Anthropogenic nesting sites and density of Burrowing Parrot (Cyanoliseus patagonus) in northern Argentinian Patagonia

Abstract

Background The expansion of human activities and the development of urban centers are among the main driving forces accounting for the transformation and loss of natural environments. At the same time, and especially for some birds, anthropogenic activity provides new habitat resources. This is the case of the Burrowing Parrot (Cyanoliseus patagonus), in and around Bahía Blanca, a city of ca. 335,000 inhabitants in northern Argentinian Patagonia, where urban and rural quarries and constructed ravines on roadsides are where most of its reproductive activity occurs. Methods In this study we monitored anthropogenic nesting sites and estimated the number of breeding pairs from 2018 to 2023 through censuses conducted annually in 23 colonies within a radius of up to 20 km from the communal roost located in the city. Results Most of the nesting sites (57%), and the breeding pairs (60 to 80%) were in urban environments, and the remaining in rural areas. Ravines along roadsides and quarries represented the substrate that was most frequently used for nesting. Mean nest density was significantly higher in roadside ravines compared to quarries, and, in turn, higher in urban roadsides compared to rural roadsides. Conclusion Anthropogenic substrates appear as key components for the reproduction of the species, with possible effects on its numbers. The ability of the Burrowing Parrot to reproduce on artificial substrates in the urban environment, and especially the rapid colonization of recently opened sites, represents a new perspective for the conservation and management of its populations.

Population Size, Non-Breeding Fraction, and Productivity in a Large Urban Population of Burrowing Parrots (Cyanoliseus patagonus)

“…On the other hand, the relatively constant number of breeding pairs detected between seasons may indicate that although artificial ravines provide additional nesting sites for the species, the region may be saturated with breeding pairs [31].…”

“…This study comprised the colonies of Burrowing Parrot located in the city of Bahía Blanca, Argentina (38 • 43 0 S, 62 • 16 0 O), and in the surrounding rural areas within a radius of 20 km [31]. All the individuals breeding in this large area congregate daily over the years in a single urban communal roost [20,25] (Figure 1a).…”

“…Colonies were defined as well-delimited nesting sites, such as quarries and slopes along main routes and country roads. These sites greatly varied in suitable nesting surface, accessibility to predators, and human disturbances [31]. In a few instances, quarries offered several artificial cliffs occupied by Burrowing Parrots within a range of 400 m but, after [32], these reproductive cores were considered as single colonies given that all individuals reacted together against human or predator intruders.…”