Research at Rockefeller
Rockefeller Wildlife Refuge is nationally and internationally known for its pioneering wildlife, fisheries, and wetlands research. Since 1955, RWR research staff and collaborators have published more than 350 research articles in peer-reviewed journals. Specific research topics vary but all generally focus on better understanding coastal wildlife (both game and non-game species), fisheries, and marshlands. The information gained from these studies allows local, state, and regional authorities to better manage for individual species, communities, and habitats.
Populations of American alligator (Alligator mississippiensis) declined in Louisiana due to unregulated harvest in the early 1900s. During the 1960s and 1970s, extensive research and monitoring conducted by Rockefeller Wildlife Refuge staff, coupled with a temporary prohibition on harvest, led to the recovery of this iconic species. Alligator numbers recovered to the point where limited, carefully regulated harvests were again allowed. There are now more than 1.5 million alligators in Louisiana, and about 30,000 to 40,000 wild alligators are harvested statewide each year. There is a limited nuisance alligator harvest conducted on the refuge to prevent conflicts between humans and alligators in areas of with a lot of public use (primarily near water control structures).
Research conducted at the refuge on alligator egg incubation, culture of juveniles, nutrition, and captive propagation led to the development of a statewide alligator farming/ranching program, which has become a multi-million dollar industry in Louisiana. Harvest of wild and farmed alligators has been valued at more than $60 million in peak years. Louisiana’s alligator research and management programs are recognized internationally as models for sustainable use and have been applied to crocodilian species worldwide.
Recent alligator research at the refuge has focused on nesting biology, DNA/genetic studies, and culture studies to refine what we know about alligator growth and nutrition. Researchers have recently published studies on commensal nesting species in alligator nests, sex ratios in wild American alligators, and microbial symbioses in alligators. Researchers have also investigated the impact of invasive feral hogs [link to feral hog page] on alligator nests and studied the long-term survival in farm-raised alligators released into the wild and the interstate movement of alligators. Collaborative studies with university researchers have led to important findings about multi-year, multiple paternity and nest-site fidelity in some alligators, often over several years.
Biologists at Rockefeller Wildlife Refuge have participated in aerial waterfowl surveys of all LDWF’s coastal refuges and wildlife management areas (WMAs) since the early 2000s. Refuge biologists also conduct special studies on waterfowl species including mottled ducks and black-bellied whistling ducks.
Studies on mottled ducks (Anas fulvigula) at the refuge Refuge have been ongoing since the mid-1980s. During the summer (June through August), biologists band mottled ducks across coastal Louisiana—the timing of these banding efforts coincides with brood rearing and molt when ducks are easily captured by hand from an airboat at night. Biologists capture flightless juvenile and molting adult ducks, attach a uniquely numbered band around the leg of a captured duck, record information about the duck, and release it. They use information from bands subsequently found and reported back to them to determine annual harvest and survival rates for mottled ducks and inform management of the species. Since 1994, biologists have banded more than 40,000 mottled ducks. Mottled ducks exhibit high site fidelity (tending to return to locations where they have been before); subsequently, many are harvested by hunters within 10 to 15 miles of where they were banded. A few stray from coastal Louisiana including one female that was harvested in South Dakota, the northernmost location recorded for the species. Other research on mottled ducks has included telemetry projects with Louisiana State University and Texas A&M to determine habitat use and movements, particularly during brood rearing and molt; documenting hybridization and population genetic structure of the western Gulf Coast population of mottled ducks, in collaboration with researchers at Louisiana State University; and ongoing winter waterfowl surveys of the coastal refuges and wildlife management areas and spring aerial surveys for breeding mottled ducks.
Black-bellied whistling ducks (Dendrocygna autumnalis) have greatly expanded their range since the mid-1990s to include southern Louisiana and as far east as the Carolinas. Refuge biologists have been banding these ducks since 2010 in areas surrounding the refuge and across southwestern Louisiana. Past research includes a study using satellite telemetry to investigate home range and movements of male black-bellied whistling ducks. More research is needed to determine annual survival rates, home range, and movements of this rapidly range-expanding species in southern Louisiana.
Endangered Species Restoration
Refuge staff have been instrumental in helping to restore populations of endangered species in Louisiana, including the Eastern brown pelican (Pelecanus occidentalis), bald eagle (Haliaeetus leucocephalus), and whooping crane (Grus americana).
The Eastern brown pelican, Louisiana’s state bird, had virtually disappeared from the state by 1963, with environmental pesticide contamination as a plausible link to the species’ decline. In 1968, staff biologists at the refuge initiated a program to reintroduce brown pelicans back into their historical range of coastal Louisiana. Between 1971 and 2010, more than 350,000 brown pelicans fledglings were produced in Louisiana. In 2003, brown pelicans naturally expanded to Rabbit Island in southwestern Louisiana (Cameron Parish). This colony has grown rapidly since then—[insert recent stats]. Refuge staff continue to monitor the successful reintroduction of Louisiana’s brown pelican population via aerial surveys.
Between 1954 and 1960, only four active bald eagle nests were found in Louisiana. In 1972, there were only six nests reported. Declines were primarily attributed to a link between pesticides and eggshell thinning as well as habitat destruction, disturbance of nests, and poaching. In 1984, refuge staff began formal surveys to determine the distribution and abundance of bald eagle populations. … By 2008, the bald eagle had been taken off the federal endangered species list, partially due to recovered populations which maintain 400 to 500 active nests throughout Louisiana. From 2011 to 2014, refuge staff collaborated with researchers at Louisiana State University to track bald eagles wintering in Louisiana. Researchers captured bald eagles with rocket nets and equipped them with satellite transmitters before releasing them. Tracking results show that many of the satellite-tagged bald eagles were faithful to migratory corridors and summered in Canada.
