Many range‐restricted taxa are experiencing population declines, yet we lack fundamental informat... more Many range‐restricted taxa are experiencing population declines, yet we lack fundamental information regarding their distribution and population size. Establishing baseline estimates for both of these key biological parameters is however critical for directing conservation planning for at‐risk range‐restricted species. The International Union for the Conservation of Nature (IUCN) Red List uses three range metrics that define species distributions and inform extinction risk assessments: extent of occurrence (EOO), area of occupancy (AOO) and area of habitat (AOH). However, calculating all three metrics using standard IUCN approaches relies on a geographically representative sample of locations, which for rare species is often spatially biased. Here, we apply model‐based interpolation using Species Distribution Models (SDMs), correlating occurrences with remote‐sensing covariates, to calculate IUCN range metrics, protected area coverage and a global population estimate for the Critica...
Quantifying home range size and habitat resource selection are important elements in wildlife eco... more Quantifying home range size and habitat resource selection are important elements in wildlife ecology and are useful for informing conservation action. Many home range estimators and resource selection functions are currently in use. However, both methods are fraught with analytical issues inherent within autocorrelated movement data from irregular sampling and interpretation of resource selection model parameters to inform conservation management. Here, we apply satellite telemetry and remote sensing technologies to provide first estimates of home range size and resource selection for six adult Philippine Eagles (Pithecophaga jefferyi), using five home range estimators and non-parametric resource selection functions. From all home range estimators, the median 95 % home range size was between 39-68 km2 (range: 22-161 km2), with the 50 % core range size between 6-13 km2 (range: 5-33 km2). The space-time autocorrelated kernel density estimate (AKDE) had the largest median 95 % home ra...
From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindana... more From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindanao. Initial results presented here are part of a long-term project that would measure home range size and habitat use of Philippine Eagles, the survival rates of juveniles as well as their dispersal patterns. Out of 3 young birds, only one yielded good telemetric data. The rest of the young birds died within 2 months of tagging. Data on the single bird with good movement data indicate an increase in activity area with increasing age. Overall, juvenile mortality appears high. Among the radio-tagged adults, only a single male bird yielded good telemetric data. Descriptions of nest site use, activity and movement patterns were based on this single male eagle. Whereas forest loss and fragmentation is the ultimate threat to wild populations, hunting and trapping appears to be one proximate reason for recent declines.
Many range-restricted taxa are currently experiencing severe population declines yet lack fundame... more Many range-restricted taxa are currently experiencing severe population declines yet lack fundamental biological information regarding distribution and population size. Establishing baseline estimates for both these key biological parameters is however critical for directing long-term monitoring and conservation planning for at-risk range-restricted species. The International Union for the Conservation of Nature (IUCN) Red List uses three spatial range metrics that define species distributions and inform extinction risk assessments: extent of occurrence (EOO), area of occupancy (AOO) and area of habitat (AOH). However, calculating all three metrics using standard IUCN approaches relies on a geographically representative sample of locations, which for rare species is often spatially biased. Here, we apply model-based interpolation using an ensemble Species Distribution Model (SDM), correlating occurrences with remote-sensing derived environmental covariates, to calculate IUCN range m...
Two pieces of information are minimally required to conserve endangered raptor species — (i) an e... more Two pieces of information are minimally required to conserve endangered raptor species — (i) an estimate of its remaining global population, and (ii) the main factors responsible for its decline. Data suggest that no more than 400 adult pairs of the Critically Endangered Philippine Eagle could remain in the wild. As to what is causing population decline, shooting and hunting continue to be the primary factor while forest habitat loss is another. This paper reflects on the growing incident of human-caused deaths in Philippine Eagles, prominently on Mindanao Island where estimates suggest more than half of the eagle’s wild population exists. By analyzing data from eagle rescues, surveys, and field monitoring through radio and satellite tracking techniques, this paper shows that shooting and trapping is a “clear and present” danger which may potentially drive the population to extinction even when suitable forest habitats still exist. Cases of death within the last decade show that the...
From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindana... more From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindanao. Initial results presented here are part of a long-term project that would measure home range size and habitat use of Philippine Eagles, the survival rates of juveniles as well as their dispersal patterns. Out of 3 young birds, only one yielded good telemetric data. The rest of the young birds died within 2 months of tagging. Data on the single bird with good movement data indicate an increase in activity area with increasing age. Overall, juvenile mortality appears high. Among the radio-tagged adults, only a single male bird yielded good telemetric data. Descriptions of nest site use, activity and movement patterns were based on this single male eagle. Whereas forest loss and fragmentation is the ultimate threat to wild populations, hunting and trapping appears to be one proximate reason for recent declines.
