The relationship between spawning stock biomass (SSB) and 3 spatial distribution metrics (SDMs), measuring range, concentration, and density, using fisheries independent survey data for 10 demersal Northwest Atlantic fish populations (9 species), show metrics of density offer the best correlate of SSB. The concave, positive relationship between high density area (HDA) and SSB indicates that a decline in HDAs beyond a spatial threshold is associated with disproportionately large SSB declines in 6 populations. HDAs might indicate highly productive areas and/or positive fitness consequences, enhancing the ability of individuals to successfully spawn, locate prey, and evade predators. HDAs can help to assess the status of a population’s spatial structure and serve as a spatial reference point. By comparing spatial reference point locations relative to existing biomass reference points (based on MSY), scenarios are described wherein spatial reference points contribute to biomass reference points and to a precautionary approach to fisheries management.

No description available.

This study investigated the critical habitat requirements of breeding Blue Swallows Hirundo atrocaerulea Sundevall, in KwaZulu-Natal, South Africa. Blue Swallows, as a 'flagship species' of the KwaZulu-Natal endemic Mistbelt Grassland, were tagged and radio-tracked to obtain positional data to determine their habitat use while breeding. This information was correlated to the type and nature of the habitat used and to the nature of the land cover to determine the likely impact of habitat transformation and fragmentation on breeding Blue Swallows. Insect type and abundance was assessed in five surrounding habitat types using Malaise insect traps and the findings correlated to Blue Swallow habitat usage. Data on environmental variables were collected using HOBO® sensors and the findings related to insect type and abundance within each habitat type. A comparative investigation was undertaken using temperature and humidity data obtained below-ground at a Blue Swallow nest site and compared to temperature and humidity findings from above-ground. Preliminary investigations were also made into the breeding system used by the Blue Swallow using unique wing markings to estimate the number of individuals involved at a single active nest. Overall, wetland and grassland were first choice habitats a function of the increased individual insect mass in these habitats. Tea plantations were the next most important habitat type and timber plantations were avoided. Furthermore, it was shown that the Blue Swallow is a species that favours ecotones as preferential forage zones, particularly the ecotone between wetland and grassland. Malaise insect traps were effective in gathering suitable insect samples for analysis, revealing that significant differences occur in insect order, number and mass between habitat types. The most significant finding is that average insect mass per order, which was correlated closely to habitat type, matches the order of positive habitat type selection by the Blue Swallow. These findings were statistically significant and it is suggested that this correlation is the main reason behind the habitat selection by Blue Swallows. This study found a clear indication that insect numbers and mass, in grassland and wetland, increase with an increase in temperature and decrease with a decrease in average temperature. Clear trends were obvious during long periods of either cold or dry weather which .negatively influenced insect abundance and potentially, in turn, Blue Swallow well-being. The underground cavity used as the nesting site by Blue Swallows, experiences a greatly moderated climate in terms of the range of environmental factors compared with those experienced above-ground. This climate moderation is thought to be a clear advantage for the well-being of the Blue Swallow eggs and nestlings. Through the use of radio-tracking, visual markers and video footage it was clear that Blue Swallows breed with a number of adult birds at one nest. The recorded average sex ratio was 1(; : 3<;2, however, the need remains to elucidate the co-operative breeding system used by the Blue Swallow. In conclusion, the findings of this work present recommendations and suggestions on habitat management, offer insight into future research opportunities, and suggest strong conservation action for the species. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Habitat selection by, ecological energetics of, and the effects of changes in white pine (Pinus strobus L.) forests on Red Crossbills (Loxia curvirostra) were studied in Algonquin Provincial Park, Ontario. Birds were surveyed in several forest habitats and daily activities were observed during the breeding season in the autumn of 1998, a good year for white pine seed production. During the autumn of 1997 and summer of 1998, surveys of white pine stumps from trees harvested in the mid-late 1800s were conducted. Breeding birds foraged in stands with a minimum of 40% white pine, and appeared to prefer stands, both mixed deciduous-coniferous (40--70% white pine) and pine (>70% white pine) along roads. Possible reasons for this were: (1) seeds from trees along the road were more available to birds; (2) open-grown trees along the road had larger crowns with more seeds; and (3) the road provided grit and was adjacent to a favorite foraging area. (Abstract shortened by UMI.)

Many grassland songbird species exhibit sensitivity to patch size in North America’s fragmented prairie ecosystems, but the mechanisms explaining this area sensitivity are not well understood. I tested the effects of patch size and artificial conspecific location cues (song playback and decoys) on grassland songbird abundance in 23 northern tall-grass prairies in Manitoba, Canada, in 2010 and 2011. Richness and relative abundances increased with patch area; this effect was not explained by differences in local habitat structure, patch configuration, and adjacent matrix. Artificial cues elicited putative territory prospecting in small, previously unoccupied treatment patches from two focal species, Savannah Sparrow (Passerculus sandwichensis; n=3 treatment sites) and Le Conte’s Sparrow (Ammodramus leconteii; n=4 treatment sites), but not in control patches (n=3 for both focal species). Social information may influence the focal species’ settlement decisions, but the lack of permanent settlement response suggests social cues are unable to reverse their area sensitivity.

