AVIS-IBIS

Birds of Indian Subcontinent

Geographic Variation in Metabolic Seasonal Acclimatization in House Finches

Publication Type:Journal Article
Year of Publication:1996
Authors:O'Connor, TP
Journal:The Condor
Volume:98
Issue:2
Date Published:1996
ISBN Number:00105422
Keywords:Burrica, Burrica mexicana, Carpodacus, Carpodacus mexicanus, Fringillidae, Haemorhous, Haemorhous mexicanus
Abstract:Seasonal acclimatization in small passerine birds is primarily a metabolic process, yet the physiological mechanism is incompletely understood. This study draws on both original and previously published data to examine physiological characteristics associated with seasonal acclimatization in House Finches (Carpodacus mexicanus) from southern California (CA), Colorado (CO), and Michigan (MI). House Finches from MI and CO demonstrate metabolic seasonal acclimatization that is not found in CA birds. The MI and CO birds show seasonal fattening and greater standard metabolic rates than CA individuals. Results from body composition analyses and enzyme activity determinations suggest that seasonal changes in fat stores and catabolic capacity are associated with acclimatization in both CO and MI birds. However, the seasonal patterns of several other physiological parameters reveal differences between MI and CO populations. For instance, the magnitude of winter fattening is much greater in MI than CO birds, and MI House Finches show seasonal changes in peak metabolic rate and lean mass that are absent in CO individuals. These findings indicate that MI birds, in the introduced eastern distribution, and CO birds, in the original western distribution, may employ different physiological mechanisms for seasonal acclimatization. Alternatively, the differences between MI and CO birds may reflect direct or indirect responses to the markedly different altitudes of the locations. The results from this study reinforce the potential dangers of extrapolating findings from single populations to a larger scale in widely distributed species.
URL:http://www.jstor.org/stable/1369155
Short Title:The Condor
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith