As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Wednesday, 27 July 2016

New data on bird population trends and the climate conditions they occupy

Work contributes to more accurate future species distribution models

Date: July 20, 2016
Source: University of Massachusetts at Amherst

A new study of population trends among 46 ecologically diverse bird species in North America conducted by avian ecologist Joel Ralston and colleagues at the University of Massachusetts Amherst overturns a long-held assumption that the climate conditions occupied by a species do not change over time.

Instead, as the researchers report in the current early online issue of Global Ecology and Biogeography, birds that have increased in abundance over the last 30 years now occupy a wider range of climate conditions than they did 30 years ago, and declining species are occupying a smaller range of climate conditions than 30 years ago, Ralston says.

Species with relatively stable population trends maintained them. The authors believe this is the first study to investigate the relationship between population trend and the range of climatic conditions occupied, or "climate niche breadth" (CNB).

Ralston, now at Saint Mary's College, Notre Dame, Indiana, says, "It was previously thought that as species expand their ranges, they would do so while maintaining their climate niche. We show that as species become more abundant, they are actually moving into new climate conditions, and declining species are disappearing from some of the climate conditions they used to be found in. This makes theoretical sense but it counters the long-held assumption that climate niche breadth doesn't change in species."

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