Research and Inventory

A unique attribute of RWR is the emphasis on wildlife, fisheries, and marsh management research. RWR has extensively disseminated the results of research findings within professional/popular publications, research reports, and published abstracts (563 since 1955). Further, staff provides public/professional presentations, while also integrating this information into the overall departmental conservation program. A list of publications by division personnel and others conducted entirely or partially on RWR can be obtained from either the main office in Baton Rouge or from the RWR; this list is also currently being compiled as an electronic resource for online access to the publication list and online document retrieval.


Research.—RWR is probably best known for its pioneering research on the American alligator (Alligator mississippiensis). A five year study on alligator nesting ecology (Joanen 1969b) was the first of many published research studies over the next three decades by Joanen and McNease. Their research on the life history, ecology, food habits, home ranges and habitat preferences, breeding biology, and population status led to the development of a statewide sustainable use management program. This involves a controlled annual harvest of subadult and adult alligators by approximately 2,000 licensed trappers annually.

The species was affected by previously unregulated harvest in the early part of the last century, but during the 1960s and 1970s extensive research and monitoring, as well as a period of time when no harvest was allowed, led to population recovery and alligator numbers recovered to the point where limited harvests (carefully regulated) were again allowed. There are now some 1.5 million alligators in Louisiana, and some 30,000 – 40,000 wild alligators are harvested statewide in peak years. A limited nuisance harvest is conducted on RWR to avoid human-alligator conflicts in areas of high public use (i.e., recreational fishing, shrimping, and crabbing), primarily with harvests targeted near water control structures.

The research conducted at RWR on alligator egg incubation, culture of juveniles, nutrition, and captive propagation led to the development of a farming/ranching program statewide, which has become a multi-million dollar industry within the state. In some years 250,000 – 300,000 farm hides have entered the international hide market, to be used for high-end luxury leather fashion items. The wild and farm programs have been valued at over $60 million in peak years. These programs and the utilization philosophy are recognized internationally as models for sustained use management and have been applied to crocodilian species worldwide.

Recent alligator research focused on nesting biology, DNA/genetic studies, and culture studies to refine alligator growth (Elsey and Trosclair 2008) and nutrition. The juvenile alligator growth studies are directly applicable for alligator husbandry recommendations to our state’s alligator farmers. In addition, we often lend guidance to farmers’ methods they use to experiment with various regimes on their alligator farms. We often host visiting researchers and collaborate on projects of mutual interest. Molecular ecology techniques such as use of microsatellites and stable isotopes are beyond the scope of our field site, but working with university professors and graduate students has led to many new findings. Our field studies on-site recently documented multi-year, multiple paternity and nest-site fidelity in some alligators, often over several years (Elsey et al. 2008; Lance et al. 2009). Many researchers from prestigious universities such as Harvard University and Yale University have visited RWR to collect valuable samples for their novel studies. We are pleased we can host visiting graduate students, to assist them in attaining their graduate degrees, and help train the next generation of field biologists.

We are pleased that we have continued to maintain an active alligator research program, despite having lost the field lab in Hurricane Rita in 2005. We converted a storage shed to a very basic lab which was used for sampling specimens until it was lost in Hurricane Ike in September 2008. As our alligator management programs have grown, staff time is increasingly directed to the day-to-day administrative needs of managing the wild alligator harvest, the alligator farm program, and the nuisance alligator program, thus leaving less time available for research. Recent budgetary constraints have required the use of more temporary and seasonal employees, who are difficult to retain and recruit, thus often requiring upper level biologist to travel to conduct mandatory alligator “releases to the wild” and hide inspections. This does limit our ability to conduct labor intensive field studies, but we strive to keep research as a priority when other administrative tasks related to our alligator harvest programs are completed. When a new lab and grow-out facility for alligators is completed, we will continue to conduct research studies on all aspects of alligator biology as scheduling allows.

Inventory.—Inventory for RWR alligator populations has primarily focused on a coastal alligator nesting survey that is completed by the LDWF Alligator Program each year. From 1991-2010, these surveys on RWR have estimated an average of 266, 723.6, and 84.7 alligator nests in brackish, intermediate, and freshwater marsh types, respectively. Furthermore, the refuge maintains a database on the number of alligators harvested annually during the nuisance alligator season, as well as sex and size of harvested individuals.

