2026/03/01 by Crinan Jarrett, Barbara Helm, Yahkat Barshep +4 · 1 voice
Environmental Science · Immunology and Microbiology · #Avian ecology and behavior #Species Distribution and Climate Change #Bird parasitology and diseases
paper · doi:10.1002/jav.03512
openalex publication_date 2026/03/01 · openalex created_date 2026/03/15 · openalex updated_date 2026/07/23
As environmental conditions change, the ability of species to adjust their phenology is important for fitness. Advantageous adjustments are often specific to location, species, and annual cycle phase, and are particularly complex in migratory birds that must account for environmental change at vast spatio‐temporal scales. Despite the heightened vulnerability of migrants, data on phenological shifts are largely unavailable for non‐breeding areas. To reduce this gap, we used ringing data from 2001–2024 from Nigeria to model passage of 10 long‐distance migrant species, accounting for a behavioural gradient between locally resident ‘stayer' species and ‘movers' which only occur on passage. By assessing temporal trends and environmental associations, we strove to discern effects of ‘pull factors' from goal areas and locally acting ‘push factors'. Passage varied substantially, whereby typically stayers showed early‐starting and long passage, whereas movers showed late‐starting, fast passage, highlighting the importance of accounting for different movement behaviour. Peak passage across species changed only slightly over time, but a few species markedly delayed post‐breeding migration and advanced pre‐breeding migration, consistent with possible evolutionary adjustment to climate change. Our findings only partly confirm reported wide‐spread delays of post‐breeding migration and advances of pre‐breeding migration. Environmental associations in Nigeria were species‐specific. For some species, post‐breeding passage was early in years with late vegetation senescence in Europe, while pre‐breeding migration occurred early in years with early green‐up in Nigeria, and particularly in cool years. These associations suggest that favourable local conditions enhance earlier departure in both migration seasons, possibly due to pull factors favouring timely post‐breeding arrival in Africa and pre‐breeding arrival in Europe. The sensitivity of pre‐breeding migration to ambient temperature requires closer investigation of migratory birds' ability to cope with warming non‐breeding grounds, and warns that projected further warming could exacerbate difficulties to keep up with earlier springs on the breeding grounds.