Variation in population size, nest distribution, colony extent, and timing of movements at the largest known parrot colony

Psittaciformes are among the most threatened birds, and population size and trend estimates are needed to aid conservation. The burrowing parrot (Cyanoliseus patagonus) is undergoing substantial changes in its population size, due to habitat degradation, trapping for the pet trade, and persecution as a crop pest. The species formerly had several large colonies, but these were severely reduced during a program of agriculture pest control. Currently, only one large colony remains, together with a decreasing number of smaller colonies spread throughout the Monte and adjacent ecoregions. The colony at El Cóndor, north-eastern Patagonia, Argentina, is of particular importance, concentrating 71% of the global breeding population of burrowing parrots. We aimed to determine changes in 1) breeding population size, 2) the extent of the colony, 3) the distribution of nests along the colony, and 4) the timing of movements from the nest to the foraging locations during the breeding season, over our ..., The dataset consist of photographs taken at the burrowing parrot Cyanoliseus patagonus colony at El Cóndor, village, adjacent to the estuary of the Río Negro in Río Negro, north-eastern Patagonia, Argentina, from 2001 to 2019.  During the earlier years of current study (breeding seasons 2004-2005, and 2005-2006), we followed the methodology of Masello et al. (2006) to estimate of the breeding population size of El Cóndor colony (breeding season 2001-2002, hereafter 2001). We photographed the entirety of the densest part of the colony (easternmost; Table 1). This is a part of the cliff, up to 27 m high, where soft sandstone layers belonging to the Río Negro geological formation make the entire cliff. In this part of the colony, the parrots dig their nests between 3 and 26.5 m above sea level. However, for the westernmost part of the colony, sample photographs were taken every 450 m, and the total number of nests in the 450-m sector was extrapolated from these photographs (Masello et..., , # Variation in population size, nest distribution, colony extent, and timing of movements at the largest known parrot colony [https://doi.org/10.5061/dryad.1ns1rn93f](https://doi.org/10.5061/dryad.1ns1rn93f) ## Description of the data and file structure The dataset consist of photographs taken at the burrowing parrot *Cyanoliseus patagonus* colony at El Cóndor, village, adjacent to the estuary of the Río Negro in Río Negro, north-eastern Patagonia, Argentina, from 2001 to 2019. The dataset is divided in the following folders: 2001-2002 2004-2005 2005-2006 2007-2008 2008-2009 2019-2020 The name of the folder corresponds to the breeding season in which the photographs were taken. The photograph series progress from the easternmost end of the colony to the westernmost, except for the breeding season 2019-2020 for which the opposite is true. For the breeding seasons 2004-2005 and 2005-2006, the photographs corresponding to the easternmost kilometre of the colony are located in...