Urban land use does not limit weaver bird movements between wetlands in Cape Town, South Africa

Calder, Jordan-Laine, Cumming, Graeme S., Maciejewski, Kristine, and Oschadleus, H. Dieter (2015) Urban land use does not limit weaver bird movements between wetlands in Cape Town, South Africa. Biological Conservation, 187. pp. 230-239.

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Abstract

Urbanisation often has profound impacts on ecological processes. Management of these impacts is central to urban conservation efforts. We used data from 6591 individually ringed weaver birds from 42 ringing locations to investigate the influence that the urban matrix, as well as patch isolation, size and quality, had on weaver bird movement between ringing locations in Cape Town, a growing city within a global biodiversity hotspot. Distance-based linear models revealed that proximity to other sites was the dominant predictor of weaver movement while the site variables (wetland size and bird abundance) had a limited and inconclusive influence. Once the variation explained by the proximity and site variables had been accounted for, the composition of the surrounding urban matrix, the length of the least cost path between wetlands, and the presence of rivers as potential movement corridors (measured at three spatial scales) all had little influence on weaver movement. Analysis of the weaver bird movement-wetland network using social network analysis showed that the network is simple, clustered, and non-random, with relatively high vulnerability to node loss and some indication of preferential attachment (i.e., increased use of more used sites). Since proximity (site isolation) is the dominant influence on weaver movements, and the network is already sparse, further wetland loss is likely to reduce population viability. Our results match the predictions of classical theory and suggest that patch management will matter more for wetland passerines than matrix management.

Item ID: 40823
Item Type: Article (Research - C1)
ISSN: 1873-2917
Keywords: biodiversity; dispersal; fynbos; habitat fragmentation; hot spot; island biogeography; passerine; urban area; urbanization, Cape Town; South Africa; Western Cape, Aves; Passeriformes; Ploceinae
Funders: DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, James S. McDonnell Foundation Grant, African Bird Club Conservation Fund, Cape Tercentenary Foundation
Date Deposited: 13 Oct 2015 10:28
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050104 Landscape Ecology @ 33%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 33%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 34%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960501 Ecosystem Assessment and Management at Regional or Larger Scales @ 33%
96 ENVIRONMENT > 9613 Remnant Vegetation and Protected Conservation Areas > 961308 Remnant Vegetation and Protected Conservation Areas at Regional or Larger Scales @ 33%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 34%
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