Abstract
BackgroundThe Slender-billed Parakeet (Enicognathus leptorhynchus) is a psittacine endemic to southern Chile and an obligate secondary cavity-nester. In the central valley of southern Chile, most (94%) of the known Slender-billed Parakeet nests have occurred in large, mature southern beech (Lophozonia obliqua) trees (locally known as “pellines”). As relicts of the original old-growth forests of southern Chile, most pellines have been lost due to extensive land-clearing throughout the region, potentially threatening long-term persistence of the Slender-billed Parakeet.MethodsWe conducted our study in the central valley of southern Chile, near the city of Osorno during three consecutive nesting seasons (November–January, 2008–2011). Nest trees used by Slender-billed Parakeets were located by direct observation of parakeet activities and through interviews with local residents, some of whom were former parrot nest poachers. Nest cavities were accessed, inspected and measured using single-rope climbing techniques. We report means, standard errors, 95% confidence intervals and ranges for 11 cavity-related variables. We also report clutch sizes encountered in active nests, and age estimates of nest trees based on known growth rates of Lophozonia trees in southern Chile. Linear regressions were used to evaluate potential relationships between cavity-related variables and clutch size.ResultsWe located and measured 38 Lophozonia tree cavities used for nesting by Slender-billed Parakeets. Compared to those used by other psittacines, nest trees were relatively large, averaging 30.4 ± 1.1 m in height with a mean diameter at breast height of 134.5 ± 4.7 cm. Based on estimated annual diameter increment, ages of nest trees ranged from approximately 209–485 years. Nest cavities entrances averaged 12.5 ± 0.9 m in height above ground level. Cavity entrance widths averaged 51.0 ± 13.3 cm (vertical) by 11.5 ± 0.7 cm (horizontal). Cavity entrance orientations were apparently random, with no directional preferences detected. Nest cavities were also relatively large, with a mean internal diameter of 39.6 ± 2.4 cm and mean depth of 90.3 ± 24.2 cm. Clutch sizes (2–9) were unusually large for psittacines of this size (ca. 280–300 g) and broods of up to seven well-developed nestlings were observed.ConclusionsWe found that the deep and spacious cavities provided by pellines facilitate successful rearing of large broods, thereby maximizing productivity and fitness. The existence of pellines has apparently allowed Slender-billed Parakeets to adapt successfully to a wholesale loss of ancestral habitat to anthropogenic modifications. Immediate and strategic conservation measures, such as protection of existing pellines and the regeneration and recruitment of additional ones, are recommended for ensuring the survival of Slender-billed Parakeet populations throughout the central valley of southern Chile.
Highlights
The Slender-billed Parakeet (Enicognathus leptorhynchus) is a psittacine endemic to southern Chile and an obligate secondary cavity-nester
We describe and quantify characteristics of southern beech (Lophozonia obliqua) trees and their associated cavities used for nesting by SBP in the central valley of southern Chile
Study area We conducted our study in the central valley of southern Chile, near the city of Osorno (40°42′S, 73°10′W; Fig. 1)
Summary
The Slender-billed Parakeet (Enicognathus leptorhynchus) is a psittacine endemic to southern Chile and an obligate secondary cavity-nester. 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, 2007; Lara et al 2012) These changes have resulted in an estimated loss of up to 98% of the original old-growth Lophozonia (formerly of the genus Nothofagus; see Heenan and Smissen 2013) forests, with only around 4000 ha remaining as scattered fragments or isolated trees (Salas et al 2006; Escanilla 2012). These relict Lophozonia forests are internationally recognized for their uniqueness and high biodiversity value (Myers et al 2000; Echeverría et al 2012)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.