I investigated the relationship between food abundance and black bear reproductive success. Black bear reproductive potential had been hypothesized to be related to natural food abundance in other studies but the effect had not been tested. Pregnant females should select dens of maximum thermal efficiency to conserve body fat used for thermoregulation. If this were so they could allocate more depot fat to lactation. I examined data on natal den type (open nest, brushpile, covered) and subsequent survival of cubs in Massachusetts and Minnesota over 11 and 13 years, respectively. I could not detect any differences in cub survival but the power of tests was low (power = 0.139 to 0.258). I could not predict either litter size or MFYS from environmental and harvest variables. When natural food abundance was low black bears used cornfields intensely and did not differ in body weight from high food years. Litter size and MFYS were related to litter order; first litters were smaller and had lower survival than subsequent litters. Sixty percent of Massachusetts females had their first litter at 3 years old. Twelve of 20 first litters were of single cubs and 10 of 12 first litters were totally lost. I hypothesized that female black bears operated according to the life history theory of tradeoffs between present and future reproduction. Having cubs is not very costly to bears, raising them is. Thus, females had cubs at an early age (3 years old) but often could not find enough food in spring to both lactate and continue structural growth. Thus, first litters were usually lost. I provide the first direct test of the hypothesis of the effect of diet quality on milk composition and cub survival in free-ranging bears. Milk composition differed between years of varying spring diet quality. Milk fat was lower when diet fat was low but MFYS was not different between the high fat and low fat years. I conclude that in Massachusetts, and likely most of eastern North America, natural food abundance has little effect on bear reproduction because bears can access alternate food sources.

Browsing by dense (>3–6 deer/km2) populations of white-tailed deer (Odocoileus virginianus) removes tree seedlings from the forest understory, making it difficult for the forest to regenerate if the overstory is damaged or removed. Hay-scented fern can invade the forest understory where deer have damaged and removed other plants. These ferns form dense (90–100 fronds/m2) colonies that cover the forest floor with a thick root mat and form a canopy 60–80cm tall. The ferns interfere with seedling growth, even if deer populations are reduced, because they limit germination sites and block light from reaching the forest floor. This research, conducted in the Quabbin Reservoir Watershed Forest, consisted of four studies that proposed to explain the current distribution of fern colonies, identify specific ways in which past deer browsing and current fern growth affected the germination and growth of several common local tree and shrub species, and evaluate mechanical treatments for hay-scented fern control. By sampling pine plantations thinned at various times over a 30 year period, it was determined that overstory thinning followed by a period of at least 15 years of excessive browsing was required for fern colonies to grow so that understory tree seedling regeneration was blocked throughout a forest stand. Rubus is able to grow through hay-scented fern and expand at the expense of fern colonies. A study of the soil seed bank determined that heavy deer browsing may be associated with depletion of Rubus spp. seeds in the soil. This may slow the recovery process. A study of seedling growth and phenology indicated that seedlings that grow above the fern canopy, Rubus, black birch and white pine, begin photosynthesis early in the spring before annual fern growth blocks the light to the forest floor. In the last study, it was found that while the root mat reduces germination, it does not stop seedling growth to the extent that the intact fern canopy does. Rubus, black birch, and white pine were able to germinate and grew well even with the root mat intact. Breaking up the root mat without removing it increased fern growth in the next growing season.

Snow leopard ecology, distribution and abundance in Mongolia were studied between 1993 and 1999. I placed VHF and satellite radio-collars on 4 snow leopards, 2 males and 2 females, to determine home ranges, habitat use, movements, and activity. Home ranges of snow leopards in Mongolia were substantially larger than reported elsewhere. Males ranged over 61–142 km2 and female 58 to 1,590 km2. Cats had crepuscular activity patterns with daily movements averaging 5.1 km. Intraspecific distances averaged 1.3 km for males to 7.8 km for males. Leopards selected moderately to very-broken habitat with slopes >20°, in areas containing ibex. Leopard distribution and abundance was determined using sign surveys. Leopard range in Mongolia is approximately 103,000 km2 but cats are not uniformly distributed within that range. High-density areas include the eastern and central Transaltai Gobi and the northern Altai ranges. Relative leopard densities compared well with relative ibex densities on a regional basis. A snow leopard conservation plan was drafted for Mongolia that identifies problems and threats, and provides an action plan. Wild Bactrian camels occur in the Great Gobi National Park (GGNP) and are thought to be declining due to low recruitment. I surveyed camels by jeep and at oases, observing 142 (4.2% young) and 183 (5.3% young) in 1997 and 1998. Current range was estimated at 33,300 km2. Some winter and calving ranges were recently abandoned. Track sizes and tooth ages from skulls were used to assess demographics. A deterministic model was produced that predicts camel extinction within 25 to 50 years under current recruitment rates and population estimates. Gobi brown bears are endemic to Mongolia and may number less than 35. Three population isolates may occur. I collected genetic material from bears at oases using hair traps. Microsatellite analyses of nuclear DNA determined sixteen unique genotypes, only two of which occurred at more than one oases. Genetic diversity was very low with expected heterozygosity = 0.32, and alleles per locus = 2.3. Mitochondrial DNA sequences were compared to other clades of brown bear and found to fall outside of all known lineages.

