Northern prairie songbirds are more strongly influenced by grassland configuration than grassland amount
The relative influence of habitat loss versus configuration on avian biodiversity is poorly understood. However, this knowledge is essential for developing effective land use strategies, especially for grassland songbirds, which have experienced widespread declines due to land use changes. Habitat configuration may be particularly important to grassland songbirds as configuration of habitat affects the extent of edge effects on the landscape, which strongly influences habitat use by grassland birds.
We examined the relative influence of grassland amount and a measure of grassland configuration per se (Landscape Shape Index; LSI) on the relative abundance and richness of grassland songbirds.
In 2013, 361 avian point counts were conducted across 47, 2.4 km radii landscapes in south-west Manitoba, Canada, selected to minimize the correlation between grassland amount and configuration. We used generalized linear mixed-effects models within a multi-model inference framework to determine the relative importance of grassland amount and configuration on songbird response variables.
Effects of grassland amount and configuration were generally weak, but effects of configuration were greater than grassland amount for most species. Relative abundance and richness of obligate species, and Savannah sparrows, showed a strong negative response to LSI, while grasshopper sparrows responded positively to grassland amount.
Our results suggest that habitat configuration must be considered when managing landscapes for conservation of grassland songbirds. Maintaining large, intact tracts of grasslands and limiting development of roads that bisect grassland parcels may be an effective means of maintaining grassland songbird diversity and abundance in northern mixed-grass prairies.
KeywordsEdge effects Grassland birds Habitat loss Habitat configuration Landscape shape index Multi-model inference
We thank the many landowners for their support, E. Prokopanko and M. Garcia for their assistance in the field, and L. Fahrig, M. Manseau and two anonymous reviewers for their comments and constructive feedback on earlier drafts of the manuscript. Funding for this work was provided by the Manitoba Graduate Scholarship, Environment and Biodiversity Stewardship Fund (Manitoba Conservation), Ghostpine Environmental Service LTD Prairie Research Award, Manitoba Hydro Graduate Scholarship, Richard C. Goulden Memorial Award, Natural Sciences and Engineering Research Council, Canadian Foundation for Innovation, the Manitoba Research and Innovations Fund, and Clayton H. Riddell Endowment Fund, University of Manitoba.
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