Riparian habitat supports the highest density and diversity of songbirds in Western North America despite covering less than 1% of the land area. Widespread destruction and degradation of riparian habitat, especially by livestock grazing, has led to habitat restoration efforts. In 2000, restoration activities in the form of permanent and seasonal exclusion of livestock from riparian areas were initiated to improve habitat for the endangered Western Yellow‐breasted Chat (Icteria virens auricollis) population, which is dependent on early successional shrub habitat for nesting, in the Okanagan Valley of British Columbia, Canada. We assessed the effectiveness of livestock exclusion by examining temporal changes in the abundance, richness, and breeding performance of birds in restoration and reference sites. The abundance of W. Yellow‐breasted Chats significantly increased between 2002 and 2013 in areas where restoration activities occurred. However, restoration did not have significant effects on the abundance, richness, or breeding performance of other riparian birds at the restoration sites independent of temporal changes that occurred at reference sites. Our results provide evidence that limiting livestock grazing in temperate riparian areas can lead to recovery of endangered riparian songbirds that rely on early successional shrub habitat but may have limited effects on common species that are not strictly reliant on this habitat.

Source: Northwestern Naturalist, 91(2):145-156.

BackgroundLong-distance migratory birds in North America have undergone precipitous declines over the past half-century. Although the trend is clear, for many migrating species underpinning the exact causes poses a challenge to conservation due to the numerous stressors that they encounter. Climate conditions during all phases of their annual cycle can have important consequences for their survival. Here, using 15 years of capture-recapture dataset, we determined the effects of various climate factors during the breeding, wintering, and migrating stages on the annual survival of a western yellow-breasted chat (Icteria virens auricollis) population breeding in southwestern Canada.ResultsEl Niño effects over the entire annual cycle had little influence on the annual apparent survival of yellow-breasted chats. However, we found evidence that wind conditions during migration, specifically average westerly wind speed or the frequency of storm events, had significant adverse effects on adult annual apparent survival. In comparison, precipitation levels on wintering ground had little to no influence on adult annual apparent survival, whereas growing degree days on the breeding ground had moderate but positive effects.ConclusionsIn the face of climate change and its predicted impacts on climate processes, understanding the influence of weather conditions on the survival of migrating birds can allow appropriate conservation strategies to be adopted for chats and other declining neotropical migrants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12898-017-0139-7) contains supplementary material, which is available to authorized users.

Other results were as follows: 44% of males and 13% of females banded as adults were re-sighted during the period 2002-2007; 33% of males and 10% of females were re-sighted the year after they were banded; 31% of males and 10% of females had fidelity to the study site where they were banded as adults; 10% of Western Yellow-breasted Chats banded as nestlings returned and, of these, 62% of males and 54% of females returned to their natal study site to breed. The dispersal distance for males banded as adults (n = 5) that did not return to their sites ranged from 6.4 km to 42.9 km. Natal dispersal ranged from 2.5 km to 15.6 km for males (n = 7) and 2.3 km to 2.6 km for females (n = 2); 16 males and 7 females banded as nestlings did not disperse. These findings contrast with predictions that species at the northern limit of their range will have low site fidelity and return rates and higher dispersal distances than passerine populations at the core of their range.

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