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Media type:
E-Article
Title:
Energy use by migrants and residents in North American breeding bird communities
Contributor:
Fristoe, Trevor S.
Published:
John Wiley & Sons Ltd, 2015
Published in:
Global Ecology and Biogeography, 24 (2015) 3/4, Seite 406-415
Language:
English
ISSN:
1466-822X;
1466-8238
Origination:
Footnote:
Description:
Aim: Of the order of 5 billion birds comprising more than 700,000 tonnes of biomass migrate across North America every year to exploit seasonal resource pulses at high latitudes during breeding. Despite this impressive scale, little is known about the metabolic role of these migrants in their breeding grounds across temperate ecosystems. I estimate the energy use of short-and long-distance migrant passerines as well as residents in over 2000 breeding bird communities covering the geographic scope of North America. My aim was to characterize the geographic patterns of energy use by each migratory group and test the hypothesis that seasonal patterns of resource availability structure temperate breeding bird communities. Location: North America from 25 to 69°N. Methods: I estimated the energy use of migrant and resident passerines using abundance data from the North American Breeding Bird Survey and scaling relationships for field metabolic rate as a function of body size. Linear regression was used to test the relationship between energy use by each migratory group and latitude as well as indirect measures of environmental productivity during different seasons. Results: Energy use by all groups showed a strong relationship with latitude except for long-distance migrants, which were surprisingly invariant across geography. Energy use by migrants was highest in environments with low winter productivity and high seasonality, while resident energy use was highest where annual productivity was the highest. Main conclusions: Migrant passerines contribute significantly to temperate breeding bird communities, especially in high latitudes. They account for 78% of consumption in habitats north of 50°N compared with 1.7% in the subtropics south of 35°N. Short-distance migrants are especially important to community energy use in the habitats where migrants consume the most. Future shifts in breeding bird community composition are likely to occur as climate change alters seasonal cycles of resource availability.