Category Archives: Avian Research

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 Scrub-Jay Translocation Research

By Karl E. Miller

Florida scrub-jay (Aphelocoma coerulescens) populations throughout the state are vulnerable from the effects of habitat fragmentation. The species is mostly sedentary and rarely disperses long distances through non-scrub habitat. Currently, >90% of the remaining scrub-jay populations consist of fewer than 25 family groups.

FWC staff are conducting experimental translocations of Florida scrub-jays to determine the feasibility of a state-wide translocation program to stabilize smaller populations and prevent genetic isolation. The conservation goal is to transport – or “translocate” – birds from a large, stable population in the Ocala National Forest to smaller populations where extensive habitat has been restored but has not been discovered or occupied by Florida scrub-jays. FWC researchers are following up these translocations with intensive monitoring to determine whether the donor population is resilient to the loss of birds and also to determine their impact on populations at recipient sites.

During winter 2017 (December 22-March 21), we relocated 9 Florida scrub-jays, constituting 4 family groups, from Ocala National Forest to Seminole State Forest, which is a distance of >32 km. This initial translocation was a collaborative effort between staff from FWC, the Florida Forest Service, and the US Forest Service.

Translocated groups were tracked using radio telemetry to determine the extent to which they moved throughout the landscape and to understand interactions with neighboring groups. All birds survived transport and release and soon established breeding territories within 200 m of where they were released. During the first week of July, the first successful nest fledged.

In Ocala National Forest, the territories that were vacated were soon occupied by other Florida scrub-jays, including some groups that immigrated from adjacent sub-optimal habitat patches that were heavily overgrown.

Overall, translocated birds appeared to acclimate well to recipient sites, and populations at donor sites did not appear to be negatively affected, which suggests that future translocations will be a worthwhile tool for stabilizing and increasing populations of Florida scrub-jays on managed lands. During winter 2018, we will increase the number of birds moved and the number of recipient sites involved and continue to test the effectiveness of moving different age classes of scrub-jays. We will also continue to test the effectiveness of novel transport and release methods.

Update on Cranes

by Tim Dellinger

Florida sandhill cranes (Grus canadensis pratensis) are one of six sandhill crane sub-species found in North America. This non-migratory sub-species ranges from southeastern Georgia to the Florida Everglades and is listed as Threatened. The current population estimate for Florida sandhill cranes is around 4,600 individuals. In 2013 the FWC began conducting annual fall recruitment surveys through the core range of Florida sandhill cranes. FWC biologists established 12 routes, totaling 1,012 km, through private and public lands to keep a finger on the pulse of the Florida sandhill crane population. The number of chicks observed has varied with spring water levels; 2014 and 2015 were wet years and the number of juveniles observed was around 90 for each year, whereas 2013 was a drought year and only 38 chicks were noted. FWC will continue to monitor the population through the recruitment surveys.

FWC is also trying to increase available habitat on public lands where only an estimated 500 birds or 15 percent of the population live. FWC began a habitat manipulation research project in 2013 with the goal to increase crane nesting on Three Lakes WMA. Like other crane species, Florida sandhill cranes require shallow, open wetlands for breeding, foraging and roosting, as well as open uplands with low vegetation for foraging. The Three Lakes site is rank with tall vegetation and saw palmetto, so we used half of the area as control and the other half was roller-chopped; both areas were later burned. We continue to monitor nesting through biweekly flights. The information from this habitat manipulation study will guide management recommendations.

aerial view of study site
Biweekly flights throughout the Florida sandhill crane breeding season is the most efficient method to locate and monitor nests over the large Three Lakes study site.
aerial view of study site
Half of the study site was roller-chopped and the other half left as control for the Three Lakes WMA habitat manipulation project. Palmetto surrounding marshes was especially targeted in treatment areas to reduce areas for predators to hide.

The FWC also continues to help with whooping crane conservation. From 1993–2004, 289 whooping cranes were released in Florida in the hopes of establishing a non-migratory population. This attempt failed due to various problems, and the decision to stop all Florida releases was made in 2008. Currently there are 8-12 birds remaining in the population. Some of these individuals continue to breed and FWC is partnering with the USFWS and Louisiana Department of Wildlife and Fisheries to capture and relocate wild chicks of the Florida birds to a whooping crane reintroduction project in Louisiana―a task that has never been attempted.

birds
Whooping cranes stand about 20 cm taller than Florida Sandhill Cranes. This whooping crane hatched in 2015 and is a translocation candidate to join the growing Louisiana whooping crane population.

