Reduced Breeding Success Suggests Trophic Mismatch Despite Timely Arrival in an Alpine Songbird

Abstract

A steady advance in the onset of spring is one of the most prominent footprints of climate warming and requires organisms, including migratory birds, to adapt their annual routines. As lower trophic levels typically adapt faster than higher trophic levels, observations of reduced fitness due to trophic mismatches are becoming more frequent, especially in long-distance migratory birds. We aimed to identify key phenological events, and quantify potential mismatches and their consequences in a migratory songbird population of the Northern wheatear (Oenanthe oenanthe) breeding at high elevations in the European Alps.We used light-level geolocators to track wheatears, and collected information on individual breeding activity and breeding success as well as environmental conditions during the reproductive season. In addition, we used citizen science data and remote sensed images to quantify longer term phenological trends.Snow melt and green-up showed an exceptionally early spring in the study region in 2020, preceded by a relatively average year in 2019. Yet, tracked individuals arrived well before the snowmelt in 2020 and clutch initiation dates across the population were earlier in 2020 compared to 2019. However, this shift lagged behind the advance in environmental conditions. While hatching success was similar in both years, fledging success and overall nest success was significantly reduced in 2020.Our results show that, despite the timely arrival at the breeding grounds, wheatears did not advance breeding activities in synchrony with environmental conditions during the exceptionally early year in 2020. The reduced fledging success suggests a trophic mismatch. However, the underlying mechanisms for hatchling mortality and nest failure remain unknown. Earlier reproductive seasons are expected to become more frequent in the future. We show that the negative effects of changing seasons in Alpine migratory birds might be similar to birds breeding at high latitudes, despite their shorter migratory distance.

pamlr: A toolbox for analysing animal behaviour using pressure, acceleration, temperature, magnetic or light data in R

“…Although PAM loggers have primarily been developed for migratory passerines (Bäckman, Andersson, Alerstam, et al, 2017; Briedis et al, 2020; Dhanjal‐Adams et al, 2018; Evens et al, 2020; Liechti et al, 2018; Sander et al, 2021; Sjöberg et al, 2018), they can be used with any species whose behaviour is likely to be detected by sensors. In such cases, it is possible for the user to develop their own classification using the classify_changepoint and classify_summary_statistics functions described in the following sections.…”

pamlr: a toolbox for analysing animal behaviour using pressure, acceleration, temperature, magnetic and light data in R

“…There are a number of other behaviours that are identifiable using multisensory geolocator tags. Though these tags have primarily been used on birds (Bäckman et al, 2017; Dhanjal-Adams et al, 2018; Liechti et al, 2018; Sjöberg et al, 2018; Briedis, Beran, Adamík, & Hahn, 2020; Evens et al, 2020; Barras, Arlettaz, & Liechti, 2021; Sander et al, 2021), they can also be used with bats (Voigt et al, 2020). There are therefore a number of behaviours that might be analysed from these tags.…”

Spatial Responses to Climate Change in a Long-Distance Migratory Songbird: the Scarlet Tanager (Piranga olivacea)

“…In the 21st century, climate change is threatening the populations of many species with extinction (Parmesan and Yohe 2003). Migratory species, some of whose breeding ranges are in poleward areas of fast-paced change, are at risk (Møller et al 2008, Sander et al 2020. Historical dispersal and vicariance at northern latitudes contribute to genomic structure that can limit current adaptive genetic diversity to impede responses to environmental change via natural selection (Wilson et al 2021).…”