Time filter

Source Type

Vaughan, Canada

Mcguire L.P.,University of Western Ontario | Guglielmo C.G.,University of Western Ontario | Mackenzie S.A.,University of Western Ontario | Taylor P.D.,Bird Studies Canada | Taylor P.D.,Acadia University
Journal of Animal Ecology | Year: 2012

Some bat species make long-distance latitudinal migrations between summer and winter grounds, but because of their elusive nature, few aspects of their biology are well understood. The need for migratory stopover sites to rest and refuel, such as used by birds, has been repeatedly suggested, but not previously tested empirically in bats. We studied migrating silver-haired bats (Lasionycteris noctivagans) at Long Point, ON, Canada. We used digital radio-transmitters to track 30 bats using an array of five towers that effectively covered the entire region (c. 20×40km). We measured stopover duration and departure direction, and documented movement patterns, foraging activity and roost sites. We measured body composition on arrival using quantitative magnetic resonance and simulated long-distance migration using observed body composition to predict migration range and rate. Migration occurred in two waves (late August and mid-September). Most bats stayed 1-2days, although two remained >2weeks. One third of the bats foraged while at the site, many foraging opportunistically on nights when rain precluded continued migration. Bats roosted in a variety of tree species and manmade structures in natural and developed areas. Half of the bats departed across Lake Erie (minimum crossing distance c. 38km) while half departed along the shoreline. Simulations predicted a migration rate of c. 250-275km per day and suggest that all but one of the bats in our study carried sufficient fuel stores to reach the putative wintering area (estimated distance 1500km) without further refuelling. Our results suggest that migrating bats stopover for sanctuary or short-term rest as opposed to extended rest and refuelling as in many songbirds. Daily torpor could reduce energy costs when not in flight, minimizing the need for extended stopovers and allowing bats to potentially complete their migration at a fraction of the time and energy cost of similar sized birds. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society. Source

Naujokaitis-Lewis I.R.,University of Toronto | Curtis J.M.R.,Canadian Department of Fisheries and Oceans | Tischendorf L.,Consulting Inc. | Badzinski D.,Bird Studies Canada | And 2 more authors.
Diversity and Distributions | Year: 2013

Aim: Species distribution models (SDMs) coupled with metapopulation dynamics models can integrate multiple threats and population-level processes that influence species distributions. However, multiple sources of uncertainties could lead to substantial differences in model outputs and jeopardize risk assessments. We evaluate uncertainties in coupled species distribution-metapopulation dynamics models and focus on two often underappreciated sources of uncertainty: the choice of general circulation model (GCM) and demographic parameter uncertainty of the metapopulation model. We rank the risks associated with potential climate changes and habitat loss on projected range margin dynamics of the Hooded Warbler (Setophaga citrina). Location: Breeding range of the Hooded Warbler, North America. Methods: Using SDMs, we quantified variability in projected future distributions using four GCMs and a consensus model at the biogeographic scale and assessed the propagation of uncertainty through to metapopulation viability projections. We applied a global sensitivity analysis to the coupled species distribution-metapopulation models to rank the influence of choice of GCM, parameter uncertainty and simulated effects of habitat loss on metapopulation viability, thereby addressing error propagation through the whole modelling process. Results: The Hooded Warbler range was consistently projected to shift north: choice of GCMs influenced the magnitude of change, and variability was spatially structured. Variability in the choice of GCMs propagated through to metapopulation viability at the northern range boundary. Although viability measures were sensitive to the GCM used, measures of direct habitat loss were more influential. Despite the high ranking of vital rates in the global sensitivity analysis, direct habitat loss had a larger negative influence on extinction risk than potential future climate changes. Main conclusions: This work underscores the importance of a global sensitivity analysis framework applied to coupled models to disentangle the relative influence of uncertainties on projections. The use of multiple GCMs enabled the exploration of a range of possible outcomes relative to the consensus GCM, helping to inform risk estimates. Ranking uncertainties informs the prioritization of management actions for species affected by dynamic anthropogenic threats over multiple spatial scales. © 2013 John Wiley & Sons Ltd. Source

