Browsing by Autor "Susan Davis"

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Hacia una interpretación mecanística de la migración de aves en américa del sur
(2006) Alex E. Jahn; Douglas J. Levey; Jennifer E. Johnson; Ana María Mamani; Susan Davis
Research to date has demonstrated that bird migration is comprised of highly diverse and plastic behavioural patterns. Our objective is to highlight the importance of studying mechanisms underlying these patterns in austral migrants. We focus on the high incidence of overlap in breeding and non-breeding ranges as a particularly thought-provoking pattern. We then explore the opportunities afforded by partial migration theory to elucidate the mechanisms underlying seasonal range overlap. We propose that a mechanistic understanding of migration in South America will both provide a deeper appreciation of the ecology, physiology and evolution of migratory species in the New World, and improve the scientific foundation for their conservation.
Patterns of austral bird migration in the Bolivian Chaco
(Association of Field Ornithologists, 2002) Alex E. Jahn; Susan Davis; Ana María Saavedra Zankys
Austral migrant birds were banded during austral fall (March–April) and spring (October–November) in the Chaco of Santa Cruz, Bolivia. The Tyrannidae was the most common family captured in terms of number of species and total individuals. The difference in capture numbers between the austral spring and fall seasons was the greatest for the Fuscous Flycatcher (Cnemotriccus fuscatus), although most species exhibited little change among seasons. In terms of numbers of captures across each season, no apparent trends in migratory timing were evident. The Creamy-bellied Thrush (Turdus amaurochalinus) exhibited similar fat class distributions among seasons. Within-season trends showed that in fall Creamy-bellied Thrushes with lower fat levels arrived at the study site earlier than fatter birds. Most migrant species captured were not sexually dimorphic or in breeding condition, so sexing was generally not possible. Our lack of knowledge on habitat use and migratory routes of austral migrants in the Chaco, combined with the current high rate of habitat destruction in the region, makes an understanding of the migratory patterns of these birds important.
Seasonal status, relative abundance, and behavior of the birds of Concepción, Departamento Santa Cruz, Bolivia / Susan E. Davis.
(Field Museum of Natural History, 1993) Susan Davis
4 3. Vegetation types in the region of Concepcion, Bolivia 5 4. Number of bird species and families re- corded in each habitat in the vicinity of Concepcion, Bolivia 29
Towards a mechanistic interpretation of bird migration in South America
(2006) Alex E. Jahn; Douglas J. Levey; Jennifer E. Johnson; Ana María Mamani; Susan Davis
Research to date has demonstrated that bird migration is comprised of highly diverse and plastic behavioural patterns. Our objective is to highlight the importance of studying mechanisms underlying these patterns in austral migrants. We focus on the high incidence of overlap in breeding and non-breeding ranges as a particularly thought-provoking pattern. We then explore the opportunities afforded by partial migration theory to elucidate the mechanisms underlying seasonal range overlap. We propose that a mechanistic understanding of migration in South America will both provide a deeper appreciation of the ecology, physiology and evolution of migratory species in the New World, and improve the scientific foundation for their conservation.