Simons-Legaard E.M.,University of Maine, United States |
Harrison D.J.,University of Maine, United States |
Krohn W.B.,University of Maine, United States |
Vashon J.H.,50 State Street
Journal of Wildlife Management | Year: 2013
We evaluated patterns of occurrence and non-occurrence for Canada lynx (Lynx canadensis) across a 16,530-km2 study area in Maine to provide a better understanding of lynx habitat selection and habitat ecology on commercially managed forestlands in the Acadian Forest. Because of the influence of forest structure on lynx habitat selection and abundance of their primary prey, the snowshoe hare (Lepus americanus), and to improve our ability to build robust models, we used habitat information derived from a time series of Landsat satellite imagery spanning the period 1973-2004. We defined and mapped 10 forest types based on forest harvest history, time since harvest, and current forest condition. We compared a suite of models to evaluate relative influences of forest composition, habitat patch configuration, and hare density on habitat selection by lynx at the landscape scale. Occupied areas had greater average hare densities and percentage of mature conifer. Average hare density in occupied areas (0.74 hares/ha) was greater than in unoccupied areas (0.62 hares/ha), but was less than previous research has suggested may be necessary to support lynx populations in the southern portion of the species' range. No occupied areas occurred where average hare density was <0.5 hares/ha. Average hare density at the landscape-scale was strongly influenced by amount of high-quality hare habitat (i.e., conifer or mixedwood regenerating forest, 15-35 yr post-harvest). Edge density between mature conifer and high-quality hare habitat was substantially greater in occupied areas compared to unoccupied areas. Juxtaposition of those 2 forest types may provide edge habitat where lynx experience easier travel and improved access to prey in landscapes with extensive areas of high-quality hare habitat where travel and access may be somewhat limited by high understory stem density. Probability of occurrence declined nonlinearly with changes in hare density and percent mature conifer forest in the landscape; thus, suitability of currently occupied landscapes could change markedly with future changes in landscape-level hare densities and changing habitat associated with forest management. Where lynx conservation is a priority, we recommend that managers focus on creating and maintaining a minimum of 27% high-quality hare habitat within 100-km2 areas to promote landscape-scale hare densities >0.5 hares/ha. © The Wildlife Society, 2013.
Maynard D.J.,National Oceanic and Atmospheric Administration |
Trial J.G.,50 State Street
Reviews in Fish Biology and Fisheries | Year: 2014
Hatchery technology has been employed for the conservation of Pacific (Oncorhynchus spp.) and Atlantic salmon (Salmo salar) for over 140 years. The initial societal paradigm was that nature is inefficient and hatcheries could be used to conserve stocks that were over utilized or suffering habitat degradation. Although these early hatcheries failed to meet their conservation objectives, they succeeded in developing the spawning-to-swimup fry culture technology used today. In the 1930s the paradigm shifted to artificial and natural production being equally effective and led to the closure of Federal hatcheries in areas with intact freshwater habitat. Hatcheries were maintained to mitigate for habitat loss from hydropower development. With the development of cost effective smolt production technology by 1960, the paradigm returned to nature being inefficient and ushered in the massive conservation utilization production of Pacific salmon that continues to this day. The early 1990s saw another paradigm shift with nature's inefficiency recognized as being the foundation for evolution to maintain the fitness of salmon in their natural environment. This shift gave rise to a focus for hatchery technology to preserve stocks in their native habitats. Using hatcheries for preservation-conservation has become the norm for Atlantic salmon in the USA and Atlantic Canada and for Pacific salmon stocks listed under the Endangered Species Act in the USA or as species at risk in Canada. © 2013 Springer Science+Business Media Dordrecht (outside the USA).
Cox O.N.,50 State Street |
Clements W.H.,Colorado State University
Journal of Great Lakes Research | Year: 2013
Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants that are known carcinogens and mutagens. This research used the sediment quality triad, an integrated weight-of-evidence approach, to evaluate sediment PAH concentrations, sediment toxicity, and benthic community structure at marina and reference sites in Isle Royale National Park, USA. The highest PAH concentrations were measured at marina locations and exceeded threshold effect concentrations (161μg PAH/g TOC) at one site. Marina locations were dominated by pyrogenic PAHs, indicating anthropogenic sources of these compounds. Survival of the amphipod Hyalella azteca was significantly reduced (p=0.0320) when exposed to sediments from marinas. Although macroinvertebrate abundance and species richness were similar at marina and reference sites, results of multivariate analyses showed that composition of benthic communities varied among sites. In particular, abundance of the PAH-sensitive amphipod, Diporeia spp. was significantly lower at marina sites compared to reference sites. In contrast to patterns observed for organochlorines (e.g., PCBS, dioxins), biota-sediment accumulation factors for PAHs measured in the burrowing mayfly Hexagenia limbata decreased with increasing Kow values, suggesting that the more lipophilic compounds were being metabolized. Increased PAH concentrations, shifts in community composition, low survival of H. azteca, and reduced abundances of Diporeia spp. at marina sites were consistent with the hypothesis that PAHs impacted these areas; however, across all sites these effects were relatively subtle. These results emphasize the need to use a weight-of-evidence approach when investigating effects of environmental contaminants that occur at relatively low concentrations. © 2013 Elsevier B.V.
Seger R.L.,University of Maine, United States |
Servello F.A.,University of Maine, United States |
Cross R.A.,50 State Street |
Keisler D.H.,University of Missouri
Canadian Journal of Zoology | Year: 2013
We studied nutritional ecology of American black bears (Ursus americanus Pallas, 1780) in Maine, including active and hibernating bears during 5 years, across three study areas, using nitrogen stable isotope analyses of blood samples (n = 152). Our central finding, in two study areas, is positive correlation between body mass and δ15N. This suggests use of large body size to acquire or guard food resources that have relatively high δ15N, consistent with importance of ungulates as food for the largest bears in Maine. In these two study areas, hibernating bears across the spectrum of body mass showed greater δ15N during 2 years of beechnut (Fagus grandifolia Ehrh.) scarcity compared with 2 years of beechnut abundance. Adiposity, measured by serum leptin, was greater in hibernating bears following a season of beechnut abundance compared with one of beechnut scarcity. Total litter mass correlated positively with maternal serum leptin and negatively with maternal δ15N, supporting the importance of mast, including beechnuts, to reproductive success of bears in Maine. In the third study area, bears across the spectrum of body mass had greater δ15N in all years, consistent with food resources relatively high in 15N that were available to bears of all sizes.
Mittelhauser G.H.,Maine Natural History Observatory |
Tudor L.,50 State Street |
Connery B.,Acadia National Park
Northeastern Naturalist | Year: 2013
We systematically surveyed the Maine coastline from Washington County to York County to provide baseline data concerning Calidris maritima (Purple Sandpiper) population status. Focusing on a particular region each winter, we conducted 66 winter surveys by boat along the entire coast of Maine between 2002 and 2007 plus three days surveying from the mainland between Kittery and Biddeford during the winter of 2005-2006. We tallied 13,318 Purple Sandpipers during these surveys. After accounting for birds present but not detected, we estimate that 14,000 to 17,000 Purple Sandpipers wintered annually in Maine between 2002 and 2007. Based on an assessment of historical records and data collected during this study, flocks of≥250 Purple Sandpipers have been reported from 48 sites along the Maine coast. The area from Isle au Haut to Swans Island along the midcoast supports the highest concentrations of wintering Purple Sandpipers in Maine and the largest wintering concentration of Histrionicus histrionicus (Harlequin Ducks) in eastern North America, highlighting the potential importance of this geographic region.