.  Furthermore, FWC has received offers of assistance from experts in veterinary medicine from around the globe in order to try and determine what is causing FLM.  Our long-term research and monitoring program has permitted us to identify this condition in a timely manner, something that could prove critical if FLM ends up being more widespread in Florida panthers.      

Florida Scrub Lizard Reintroduction in Palm Beach County

By Kevin Enge

In February-March 2019, FWC staff and volunteers collected 100 Florida scrub lizards (Sceloporus woodi) from two state parks in southern Martin County and released them in county-owned Hypoluxo Scrub Natural Area in central Palm Beach County.  The endemic Florida scrub lizard has been petitioned for federal listing as threatened, and an FWRI status survey conducted in 2017-18 determined that the southern extent of its range along the Atlantic coast now consists of two scrub preserves in northern Palm Beach County.  A 1986 status survey recorded the species from 15 of 16 sites visited in Palm Beach County and four sites in Broward County.  Since then, its range has contracted 77 km northward along the coast.  The species is still widely distributed on ridges in the central peninsula, but disjunct populations that once occurred along the southwestern Gulf coast in Lee and Collier counties are extinct.

Hypoluxo Scrub Natural Area contains approximately 24 hectares of suitable habitat, which consists of extensive areas of bare sand and clumps of scrub oaks that provide shade and cover.  Areas of bare sand are used for foraging, basking, and social interactions.  Scrub lizard populations disappeared from this urban preserve circa 2005, possibly because of feral cat predation (this is no longer such a problem). Hatchling scrub lizards were observed in the preserve on 12 June.

If this reintroduction is successful, the occupied range of the species will be extended 37 km south.  This population will be monitored using visual encounter surveys every two months for the next two years.  A toe was removed from each released lizard and preserved as a genetic sample in case we wish to know the number of founder animals contributing to the established population and their relatedness.  This experimental project was a collaborative effort between FWRI staff, HSC staff in the West Palm Beach office, Palm Beach County Department of Environmental Resources Management, and Florida Department of Environmental Protection.  There is an FWRI video on this project, here: https://youtu.be/tENf2P80FFU.

Surveying With Autonomous Acoustic Recording Units

By Tyler Pittman

Autonomous acoustic recording units (ARUs) are a popular technology for surveying and monitoring vocal wildlife populations from bats to birds to marine mammals. ARUs are popular because they can collect huge quantities of data across large areas and time spans with very little effort. However, the sheer quantity of data requires advanced computer programs for efficient processing, and current commercial software cannot effectively detect species like wild turkeys that have calls that cannot be easily distinguished from background noises.

An autonomous acoustic recording unit, pictured here.

In 2017, after manually listening to thousands of hours of wild turkey audio, FWRI began development of a custom program to automate the processing of these audio files by partnering with researchers from Southeastern Universities Research Association (SURA). Commercially available programs are based on the concept of matching the spectrogram of a potential turkey call with that from a known turkey call (i.e., a template).  Our approach differs from that by breaking the template into smaller different sized and positioned sections called sub-masks. Additionally, our program weights the sub-masks either positively or negatively toward correct identification and allows the user to assign a set of rules to define which sub-masks take priority over other sub-masks. To date, the preliminary versions of the program have proven to be effective at identifying wild turkey gobbles from unknown audio recording on training datasets. The best-documented performance was 83% correct identifications with only 17% false-positive detections compared to 99% false-positive detection rates from commercially available software. Testing will continue in 2019 to further develop the program in to a useful and efficient tool for monitoring populations of birds and other wildlife.

Note: Cover image shows a recording of a wild turkey gobble represented as the amplitude of sound plotted against frequency and time, also known as a spectrogram.

Sea Turtles and Red Tide

By Allen Foley

Red tide often kills fish, but when the concentration of Karenia brevis reaches around 100,000 cells per liter, it can also kill sea turtles, birds, dolphins and manatees. In Florida, we have been documenting stranded (i.e., dead, sick or injured) sea turtles since 1980. We have documented unusually large numbers of stranded sea turtles coincident with red tides primarily along the Gulf coast (especially in the southwest) but also along a portion of the Atlantic coast (Brevard County). These strandings are typically adult and large immature loggerheads and Kemp’s ridleys, and small immature green turtles and hawksbills. Stranding data modeling and sampling of strandings to determine brevetoxin concentrations all indicate that red tides mostly kill loggerheads and Kemp’s ridleys. There are almost no strandings attributed to red tide during some years but there are many hundreds attributed to red tide during other years.

