Analysis of California Condor () Activity Using Satellite Telemetry Data

ABSTRACT

We describe new methods for quantifying specific in-situ activities of wildlife, in this case the endangered Cali-fornia condor (Gymnogyps californianus). These methods extract information from hundreds of thousands of temporally continuous and spatially explicit satellite telemetry reports. Visual observations and ground-based telemetry can provide behavioral data, although the information is often spatially and temporally limited and sample sizes can be small for wide-ranging species. Automated satellite telemetry offers continuous position reporting and unbiased spatial coverage, but to date has lacked thematic content such as the time, place, and duration of particular activities. Procedures developed for this study use a combination of models and geographic information systems (GIS) to identify condor transit flight, perch-ing, roosting, and nesting activity based only on hourly telemetry position reports. This approach combines the temporal and spatial advantages of automated telemetry with increased thematic quality from activity models. The analytical meth-ods were applied to 340,694 satellite-based position records from 51 California condors which were collected from June 2005 to April 2012. We identified 31,268 extended perch locations and an additional 15,483 overnight roost locations by translating basic location, speed, and time data into characterizations of bird activities. This approach correctly identified nine of the ten known nest sites occupied by condors outfitted with telemetry transmitters based only on the telemetry da-ta. The spatial locations of these activities were mapped using GIS. This represents a significant advantage over simple location and movement data normally associated with wildlife telemetry, and is applicable to a wide range of species.

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