# Landscape, Environmental, and Socioeconomic Impacts of an Invasive Bird Species: The Yellow-Legged Gull (Larus michahellis) in the Natural Park Salinas de San Pedro del Pinatar (Murcia, Southeastern Spain)

## TL;DR

This study examines the environmental and socioeconomic impacts of the invasive yellow-legged gull in a natural park in Spain and evaluates control measures.

## Contribution

The study provides a comprehensive analysis of gull population control effectiveness and recommends strategies to prevent human food access.

## Key findings

- Control activities led to a decrease in yellow-legged gull pairs and recovery of waterfowl populations.
- New bird species colonized the area after gull population reduction.
- Damage to salt production and incidents with workers were reduced through control measures.

## Abstract

The yellow-legged gull (Larus michahellis) increased its population throughout the 20th century in its worldwide distribution area. In the Salinas de San Pedro del Pinatar, the population increased from having two breeding pairs in 1993 to 676 pairs in 2010 and from a wintering population of approximately 100–200 individuals in the 1980s to 1500–2000 individuals recorded in the 2010s, which has led to changes in habitats due to guano deposition, bird predation, incidents involving workers, and salt production. The objective of this study is to analyze the impacts of L. michahellis on the landscape, habitats, waterfowl, salt production, and workers, as well as to evaluate the effectiveness of control activities. Censuses of wintering L. michahellis have been carried out between 1990 and 2021, of nesting aquatic birds between 1994 and 2021, and nests and eggs of L. michahellis have been eliminated between 2000 and 2021. The result has been a decrease in pairs of L. michahellis, recovery of waterfowl populations, colonization of new bird species, absence of incidents with workers, and reduction in damage to salt production. Importantly, to reach a definitive solution, measures should be adopted to prevent L. michahellis from accessing the main sources of human food: urban solid waste dumps, aquaculture farms, and fish discards.