Whinchat survival estimates across Europe: can excessive adult mortality explain population declines?

Abstract

European farmland birds show massive large‐scale population declines due to agricultural intensification. Long‐distance migrants are particularly affected as their populations appear to undergo larger declines than those of residents and short‐distance migrants, raising the question about the impact of non‐breeding environmental conditions and their potential impact on annual survival. The whinchat Saxicola rubetra, an Afro‐Palaearctic migrant inhabiting open habitats, has strongly declined over the last decades. Most of the conservation effort for this species has focused on improving the breeding success in Europe, but it remains unclear whether habitat changes in non‐breeding areas may also have contributed to the population declines through a decrease in adult survival. We studied survival of whinchats from eight breeding populations across Europe by analysing capture–recapture data. We found that apparent survival was consistently higher in males than in females and higher in successful than in failed breeders independently of the sex. True adult survival may, however, hardly differ between sexes being about 0.5 and 0.6 and a simple population model suggests true juvenile survival to be between 0.2 and 0.35. Adult survival was unrelated to population trends suggesting that the main demographic problem of the whinchats is likely insufficient reproduction, a feature that is shared with other declining grassland specialists. Finally, in line with results on other migratory farmland species, our study suggests that conservation activities for whinchats should in first place focus on Europe.

Early life conditions influence fledging success and subsequent local recruitment rates in a declining migratory songbird, the Whinchat Saxicola rubetra

“…Like many other Afro‐Palearctic migrants, Whinchat populations have decreased substantially over recent decades, 89% since 1980 across Europe (PECBMS, 2020) and 57% since 1995 in the UK (Woodward et al, 2020). Previous studies indicate that breeding productivity and dispersal dynamics are key drivers of population change (Fay et al, 2021), but the mechanisms remain poorly understood. We investigate the effects of natal habitat and weather on in‐nest survival (i.e.…”

Effects on Birds of the Conversion of Savannah to Farmland in the Sahel: Habitats are Lost, But Not Everywhere and Not For All Species

“…These species are known to have faced serious habitat loss and habitat degradation on their breeding grounds (e.g. Brown & Aebischer 2004, Fay et al 2021), but the large-scale changes in land use in their African wintering quarters presents them with double jeopardy, simply because they spend half their lives in the sub-Sahara.…”

The Fortunes of Migratory Birds from Eurasia: Being on a Tightrope in the Sahel

“…Population changes as measured by European bird surveys include the effects of environmental conditions in the European breeding areas in addition to carry-over effects from the wintering grounds and incurred en route . For European Turtle Dove Streptopelia turtur (Brown & Aebischer 2004), Eurasian Wryneck (Coudrain et al 2010), Northern Wheatear Oenanthe oenanthe (Arlt & Pärt 2017) and Whinchat Saxicola rubetra (Fay et al 2021), the emphasis on variables explaining declines has been increasingly focused on habitat fragmentation and destruction on the breeding grounds. As most of these species spend a larger part of their lives in Africa than in Europe, and fare worse than bird species remaining in Europe in winter (Berthold et al 1998, Sanderson et al 2006, Heldbjerg & Fox 2008, Kamp et al 2020, Bowler et al 2021), the chances are that Africa is a leading actor in the weal and woe of long-distance migrants.…”