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Jaime E Jimenez - One of the best experts on this subject based on the ideXlab platform.
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lophozonia tree cavities used for nesting by slender billed parakeets enicognathus leptorhynchus in the central valley of southern chile a potentially vanishing keystone resource
Avian Research, 2017Co-Authors: Thomas H White, Jaime E JimenezAbstract:The 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. We 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. We 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. We 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.
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Lophozonia tree cavities used for nesting by Slender-billed Parakeets (Enicognathus leptorhynchus) in the central valley of southern Chile: a potentially vanishing keystone resource
Avian Research, 2017Co-Authors: Thomas H White, Jaime E JimenezAbstract:Background The 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. Methods We 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. Results We 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. Conclusions We 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.
Maney, Pamela Lynn - One of the best experts on this subject based on the ideXlab platform.
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Survey of Reproduction of the Southeastern American Kestrel (Falco Sparverius Paulus) in Electrical Transmission Towers in South-Central Georgia
Digital Commons@Georgia Southern, 2006Co-Authors: Maney, Pamela LynnAbstract:This study involved a survey of the distribution and the reproductive biology of the rare southeastern subspecies of the American kestrel, Falco sparverius paulus, which was found to be breeding in the hollow cross-arms of the 230 kV electrical transmission towers between the Offerman substation in the east, to Plant Mitchell (Putney), in the west, in south-central Georgia. This subspecies of the kestrel has declined in the southeastern United States by more than 80% over the last fifty years, and populations of F.S. Paulus have nearly disappeared below the Fall Line in Georgia. The major factor contributing to this decline is the lack of adequate nest sites in this obligate secondary Cavity Nester. The current research showed this population in south-central Georgia to be the largest population of kestrel anywhere in the state of Georgia, and likely larger than any other population in the southeastern United States, other than in Central Florida, with more than two hundred fifty nesting pairs being found in both summers of the study. The highest usage of tubular poles occurred when a second, nontubular line ran parallel with the tubular cross-armed line. A higher number of kestrels were observed nesting in poles that were located in farmland regions in both 2003 and 2004 than woodland or residential regions. In addition, kestrels were observed to nest in a tubular PVC-nest site, which was erected as a possible alternative nest site should any of the tubular, cross-armed transmission towers have to be removed in future years. Overall, this research continues the collection of data on F.s. paulus in southern Georgia, and continues to provide essential demographic data of this subspecies of concern in Georgia, as has been shown in previous studies of this subspecies in Florida
Beasley, Hope Alyce - One of the best experts on this subject based on the ideXlab platform.
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Reproductive Success of Southeastern American Kestrels (Falco Sparverius Paulus) Nesting in 230Kv Transmission Towers and Alternative Nest Structures in South-Central Georgia
Digital Commons@Georgia Southern, 2007Co-Authors: Beasley, Hope AlyceAbstract:This research involved a survey of the distribution and reproductive biology of the threatened southeastern subspecies of the American Kestrel (Falco sparverius paulus). Numbers of Southeastern American Kestrels are estimated to have declined by more than 80% over the last fifty years in the southeastern United States. In Georgia, populations have nearly disappeared below the Fall Line. The paucity of adequate nest sites is the major factor contributing to the decline of this obligate secondary Cavity Nester. The largest breeding population of this subspecies in Georgia is located in the south-central part of the state in the hollow cross-arms of a 230kV transmission line extending from the Offerman substation (Pierce County) in the east, to Plant Mitchell (Putney, Dougherty County, GA) in the west. Current data show this kestrel population remains stable in spite of high electromagnetic fields. Of the 373 usable transmission towers, 284 (76%) were used by breeding kestrel pairs in 2005 and 2006. The majority of the sites used for breeding occurred along the middle transect of the line where it is paralleled by an additional transmission line lacking hollow cross-arms. The study also indicated that kestrels will utilize human-made, alternative nest sites. Four of 17 (24%) and three of 17 (18%) PVC-tubes and nest boxes were used by kestrels in 2005 and 2006, respectively. Additional data from a transmission line in central Georgia (near Butler, Taylor County, GA) support this finding by showing kestrel use of nest boxes placed on replacement towers lacking potential nest sites that were erected once the hollow cross-armed transmission towers were removed. Overall, this research continues the collection of data on F.s. paulus in Georgia, providing essential demographic and reproduction data of this subspecies of concern in Georgia
Thomas H White - One of the best experts on this subject based on the ideXlab platform.
