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19 February 2020 THE IMPORTANCE OF RESTORATION AT AN URBAN RIPARIAN SITE IN SOUTHWESTERN OREGON FOR NON-BREEDING BIRDS
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Abstract

Riparian systems support disproportionately high biodiversity and are critical for avian conservation in the western United States, yet much historic riparian habitat has been lost or degraded. Restoration of riparian vegetation and associated ecological processes is a high priority, and birds can serve as indicators of restoration success. Here, we analyze data from 17 y of constant-effort mist netting at an urban riparian restoration site to examine changes in capture rates from 2001 to 2017. Capture rates of 4 of 17 species commonly using the site during autumn, and 6 of 14 species using the site during winter, increased over time, and more so in the restored area compared to the mature riparian reference area. This suggests that these birds increased use of the restored habitat area as riparian tree and shrub plantings matured. Birds that responded positively to restoration included several species that breed in and are considered indicators of coniferous forest habitats (Purple Finch, Oregon Junco, Hermit Thrush, and Fox Sparrow) that often inhabit riparian areas during the non-breeding season. Species that breed in riparian habitat did not show as consistent or as strong of a non-breeding season response to restoration. Riparian birds associated with open, wet herbaceous vegetation (Common Yellowthroat and Lincoln's Sparrow) declined in the restored area in autumn while maintaining stable capture rates in the reference area. Three species of finch (Spinus spp.) used the restored habitat, and the site as a whole, in far fewer numbers during the autumn dispersal and migration period in the years following restoration, likely owing to invasive teasel removal efforts. Taken together, these results suggest that restoration actions can result in trade-offs that benefit some birds while reducing suitable habitat for others. Birds complete important activities in the autumn and winter, including dispersal, migration stopover, and molt, so restoration work that supports bird populations during the non-breeding season, even at relatively small urban sites, can make important contributions to their conservation. However, managers should consider the goals of restoration actions in the context of species- or guild-specific responses to restoration-associated changes in vegetation structure.

Sarah M Rockwell, Jaime L Stephens, Robert I Frey, and John D Alexander "THE IMPORTANCE OF RESTORATION AT AN URBAN RIPARIAN SITE IN SOUTHWESTERN OREGON FOR NON-BREEDING BIRDS," Northwestern Naturalist 101(1), 1-13, (19 February 2020). https://doi.org/10.1898/1051-1733-101.1.1
Received: 22 February 2019; Accepted: 21 October 2019; Published: 19 February 2020
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