Warmer April Temperatures on Breeding Grounds Promote Earlier Nesting in a Long-Distance Migratory Bird, the Prothonotary Warbler

Abstract

Global climate change and warming are altering hemispheric and local weather patterns. Altered weather patterns have great potential to affect the phenology of life history events, such as the initiation of breeding in organisms that reproduce seasonally. Long-distance migratory birds may be particularly challenged by changes in local weather on breeding grounds because they arrive from distant locations and must commence breeding when conditions are appropriate. Here we explore the effects of local temperature on first egg dates and annual productivity in a long-distance Neotropical migratory songbird, the prothonotary warbler Protonotaria citrea. We present results from a 20-year (1994 to 2013) study documenting the detailed nesting activities of a color-marked population (average of 155 individual females each year) of warblers in southern Illinois, United States. The warblers typically arrive in April and start breeding in late April and May in our study system. We tested for an effect of local average April daily temperature and female age on first egg dates, total number of offspring produced per female, and the probability of fledging two broods. We found that warmer April temperatures promoted earlier first egg dates and higher average annual productivity in the warblers. On average, older females had earlier first egg dates than 1-year-old females, but both age groups responded similarly to local April temperatures. The reproductive gains associated with earlier first egg dates in warmer years stemmed from an increased probability of successfully fledging two broods, suggesting that earlier first egg dates do not currently create a mismatch with food (insect) resources. Earliest arrival dates of warblers to the region of our study system were not affected by local April temperatures, suggesting that females vary their first egg date based on conditions they experience/assess after their arrival. Whereas these birds currently adjust the timing of their breeding and actually produce more offspring in warmer years, continued global warming may eventually upset the current balance between arrival dates, food resources, and the commencement of nesting.

Agriculture is adapting to phenological shifts caused by climate change, but grassland songbirds are not

“…There is, though, evidence of long-distance migrants adjusting the timing of nest initiation relative to breeding grounds temperature (Hoover & Schelsky, 2020) and relative to the snow conditions on the spring migratory path (Oliver et al, 2020). While our models for Bobolinks, a long-distance migrant, may be consistent with projections for other long-distance migrants (Miller-Rushing et al, 2008), to adjust the timing of their migration to respond to climatic-induced phenological changes (Pulido & Widmer, 2005).…”

High nest failure but better nestling quality for early breeders in an alpine population of Northern Wheatear (Oenanthe oenanthe)

“…Recent literature reflects that climate-driven adaptations in breeding phenology are evident in several songbird species in that they advance the onset of breeding in warmer springs (Kluen et al 2011, Fossøy et al 2015, Bründl et al 2020, Hoover & Schelsky 2020, Shipley et al 2020, Nicolau et al 2021. The arrival of migrants at the breeding grounds is strictly connected to their migration schedule (Schmaljohann 2019), bringing an additional challenge to the successful timing of life-history events and determining the ability to adjust lay date to the local green-up (Low et al 2019, Amélineau et al 2021, Lamarre et al 2021, Sander et al 2021.…”

Climate in Africa sequentially shapes spring passage of Willow WarblerPhylloscopus trochilusacross the Baltic coast

“…, Tøttrup et al, 2012 ; Aloni, Markman & Ziv, 2019 ). The gradually warmer spring season in the northern hemisphere favours the early breeding of migrants ( Ouwehand & Both, 2017 ; Hoover & Schelsky, 2020 ). Our results showed that climate changes at remote wintering grounds and at stopover sites are important drivers of changes in the arrival timing of migrants in Europe.…”