Historically, more whooping cranes called Louisiana home than any other area in North America. Both resident and migrant populations inhabited the state’s coastal marshes and historic Cajun Prairie of southwestern Louisiana. Populations of whooping cranes in Louisiana declined throughout the late 19th and early 20th centuries due to hunting and conversion of habitat from prairie to rice agriculture. Conversion of the species’ prairie and wetland habitat to farmland and unregulated hunting led to the decline of this species both in Louisiana and across the nation. By 1945, only two whooping cranes remained in Louisiana. In March of 1950, the last remaining whooping crane in Louisiana was captured at White Lake and transported to Aransas National Wildlife Refuge on the central Texas coast with the hopes that it would join the small migratory flock of whooping cranes there.
For 60 years, whooping cranes were absent from Louisiana's landscape. However, in 2011, LDWF and partners began a reintroduction project, releasing 10 juvenile cranes at White Lake Wetlands Conservation Area. LDWF and partners will continue to release a new cohort of birds every year as part of the overall recovery of the species.
Diamondback Terrapin (Malaclemys terrapin) research at the refuge has focused on the distribution and abundance of terrapins in southwestern Louisiana, particularly to determine if terrapin populations persist in historical locales and/or if they occur in new locations. Researchers are also using ultrasound and radiographic studies (x-rays) to document the specifics of terrapin reproduction, including clutch size (number of eggs) and clutch frequency (number of clutches per nesting season). Researchers are investigating population structure and demography, focusing on population genetics of terrapins in Louisiana, temporal and spatial variation in diet, and pattern/color analysis—many of these studies are being conducted in collaboration with graduate students.
Refuge staff are involved with non-game bird species monitoring and conservation projects. Biologists completed a year-long bird inventory of Rabbit Island, the most important colonial waterbird nesting island in Calcasieu Lake (Cameron Parish). Rabbit Island is home to the only brown pelican (Pelecanus occidentalis) nesting colony in southwestern Louisiana, with around 2,000 nests, as well as more than 60 other species including nesting American oystercatchers (Haematopus palliatus) and reddish egrets (Egretta rufescens), representing the first nesting records for either species in southwestern Louisiana. Both American oystercatchers and reddish egrets are poorly understood in coastal Louisiana—future research will investigate the nesting ecology of both species in Louisiana and track reddish egrets throughout coastal Louisiana to determine important foraging areas, movements, and seasonal habitat use. Every winter, refuge staff conduct surveys of piping plover (Charadrius melodus) along beaches in southwestern Louisiana. However, as little else is known about shorebird communities in southwestern Louisiana, staff are collaborating with researchers from McNeese State University to investigate seasonal abundance of shorebirds and available prey at four beaches in Cameron Parish (including Rockefeller Beach). Each beach is structurally different from the others, so each beach is likely home to a unique community of shorebirds and prey.
Refuge staff assess and inventory marsh status through two methods:
- Water level and salinity surveys: staff monitor water levels and salinities across the refuge on a weekly and monthly basis.
- Vegetation surveys: staff monitor composition of refuge marsh vegetation to determine the impacts of management strategies on vegetation communities. Historical data on marsh types and vegetation data are found in O’Neil (1949). Staff are planning to monitor vegetation with contemporary methods (such as digital imaging and radar) in collaboration with the U.S. Geological Survey.
Fisheries Ecology and Aquaculture
Fisheries research has been a significant part of Rockefeller’s research program since 1965. Biologists designed and management strategies to benefits to marine organisms at the refuge. Early studies in the 1960s focused on the life history of catfish, shrimp, and other marine organisms. Later, biologists screened several species for their aquaculture potential to encourage private landowners to continue managing their property as coastal wetlands.
In 1972, refuge staff initiated a program to reintroduce striped bass (Morone saxatilis) into waterways of southwestern Louisiana. From 2000 to present, staff have been rearing Florida largemouth bass (Micropterus salmoides) in ponds at the refuge to stock waterbodies on the refuge and throughout the state to assist with Louisiana’s freshwater fishery management objectives.
Several cooperative studies with Louisiana State University and University of Louisiana - Lafayette were conducted in the late 1980s to understand the impact of management regimes on marine organisms.
Rockefeller Wildlife Refuge provides an outdoor laboratory for high-quality wildlife, fisheries, and wetlands research. Since the 1950s, staff at the refuge have collaborated with numerous governmental and academic researchers from Louisiana, throughout the United States, and beyond.
If you desire a field site to conduct research in coastal Louisiana, Rockefeller Wildlife Refuge may be the place for you. To conduct research at the refuge, download a copy of the Research Request form to the right and follow the submission instructions.
Even though the refuge is remote, there are many on-site amenities for visiting researchers, including
- Laundry and kitchen facilities
Depending on availability, researchers may be able to stay on-site for extended periods of time for their research (1 to 3 months). There are some logistical complexities that researchers should be aware of before they commit to researching or staying at the refuge—see Visiting Researcher Information below.
Please contact us at [fill in contact info—contact name, phone, and/or email] for more information about conducting research at Rockefeller Wildlife Refuge.