The latest red tide event began in southwest Florida during November 2017. Since then, we have attributed 589 stranded sea turtles (252 loggerheads, 265 Kemp’s ridleys and 72 green turtles) to that red tide bloom — the largest number of stranded sea turtles we have ever attributed to a red tide. The next largest groups of these stranded sea turtles were documented during 2006 (N = 345), 2003 (N = 230), and 2005 (N = 223).

Monitoring Suburban Florida Sandhill Cranes

By Tim Dellinger

The Florida sandhill crane (Antigone canadensis pratensis) is one of five sandhill crane sub-species found in North America.  Florida sandhills are non-migratory and range from southeastern Georgia to the Everglades.  The current population estimate is around 4,600 birds and it is state-listed as Threatened in Florida.

Like other crane species, Florida sandhills need wetlands as well as uplands.  Wetlands such as shallow depression marshes and lake edges are used for nesting, foraging, and roosting.  Uplands with low vegetation, such as private ranchland and dry prairie, are used for foraging and loafing.  Both habitat types are equally important to cranes.  Unfortunately, wetlands are often drained and open uplands bulldozed to make way for roads, shopping malls, and subdivisions.  Remarkably, however, some cranes are remaining in or moving to urbanized areas and living among us.

Staff banding and tagging a Florida sandhill crane captured in a strip mall parking lot in Seminole County.

In 2017 we began a project examining how Florida sandhills are using urbanized areas.  We are currently tagging adult cranes with cellular GPS transmitters in suburbs and developed areas.  The transmitters collect GPS locations at 30-minute intervals and are uploaded to us daily.  We are also tagging Florida sandhills in rural and conservation areas to help us better understand survivorship, productivity, and habitat use along the urban gradient.

Preliminary data show that some urban cranes solely inhabit suburban or developed areas.  They use suburban yards, grassy roadsides, golf courses, and open areas around colleges and hospitals as uplands, and retention ponds or lake edge for wetlands.  However, most urban cranes regularly moved between rural areas or conservation lands to suburban areas to meet their daily needs.  Preliminary movement data for Florida sandhills tagged on conservation lands show that all individuals use some man-made habitat daily, either a mowed area near a road, a yard with a bird feeder, or improved pastureland. We will continue to tag cranes during 2019.

Diamondback Terrapin Status Assessment

By Traci Castellón

The diamondback terrapin (Malaclemys terrapin) is a once common estuarine turtle that experienced serious declines a century ago and has declined further in recent decades due to numerous pressures including habitat loss and drowning in crab traps. The Florida coastline represents approximately 20% of the species range and is home to five of seven subspecies, three of which occur only in Florida. However, little is known about the status and distribution of diamondback terrapins in Florida.

Ornate diamondback terrapin (M.t. macrospilota)

With funding from a State Wildlife Grant, FWRI is collaborating with partners statewide to conduct a biological status assessment of the diamondback terrapin in Florida. The project includes population assessments in three locations with known terrapin populations (Banana River, Florida Bay and the middle Florida Keys), and, where possible, we are also helping facilitate population assessments and surveys by partners elsewhere in the state.

Another major component of the work is collection of tissue samples from terrapins statewide for a genetic analysis to assess validity of the currently recognized subspecies taxonomy and, where possible, to conduct population-level genetic analyses to assess effective population sizes, gene flow and possible signs of inbreeding depression. Other efforts include gathering and consolidating existing data from partners to update the known distribution of terrapins statewide and using these data to develop a spatial model to quantify habitat availability. Finally, we will estimate the magnitude of past and future population reductions based on historic and projected future habitat losses.

East coast Florida diamondback terrapin (M.T. tequesta)

To date we have developed numerous partnerships, mapped > 5,500 individual sightings, collected > 300 tissue samples for genetic analysis, completed one season of mark-recapture work in the Banana River, and will begin fieldwork in Florida Bay and the Florida Keys in November 2018.

Major partners include Eastern Florida State College; Sanibel-Captiva Conservation Foundation; the US Geological Survey’s Wetland and Aquatic Research Center; University of Florida’s Department of Wildlife Ecology and Conservation, Florida Sea Grant Extension, Nature Coast Biological Station, and Florida Museum of Natural History; Florida Department of Environmental Protection’s Indian River Lagoon and Tomoka Marsh Aquatic Preserves; North Florida Land Trust; Florida Audubon; Flagler College; Brevard Zoo; and FWC’s Fisheries Independent Monitoring, Habitat and Species Conservation Section, and Florida Keys Wildlife Environmental Area; as well as many dedicated volunteers, students and citizen scientists.

Ornate diamondback terrapin (M.t. macrospilota)

Please send diamondback terrapin sightings to Traci.Castellon@MyFWC.com.

