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Cavity-nesting communities are structured by the creation of and competition for cavities as nest-sites. Viewing these communities as interconnected webs can help identify species interactions that influence community structure. This study examines cavity-nesting bird community interactions within the fire-maintained longleaf pine (Pinus palustris) ecosystem at Eglin Air Force Base, Florida. In chapter 1, I provide a background review of the ecology of my study system. In chapter 2, I use nest webs to depict the flow of cavity-creation and use at Eglin. I identified 2 webs into which most species could be placed. One web contained 6 species associated with pines. The second web contained 5 species associated with hardwoods. Red-cockaded woodpeckers (Picoides borealis) and northern flickers (Colaptes auratus) created most cavities used by other species within this community. In chapter 3, I describe snag densities and nest-site selection of the cavity-nesting bird community at Eglin. Large, mature pine snags were abundant, exceeding other reported densities for southern pine forests. Pine snags were heavily-used, despite the abundance of available red-cockaded woodpecker cavities in living pine. Hardwood snags accounted for 10% of nests found, and were used by 12 of 14 species. Diameters of nest-trees and available snags were below the range of optimal nest-snag diameters reported in other studies, indicating the need for site-specific snag management guidelines. In chapter 4, I combine a study of basic ecological principles with endangered species management to examine interactions within the cavity-nesting bird community at Eglin. I used a nest web to identify a potential indirect interaction between the red-cockaded woodpecker and large secondary cavity-nesters, mediated by the northern flicker. I used structural equation modeling to test a path model of this interaction. By experimentally manipulating cavity availability, I blocked links described in the model, confirming cavity creation and enlargement as mechanisms that influence this indirect relationship. I demonstrated that a red-cockaded woodpecker cavity-management technique could disrupt this indirect relationship by affecting northern flicker behavior, and provided an empirical example of how, in interactive ecological communities, single-species management can have indirect effects on non-target species. / Ph. D.

Over the 21st century, climate change and wetland habitat loss will pose major threats to the Eastern Massasauga (Sistrurus catenatus), a federally threatened and Great Lakes region endemic rattlesnake. I collected capture-recapture data from sites across the range and modeled the effect of climatic variables on growth rate and asymptotic size. I found that high snow residence time was associated with larger asymptotic sizes but slower growth, while high spring precipitation increased growth rate. I then projected future growth and size under different carbon emission scenarios. Given the threat posed by successional encroachment of woody vegetation, I used spatially explicit capture-recapture models to examine the effects of landscape characteristics and phenology on the spatial distribution of density for a population in Michigan. I found highest density in areas close to a stream and with low vegetation intensity, which can inform prescribed burn programs and give additional insights into life history.

We studied piping plovers (Charadrius melodus Ord) on Assateague Island National Seashore, Maryland, during the 1988-1990 breeding seasons. The estimated breeding population declined from 25 pairs in 1988 to 14 pairs in 1990. Nest predation by red foxes (Vulpes vulpes) was high. Predator exclosures constructed around individual nests did not increase nest survival. Chick survival was higher in bay beach and island interior brood-rearing habitats than on the ocean beach. Our evidence supports the hypothesis that the availability of adequate food is driving the differences in survival observed among brood-rearing habitats. Chicks raised on the bay beach or island interior weighed more, had higher foraging rates, and spent a greater proportion of their time foraging than chicks reared on the ocean beach. Indices of invertebrate prey abundance indicated that insects were more abundant on the bay beach and island interior than on the ocean beach. Disturbance did not differ among brood-rearing habitats. Human disturbance was higher in 1990 than in previous years. Overall productivity was 0.71 chicks fledged/breeding pair, well below our estimate of the productivity needed to deter a population decline. Management efforts should focus on reducing nest predation and maintaining overwash access paths to high quality brood-rearing habitat. / Master of Science

Freshwater mussels (Unionidae) in the United States have experienced dramatic declines, and 25% species are listed as federally endangered. Hence, recovery plans for endangered species proposed a strategy of propagation of young mussels for release to natal rivers to augment declining populations. In this study, I conducted laboratory experiments, assessed site suitability for mussel restoration, and evaluated survival and growth rates of released mussels to meet the requirements of recovery plan. I conducted multiple experiments to develop an improved protocol for juvenile mussel propagation and culture. Significantly greater survival and growth rates were found in newly metamorphosed juveniles of the rainbow mussel (Villosa iris) reared in a substrate of fine sediment and one-month-old juveniles of wavy-rayed lampmussel (Lampsilis fasciola) fed on natural food in pond water. Bio-filter media greatly increased water quality by reducing the concentration of ammonia and nitrite. The negative impacts of flatworm predation and filamentous algae in juvenile culture were controlled, and juvenile escapement was prevented. Juvenile mussels were successfully produced and cultured to stockable size (>15 mm) for release. I released laboratory-propagated mussels at three historically important sites in Clinch and Powell rivers for the assessment of site suitability. Use of cages was the most effective method to determine site suitability because the free-released mussels (untagged, tagged) had low catchability. Mussels released at Horton Ford, Clinch River, exhibited significantly faster growth. Horton Ford is the most suitable site, while environmental conditions at Fugate Ford, Powell River, are deemed unsuitable for mussel restoration and recovery. To facilitate the detection of released mussels, I applied Passive Integrated Transponder tags to laboratory-produced juveniles of the endangered Cumberlandian combshell (Epioblasma brevidens) and released them near Brooks Bridge, Powell River. The detection probability increased above 98%. I developed a set of hierarchical Bayesian models incorporating individual variations, seasonal variations, periodic growth stages and growth cessation to estimate survival, detection probability and growth of released mussels in a changing environment. Mussels of E. brevidens exhibited great survival (> 99% per month) and growth, indicating suitable conditions for recovery of this endangered species at this site. / Ph. D.

