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Venier L.A.,Natural Resources Canada | Holmes S.B.,Natural Resources Canada | Pearce J.L.,Pearce and Associates Ecological Research | Fournier R.E.,Natural Resources Canada
Journal of Wildlife Management

In a recently published article Sleep et al. (2009) suggested that 30-yr declines in Canada warbler (1975-2005) based on Breeding Bird Survey (BBS) data could be attributed to 30-yr declines in spruce budworm through a series of analyses based principally on correlations. We demonstrate that the relationship does not hold when a longer-term data set (1968-2008) is used for the analysis. Sleep et al. (2009) also demonstrated a positive relationship between correlations of Canada warbler abundance and time and spruce budworm defoliation and time using provincial data sets. We examined the underlying BBS data and found that there were insufficient observations of Canada warbler in the western provinces (Alberta and Manitoba) to support the conclusion because most Canada warbler observations occurred far (>100 km) from any budworm defoliation. As well, we used a density-dependent stochastic population growth model as proposed by Sleep et al. (2009) and found only 2 significant relationships (Nova Scotia, Alberta) between Canada warbler population growth rate and budworm defoliation at the provincial scale. We conclude that little analytical evidence exists to support the idea that Canada warbler decline is a function of spruce budworm decline. © 2011 The Wildlife Society. Source

Thogmartin W.E.,U.S. Geological Survey | Crimmins S.M.,U.S. Geological Survey | Pearce J.,Pearce and Associates Ecological Research
Biological Conservation

Large-scale planning for the conservation of species is often hindered by a poor understanding of factors limiting populations. In regions with declining wildlife populations, it is critical that objective metrics of conservation success are developed to ensure that conservation actions achieve desired results. Using spatially explicit estimates of bird abundance, we evaluated several management alternatives for conserving bird populations in the Prairie Hardwood Transition of the United States. We designed landscapes conserving species at 50% of their current predicted abundance as well as landscapes attempting to achieve species population targets (which often required the doubling of current abundance). Conserving species at reduced (half of current) abundance led to few conservation conflicts. However, because of extensive modification of the landscape to suit human use, strategies for achieving regional population targets for forest bird species would be difficult under even ideal circumstances, and even more so if maintenance of grassland bird populations is also desired. Our results indicated that large-scale restoration of agricultural lands to native grassland and forest habitats may be the most productive conservation action for increasing bird population sizes but the level of landscape transition required to approach target bird population sizes may be societally unacceptable. © 2014. Source

Pratt T.C.,Canadian Department of Fisheries and Oceans | Gardner W.M.,Canadian Department of Fisheries and Oceans | Pearce J.,Pearce and Associates Ecological Research | Greenwood S.,Ontario Ministry of Natural Resources | Chong S.C.,Ontario Ministry of Natural Resources
Journal of Applied Ichthyology

Lake Sturgeon (Acipenser fulvescens Rafinesque, 1917) in Lake Superior are greatly depressed from their historic abundance, and few populations meet the rehabilitation goals identified by management agencies. A netting program targeting juvenile Lake Sturgeon (ages 3-15) was implemented from 2010 to 2012 in Goulais Bay, a shallow, productive bay in the south-eastern part of the lake, to determine abundance, distribution, population characteristics (size structure, condition, age structure, mortality and growth), and recruitment patterns. Five-hundred and thirty-one individuals were captured over the 3-year study, resulting in a mark-recapture estimate of 4977 (95% CIs 3295-7517) juveniles. Catch rates in this study were higher than in any other location in Lake Superior, with sturgeon being broadly distributed around the bay. Estimated annual survival rate ranged from 0.691 to 0.858, depending on the method used. The majority of fish captured were between 620 and 800 mm in total length and were between 4 and 10 years of age (range 1-29 years). Recruiting year-classes were apparent every year, with no apparent effects due to lampricide treatments (a suspected threat to age-0 Lake Sturgeon) in the Goulais River. Year-class strength was positively related to spring water levels. It is possible that this robust Goulais Bay population could help re-populate the south-eastern part of Lake Superior, which contains a number of large, productive embayment areas that formerly supported large Lake Sturgeon populations. © 2014 Blackwell Verlag GmbH. Source

Gordon A.,RMIT University | Wintle B.A.,University of Melbourne | Bekessy S.A.,RMIT University | Pearce J.L.,Natural Resources Canada | And 3 more authors.
Canadian Journal of Forest Research

Spatial models of population dynamics have been proposed as a useful method for predicting the impacts of environmental change on biodiversity. Here, we demonstrate advances in dynamic landscape metapopulation modelling and its use as a decision support tool for evaluating the impacts of forest management scenarios. This novel modelling framework incorporates both landscape and metapopulation model stochasticity and allows their relative contributions to model output variance to be characterized. It includes a detailed sensitivity analysis, allowing defensible uncertainty bounds and the prioritization of future data gathering to reduce model uncertainties. We demonstrate this framework by modelling the landscapelevel impacts of eight forest management scenarios on the red-backed salamander (Plethodon cinereus (Green, 1818)) in the boreal forest of Ontario, Canada, using the RAMAS Landscape package. The 100 year forest management scenarios ranged in intensity of timber harvesting and fire suppression. All scenarios including harvesting predicted decreases in salamander population size and the current style of forest management is predicted to produce a 9%-17% decrease in expected minimum population size compared with scenarios ithout harvesting. This method is amenable to incorporating many forms of environmental change and allows a meaningful treatment of uncertainty. Source

Aubin I.,Natural Resources Canada | Venier L.,Natural Resources Canada | Pearce J.,Pearce and Associates Ecological Research | Moretti M.,Swiss Federal Institute of forest
Biodiversity and Conservation

Harvest impact on forest biodiversity has been widely studied, but for managers confronted with a need for integrated cross-taxa assessment, application remains a significant challenge. Using post-harvest boreal forest succession as a model system, we investigate the usefulness of a trait-based multi-taxa approach to improve our understanding of the community dynamics after disturbance. We assess the strength of response to forest harvesting and recovery patterns of four taxa with contrasting attributes (vegetation, carabids, spiders and birds) along a post-harvest chronosequence of jack pine stands in the boreal forests of Canada. We used a complementary set of functional and taxonomic diversity metrics to identify commonalities and dissimilarities in the community assembly processes and sensitivities to harvesting among taxa. Despite the overall similarity of community response for most pairs of taxa and metrics, the strength of cross-taxa congruency varied greatly among metrics, illustrating the complexity of taxa response to harvest as well as the necessity of including a variety of biodiversity metrics in impact assessments. Of the four selected taxa, spiders were found the most sensitive to harvesting, with a strong response to environmental changes after harvest and a slow community recovery process. Birds and carabids showed highly congruent response patterns, with a strong response to harvest followed by a marked recovery process. Ground vegetation was the most resilient to harvesting. We discuss the management implications of these contrasting recovery processes, outline the current limitations of this method and suggest steps toward the implementation of effective integrated multi-taxa monitoring programs. © 2013 Her Majesty the Queen in Rights of Canada. Source

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