Winter Diet and Prey Availability of the Long-Billed Curlew (Numenius americanus) in the Chihuahuan Desert, Mexico

Abstract

The long-billed curlew (Numenius americanus) is a species of international conservation concern. Effective long-term conservation measures for a species require knowledge of all aspects of the species' ecology within its range. We analyzed 210 pellets regurgitated by long-billed curlews that were collected at two sites in the Chihuahuan Desert in Mexico. From these pellets, we identified 34 prey items corresponding to three classes of invertebrates (10 orders, 18 families, and 9 morphospecies), one class of reptiles (one order and one family), one class of plants (one order, one family, and four morphospecies), as well as gastroliths. We selected three habitat types used by the curlews and conducted a prey availability analysis with pitfall traps and a sweep net; we estimated a biomass of 20.78 g of ground-dwelling invertebrates and 64.73 g of flying and foliage invertebrates for every 10 m2 during the winter season. Our results demonstrate that the long-billed curlew has high dietary flexibility and uses different habitats during its wintering stay in the Chihuahuan Desert in Mexico. One main threat was detected on wintering grounds: exposure to pesticides, which can lead to both physiological problems and the reduction of its main prey.