# Use of Stable Isotopes (δ13C and δ15N) to Infer Post-Breeding Dispersal Strategies in Iberian Populations of the Kentish Plover

## TL;DR

This study uses stable isotopes to understand how Kentish plovers disperse after breeding in Iberia, revealing habitat fidelity in the northwest and varied strategies elsewhere.

## Contribution

The study provides new insights into post-breeding dispersal strategies of Kentish plovers using isotopic analysis, highlighting regional differences in habitat use.

## Key findings

- Birds from the Iberian northwest show greater habitat fidelity compared to those from the Mediterranean and Andalusian coasts.
- Variability in isotopic signatures indicates diverse dispersal strategies in the post-reproductive period.
- Threats like sea level rise and human pressure endanger the Iberian northwest population due to limited alternative habitats.

## Abstract

Beaches are important habitats for migratory birds, but human pressure and sea level rise threaten their availability. This study reveals post-reproductive habitat-use strategies of the Kentish plover (Charadrius alexandrinus) in the Iberian Peninsula by analysing C and N isotopes in feathers. Birds from the northwest of the Iberian Peninsula exhibit greater fidelity to a single habitat type, while those from the Mediterranean coast and the Atlantic coast of Andalusia show variety in their dispersal. The lack of alternative habitats, the reduction of beaches due to sea level rise, and human pressure threaten the survival of the species in the northwest of the Iberian Peninsula.

Beaches are among the habitats most frequented by migratory birds for breeding and/or wintering. However, threats such as human pressure and sea level rise can reduce the availability of these habitats for different species. The presence of alternative areas, such as salt pans and brackish habitats, is essential for many migratory shorebird populations. This study addresses the post-breeding dispersal of the Kentish plover (Charadrius alexandrinus) in the Iberian Peninsula by analysing C and N isotopes in feathers. The study was conducted at six locations along the Iberian coast, which were categorized into three areas: the NW Atlantic coast, the Atlantic coast of Andalusia, and the Mediterranean coast. Although linear mixed models did not reveal any significant effects of sex or coastal area on isotopic levels, the variability in the data suggests different habitat-use strategies in the post-reproductive period. Isotopic levels in birds from the northwest of the Iberian Peninsula exhibit greater fidelity to a single habitat type, while those from the Mediterranean coast and the Atlantic coast of Andalusia show greater variability, indicating different individual dispersal strategies. The lack of alternative habitats for the northwest Iberian population, the reduction in available habitat due to rising sea levels, and human pressure together pose a serious threat to the survival of this species, already with an unfavourable conservation status.