title: The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird.
abstract: Although long-distance migratory songbirds are widely believed to be at risk from warming temperature trends, species capable of attempting more than one brood in a breeding season could benefit from extended breeding seasons in warmer springs. To evaluate local and global factors affecting population dynamics of the black-throated blue warbler (Setophaga caerulescens), a double-brooded long-distance migrant, we used Pradel models to analyze 25 years of mark-recapture data collected in New Hampshire, USA. We assessed the effects of spring temperature (local weather) and the El Niño Southern Oscillation index (a global climate cycle), as well as predator abundance, insect biomass, and local conspecific density on population growth in the subsequent year. Local and global climatic conditions affected warbler populations in different ways. We found that warbler population growth was lower following El Niño years (which have been linked to poor survival in the wintering grounds and low fledging weights in the breeding grounds) than La Niña years. At a local scale, populations increased following years with warm springs and abundant late-season food, but were unaffected by spring temperature following years when food was scarce. These results indicate that the warming temperature trends might have a positive effect on recruitment and population growth of black-throated blue warblers if food abundance is sustained in breeding areas. In contrast, potential intensification of future El Niño events could negatively impact vital rates and populations of this species.
authors.affiliation: Department of Biology, Hamilton College, Clinton, NY, 13323, USA.|Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, 20013, USA.|Cornell Lab of Ornithology & Department of Neurobiology & Behavior, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Townsend
authors.affiliation: Department of Natural Resources, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Evan G
authors.initials: EG
authors.lastname: Cooch
authors.affiliation: Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, 20013, USA.
authors.forename: T Scott
authors.initials: TS
authors.lastname: Sillett
authors.affiliation: Department of Biological Sciences, Wellesley College, Wellesley, MA, 12482, USA.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Rodenhouse
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Holmes
authors.affiliation: Cornell Lab of Ornithology & Department of Neurobiology & Behavior, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Webster
mesh_terms: D025041:Animal Migration; D000818:Animals; D002980:Climate; D057231:Climate Change; D005260:Female; D005502:Food; D008297:Male; D008962:Models, Theoretical; D009513:New Hampshire; D011157:Population Dynamics; D012621:Seasons; D020308:Songbirds; D013696:Temperature
keywords: Black-throated blue warbler; El Niño Southern Oscillation; Pradel models; Setophaga caerulescens; climate change; mark-recapture; migratory songbird; phenotypic mismatch; population dynamics; recruitment