Waterfowl and Marsh Management

Research.—Mottled Duck (Anas fulvigula) population dynamics is a major waterfowl study that RWR personnel are conducting. Since banding efforts began in 1994, over 35,000 mottled ducks have been banded in Louisiana. During the summer (June-August) Mottled Ducks are banded across coastal Louisiana, with Rockefeller staff focusing efforts primarily within refuge boundaries and also by permission on Miami Corporation property holdings (Cameron/Creole marsh); these banding efforts are critical to determine annual harvest rates and survivorship for Mottled Ducks, as well as to assist in the management of the species (i.e., information for daily bag limits). The timing of banding efforts coincides with brood rearing and molt when ducks are easily captured by hand from an airboat at night. Recently, a Mottled Duck banded in 2007 on Rockefeller Refuge was harvested in Alpena, South Dakota (approximately 1,450 mile trip; Selman et al., in press); this represents the northernmost documented record for this species. In 2007-2009, RWR collaborated on telemetry projects with LSU and Texas A & M on Mottled Ducks to determine habitat use and movements, particularly during brood rearing and remigial molt. RWR and alligator management staff also participates in wintering waterfowl surveys of the coastal refuges/wildlife management areas, as well as spring aerial surveys for breeding Mottled Ducks.

The future of RWR waterfowl research will focus primarily on Mottled Ducks due to the long-term commitment of the refuge to the research/management of this species. Future topics of interest may be the effects of marsh management on nest choice and nest success of female Mottled Ducks, hybridization genetic studies, and harvest and recovery analysis.

Inventory.—Inventory for waterfowl on RWR is primarily in the form of coastal waterfowl surveys conducted by LDWF. Fall and winter surveys regularly encounter 100,000+ waterfowl with historical highs of approximately 600,000 waterfowl (Palmisano 1969, Appendix 3). Data is currently being compiled for yearly and species comparisons.

Two methods allow RWR staff to assess and inventory marsh status: 1) water level and salinity surveys and 2) vegetative surveys. RWR staff monitors water levels and salinities across the refuge on a weekly and monthly basis; these data are currently being compiled in a master dataset. RWR staff also historically and currently monitors vegetative composition of refuge marshes to determine the impacts of management strategies on vegetative communities. A comparative database on RWR vegetative data does not exist due to the long history of collection and variable methods uses. However, historical data on marsh types and vegetation data are found in O’Neil (1949), with future vegetative monitoring planned with contemporary methods (i.e., digital imaging and radar) in collaboration with U.S. Geological Survey. The refuge also plans to implement integrated staff gauges across the refuge to in the near future to allow a more accurate and consistent measurement of water levels across the refuge.


Past Research.—Fisheries research has been a significant part of the Rockefeller research program since 1965. Biologists have worked closely in the design and implementation of management strategies with positive benefits to marine organisms. Early projects in the 1960s focused on life history studies of catfish, shrimp, and other marine organisms. Later, several species were screened for aquaculture potential to possibly develop an additional source of revenue for coastal landowners; this was done in an effort to encourage private landowners to continue managing their property as coastal wetlands.

In 1972, Rockefeller staff initiated a program to reintroduce striped bass (Morone saxatils) to southwestern Louisiana. Between 1972 and 2000, over 4.5 million striped bass were raised at RWR and released into local water bodies (Mermentau and Calcasieu rivers; Rockefeller Wildlife Refuge; Toledo Bend Reservoir), which was to assist the Inland Fisheries Division achieve goals of their anadromous striped bass project. Following the striped bass project, the ponds were stocked with Florida-strain largemouth bass (Micropterus salmoides) from 2000 to present, with exception of 2005-2007 due to hurricane damage to the ponds. Advanced fingerlings from Rockefeller have been stocked into the Refuge’s Superior Canal System as well as Lacassine National Wildlife Refuge, Mermentau River, and the Atchafalaya Basin. Local bass fishermen report excellent catches from Rockefeller waters.

In addition to understanding the impacts of management units on waterfowl, it was equally important to understand the impact of management regimes on marine organisms, with several cooperative studies with LSU and ULL initiated in the late 1980s. Rockefeller staff modified the sampling techniques and continued the study to better understand the relationship under different climate/management scenarios; this study was also important to determine the impacts of Hurricane Rita on the local fisheries communities.

