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

Abstract

Organisms living in high‐elevation habitats are usually habitat specialists who occupy a narrow ecological niche. To envision the response of alpine species to a changing environment, it is fundamental to understand their habitat preferences on multiple spatial and temporal scales. However, information on small‐scale habitat use is still widely lacking. We investigated the foraging habitat preferences of the migratory northern wheatear Oenanthe oenanthe during the entire presence at a breeding site in the central Alps. We repeatedly observed 121 adult and juvenile individuals. We applied Bayesian logistic regression models to investigate which habitat characteristics influenced foraging habitat selection on a fine spatial scale, and how habitat use varied temporally. Throughout their presence on the breeding grounds, northern wheatears showed a consistent preference for a mosaic of stones and bare ground patches with slow‐growing, short vegetation. The proximity of marmot burrows was preferred, whereas dense and low woody vegetation was avoided. After arrival at the breeding site, short vegetation, preferably close to the snow, was favored. The preference for open habitat patches that provide access to prey underlines the critical role of small‐scale habitat heterogeneity for northern wheatears. The strong and consistent preference for a habitat that is under pressure from land‐use and climate change suggests that this alpine bird species may be sensitive to habitat loss, leading to a potential range contraction. We highlight the need to conserve habitat diversity on a small spatial scale to ensure the long‐term availability of suitable habitat for northern wheatears in the Alps.

Abstract

Repeated observations of northern wheatears ( Oenanthe oenanthe) in their Alpine breeding range underline the importance of small‐scale habitat heterogeneity on the availability of suitable foraging habitat for this alpine passerine. The study revealed that a mosaic of short vegetation and bare ground patches within more productive areas are favored throughout the presence of the species at the breeding site. Conservation of structural heterogeneity that is affected by climate and land‐use change is crucial, as Alpine areas are becoming increasingly important for this habitat specialist.