The Effects of Agricultural Landscape on the Functional Diversity of Bird Species in the Neotropical Dryland

The challenges of sustaining biodiversity underscore the management of agricultural landscapes, particularly in regions facing historical land-use challenges. Little is known about the effects of landscape on functional diversity in the tropics, which metrics of functional diversity are influenced by landscape and how they lead to changes in ecosystem function. We investigated the impact of landscape on avifaunal functional diversity in the Caatinga, the Brazilian drylands. We examined the relationship between landscape attributes, specifically complexity, composition and configuration—on the functional diversity, richness and evenness of birds. Field data encompassing avifauna across 30 plots alongside functional traits including body mass, foraging strata and diet of 176 bird species were collected within the study area. Our findings reveal that landscape complexity and configuration shaped overall avifauna functional diversity (FD), with complexity also driving functional richness (FRic) and configuration driving functional evenness (FEve), while landscape composition did not affect these community-level indices. However, composition was significantly linked to specific functional traits, particularly foraging strata (ground, understory and mid-high), whereas complexity was associated with diet-related traits (vertebrate consumption, nectarivory) and body mass; configuration showed no significant relationship with individual traits. Traits such as insectivory and understory use predominated in areas retaining natural cover, whereas terrestrial foraging and granivory were more common in croplands and degraded zones. These results indicate that landscape complexity and composition act as complementary, rather than redundant, filters shaping avifaunal functional diversity and associated ecosystem services, including pollination, seed dispersal and pest control.