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lophozonia tree cavities used for nesting by slender billed parakeets enicognathus leptorhynchus in the central valley of southern chile a potentially vanishing keystone resource
Avian Research, 2017Co-Authors: Thomas H White, Jaime E JimenezAbstract:The 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. We 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. We 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. We 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.
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Lophozonia tree cavities used for nesting by Slender-billed Parakeets (Enicognathus leptorhynchus) in the central valley of southern Chile: a potentially vanishing keystone resource
Avian Research, 2017Co-Authors: Thomas H White, Jaime E JimenezAbstract:Background The 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. Methods We 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. Results We 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. Conclusions We 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.
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Artificial Cavities and Nest Site Selection by Puerto Rican Parrots: a Multiscale Assessment
Resilience Alliance, 2006Co-Authors: Thomas H White, Gordon. G. Brown, Jaime A. CollazoAbstract:We examined nest site selection by Puerto Rican Parrots, a secondary Cavity Nester, at several spatial scales using the nest entrance as the central focal point relative to 20 habitat and spatial variables. The Puerto Rican Parrot is unique in that, since 2001, all known nesting in the wild has occurred in artificial cavities, which also provided us with an opportunity to evaluate nest site selection without confounding effects of the actual nest Cavity characteristics. Because of the data limitations imposed by the small population size of this critically endangered endemic species, we employed a distribution-free statistical simulation approach to assess site selection relative to characteristics of used and unused nesting sites. Nest sites selected by Puerto Rican Parrots were characterized by greater horizontal and vertical visibility from the nest entrance, greater density of mature sierra palms, and a more westerly and leeward orientation of nest entrances than unused sites. Our results suggest that nest site selection in this species is an adaptive response to predation pressure, to which the parrots respond by selecting nest sites offering advantages in predator detection and avoidance at all stages of the nesting cycle. We conclude that identifying and replicating the “nest gestalt” of successful nesting sites may facilitate conservation efforts for this and other endangered avian species
Maurizio Sarà - One of the best experts on this subject based on the ideXlab platform.
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An integrated analysis of micro- and macro-habitat features as a tool to detect weather-driven constraints: A case study with Cavity Nesters.
PloS one, 2017Co-Authors: Daniela Campobello, Jan Lindström, R. Di Maggio, Maurizio SaràAbstract:The effects of climate change on animal populations may be shaped by habitat characteristics at both micro- and macro-habitat level, however, empirical studies integrating these two scales of observation are lacking. As analyses of the effects of climate change commonly rely on data from a much larger scale than the microhabitat level organisms are affected at, this mismatch risks hampering progress in developing understanding of the details of the ecological and evolutionary responses of organisms and, ultimately, effective actions to preserve their populations. Cavity Nesters, often with a conservation status of concern, are an ideal model because the Cavity is a microenvironment potentially different from the macroenvironment but nonetheless inevitably interacting with it. The lesser kestrel (Falco naumanni) is a Cavity Nester which was until recently classified by as Vulnerable species. Since 2004, for nine years, we collected detailed biotic and abiotic data at both micro- and macro-scales of observation in a kestrel population breeding in the Gela Plain (Italy), a Mediterranean area where high temperatures may reach lethal values for the nest content. We show that macroclimatic features needed to be integrated with both abiotic and biotic factors recorded at a microscale before reliably predicting nest temperatures. Among the nest types used by lesser kestrels, we detected a preferential occupation of the cooler nest types, roof tiles, by early breeders whereas, paradoxically, late breeders nesting with hotter temperatures occupied the overheated nest holes. Not consistent with such a suggested nest selection, the coolest nest type did not host a higher reproductive success than the overheated nests. We discussed our findings in the light of Cavity temperatures and nest types deployed within conservation actions assessed by integrating selected factors at different observation scales.