Many grassland songbird species exhibit sensitivity to patch size in North America’s fragmented prairie ecosystems, but the mechanisms explaining this area sensitivity are not well understood. I tested the effects of patch size and artificial conspecific location cues (song playback and decoys) on grassland songbird abundance in 23 northern tall-grass prairies in Manitoba, Canada, in 2010 and 2011. Richness and relative abundances increased with patch area; this effect was not explained by differences in local habitat structure, patch configuration, and adjacent matrix. Artificial cues elicited putative territory prospecting in small, previously unoccupied treatment patches from two focal species, Savannah Sparrow (Passerculus sandwichensis; n=3 treatment sites) and Le Conte’s Sparrow (Ammodramus leconteii; n=4 treatment sites), but not in control patches (n=3 for both focal species). Social information may influence the focal species’ settlement decisions, but the lack of permanent settlement response suggests social cues are unable to reverse their area sensitivity.

A primary focus of wildlife research is to understand how habitat conditions and human activities impact the health of wild animals. External factors, both natural and anthropogenic that impact the ability of an animal to acquire food and build energy reserves have important implications for reproductive success, avoidance of predators, and the ability to withstand disease, and periods of food scarcity. In the analyses presented here, I quantify the impacts of habitat quality and anthropogenic disturbance on indicators of health for individuals in a threatened grizzly bear population in Alberta, Canada. The first analysis relates spatial patterns of hair cortisol concentrations, a promising indicator of long-term stress in mammals, measured from 304 grizzly bears to a variety of continuous environmental variables representative of habitat quality (e.g., crown closure, landcover, and vegetation productivity), topographic conditions (e.g., elevation and terrain ruggedness), and anthropogenic disturbances (e.g., roads, forest harvest blocks, and oil and gas well-sites). Hair cortisol concentration point data were integrated with continuous variables by creating a stress surface for male and female bears using kernel density estimation validated through bootstrapping. The relationships between hair cortisol concentrations for males and females and environmental variables were quantified using random forests, and landscape scale stress levels for both genders was predicted based on observed relationships. Low female stress levels were found to correspond with regions with high levels of anthropogenic disturbance and activity. High female stress levels were associated primarily with high-elevation parks and protected areas. Conversely, low male stress levels were found to correspond with parks and protected areas and spatially limited moderate to high stress levels were found in regions with greater anthropogenic disturbance. Of particular concern for conservation is the observed relationship between low female stress and sink habitats which have high mortality rates and high energetic costs. Extending the first analysis, the second portion of this research examined the impacts of scale-specific habitat selection and relationships between biology, habitat quality, and anthropogenic disturbance on body condition in 85 grizzly bears represented using a body condition index. Habitat quality and anthropogenic variables were represented at multiple scales using isopleths of a utilization distribution calculated using kernel density estimation for each bear. Several hypotheses regarding the influence of biology, habitat quality, and anthropogenic disturbance on body condition quantified using linear mixed-effects models were evaluated at each habitat selection scale using the small sample Aikake Information Criterion. Biological factors were influential at all scales as males had higher body condition than females, and body condition increased with age for both genders. At the scale of most concentrated habitat selection, the biology and habitat quality hypothesis had the greatest support and had a positive effect on body condition. A component of biology, the influence of long-term stress, which had a negative impact on body condition, was most pronounced within the biology and habitat quality hypothesis at this scale. As the scale of habitat selection was represented more broadly, support for the biology and anthropogenic disturbance hypothesis increased. Anthropogenic variables of particular importance were distance decay to roads, density of secondary linear features, and density of forest harvest areas which had a negative relationship with body condition. Management efforts aimed to promote landscape conditions beneficial to grizzly bear health should focus on promoting habitat quality in core habitat and limiting anthropogenic disturbance within larger grizzly bear home ranges. / Graduate / 0768 / 0463 / 0478 / mathieub@uvic.ca

I investigated if constructed wetlands provide breeding habitat for the Horned Grebe (Podiceps auritus) in northwest Alberta. Over two years, I conducted bird surveys of 201 borrow-pits (ponds created during road construction) and 18 natural wetlands and collected data on local habitat and landscape features. For subsets of ponds, I also collected water chemistry and invertebrate data, and conducted stable isotope analysis. Grebes occurred on 36% of borrow-pits and produced chicks on 61% of occupied sites in 2007 and 81% in 2008. Grebes occurred more frequently on larger ponds, with more emergent vegetation, and avoided forested ponds that supported beaver activity. Horned Grebes are generalist foragers that did not select nesting ponds based on food-web structure. Twenty-six other bird species used borrow-pits, with distinct assemblages occurring on agricultural versus forested ponds. My study indicates that wetland construction offers a viable method for creating habitat for Horned Grebes and other species. / Ecology

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 84-98). / xii, 98 leaves, bound 29 cm

Thesis (M.S.)--University of Pretoria, 2005. / Includes bibliographical references.