Abstract.We here describe the largest colony of Burrowing Parrots (Cyanoliseus patagonus), located in Patagonia, Argentina. Counts during the 2001?02 breeding season showed that the colony extended along 9 km of a sandstone cliff facing the Altantic Ocean

JUAN F. MASELLO; MARÍA LUJÁN PAGNOSSIN; CHRISTINA SOMMER; PETRA QUILLFELDT

EMU

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2006 p. 69 - 79

0158-4197

Abstract.We here describe the largest colony of Burrowing Parrots (Cyanoliseus patagonus), located inPatagonia, Argentina. Counts during the 2001?02 breeding season showed that the colony extended along 9 km ofa sandstone cliff facing the Altantic Ocean, in the province of Río Negro, Patagonia, Argentina, and contained51 412 burrows, an estimated 37 527 of which were active. To our knowledge, this is largest known colony ofPsittaciformes. Additionally, 6500 Parrots not attending nestlings were found to be associated with the colonyduring the 2003?04 breeding season. We monitored activities at nests and movements between nesting and feedingareas. Nestlings were fed 3?6 times daily. Adults travelled in flocks of up to 263 Parrots to the feeding grounds inearly mornings; later in the day, they flew in smaller flocks, making 1?4 trips to the feeding grounds. Overall, themost frequent flock size was two, indicating that the pair is the basic social unit during the breeding season. Theaverage flight-speed was 36.9 km h?1. Terrestrial and aerial surveys during the 2003?04 and 2004?05 breedingseasons suggest that Burrowing Parrots performed long daily movements in order to feed in the remaining patchesof natural vegetation, travelling 58 and 66 km over the two main routes to the feeding areas. The colony is seriouslythreatened by human activity, and surrounding habitat is being rapidly transformed to agricultural land. Based onthe data presented, we recommend monitoring the colony using detailed counts of numbers of nests, thedocumentation of the extent of the entire colony, together with data on breeding success, nestling growth andfeeding rates. The number of non-breeders associated with the colony should be monitored, and as an additionalindex of abundance, counts from stationary locations should be continued.