Forest gaps play a major role in forest dynamics because increased resource availability favors plant species that differ from those in undisturbed forest. This dissertation investigates the spatial heterogeneity of resource availability in gaps, how it varies by site, and how it affects regeneration. Gap effects on resource availability and seedling growth were studied at three sites, which differed in drainage, using large gaps (108 m × 30 m) where light ranged from understory shade to full sun. Light levels in plots were measured using hemispherical photos; soil moisture, with a capacitance probe; soil temperature, with a portable thermocouple; and nitrogen, with buried-bag incubations. The strong asymmetric, light-induced temperature gradient drove nitrogen mineralization rates. Patterns of mineralization were modified by variation in soil moisture within sites and increased with the average moisture levels among sites. Nitrogen availability was highest in the center of gaps, while root uptake reduced nitrogen availability at the north edge. Contrary to predictions, relative height growth of Betula lenta growing in the north center of gaps was greater than that of B. papyrifera. For both species, the difference between understory and gap growth increased from least to most fertile sites. To separate the effects of resources on plant- and leaf-level responses in the two species, a greenhouse experiment was conducted with high and low levels of light, nitrogen, and water. High nitrogen increased height growth even in shade. Nitrogen also increased leaf area through greater leaf initiation and retention. High rates of growth in gaps is caused by nitrogen effects on leaf display and light effects on realized carbon gain. This research shows that increased nitrogen availability only occurs if gaps are large enough to increase soil temperatures that drive mineralization and to overcome the effects of root uptake near gap edges. It also highlights how the effects of canopy openings varies by site and how this can influence the regeneration of gap-dependent species.

Habitat loss and fragmentation are among the most serious threats facing amphibian populations globally. Given the prevalence of these threats, it is essential that conservation planners understand the spatial scales at which amphibian populations operate and minimize local and regional extinction risks. We conducted a landscape-level investigation of population processes in marbled salamanders (Ambystoma opacum) distributed among 14 seasonal ponds in western Massachusetts. Using capture-recapture methods, we monitored breeding populations from 1998 to 2005 to evaluate terrestrial movement distances (Chapter 1), develop methodology for identifying individuals (Chapter 2), quantify dispersal probabilities and distances (Chapter 3), and evaluate survival and breeding probabilities in adults and the degree to which they are correlated among breeding populations (Chapter 4). In six field seasons, we recorded over 6,000 captures of adult marbled salamanders and 8,000 captures of newly emerging juveniles. Six of the 14 ponds supported relatively persistent breeding populations. Nearly 100% of adults and over 70% of juveniles moved to terrestrial habitats farther than 30 m from breeding ponds, and some juveniles moved greater than 1,200 m in their year of emergence. Both first-time and experienced breeders showed high fidelity to natal ponds; however, 9% and 3.6% of these individuals, respectively, dispersed to non-natal breeding sites. Adult survival probabilities did not vary substantially between sexes or among most breeding populations. Simulations estimated that approximately 50% of individuals that survive to breed once do not live to breed again, but approximately 25% will survive to breed 3 or more times. Collectively, our results demonstrate that breeding populations of marbled salamanders are prone to significant variability over time, with much of this variability concentrated in the egg and larval life stages. Given relatively limited life spans and frequent reproductive failures, many breeding populations may be vulnerable to local extinctions over the course of several decades; however, occasional dispersal among populations may offset both genetic and demographic factors contributing to local extinction risks. Marbled salamanders in Massachusetts may be best described by a dynamic “source-sink” metapopulation model, suggesting that conservation strategies must extend beyond breeding wetlands to maintain adult survival and metapopulation processes.