Many range‐restricted taxa are experiencing population declines, yet we lack fundamental informat... more Many range‐restricted taxa are experiencing population declines, yet we lack fundamental information regarding their distribution and population size. Establishing baseline estimates for both of these key biological parameters is however critical for directing conservation planning for at‐risk range‐restricted species. The International Union for the Conservation of Nature (IUCN) Red List uses three range metrics that define species distributions and inform extinction risk assessments: extent of occurrence (EOO), area of occupancy (AOO) and area of habitat (AOH). However, calculating all three metrics using standard IUCN approaches relies on a geographically representative sample of locations, which for rare species is often spatially biased. Here, we apply model‐based interpolation using Species Distribution Models (SDMs), correlating occurrences with remote‐sensing covariates, to calculate IUCN range metrics, protected area coverage and a global population estimate for the Critica...
Quantifying home range size and habitat resource selection are important elements in wildlife eco... more Quantifying home range size and habitat resource selection are important elements in wildlife ecology and are useful for informing conservation action. Many home range estimators and resource selection functions are currently in use. However, both methods are fraught with analytical issues inherent within autocorrelated movement data from irregular sampling and interpretation of resource selection model parameters to inform conservation management. Here, we apply satellite telemetry and remote sensing technologies to provide first estimates of home range size and resource selection for six adult Philippine Eagles (Pithecophaga jefferyi), using five home range estimators and non-parametric resource selection functions. From all home range estimators, the median 95 % home range size was between 39-68 km2 (range: 22-161 km2), with the 50 % core range size between 6-13 km2 (range: 5-33 km2). The space-time autocorrelated kernel density estimate (AKDE) had the largest median 95 % home ra...
From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindana... more From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindanao. Initial results presented here are part of a long-term project that would measure home range size and habitat use of Philippine Eagles, the survival rates of juveniles as well as their dispersal patterns. Out of 3 young birds, only one yielded good telemetric data. The rest of the young birds died within 2 months of tagging. Data on the single bird with good movement data indicate an increase in activity area with increasing age. Overall, juvenile mortality appears high. Among the radio-tagged adults, only a single male bird yielded good telemetric data. Descriptions of nest site use, activity and movement patterns were based on this single male eagle. Whereas forest loss and fragmentation is the ultimate threat to wild populations, hunting and trapping appears to be one proximate reason for recent declines.
Many range-restricted taxa are currently experiencing severe population declines yet lack fundame... more Many range-restricted taxa are currently experiencing severe population declines yet lack fundamental biological information regarding distribution and population size. Establishing baseline estimates for both these key biological parameters is however critical for directing long-term monitoring and conservation planning for at-risk range-restricted species. The International Union for the Conservation of Nature (IUCN) Red List uses three spatial range metrics that define species distributions and inform extinction risk assessments: extent of occurrence (EOO), area of occupancy (AOO) and area of habitat (AOH). However, calculating all three metrics using standard IUCN approaches relies on a geographically representative sample of locations, which for rare species is often spatially biased. Here, we apply model-based interpolation using an ensemble Species Distribution Model (SDM), correlating occurrences with remote-sensing derived environmental covariates, to calculate IUCN range m...
Two pieces of information are minimally required to conserve endangered raptor species — (i) an e... more Two pieces of information are minimally required to conserve endangered raptor species — (i) an estimate of its remaining global population, and (ii) the main factors responsible for its decline. Data suggest that no more than 400 adult pairs of the Critically Endangered Philippine Eagle could remain in the wild. As to what is causing population decline, shooting and hunting continue to be the primary factor while forest habitat loss is another. This paper reflects on the growing incident of human-caused deaths in Philippine Eagles, prominently on Mindanao Island where estimates suggest more than half of the eagle’s wild population exists. By analyzing data from eagle rescues, surveys, and field monitoring through radio and satellite tracking techniques, this paper shows that shooting and trapping is a “clear and present” danger which may potentially drive the population to extinction even when suitable forest habitats still exist. Cases of death within the last decade show that the...
From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindana... more From 1998-2001, six Philippine Eagles Pithecophaga jefferyi, were radio-tagged in Central Mindanao. Initial results presented here are part of a long-term project that would measure home range size and habitat use of Philippine Eagles, the survival rates of juveniles as well as their dispersal patterns. Out of 3 young birds, only one yielded good telemetric data. The rest of the young birds died within 2 months of tagging. Data on the single bird with good movement data indicate an increase in activity area with increasing age. Overall, juvenile mortality appears high. Among the radio-tagged adults, only a single male bird yielded good telemetric data. Descriptions of nest site use, activity and movement patterns were based on this single male eagle. Whereas forest loss and fragmentation is the ultimate threat to wild populations, hunting and trapping appears to be one proximate reason for recent declines.
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