Locally adapted migration strategies? Comparing routes and timing of northern wheatears from alpine and lowland European populations

Abstract

The northern wheatear Oenanthe oenanthe has an almost circumpolar breeding distribution in the Northern Hemisphere, but all populations migrate to sub-Saharan Africa in winter. Currently, tracking data suggest two main access routes to the northern continents via the Middle East and the Iberian Peninsula. These routes would require detours for birds breeding in the European Alps. Our aim was to map the migration routes and determine annual schedules for birds breeding in Switzerland and Austria, using light level geolocators. We compared their migration patterns with birds from a lowland breeding population in Germany. Birds from the Alps cross the Mediterranean Sea directly heading straight to their non-breeding sites. In contrast, birds from Germany travelled further west via the Iberian Peninsula. While the German population initiated autumn migration relatively early, arrival on the wintering sites was nearly synchronous across the three populations. During spring migration, German birds arrived earlier at their breeding grounds than birds from the Alps. A comparison with the literature indicated that the breeding populations in the Alps use their own route and are among the latest to arrive in spring, showing resemblance to the phenology of Arctic breeding populations. Our results indicate that the annual cycle of Alps-breeding wheatears is influenced primarily by breeding ground conditions, and not solely by migration distance.

Finding food in a changing world: Small‐scale foraging habitat preferences of an insectivorous passerine in the Alps

“…In the frame of a project on migration and ecology of northern wheatears, individuals have been ringed in the study area since 2010 (Meier et al, 2022;Rime et al, 2023;Schmaljohann et al, 2016).…”

“…In the frame of a project on migration and ecology of northern wheatears, individuals have been ringed in the study area since 2010 (Meier et al, 2022 ; Rime et al, 2023 ; Schmaljohann et al, 2016 ). Each bird was ringed with a unique combination of one metal ring and three plastic color rings (Figure 1 ).…”

“…We observed ringed individuals between May 12 and September 03, 2021, covering the arrival, incubation, feeding (period of food provisioning for chicks), and postbreeding stages. Northern wheatears arrive on their Alpine breeding grounds between the end of April and mid‐May and depart for fall migration around mid‐September (Glutz Von Blotzheim & Bauer, 2001 ; Meier et al, 2022 ; Rime et al, 2023 ; Sander et al, 2021 ). During this period, ringed birds were followed weekly from the distance, using binoculars and a scope, until the first foraging attempt of each observation.…”

“…The species has a circumpolar distribution and overwinters in sub-Saharan Africa (Bairlein et al, 2012;Dunn et al, 2020;Meier et al, 2022;Rime et al, 2023). In Northern European lowland breeding sites, where seasonality is less strong compared to alpine habitats, northern wheatears favor open fields with short vegetation Arlt & Pärt, 2007;Paquet et al, 2019) and seem to be more limited by prey accessibility than by prey abundance (van Oosten et al, 2014).…”

“…As a long‐distance migratory songbird, the northern wheatear ( Oenanthe oenanthe ) is affected by changing habitat characteristics and shifting vegetation and prey phenology on multiple spatial and temporal scales (Jähnig et al, 2020 ; Sander et al, 2021 , 2022 ). The species has a circumpolar distribution and overwinters in sub‐Saharan Africa (Bairlein et al, 2012 ; Dunn et al, 2020 ; Meier et al, 2022 ; Rime et al, 2023 ). In Northern European lowland breeding sites, where seasonality is less strong compared to alpine habitats, northern wheatears favor open fields with short vegetation (Arlt et al, 2008 ; Arlt & Pärt, 2007 ; Paquet et al, 2019 ) and seem to be more limited by prey accessibility than by prey abundance (van Oosten et al, 2014 ).…”