Modern silviculture is shifting from even-aged management toward sustainable management of the diversity of forest communities. Traditional growth-and-yield models are too simple for this new approach, but mechanistic models that can incorporate the complexity are too general. This shift in emphasis presents important scientific challenges and creates a critical need to update our modeling approaches. One response has been to manage forests by mimicking natural disturbance. Windstorm is the dominant natural disturbance in forests of northeastern North America. In Chapter 1, I use a mechanistic model (SORTIE) to explore the sensitivity of forest composition and structure to the resistance of individual trees to wind disturbance and the roles of local dispersal and seedling establishment. The results show that species-specific resistance to wind: drives the community response to disturbance; interacts with local dispersal patterns to influence succession; and interacts with seedbed substrate dynamics to influence canopy population dynamics. Biotic disturbances are also an important natural disturbance in these forests. In Chapter 2, I quantify how the presence of beech bark disease (BBD) alters the resistance of beech to uprooting and stem break, and explore the sensitivity of forests to subsequent increases in coarse woody debris (CWD). Results show that small seeded species increased in basal area primarily due to the increase in CWD caused by BBD. The results highlight the important indirect effects that pathogens can have on forest community dynamics. Managing complexity also requires improving our understanding of competition among trees and species responses along environmental gradients. In Chapter 3, I use USFS FIA data to analyze the effects of competition on tree growth along gradients for eight tree species in New England. I use information theory to determine the relative weight of evidence for each model. No species showed strong evidence in support of one model over others, implying that the robustness of predictions based on the selected best model is questionable. The complexity of competitive interactions and growth along gradients and the importance of including secondary effects via model averaging highlight key challenges for the management of mixed-species, uneven-aged stands.

The ambermarked birch leafminer (AMBLM) (Profenusa thomsoni) is an invasive leafminer native to the Palearctic from the United Kingdom to Turkey to Japan. It was introduced to the eastern United States in 1921 and has since spread to the mid-western U.S. states and Canadian provinces. This leafminer was introduced to Alaska in 1996, where it has since spread over 140,000 acres, from Haines to Fairbanks. The most severe damage is found throughout the Anchorage bowl, which extends south to Girdwood and North to Wasilla. The damage caused by P. thomsoni can be severe, defoliating entire trees. In 2006, it was noted that urban areas in Alaska experienced higher densities of AMBLM leafminer than adjacent forested areas. To examine the effects of habitat on leafminer densities, twenty permanent plots were established in Anchorage, Alaska in 2006 and were classified as urban and forest (ten each). Temperature records for the twenty permanent sites showed that average daily temperatures and average accumulated degree-days differed significantly between urban and forest sites. In 2007 and 2008, leafminer abundance in each habitat was examined weekly at six plots (three urban and three forest) within the city of Anchorage. Asynchronous emergence, flight, and oviposition times were observed between leafminers in forests versus urban areas, with peaks of these parameters in forests being about three weeks later than in urban areas. To control the spread and effects of P. thomsoni, a cooperative biological control project was launched in 2003 and the parasitoid wasp Lathrolestes thomsoni (Hymenoptera: Tenthredinidae) was selected for release. Parasitized leafminer larvae were collected from the provinces of Northwest Territories and Alberta, in Canada and transferred in soil tubs as pre-pupae to Alaska. From 2004-2008, 3636 adult L. thomsoni adults were released in birch tree stands in Anchorage, Soldotna, and Fairbanks, Alaska. Parasitoids have been recovered at all release sites in Alaska and have established populations at most release sites. Currently, AMBLM densities have declined by over 40% in the Anchorage area and the spread of the leafminer throughout the state appears to have slowed. Throughout the course of the biological control program two additional parasitoids were discovered attacking P. thomsoni in Alaska. The first, Lathrolestes soperi, an endoparasitoid with similar biology to the released parasitoid L. thomsoni, was found to attack early instar larvae within the leaf. The second species, Aptesis segnis, is an ecotoparasitoid that attacks pupae and prepupae in their earthen cells in soil. Lathrolestes soperi was found to contribute a significant proportion of mortality against the leafminer. The presence of A. segnis in the parasitoid guild raised mortality of P. thomsoni to 40.3%, showing that the percent parasitism by A. segnis was 26%, double that provided by L. soperi. This suggests that A. segnis is the dominant parasitoid in the guild. It is unknown what effect that the introduced wasp L. thomsoni will have on the presumably native L. soperi and if one species will outcompete the other over time, or both will coexist. Future work on this system is recommended in five to ten years to see if L. thomsoni and L. soperi populations remain stable or to see if one parasitoid outcompetes the other and if A. segnis maintains its dominant place in the system.

