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Accueil du site → Doctorat → États-Unis → 2000 → Avian abundance and productivity at the landscape scale in the northern Chihuahuan Desert

University of Wisconsin - Madison (2000)

Avian abundance and productivity at the landscape scale in the northern Chihuahuan Desert

Pidgeon, Anna Michle

Titre : Avian abundance and productivity at the landscape scale in the northern Chihuahuan Desert

Auteur : Pidgeon, Anna Michle

Université de soutenance : University of Wisconsin - Madison

Grade : Doctor of Philosophy (PhD) 2000

Many theories about habitat selection have been invoked to explain the spatial and temporal patterns within animal populations. This dissertation addresses questions about spatial and temporal patterns of habitat use by avian communities in the northern Chihuahuan Desert, and suggests causal mechanisms for these patterns. The study area was McGregor Range, Ft. Bliss Military Reserve, in south central New Mexico. It encompasses 2825 km 2 , and spans an elevation range of 1200-2400m. Field data in seven habitats was collected March-August, 1996-1998. The research question of chapter 1 was whether the breeding bird community has changed due to habitat conversion from grassland to shrubland from the time of European settlement to the present. Second, I asked whether breeding bird communities in the four dominant shrubland habitat types display distinct habitat associations. I estimated changes in the avian community since the 1880s and assessed landcover change of 5 habitat types through analysis of U.S. Government Land Office records. Present day vegetation patterns and avian abundance patterns were compared with 1880s data. First, I concluded that there has been a major turnover in avian community composition in the study area since the 1880s. Moreover, avian community distribution and abundance is distinct among the four shrub communities. The research question of Chapter 2 is how do patterns of productivity of avian species vary through space and time. To address this problem, I developed a method for scaling up plot-based nest success estimates to the landscape level in a way that controls for accuracy and assigns a measure of confidence to estimates. I examined differences in nesting success rates for 18 species, among 7 habitats and among years. I found that there is great variability in resource use among years, and that the assumption that nest success is correlated with nest abundance is not valid. The ecological patterns and processes researched in this desert ecosystem contribute to understanding of habitat selection for animal populations as a whole. The landscape scale and temporal scope provide context for understanding local, present day patterns as well as broad, region-wide conservation assessments.

Mots clés : Ecology, Landscape scale, Habitat selection, Avian communities, Biological sciences, Chihuahuan Desert Forestry

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Page publiée le 20 février 2015, mise à jour le 8 décembre 2018