Light Pollution and Sea Turtle Hatchling Orientation

By Shigetomo Hirama

Sea turtles are long-lived animals that utilize multiple developmental habitats. In all of the habitats, sea turtles encounter with various threats. Although some are naturally occurring (at least they seem to be), the majority of threats are caused by human. These anthropogenic threats in-water habitats include: fisheries’ activities, oil spills, debris ingestions, debris entanglements, boat strikes, dredging, and direct harvesting. On the beach, beach driving, artificial lighting (light pollution), armoring (sea walls, rock revetments, and other infrastructures), oil spills, and egg poaching are threats to nesting and hatchling turtles. Among these threats on the beaches, the installment of armoring structure – sea walls, rock revetments, and other infrastructures – are probably the most important threats, considering sea level rise as a consequence of climate change. Armoring structures are known to increase speed of erosion and may cause permanent loss of beach sand. Although it may not be as important, artificial lighting also is significant threats to the turtles. The artificial lighting differs from the armoring in terms of solving the issues. Coastal armoring, such as a sea wall, is difficult to remove once it is placed; however, we can change light bulb or retrofit light fixtures relatively easily. Through the present project, we provide valuable information to stakeholders to reduce hatchling mortality and increase chance of hatchlings’ survivorship.

Playalinda Beach. An example of a beach with no light pollution.

Artificial lighting alters natural illuminant environment and impacts behavior of wildlife. Nocturnal animals such as bats, moths, and some species of birds, are more susceptible to light pollution than others. Sea turtle hatchlings crawl toward ocean using the visual cues immediately after emerging from sand. The hatchlings disorient on the beach if the intensity of artificial light is relatively high and may never enter the ocean.

Cocoa Beach. An example of a beach with moderate to severe light pollution.

We have been quantifying accuracy of hatchling orientation in over the 20 Florida beaches in past five years. Hatching orientation is one of the subjects of sea turtle biology that has been studied well. Surprisingly, no known work has provided the benchmark orientation data that were collected at a natural beach and compared with the information that were collected at the beaches with varying levels of light pollution. The results of present project showed the accuracy of hatchling orientation varied widely depending on the beaches. The quantitative data of the project are currently in process of publishing in a peer-reviewed journal. In the present article, I provide photographic images that were taken by same camera, setting, and lens at the beaches with no (Playalinda), moderate to severe (Cocoa Beach), and severe (Miami Beach) light pollutions. We hope the data we provide would guide to take practical actions to reduce light pollution.

Miami Beach. An example of a beach with severe light pollution.

Gopher Frog Monitoring Project

By Aubrey Greene

The gopher frog is currently being considered for federal protection under the Endangered Species Act. While the gopher frog has experienced serious declines throughout the rest of its range, Florida currently represents a stronghold for the species. Consequently, the gopher frog was delisted as a state-designated Species of Special Concern in January 2017. As a part of the delisting process, a state species action plan was developed for the gopher frog. This action plan calls for the development of a statewide monitoring program for the species. Before the species was delisted, we began a pilot study to increase our understanding of species detection and wetland occupancy rates, as well as to determine the best methodology for a long-term gopher frog monitoring program.

Surveys for the gopher frog monitoring project started in Fall 2015. This project uses seasonal dipnet surveys and frogloggers (automated frog call recorders) to track the status of gopher frogs in 100 wetlands over time. Additional wetlands are also surveyed as time allows to locate new breeding wetlands and track the status of the species in additional known breeding ponds. During FY 2017-18, we surveyed 114 ponds in 22 counties on 29 public or conservation lands for gopher frogs, finding tadpoles in 72 ponds in 21 counties on 24 public lands. These surveys discovered one previously unknown gopher frog breeding pond and observed breeding for the first time in decades in some previously known ponds. Many of the “rediscovered” observations were made in the months following Hurricane Irma, which filled most of the study ponds.

An image of a sonogram of a gopher frog call.

As the data collection phase of this project comes to a close at the end of 2018, in-depth data analyses will begin. Froglogger recordings are already being analyzed using software that recognizes the specific call signature of the species. Unfortunately, this is a very long process due to the large amount of data collected over the three-year project. Dipnet and froglogger data will be analyzed to determine the annual and seasonal patterns of wetland occupancy in each region of the state, as well as the effects of different variables on species detection and wetland occupancy. We will also examine data from both methods to make recommendations about the most efficient sampling methods.

Wrapping Up the Statewide Reddish Egret Survey

By Andrew Cox

The reddish egret (Egretta rufescens) is North America’s rarest heron and is state-listed as Threatened in Florida. In 2016 we visited 305 coastal islands during the first statewide survey of the species to document its distribution, estimate Florida’s population size, and learn more about its nest-site selection patterns. In 2017 we attended to the less glamorous side of our work – sitting at our desks, crunching numbers and writing.

