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Wednesday, November 28, 2012

GEOGRAPHIC PATTERNS IN CONNECTICUT'S FOREST BIRD DIVERSITY


The northern hardwood forests of mountainous northeastern Connecticut support  bird communities characteristic of northern New England.

The latest technical publication derived from the Forest Bird Survey of Southern New England is entitled Factors Influencing Geographic Patterns in Diversity of Forest Bird Communities of Eastern Connecticut, USA.  It has been published in the latest edition of the international scientific journal Ecography.  The definitive version may be viewed by journal subscribers here, although we also will post a freely available version to our own Bird Conservation Contributions next year (per our publishing agreement with Ecography).

The study examines the components of diversity- species richness and species evenness (how individuals are distributed among species)- as they vary across nearly a million acres of forested landscape.  It documents that 1) summer richness and populations are roughly equal in northeastern and southeastern Connecticut, whereas in winter both concentrate toward the coast, 2) temperature explained much of winter diversity patterns, but energy-related variables showed little relationship to summer diversity, 3) the effect of habitat on diversity parameters predominated in summer, although their effect was generally weak, 4) contrary to theory, evenness increased from summer to winter, and 5) support for predictions of a branch of ecological theory known as species-energy theory was limited and primarily restricted to winter data.  Although energy and habitat played a role in explaining community patterns, they left much of the variability in regional diversity unexplained, suggesting that, as is predicted by other ecological theories, a large random component to diversity also may exist.

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