Factors predicting distribution and threat for island and continental birds

Author

Lisa Louise Manne

Date of Award

8-1999

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Ecology and Evolutionary Biology

Major Professor

Stuart L. Pimm

Committee Members

Sally P. Horn, John L. Gittleman, Mark Kot, James A. Drake

Abstract

In this study I look at factors that contribute to survival and extinction of birds on islands and in continental regions. I introduce the work in Part 1. In Part 2,1test MacArthur and Wilson's theory of island biogeography with a long and complete data set. I find that indeed, species number helps to predict bird immigration to and extinction from the islands surrounding Great Britain. Area of the island and distance from the mainland do not contribute to immigration or extinction probability for this particular data set. In Part 31 examine the risk of extinction to passerine birds in lowland, montane, and island regions of the NewWorld. Lowland species with breeding ranges of not more than 100,000 km² are much more likely to be threatened than montane and island species with similar ranges. This increased vulnerability of extinction has important implications for conservation: areas rich in lowland species with small ranges hold many candidates for the endangered species list. In Part 41 follow up with an assessment of factors in combination that contribute to extinction risk for passerine species. I look at width of elevational band, range size, abundance and lowland/montane/island residence in particular. I find that once I have factor abundance and range in together, place of residence and width of elevation band are not significant in predicting extinction risk for New World passerines.Last, in Part 51 test for phylogenetic predictors of threat. I examine two simple indices, number of monotypic genera and number of polytypic genera; unusually many monotypic genera within the threatened New World passerines would indicate that there were many "relict" taxa that were contributing to the number of threatened species. Unusually many polytypic genera in the threatened NewWorld passerines would indicate that genera with the capacity to generate many new species are disproportionately threatened, either because they have tiny ranges, or because they are located in regions of high human impact. I found neither effect in our data set. The threatened New World passerines are phylogenetically "normal".

Recommended Citation

Manne, Lisa Louise, "Factors predicting distribution and threat for island and continental birds. " PhD diss., University of Tennessee, 1999.
https://trace.tennessee.edu/utk_graddiss/8882