Gratto-Trevor C.L.,Environment Canada | Abbott S.,Bird Studies Canada
Canadian Journal of Zoology | Year: 2011

There are only about 8000 Piping Plovers (Charadrius melodus Ord, 1834) in existence. Because they depend on environments that are under intense human pressures and controls in both their breeding and wintering grounds, these birds and their habitats are highly managed in many areas across their range. Efforts to recover this endangered and threatened species have engaged thousands of people from Newfoundland to the Caribbean, and have provoked a ground-swell of public support and, at times, fury, as well as a considerable body of research. Although populations have increased substantially in the U.S. Atlantic and U.S. Great Lakes, this is not true of all regions. Significant issues still exist with respect to the efficacy of predator management; need for more accurate model input information; effects of climate, pollutants, and water management; habitat loss and degradation from recreation and development; and whether the cost and effort of management for this species can be maintained or increased where needed. Source

Melles S.J.,University of Toronto | Fortin,University of Toronto | Lindsay K.,Natural Resources Canada | Badzinski D.,Bird Studies Canada
Global Change Biology | Year: 2011

Species' ranges are dynamic, shifting in response to a large number of interrelated ecological and anthropogenic processes. Climate change is thought to be one of the most influential drivers of range shifts, but the effects of other confounded ecological processes are often ignored even though these processes may modify expected range responses to climate change. To determine the relative effects of climate, forest availability, connectivity, and biotic processes such as immigration and establishment, we examine range changes occurring in a species of bird, the Hooded Warbler (Wilsonia citrina). We focus predominantly on the periphery of the species' northern range in Canada but we also examine data from the entire species' range. Nesting records in southern Ontario were obtained from two breeding bird Atlases of Ontario separated by a period of 20 years (1981-1985 and 2001-2005), and the rate of range expansion was estimated by comparing the number of occupied areas in each Atlas. Twelve hypotheses of the relationship between the rate of range expansion and factors known to influence range change were examined using model-selection techniques and a mixed modeling approach (zero-inflated Poisson's regression). Cooler temperatures were positively related to a lack of range expansion indicating that climate constrained the species' distribution. Establishment probability (based on the number of occupied, neighboring Atlas squares) and immigration from populations to the south (estimated using independent data from the North American Breeding Bird Survey) were also important predictors of range expansion. These biotic process variables can mask the effects of forest availability and connectivity on range expansion. Expansion due to climate change may be slower in fragmented systems, but the rate of expansion will be influenced largely by biotic processes such as proximity to neighboring populations. © 2010 Blackwell Publishing Ltd. Source

Chin A.T.M.,York University | Tozer D.C.,Bird Studies Canada | Fraser G.S.,York University
Journal of Great Lakes Research | Year: 2014

Marsh bird habitats are influenced by water levels which may pose challenges for interpreting bird-based indices of wetland health. We determined how much fluctuating water levels and associated changes in emergent vegetation influence the Index of Marsh Bird Community Integrity (IMBCI) using data collected in Great Lakes coastal wetlands by participants in Bird Studies Canada's Great Lakes Marsh Monitoring Program. IMBCI scores for 90 wetlands in Lake Erie and 131 wetlands in Lake Ontario decreased with decreasing water levels due to decreasing number of marsh-dependent species in Lake Erie and perhaps also in Lake Ontario. The average magnitude of the decrease in scores between extremely high and low water periods for wetlands with sufficient data was 15% in Lake Erie where water dropped 0.9. m on average (n=11 wetlands) and 18% in Lake Ontario where water dropped 0.5. m (n=7). Scores in Lake Erie increased with increasing Typha due to increasing numbers of marsh-dependent species and decreased with increasing Phragmites due to increasing numbers of generalist species. The opposite was observed in Lake Ontario, perhaps due to denser Typha and sparser Phragmites. Scores were explained by the naturally fluctuating water levels of Lake Erie, which favored Phragmites expansion and the regulated water levels of Lake Ontario which promoted Typha expansion. Scores were influenced by fluctuating water levels and associated changes in emergent vegetation. Inter-annual water level fluctuations should be considered when interpreting any indicator of wetland health that is based on marsh-dependent bird species. © 2014 Elsevier B.V. Source

Discover hidden collaborations