Overcoming biases of birds’ research in the Caatinga

Abstract

“The biodiversity of the Caatinga is poorly known” has been a mantra among studies on biodiversity in Brazil, including birds. However, species richness in semiarid regions is expected to be lower than that in other ecosystems, and studies in the Caatinga have increased in recent decades. Therefore, this narrative may not only reflect knowledge bias. Here, we gathered complementary datasets of bird assemblages from literature and an online database of the Caatinga and other phytogeographic domains in Brazil. We then employed novel spatial and temporal predictive statistics to address this question. We estimate that the Caatinga is only six species short of fully knowing its taxonomic diversity. We did find important spatial knowledge gaps regarding species distribution, but only higher than that of the Atlantic Forest. The species richness and distribution of Caatinga birds are as well-known as the Pampa and Pantanal and are better known than the Cerrado and the Amazon rainforest. Our findings challenge the notion that the Caatinga is the poorest known region regarding birds. Bird research in the region should focus on advancing a research and conservation agenda that enhances understanding of regional biodiversity and ecosystem dynamics while promoting ecological syntheses for tropical dry forests.

Keywords

• Avifauna
• Brazilian biodiversity
• Linnean shortfall
• Regression-kriging
• Seasonally dry tropical forest
• Wallacean shortfall