Reddish egrets were primarily concentrated in four areas of Florida: in and near Merritt Island National Wildlife Refuge, Florida Bay, the Lower Keys, and the Tampa Bay area south to Marco Island. The species has continued to slowly expand northward on the Gulf coast, with nesting occurring in Cedar Keys National Wildlife Refuge. There were an estimated 480 (95% CI: 375–606) nesting pairs at the 58 sites where birds we found birds. The largest colony we found had 23 nesting pairs, which is fewer than the three largest colonies documented in Florida Bay during 1978. Half of all colonies had 3 or fewer pairs.

Reddish egret foraging behavior can be something of a spectacle as birds move throughout tidal flats and other shallow estuarine waters in a graceful, high-energy pursuit of prey. Foraging habitat is probably the largest limiting factor for reddish egret populations, and our nest-site selection analysis confirmed that it was the most substantial predictor of occupancy and abundance of nesting reddish egrets. These results confirm the importance of incorporating foraging habitat into our restoration planning and highlight the need to understand how the shallow flats upon which reddish egrets rely will be affected by sea-level rise.

The photo accompanying this article was taken by Anne Macias. Anne was a retiree in Bonita Springs and a strong advocate for Florida’s birds. She took great pride in the colony of nesting wading birds in her neighborhood and raised awareness of their importance within her community. Our jobs are made that much easier by people like Anne. Anne unfortunately passed away earlier this year and will be deeply missed.

Florida Bonneted Bat Roost Selection: Implications for Conservation

By Elizabeth Braun de Torrez

The Florida bonneted bat (Eumpos floridanus), which occurs only in Florida, is federally endangered and extremely rare. These bats can traverse extensive areas to forage but their distribution may be restricted by the availability and security of roosting sites. However, we know very little about what types of natural roosts the bats use or whether tree roosts are readily available across the landscape. In our current study, we are working to identify and characterize previously unknown roost locations in conservation areas across southwest Florida. This information will allow us to protect existing roost structures and to develop guidelines for conserving or enhancing roosting habitat for this species.

Building upon research started with the University of Florida, we are using a combination of acoustic surveys, mist netting and radio-telemetry. Florida bonneted bats are notoriously difficult to capture in mist nets due to their high-altitude flight, and prior to our recent research this species had only been captured once away from known roost sites. Using a technique we developed involving an acoustic lure that broadcasts conspecific social calls to attract this species to nets, we now have the ability to capture free-flying individuals, attach radio-transmitters and track them back to unknown roost sites using radio-telemetry.

Florida bonneted bat with VHF radio-transmitter attached to break-away collar.

To capture bats, we erect a triple high mist net system (9 m high) coupled with an acoustic lure. Upon capture, we identify the individual’s species, sex, reproductive status and take standard measurements (e.g., mass, forearm length). We also collect a 4mm wing biopsy and guano sample for genetic and diet analysis. For adult, non-pregnant Florida bonneted bats, we secure a VHF radio-transmitter attached to a break-away collar and track the bats to roost structures using a combination of aerial and ground-based radio-telemetry. Due to the suspected distance that these bats are capable of flying between foraging areas and roost sites (ca. 25 miles) and the challenges of navigating throughout the south Florida terrain, aerial telemetry is essential to locate roost sites!

Once we locate a potential roost, we verify occupancy and colony size by counting the number of Florida bonneted bats that emerge around dusk, and measure characteristics of the roost tree (e.g. height, size and orientation of roost opening). We also measure characteristics of the surrounding vegetation (e.g., tree density, canopy height, canopy cover) in a plot around the roost tree and at four random tree plots.

Royal palm snag in Fakahatchee Strand Preserve State Park containing 80 Florida bonneted bats. This is the largest known colony for this species.

We are in the process of compiling data from natural roosts that we have located, in conjunction with our research partners, over the last several years. In total, we have located 17 roost trees, with 5 new roosts located in 2018. The roosts include enlarged woodpecker cavities, cavities formed from decay, and spaces under loose bark, and they occur in live and dead long leaf pine, slash pine, royal palm and cypress trees. Colony sizes range from 1 individual to a new record of 80 bats in a recently discovered royal palm roost in Fakahatchee Strand Preserve State Park in May 2018. Of these 17 roost trees, 6 have since been damaged or destroyed by fire or hurricanes. Ultimately, we will use the data collected on new Florida bonneted bat roost structures to examine patterns of roost site selection relative to a variety of local and landscape-scale variables, and make appropriate habitat management recommendations.