bd corridor new spatial tools eyed for Philippine eagle 600px

New spatial methods to conserve the critically endangered Philippine Eagle are being used for the first time, which will also benefit the vulnerable Mindanao bleeding-heart pigeon, in conservation management primarily in the Eastern Mindanao Biodiversity Corridor.

This was revealed during a recent webinar on Philippine Eagle range metrics and spatial conservation planning organized by the Biodiversity Corridor Project, under the Department of Environment and Natural Resources (DENR) in partnership with the United Nations Development Programme (UNDP) and the Global Environment Facility (GEF).

Spearheaded by the Philippine Eagle Foundation (PEF) based in Davao City, and The Peregrine Fund based in Boise, Idaho, USA, the webinar last September 30 cited earlier technical reports on space-time home range estimates and resource selection for the national bird, one of the biggest raptors in the world.

PEF’s Dr. Jayson Ibañez and The Peregrine Fund’s Dr. Luke Sutton, UK-based ornithologist and montane forest botanist, who were the main authors of earlier scientific reports on novel processes and approaches on Philippine eagle telemetry and range estimates, served as the main resource speakers.

Density Estimate

“For the first time, we determine two important spatial processes for this critically endangered raptor that can help in directing conservation management,” Sutton cited in the reports. “Rather than employing a single home range estimator, we recommend that analysts consider multiple approaches to animal movement data to fully explore space-time and resource use.”

Quantifying home range size and habitat resource selection have been important elements in wildlife ecology and they are useful for informing conservation action, such as in the case for the Philippine Eagle, while many home range estimators and habitat resource selection functions are currently in use.

Using space-time autocorrelated kernel density estimate (AKDE) to measure the largest median 95% home range size (68 kms) and a 50% core range (13 kms) for the Philippine Eagle, “from the resource selection functions, all adults used areas high in photosynthetic leaf and canopy structure but avoided areas of old growth biomass and denser areas of vegetation, possibly due to foraging forays into fragmented areas away from nesting sites.”

Priority conservation areas and a global population estimate for the Philippine Eagle were derived from earlier modelled range metrics using remote sensing habitat characteristics. 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,” their report said. “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 Philippine Eagle, with their final range wide continuous SDM having high predictive accuracy (using Continuous Boyce Index).”

Based on the latest inferred habitat of Philippine Eagle, the current global population estimate is 352 breeding pairs, or 704 mature individuals across the Philippine Eagle global range. (BD Corridor/ Mitch R. Confesor)

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