Uso do hábitat e padrão de estruturação das assembléias de aves Charadriiformes (Charadriidae, Scolopacidae e Laridae) na Ilha de São Luís, zona costeira maranhense

Abstract

The coastal ecosystem of São Luís Island harbors a diverse array of habitats utilized by Charadriiform birds during parts of their life cycle. These habitats are selected during the overwintering period based on food availability, refuge from predators, and suitability as stopover sites during migration. This study investigated the structure, diversity, and habitat preferences of Charadriiform bird assemblages in the coastal zone of São Luís Island across four distinct areas—Porto do Itaqui, Praia do Cajueiro, Ferry Boat, and Canal da Raposa—using 500-meter transects surveyed on foot and by boat between March 2023 and July 2025. Direct counting and bioacoustic methods were employed for species identification, and comprehensive statistical analysis was conducted using Generalized Linear Mixed Models (GLMMs). A total of 31 species were recorded, eight of which are classified as threatened at the national level. The Raposa area exhibited the highest species richness (31), followed by Porto do Itaqui (22), Cajueiro (19), and Ferry (18). Regarding maximum abundance across the areas, *C. pusilla* showed the highest count (8,000) at Cajueiro, while *Calidris minutilla* showed the lowest count (2) at Raposa. Of the 36 models generated, the GLMM accounting for the interaction between area and habitat—including time as a factor and a zero-inflated component—was identified as the most competitive model for explaining bird diversity. Porto do Itaqui stood out in pairwise comparisons of diversity indices among the areas, demonstrating greater evenness between diversity and abundance. Regarding habitat preference, *C. pusilla* was primarily associated with "Lavado" (LAV) and mangrove (MAN) habitats, while *C. semipalmatus* and *A. interpres* preferred dune habitats with temporary lagoons (DLT). *C. cirrocephalus* in Sea and River (MR) and Sandy Intertidal Zone (ZIA) habitats; *P. simplex* in Beach (PRA) habitat; *L. atricilla*, *G. nilotica*, *S. superciliaris*, and *S. antillarum* in Sea and River (MR) habitats; *C. canutus*, *T. acuflavidus*, *S. hirundo*, and *R. niger* in Beach (PRA) and Sandy Intertidal Zone (ZIA) habitats. The results underscore the importance of coastal environments in Maranhão in the face of anthropogenic threats to habitat quality at migratory bird wintering and stopover sites, contributing relevant information to conservation policies for the study areas—such as the National Coastal Management Plan (PNGC) and the Coastal Management Law (Law No. 7.661/1988)—given that these habitats are crucial for population continuity during migration, particularly for species experiencing population declines, such as *C. pusilla*, *S. antillarum*, and *C. wilsonia*; the study also supports monitoring efforts for the National Action Plan (PAN) for the Conservation of Migratory Birds.