Breeding Biology of the Burrowing Parrot Cyanoliseus Patagonus at the Third Largest Colony in Northern Argentine Patagonia

Data on reproductive parameters from different populations of a species may elucidate variations in reproductive strategies, and identify factors affecting local populations. We present data on reproductive biology of the Burrowing Parrot Cyanoliseus patagonus from a poorly studied colony at Las Grutas, in Río Negro, northern Argentine Patagonia. We estimated colony size, and over two breeding seasons in 2019–2020 and 2021–2022, we inspected 46 and 82 nests to determine reproductive parameters of clutch and brood size, hatching success, nestling survival, and nest success. We recorded 960 burrowing parrots in the colony. Mean clutch and brood sizes were 3.2 ± 1.3 eggs and 2.8 ± 1.2 nestlings in 2019, and a lower 2.8 ± 1.3 eggs and 1.6 ± 1.6 nestlings in 2021. Hatching success and nestling survival were also higher during 2019–2020 with 81.3% and 63.4% respectively, whereas in the 2021–2022 season there was 64.1% hatching success and 40.6% nestling survival. Apparent nest success was higher in 2019–2020 with 80.4% of the nests fledging at least one chick, against 51.2% for the 2021–2022 breeding season. Hatching failure and brood reductions were observed during both seasons, as well as nest abandonment, which was more pronounced during the 2021–2022 breeding season. Our data suggest that the Las Grutas colony has remained stable over the last 16 years. The reproductive parameters observed in the present study are lower than for the large El Condor population, but similar to an urban colony in southern Buenos Aires Province.