The display of the White-winged Nightjar

In 1995, we discovered a population of the poorly known and critically enda ngered White-winged Nightjar (Caprimulgus candicans) in Yata'i (Butia parag uayensis) palm cerrado at the Mbaracayu Forest Nature Reserve, Paraguay. We provide the first description of the dislay of C. candicans, as observed i n December 1995. The display, which appears to function primarily for mate attraction, took place in small arenas and consisted of a regular flight pa ttern between perches. Noises that accompany the display appear to be mecha nical in origin. The modified shape of the outer remiges of male C. candica ns suggests a role in the production of this display noise. Male territorie s were situated exclusively on the upper slopes of ridges in open grassland with a low palm density (termed campo sucio). Territories appeared to be r elatively clustered, thus suggesting either a lek-mating system or male agg regation due to the use of specialized habitats as encounter sites for mati ng. Improved knowledge of the species behavior, breeding systems, and habit at use will facilitate its location at other sites and the development of h abitat-based conservation management plans.