Best environmental predictors of breeding phenology differ with elevation in a common woodland bird species.

Marjorie Bison,Anne Delestrade,Nigel G Yoccoz,Colin Van Reeth,Daphné Asse,Bradley Carlson,Idaline Laigle,Geoffrey Klein

doi:10.1002/ece3.6684

Abstract

Temperatures in mountain areas are increasing at a higher rate than the Northern Hemisphere land average, but how fauna may respond, in particular in terms of phenology, remains poorly understood. The aim of this study was to assess how elevation could modify the relationships between climate variability (air temperature and snow melt‐out date), the timing of plant phenology and egg‐laying date of the coal tit (Periparus ater). We collected 9 years (2011–2019) of data on egg‐laying date, spring air temperature, snow melt‐out date, and larch budburst date at two elevations (~1,300 m and ~1,900 m asl) on a slope located in the Mont‐Blanc Massif in the French Alps. We found that at low elevation, larch budburst date had a direct influence on egg‐laying date, while at high‐altitude snow melt‐out date was the limiting factor. At both elevations, air temperature had a similar effect on egg‐laying date, but was a poorer predictor than larch budburst or snowmelt date. Our results shed light on proximate drivers of breeding phenology responses to interannual climate variability in mountain areas and suggest that factors directly influencing species phenology vary at different elevations. Predicting the future responses of species in a climate change context will require testing the transferability of models and accounting for nonstationary relationships between environmental predictors and the timing of phenological events.

Highlights

| INTRODUCTIONWe aimed to quantify and understand relationships between environmental variables and the breeding phenology of a common mountain forest bird species the coal tit (Periparus ater), at different elevations on a mountain slope
Climate change is causing large shifts in phenology, that is, the timing of seasonal events, at broad spatial scales and across a wide range of taxa (Dunn, 2004; Menzel et al, 2006; Parmesan & Yohe, 2003; Primack & Gallinat, 2016; Visser, Holleman, & Gienapp, 2006)
Breeding phenology is often decisive for the reproductive success of many vertebrate species, as birth or hatching dates have to coincide with resource emergence which itself depends on plant phenology

Summary

| INTRODUCTION

We aimed to quantify and understand relationships between environmental variables and the breeding phenology of a common mountain forest bird species the coal tit (Periparus ater), at different elevations on a mountain slope. We tested whether annual measures of local environmental variables (air temperature, snow melt-out date, and tree phenology) explain interannual variation in the timing of coal tit breeding phenology at two elevations. Egglaying date and environmental variables (air temperature, snow melt-out date, and plant phenology) were locally measured every year in the field from 2011 to 2019 at two elevations (~1,300 m and ~1,900 m of elevation) in the Mont-Blanc Massif located in the French Alps

| MATERIAL AND METHODS

Findings

| DISCUSSION