One major lesson derived from the implementation of the Endangered Species Act (ESA) over the past 30 years is that direct regulation is not the only nor the optimal way to protect endangered species on working lands because of an undue burden imposed on private landowners. The role of a voluntary conservation program is to rearrange incentives so that society bears the cost rather than the landowner. Employing a survey research methodology, I used theories of reasoned action and random choice to explore landowners? stated preferences for conservation programs. I found landowners? stated interest in compensation programs to be moderate at best. For those willing to consider programs involving endangered species, associating land management requirements for species conservation with direct benefits to the landowner is important, but perhaps not as important as ensuring that the program provides adequate financial incentives, consideration of the term of the program, and a level of certainty regarding the landowner?s future obligations under the ESA. Landowners are not a homogenous group. I identified two classes of landowners according to preferences for program structure. One group was highly sensitive to program structure, aside from financial incentives, while the other was likely to participate if adequately compensated with financial and technical assistance. These differences related to opinions on endangered species protection and dependence on their land for income. Voluntary incentive programs increasingly are a popular tool to maintain and enhance conservation; however, these programs are only successful insofar as landowners choose to enroll. This research demonstrates that improving recovery efforts on private lands requires program administrators to have a more complete understanding of landowners? views on endangered species and conservation programs in general, as well as their motivations for owning and operating their land. By doing so, programs with broader appeal and greater efficacy can be designed and implemented.

Prior to 1993, freshwater angling in South Africa had been governed by the respective nature conservation legislation of the four South African provinces, the four “independent homelands" and the six so-called Bantustans. In 1993 a South Africa with nine provinces was created, of which only Limpopo and Mpumalanga promulgated its own laws governing freshwater angling. From 2008 angling for listed threatened and protected freshwater fish species has been regulated by the National Environmental Management: Biodiversity Act, supplemented by the Threatened or Protected Species Regulations. In addition, it is anticipated that the Alien and Invasive Species Regulations, which will regulate angling for listed alien and invasive freshwater fish, will be promulgated in the near future. The result is that freshwater angling is currently being governed by a plethora of pre-1993 provincial, homeland and Bantustan legislation, two post-1993 provincial acts, as well as post-1993 national legislation. In this dissertation the South African freshwater angling legislative framework was critically analysed. It was found that the multitude of fragmented and complex laws, created 15 “angling provinces” which leads to confusion amongst anglers and government officials alike. In the process legal certainty and reasonableness, cornerstones of a sound legal system, are being compromised, indigenous freshwater fish are not adequately protected and alien or invasive freshwater fish are not properly managed. In the light of the above, and after taking comments by anglers and enforcement officials into account, recommendations are made for an improved legislative framework for freshwater in South Africa. It is recommended that all freshwater fish species be managed and/or protected on a catchment basis, as opposed to the current provincial basis. This will ensure legal certainty and reasonableness and that all indigenous freshwater fish which are subject to the similar threats are protected adequately and uniformly. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2010.

Prior to 1993, freshwater angling in South Africa had been governed by the respective nature conservation legislation of the four South African provinces, the four “independent homelands" and the six so-called Bantustans. In 1993 a South Africa with nine provinces was created, of which only Limpopo and Mpumalanga promulgated its own laws governing freshwater angling. From 2008 angling for listed threatened and protected freshwater fish species has been regulated by the National Environmental Management: Biodiversity Act, supplemented by the Threatened or Protected Species Regulations. In addition, it is anticipated that the Alien and Invasive Species Regulations, which will regulate angling for listed alien and invasive freshwater fish, will be promulgated in the near future. The result is that freshwater angling is currently being governed by a plethora of pre-1993 provincial, homeland and Bantustan legislation, two post-1993 provincial acts, as well as post-1993 national legislation. In this dissertation the South African freshwater angling legislative framework was critically analysed. It was found that the multitude of fragmented and complex laws, created 15 “angling provinces” which leads to confusion amongst anglers and government officials alike. In the process legal certainty and reasonableness, cornerstones of a sound legal system, are being compromised, indigenous freshwater fish are not adequately protected and alien or invasive freshwater fish are not properly managed. In the light of the above, and after taking comments by anglers and enforcement officials into account, recommendations are made for an improved legislative framework for freshwater in South Africa. It is recommended that all freshwater fish species be managed and/or protected on a catchment basis, as opposed to the current provincial basis. This will ensure legal certainty and reasonableness and that all indigenous freshwater fish which are subject to the similar threats are protected adequately and uniformly. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2010.