Volunteer opportunity to work as field assistant in a long-term study of breeding biology of various ground-nesting birds (Anthus spp., Sicalis luteola, Ammodramus humeralis, Nothura maculosa).  Volunteers needed from October 10th to January 30th. Minimun stay required: 35 days. Volunteers will stay in a rustic field camp 25 km from the nearest town. Applicants must get along well with others, be willing to work hard, and be self motivated. Good physical condition and ability to make careful observations are preferred.  We collect information on reproductive success, foraging behavior, chick growth rates, population trends and behavior ecology. Field work consists of nest searching, monitoring, census, banding, conducting behavioral observations and vegetation measurements. Research work is part of a PhD thesis at Universidad Nacional de La Plata.  Volunteers should bring their own tent and sleeping bag. They must provide their own airfare to Buenos Aires, Argentina, and transportation from Buenos Aires to La Plata (55 km).