No description available.

The conservation of large carnivores is dependent on comprehensive research programs within and surrounding protected areas. In many locations, protected areas are not large enough to support viable large carnivore populations, and thus it is essential to understand the ecology of predators outside of protected areas. On the commercial farms of northcentral Namibia, farmers have systematically removed the largest predators in order to protect their livestock. Leopards are the largest remaining carnivore, aided by their adaptable and secretive nature. In order to properly manage regional leopards, there were several questions about their population size, feeding ecology and movements that needed to be addressed. Leopard population estimates were generated through camera-trapping surveys within and surrounding the Waterberg Plateau Park. These surveys suggest that leopard population density is significantly higher outside of the park, most likely due to environmental factors within the park that limit potential prey. Leopards were shown to primarily feed on wild ungulates, preferring kudu over livestock which they appear to avoid even when livestock densities are higher than individual wild ungulate species. Leopard home ranges and movements were investigated on commercial farmlands where they were not shown to move between the farms and the park. Home range estimates were similar to previous studies for similar environments with marginal resources. Beyond the ecological studies, the attitudes and perceptions of farmers were incorporated into the study in order to assess local predator management with particular emphasis on leopards. Farmers used a variety of livestock husbandry techniques, with varying success. Although there were no clear techniques to reduce conflict, farmers were able to substantially reduce losses by using at least one technique to protect their stock against predators. Farmers listed depredation as the source of highest livestock loss, and leopards the species which caused the most conflict by occurrence. Farmers removed approximately 11 leopards per year in the region which is equal to a 14% off-take for the local population. Farmer tolerance was assessed by the % calf loss that farmers were willing to lose to predators annually. Tolerance rates were then compared to annual livestock loss. Leopards, being a charismatic animal for tourists and trophy hunters, were evaluated for potential financial benefits for farmers to mitigate losses. Region-wide management strategies are discussed.

Macro- and micro-habitat associations of small mammals in seral aspen-birch and mature red spruce habitats in Acadia National Park, Maine, were studied by live-trapping during the summers of 1987 and 1988. The aspen-birch habitat was structurally more diverse than the mature conifer habitat, but diversity, richness, and evenness of species of small mammals were not different between habitats. Blarina brevicauda, Sorex cinereus, Tamias striatus, and Peromyscus leucopus exhibited preference for seral hardwoods, whereas Tamiasciurus hudsonicus showed preference for the red spruce habitat. Most species in the aspen-birch habitat exhibited some degree of microhabitat selection and used microhabitat separate from other species. Small mammals in the red spruce habitat were less selective. Microhabitat used by a species and segregation by microhabitat among species varied between years in both habitats and appeared to be related to intraspecific interactions. Microhabitat use by sexes of Clethrionomys gapperi, P. maniculatus, and P. leucopus in the aspen-birch habitat was related to degree of habitat specialization. A spatial simulation system was developed to examine the responses of habitats of B. brevicauda, P. leucopus, T. striatus, and T. hudsonicus over time to varying levels of disturbance in the western section of Acadia National Park. The system consists of a raster-based data base containing descriptors of cover types, and models of vegetative succession and disturbance by windthrow and wildfire. Simulation experiments were conducted without disturbance, under three levels of windthrow, and with two sizes of wildfires (100 and 500 ha) at the three levels of windthrow. Occupancy of available habitat was based on the dispersion of a species during the previous simulation interval, the dispersal distance of a species, and patch size. Habitat for species associated with hardwoods increased with the rate of disturbance. Regardless of disturbance size or rate, each species was able to occupy almost all of its available habitat over a 300 yr period owing to the dispersion of habitat patches created by windthrow. Results suggest that windthrow alone can produce long-term spatial diversity of wildlife habitats in Acadia.