NEW GRASSLAND BIRD RESEARCH: Linking Migratory Songbird Declines With Increasing Precipitation and Brood Parasitism Vulnerability

 

 

Not Singing in the Rain: Linking Migratory Songbird Declines With Increasing Precipitation and Brood Parasitism Vulnerability

 https://www.frontiersin.org/articles/10.3389/fevo.2020.536769/full?fbclid=IwAR1WemvVET4Y2-5oOC6pfN2tLOUyl1-KFaj1KDIDUjWRJiWH3McLTTDjFsw

 

Kristen M. Rosamond¹, Sandra Goded¹, Alaaeldin Soultan², Rachel H. Kaplan^1,3, Alex Glass^3,4, Daniel H. Kim^3,5 and Nico Arcilla^1,3,6*

• ¹International Bird Conservation Partnership, Monterey, CA, United States
• ²Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
• ³Crane Trust, Wood River, NE, United States
• ⁴Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, IL, United States
• ⁵U.S. Fish and Wildlife Service, Pierre, SD, United States
• ⁶Center for Great Plains Studies, University of Nebraska–Lincoln, Lincoln, NE, United States

ABSTRACT

 Few empirical studies have quantified relationships between changing weather and migratory songbirds, but such studies are vital in a time of rapid climate change. Climate change has critical consequences for avian breeding ecology, geographic ranges, and migration phenology. Changing precipitation and temperature patterns affect habitat, food resources, and other aspects of birds’ life history strategies. Such changes may disproportionately affect species confined to rare or declining ecosystems, such as temperate grasslands, which are among the most altered and endangered ecosystems globally. We examined the influence of changing weather on the dickcissel (Spiza americana), a migratory songbird of conservation concern that is an obligate grassland specialist. Our study area in the North American Great Plains features high historic weather variability, where climate change is now driving higher precipitation and temperatures as well as higher frequencies of extreme weather events including flooding and droughts. Dickcissels share their breeding grounds with brown-headed cowbirds (Molothrus ater), brood parasites that lay their eggs in the nests of other songbirds, reducing dickcissel productivity. We used 9 years of capture-recapture data collected over an 18-year period to test the hypothesis that increasing precipitation on dickcissels’ riparian breeding grounds is associated with abundance declines and increasing vulnerability to cowbird parasitism. Dickcissels declined with increasing June precipitation, whereas cowbirds, by contrast, increased. Dickcissel productivity appeared to be extremely low, with a 3:1 ratio of breeding male to female dickcissels likely undermining reproductive success. Our findings suggest that increasing precipitation predicted by climate change models in this region may drive future declines of dickcissels and other songbirds. Drivers of these declines may include habitat and food resource loss related to flooding and higher frequency precipitation events as well as increased parasitism pressure by cowbirds. Positive correlations of June-July precipitation, temperature, and time since grazing with dickcissel productivity did not mitigate dickcissels’ declining trend in this ecosystem. These findings highlight the importance of empirical research on the effects of increasing precipitation and brood parasitism vulnerability on migratory songbird conservation to inform adaptive management under climate change.

 

Habitat ecology of Nearctic–Neotropical migratory landbirds on the nonbreeding grounds

Steven Albert, Jared D Wolfe, Jherime Kellerman, Thomas Sherry, Bridget J M Stutchbury, Nicholas J Bayly, Angelina Ruiz-Sánchez

The Condor, Volume 122, Issue 4, 2 November 2020

https://academic.oup.com/condor/article-abstract/122/4/duaa055/5923266?redirectedFrom=fulltext&fbclid=IwAR2MvKxUIGW5mOX-UMbny2etmaPf6TNMTQ3KJ5WRtfKbsYRldp3IIenX_IU

 The abstract reads (in part):

" Of the approximately 716 bird species that breed in North America, 386 (54%) are considered Nearctic–Neotropical migrants by the U.S. Fish and Wildlife Service. In the past 50 yr, scores of these migratory species, including some once considered common, have declined dramatically. Nearctic–Neotropical migrants normally spend 6–8 months in tropical habitats, making the identification, availability, and management of Neotropical habitats critical issues for their conservation. Yet, for most species, complete and nuanced information about their use of tropical habitats and the relative effects of breeding vs. wintering conditions on survival, productivity, and population trends is not available, though many studies point to Neotropical overwintering habitats as being a strong driver of population change. Particularly important for long-distance Nearctic–Neotropical migrants is an understanding of how “carry-over effects” arise and influence population trends when conditions on wintering grounds and tropical stopover areas affect subsequent reproductive performance on breeding grounds."