Current Research.—RWR staff is currently collaborating with researchers from LSU Ag-Center with the Gulf killifish (Fundulus grandis). Known locally in the fishing community as cocahoe minnows, this is a popular bait species with large aquaculture potential for local landowners due to the small investment and low maintenance. Different grow-out trials will be held in research ponds at RWR to try to help find the most favorable growing conditions, while also promoting its economic potential for the community. Further, fisheries staff is collaborating with researchers from Nicholls State University (Thibodaux, LA) in a demographic study of Alligator gar (Atractosteus spatula). There is little is known about the biology of this species, and possibly because of this, it has been listed as Rare, Endangered, or Extirpated in many areas on the periphery of its range (Boschung and Mayden 2004). Though populations in Louisiana seem stable, this collaboration should gain additional information about this one of the largest freshwater fish in North America.

Future Research.—Though data currently exists on the public consumptive uses at RWR, as well as a breakdown of percentages of the main three species groups (shrimp, fish, and crabs), there is a need to supplement that data with new creel survey data. National trends show a decrease in hunting and fishing license sales, while there have been major decreases in local population due to hurricane displacement; these could have meaningful impacts on consumptive practices, further justifying the need for additional surveys. New surveys should allow us to establish if there have been any changes in consumptive use since the previous study.

Future research is also needed in developing a sampling and monitoring protocol for freshwater game fish throughout the freshwater marshes of the refuge. As previously mentioned, refuge staff have spent considerable time growing out and stocking Florida-strain largemouth bass (Micropterus salmoides floridanus) across RWR freshwater areas. Genetic samples from fish collected would allow better determination of the ratio of stocked Florida-strain largemouth (M. s. floridanus) to that of the native largemouth bass (M. s. salmoides) in these areas. This information could help in justify the future need (or lack thereof) to continue stocking fish.

As RWR continues to rebuild from the damage done by both hurricanes Rita and Ike, new laboratory facilities will allow more in-depth fisheries research and longer spanning aquaculture studies to be conducted.

Inventory.—RWR currently maintains a large database of monthly fish samples collected over many years across the refuge and within the various marsh management schemes. This data is currently being compiled and organized for data analysis. Future inventory needs include a refuge-wide survey for all game and non-game fish species, similar to Perry (1965).

Brown Pelican

Research.—The eastern Brown Pelican (Pelecanus occidentalis) is the Louisiana state bird, but it had virtually disappeared from the state by 1963 (Williams and Martin 1968), with environmental pesticide contamination and subsequent eggshell thinning as a plausible link to declines (Blus et al. 1979). In 1968, LDWF administration and staff biologists at RWR initiated a program to reintroduce Brown Pelicans back into historical localities (i.e., barrier islands for nesting) in southeastern coastal Louisiana. Since the inception of the program, RWR personnel have monitored the incredibly successful reintroduction via aerial surveys. Since 1971, over 350,000 Brown Pelicans have been produced in Louisiana, with 14 active colonies in 2008 producing ~24,620 fledglings. Another important milestone during the program was the natural expansion of Brown Pelicans to Rabbit Island in southwestern Louisiana (Cameron Parish) in 2003. This colony has grown rapidly in seven years to approximately 2000 individuals with 530 nests produced in 2010. Aerial surveys were discontinued in 2009 due to budgetary constraints and the federal delisting of the Brown Pelican.

In 2010, in response to the Deepwater Horizon Oil Spill, RWR staff participated in translocating oil-rehabilitated Brown Pelicans from southeastern Louisiana to Rabbit Island (Calcasieu Lake, Cameron Parish). Following translocation of 182 pelicans, monitoring was completed over three months following the initial release. Preliminary analyses indicate that in the short-term, the translocations were a success; no mortality of rehabilitated pelicans was documented and translocated pelicans integrated into native pelican groups (Selman et al. submitted manuscript). In the future, RWR refuge staff should continue to monitor this population to assess long-term success of the translocation and also monitor the growing population.

Inventory.—Inventory and population/nesting data on Brown Pelicans is available from the initial reintroduction in 1968 to 2008. These data have been presented in previous publications (Nesbitt et al. 1978, McNease et al. 1984, Holm et al. 2003) and recent data are currently being compiled for data analysis and publication. In 2009, population surveys were discontinued due to budgetary constraints. RWR biologists plan to reinitiate these surveys in the spring 2012 due to the potential long-term impacts on the population and nesting of pelicans following the Deepwater Horizon Oil Spill. Furthermore, if reinitiated, these data will be directly comparable to pre-oil spill data.

