Urban and fishery waste tips as food sources for birds in northern coastal Patagonia, Argentina

YORIO, P.; GIACCARDI, M.

ORNITOLOGIA NEOTROPICAL

Año: 2002 vol. 13 p. 283 - 292

1075-4377

Waste tips constitute important food sources widely utilized by a large number of bird species worldwide, particularly by opportunistic and scavenging species. We conducted a regional survey of urban and fishery waste tips in northern coastal Patagonia to (1) identify bird species that use waste tips, (2) determine seasonal changes in occurrence and abundance, and (3) assess differences in use between locations. During 1996, we surveyed 17 urban and fishery waste tips along the coasts of the provinces of Río Negro and Chubut, Argentina. Four visits were made to each waste tip, once in each of the four seasons. Birds were observed taking advantage of waste at most of the visited tips. Eleven species were identified. The Kelp Gull (Larus dominicanus) was the most frequently recorded species, being present at 82–88% of the tips sampled, with numbers that varied depending on the site and season and showing a maximum of 7300 individuals during the summer count. In contrast, the other bird species were observed less regularly and, of these, only the Rock Dove (Columba livia) and the Chimango (Milvago chimango) were recorded in significant numbers at some of the sites. Kelp Gulls were also more abundant at fishery waste tips and the number of adults was significantly larger than that of younger age-classes in all seasons. Number of Kelp Gulls present at the tips was significantly correlated with the size of human settlements at all seasons except spring. Differences between species in the patterns of occurrence and abundance at waste tips may be related to their distribution, population size and feeding ecology.