Wild Turkey Research 

by Tyler Pittman 

The wild turkey is one of the most wide-ranging upland gamebirds in North America with five sub-species inhabiting all of the contiguous United States as well as regions of southern Canada and northern Mexico. The common eastern sub-species inhabits northern Florida, and the Osceola sub-species, unique to Florida, inhabits the central and southern parts of the state. Wild turkey were almost extirpated from Florida in the early 20th century due to overharvest but after successful restoration efforts wild turkey are now found and harvested in all of Florida’s 67 counties.  Florida has become a destination for hunters from around the world who travel here for an opportunity to harvest an Osceola turkey. Hunters in Florida harvest over 20,000 wild turkey annually, making continued research and monitoring essential to maintaining the population and preventing another extirpation event.

Beginning in 2014, FWC partnered with researchers from Tall Timbers Research Station and Land Conservancy, the University of Tennessee-Knoxville, and the University of Florida to document the breeding chronology of wild turkey across the state of Florida in an effort to establish harvest season dates that benefit both wild turkey populations and wild turkey hunters. We are currently documenting nesting chronology using 68 wild turkey hens, captured and fitted with tracking devices, and we have deployed 36 automated audio recording devices to document the chronology of male breeding activity by recording gobbling. Eventually, the chronology information from female and male breeding activity will allow us to establish season dates after the peak of female nesting activity and during the peak of male breeding activity when fewer females are available to breed with. This will minimize the impact of harvest on females and maximize hunter satisfaction.

Statewide Survey of Nesting Reddish Egrets

by Andrew Cox

 

Birds in tree
Photo by Anne Macias, BBRWS Photographer

The reddish egret is North America’s rarest (and coolest) heron, with an estimated global population size of 3,500-4,250 breeding pairs.  A coastal specialist that nests on islands in estuarine and marine waters, the species was extirpated from Florida in the early 20th century due to plume hunting.  It subsequently rebounded and can now be found nesting on the gulf coast from Cedar Key south to Marco Island, throughout the Florida Keys, and on the east coast at Merritt Island National Wildlife Refuge.  The rarity of the species and potential recent declines across its range have led FWC to partner with Audubon Florida and the Avian Research and Conservation Institute on a two-year project to identify the most important breeding locations, estimate the number of breeding pairs in Florida, and learn more about the species’ nest-site selection habits in Florida.

In 2015, we intensively sampled 12 breeding sites to assess the accuracy and precision of several survey techniques.  We also scouted extensively for nesting birds throughout the Florida Keys in preparation for the actual survey.  We found that detectability was an issue during ground-based counts with this dark-plumaged, sub-canopy nesting species.  We also documented substantial breeding asynchrony in Florida Bay, precluding the use of a commonly implemented counting method that requires all nesting pairs to be incubating eggs.  These results have helped us refine on our sampling strategy for the upcoming breeding season when we will implement the statewide survey.

Return to Wildlife Research

Monitoring Scrub Jay Populations

by Karl Miller

Habitat loss and fire suppression are well known threats to the persistence of the threatened Florida scrub-jay.  However, many populations are also becoming increasingly isolated by changes to the surrounding landscape.  Connectivity within and among metapopulations has been greatly reduced by human development, especially in coastal counties.  Translocation is one strategy that is being evaluated to boost the size of smaller populations and to better link these populations with each other.

full hacking cageEfforts to translocate Florida scrub-jays are still in their early stages and have been successful in only two regions of the state.  During the past few years, I have participated in experimental translocations of isolated scrub-jay family groups to recently restored public lands which have populations below their potential carrying capacity.  An ongoing partnership of staff from FWRI, the Brevard Zoo, and FWC’s Division of Habitat and Species Conservation conducts these targeted scrub-jay translocations in Brevard County and Volusia County.

In January, we trapped and banded a family of Florida scrub-jays in a heavily developed urban area in Brevard County and moved them to nearby Buck Lake Wildlife Management Area.  Birds were captured from a utility right-of-way behind a car wash.  Not only was this one of the coldest days I have ever banded birds but it was also my first ever experience bird banding in the parking lot of a car wash!  A family of four individuals was moved to a hacking cage at Buck Lake and then released 24 hours later.  A resident scrub-jay immediately joined the group and they began to set up a territory in the immediate area around the hacking cage.  Continued monitoring efforts will be vital in determining the effectiveness of these efforts.