The ecological literature presents considerable evidence for top-down forcing on the maintenance of species diversity. Yet, in temperate forests, bottom-up forces often exert a strong influence on ecosystem functioning. Here, we report on the indirect influence of a pulsed resource, sugar maple () seed production, on nest survival in a migratory songbird.
View Article and Find Full Text PDFThe objectives of this study were to describe and evaluate potential drivers of genetic structure in Canadian breeding populations of the Ovenbird, . We performed genetic analyses on feather samples of individuals from six study sites using nuclear microsatellites. We also assessed species identity and population genetic structure of quill mites (Acariformes, Syringophilidae).
View Article and Find Full Text PDFFederal funding for basic scientific research is the cornerstone of societal progress, economy, health and well-being. There is a direct relationship between financial investment in science and a nation's scientific discoveries, making it a priority for governments to distribute public funding appropriately in support of the best science. However, research grant proposal success rate and funding level can be skewed toward certain groups of applicants, and such skew may be driven by systemic bias arising during grant proposal evaluation and scoring.
View Article and Find Full Text PDFAdult mortality can be a major driver of population decline in species whose productivity is relatively low. Yet, little is known about the factors influencing adult survival rates in migratory bird species, nor do we know much about the longer-term effects of habitat disturbance on the fitness of individuals. The Ovenbird (Seiurus aurocapilla) is one of the vertebrate species most sensitive to forest management, yet it is still common and widespread.
View Article and Find Full Text PDFAdult birds tend to show high fidelity to their breeding territory or disperse over relatively short distances. Gene flow among avian populations is thus expected to occur primarily through natal dispersal. Although natal dispersal is a critical demographic process reflecting the area over which population dynamics take place, low recapture rates of birds breeding for the first time have limited our ability to reliably estimate dispersal rates and distances.
View Article and Find Full Text PDFEcological traps and other cases of apparently maladaptive habitat selection cast doubt on the relevance of density as an indicator of habitat quality. Nevertheless, the prevalence of these phenomena remains poorly known, and density may still reflect habitat quality in most systems. We examined the relationship between density and two other parameters of habitat quality in an open-nesting passerine species: the Ovenbird (Seiurus aurocapilla).
View Article and Find Full Text PDFSource-sink dynamics are commonly thought to occur among Wood Thrush (Hylocichla mustelina) and other songbird populations, allowing for the persistence of populations with negative growth rates ("sinks") through immigration from populations with positive growth rates ("sources"). Knowledge of source-sink dynamics is important for management and conservation because the removal of source habitat should result in the extinction of dependent sinks. However, since research has focused on identifying individual sources/sink populations, not source-sink pairs, we cannot predict these effects or the scale over which they occur.
View Article and Find Full Text PDFEnviron Monit Assess
August 2002
We review critical issues that must be considered when selecting indicator species for a monitoring program that aims to maintain or restore ecological integrity. First, we examine the pros and cons of different management approaches on which a conservation program can be based and conclude that ecosystem management is most appropriate. We then identify potential indicators of ecological integrity at various levels of the ecosystem, with a particular emphasis on the species level.
View Article and Find Full Text PDFWe examined the relationship between the ability of bird species to persist in fragmented forests and their ability to colonize new forest habitat. Using a long-term data set on the colonization of a forest plantation, we tested the hypothesis that bird species tolerant to habitat fragmentation would detect and colonize the new habitat faster than intolerant species. The forest plantation under study is situated on an area of land reclaimed from the sea (a polder) in the central part of The Netherlands.
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