Bald Eagle

Research.—The Bald Eagle (Haliaeetus leucocephalus) had a similar fate in the 1950s and 1960s as the Brown Pelican: only four active nests were found in Louisiana between 1954 and 1960. In 1972, only six nests were reported and the decline was attributed primarily to the link between pesticides and eggshell thinning (Grier 1982); other secondary factors also attributed to its decline, including habitat destruction, disturbance of nests, and poaching. Formal Bald Eagle surveys by RWR staff began in 1984 to determine the distribution/abundance of Bald Eagle populations. By 2008, the Bald Eagle had been taken off the federal endangered species list due to recovered populations and Louisiana maintained 387 active nests which produced 530 fledglings (T. Hess, unpubl. data). Due to budget limitations, formal Bald Eagle surveys by RWR staff were discontinued in 2008.

In the future, research is proposed by RWR staff to work on a Bald Eagle satellite telemetry project to determine the movements, habitat use, and migratory paths of Louisiana Bald Eagles.

Inventory.—Inventory and population/nesting data of Bald Eagles is available from the initial reintroduction in 1984 to 2007. These data are currently being compiled for data analysis and publication.

Whooping Crane

Historically, both migratory and non-migratory Whooping Cranes inhabited the marshes and ridges of southwest Louisiana’s Chenier Plain as well as the Cameron Prairie to the north. In May 1939 the presence of a non-migratory population of Whooping cranes in and around the White Lake Wetland Conservation Area (WLWCA) was confirmed during an aerial survey in which 13 Whooping Cranes, including two juveniles were discovered. A hurricane the following year scattered the birds and only 6 returned to the WLWCA after the storm. The population continued to decline until 1947 when only one crane survived. In March 1950, the lone crane was captured and relocated to the Aransas NWR to be with other Whooping Cranes.

Although the idea of reintroducing whooping cranes to LA had been discussed as early as 1977, an approved plan did not come together until over 30 years later. Prior to developing the whooping crane reintroduction project, RWR staff participated in a study to evaluate Whooping Crane foraging/breeding habitat at White Lake (in collaboration with Song-Ryong “Jackie” Kang and Sammy King, LSU). Then in 2009 LDWF began work on a plan to bring Whooping Cranes back to southwestern Louisiana with Rockefeller staff heavily involved in developing the plan and the project. Prior to the release, RWR staff members were primarily responsible for selecting the reintroduction site, constructing the release pen, assisting with public meetings and presentations in order to gain support from the local community and stakeholders. Further, RWR staff, in collaboration with LSU, was responsible for implementing the project and for the monitoring/caring for released whooping cranes. On 16 February, 10 juvenile Whooping Cranes were transported to the WLWCA release pen and put into a top-netted pen. Later in March, the 10 juveniles were released into a larger 1.5 acre open pen, which gave them the ability to fly in and out of the release pen and explore the surrounding marsh. Pelletized food was provided for the next 8 weeks before being discontinued. The birds are regularly monitored and research on the habitat used by the birds has begun. Research projects will continue to develop from this reintroduction project and RWR staff will participate, and be involved in these, as well as other aspects of this project and overall Whooping Crane recovery.

Miscellaneous Research

RWR staff have conducted or participated in other research topics including alligator snapping turtle (Macrochelys temminckii) dietary studies (Elsey 2006), mineral development compatibility with wildlife, effects of in-situ burning as a cleanup tool for small oil spills, development of capture techniques for rails (Perkins et al. 2010), king rail stable isotope analysis (Perkins 2007), and king/clapper rail differentiation via morphometrics (Perkins et al. 2009).

Future Research/Inventory Opportunities and Goals

With the recent addition of three new staff biologists at RWR, it is likely that new research avenues will be investigated since each biologist comes with a unique research background (i.e., herpetofaunal species, non-game fish species, and non-game small mammals). Fortunately, many of these areas have not been previously explored by Rockefeller staff biologists and more funding sources, including State Wildlife Grants and Section 6: Endangered Species Funding, are available to research rare, threatened, and endangered species that occur on RWR. Future inventory projects that are needed include 1) surveys for rare shorebirds, particularly for wintering plover species; 2) herpetofaunal inventory of RWR; 3) status surveys of Diamondback Terrapins (Malaclemys terrapin) on RWR; 4) status surveys for rare non-game fish species on RWR; and 5) status surveys for bats/non-game mammal species. Additional studies on neotropical migrants and stopover ecology on chenier sites would also be of research interest due to the decline of chenier habitat in southwestern Louisiana. In summation, RWR staff will continue to balance individual research projects and cooperative research projects with other agencies and/or academic institutions.