Conserving Galapagos landbirds in agricultural landscapes: forest patches of native trees needed to increase landbird diversity and abundance

One of the principal drivers of biodiversity loss is habitat loss due to land conversion for agriculture. Understanding how agricultural landscapes can be more biodiverse is critical in devising a working lands conservation plan. For at least 20 years, some bird populations in the Galapagos have been in sharp decline, especially in the agricultural zone. Since 2010, we found that the relative abundance of ten out of eleven monitored landbird species has further decreased. We examined the existing habitat structures in the agricultural zone of Santa Cruz, historically established in former areas of native humid forest (Scalesia), and analyzed which structures associated with higher landbird diversity and abundance of four declining species. We conducted standardized point counts and surveyed surrounding vegetation during the breeding period. Landbird diversity was highest in forest and coffee sites and least diverse in pasture sites. Main predictors of higher landbird diversity were forest patch presence, increased abundance of native vegetation and lower elevations. Main predictors of higher landbird relative abundance were percentage of forest in the surrounding 200 m radius buffer and forest patch presence. Our results suggest that to increase the contribution of farmlands to landbird conservation during the reproductive period, habitat management efforts should be targeted at increasing forest patches and/or corridors, particularly within pasture farms. Nevertheless, to ensure sustainability of these measures, economic value to the considered farmlands needs to be secured, social perspectives incorporated and other important threats to landbirds assessed.

Automated summary

Habitat loss due to land conversion for agriculture is a main driver of biodiversity loss. In the agricultural zone of the Galapagos, bird populations have been declining, with ten out of eleven monitored landbird species showing reduced relative abundance since 2010. Forest and coffee sites had the highest landbird diversity, while pasture sites had the least diversity. Main predictors of higher landbird diversity were the presence of forest patches, abundance of native vegetation, and lower elevations.