Nest-site selection by Slender-billed Parakeets in a Chilean agricultural-forest mosaic

Abstract

Species in the family Psittacidae may be particularly vulnerable to anthropogenic habitat transformations that reduce availability of suitable breeding sites at different spatial scales. In southern Chile, loss of native forest cover due to agricultural conversion may impact populations of Slender‐billed Parakeets (Enicognathus leptorhynchus), endemic secondary cavity‐nesting psittacids. Our objective was to assess nest‐site selection by Slender‐billed Parakeets in an agricultural‐forest mosaic of southern Chile at two spatial scales: nest trees and the habitat surrounding those trees. During the 2008–2009 breeding seasons, we identified nest sites (N= 31) by observing parakeet behavior and using information provided by local residents. Most (29/31) nests were in mature Nothofagus obliqua trees. By comparing trees used for nesting with randomly selected, unused trees, we found that the probability of a tree being selected as a nest site was positively related to the number of cavity entrances, less dead crown, and more basal injuries (e.g., fire scars). At the nesting‐habitat scale, nest site selection was positively associated with the extent of basal injuries and number of cavity entrances in trees within 50 m of nest trees. These variables are likely important because they allow nesting parakeets to minimize cavity search times in potential nesting areas, thereby reducing energetic demands and potential exposure to predators. Slender‐billed Parakeets may thus use a hierarchical process to select nest sites; after a habitat patch is chosen, parakeets may then inspect individual trees in search of a suitable nest site. Effective strategies to ensure persistence of Slender‐billed Parakeets in agricultural‐forest mosaics should include preservation of both individual and groups of scattered mature trees.

Lophozonia tree cavities used for nesting by Slender-billed Parakeets (Enicognathus leptorhynchus) in the central valley of southern Chile: a potentially vanishing keystone resource

“…Nests were located by direct observation of SBP activities and through interviews with local residents, some of whom were former parrot nest poachers (Carneiro et al 2013). Because non-breeding SBPs are not known to use cavities for roosting (Carneiro 2010), birds entering cavities were assumed to be breeders.…”

“…Small dispersed stands of native second-growth forests and remnant fragments of old-growth forests, as well as scattered and isolated trees, comprised mainly of mature individual trees of L. obliqua (locally known as "pellines"), persist throughout the area Jiménez and White 2011). The area climate is classified as oceanic wet-temperate (Köp-pen climate classification Cfb; Kottek et al 2006) with an average annual precipitation of 1383 mm and average temperature of 11.4 °C (Carneiro et al 2013). The Keywords: Conservation, Deforestation, Habitat loss, Lophozonia obliqua, Pellines, Psittacidae, Regeneration topography is generally level to rolling, with elevations ranging from around 100-400 m above sea level (Veblen et al 1979).…”

“…Although considered of "Least Concern" globally (IUCN 2015), the Chilean government considers the species as "Vulnerable" in southern Chile due to an apparent population decline (SAG 2008), but there has been little research into the reasons for this decline. In fact, only recently some habitat requirements of this species have become known (Peña-Foxon et al 2011;Carneiro et al 2011Carneiro et al , 2013, among which large, mature trees with ample cavities are essential. However, to date there has been no comprehensive quantitative description of the actual nesting cavities used by SBP in the central valley of southern Chile, an extensive area which has undergone dramatic landscape-level changes in habitat composition over the past century (Echeverría et al 2006(Echeverría et al , 2007Lara et al 2012).…”

“…This is the dominant tree species used for nesting by SBP in the region, accounting for at least 94% of all reported nesting cavities to date (Carneiro et al 2013). Accordingly, old-growth L. obliqua likely plays a key role in the ecology of SBP throughout the region, as suggested by Carneiro et al (2013).…”

“…This is the dominant tree species used for nesting by SBP in the region, accounting for at least 94% of all reported nesting cavities to date (Carneiro et al 2013). Accordingly, old-growth L. obliqua likely plays a key role in the ecology of SBP throughout the region, as suggested by Carneiro et al (2013). Thus, any information on how SBP currently utilizes these relict forest fragments with large, but isolated trees is essential for habitat conservation planning aimed at maintaining and perpetuating the SBP throughout the region.…”