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Visualization of 3D Home Ranges for a California Condor Breeding Pair

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The critically endangered California condor (Gymnogyps californianus) is the one of the largest vultures in the world, and its wingspan of approximately three meters is the widest of any North American bird. Center developed and implemented 3D movement-based kernel density estimator (3D MKDE) to help understand condor spatial behaviors, habitat use, and the risks they encounter in their environment. In this novel method, a trivariate normal kernel with time-dependent variance is integrated over time along the animal movement path, interpolated between observed locations, to produce the 3D MKDE. Here, we visualize the animation of 3D MKDEs within a two-day moving time window for a pair of condors. The pair was introduced into Baja, Mexico in 2003, and has been tracked discontinuously via GPS since 2007. Condor locations were captured every hour from 5:00 a.m. to 8:00 p.m., when the birds were active. In late 2010, the pair was recaptured and quarantined for treatment from lead poisoning, and were re-released in early 2011. In 2011, the pair reproduced for the first time. In this animation, we show the 99%, 95%, 75% and 50% isosurfaces of the 3D MKDEs and the interpolated move path for each condor (female – orange, male – blue). We can see that these condors often traveled together in addition to making independent flights. Most of their activity is centered on the mountain range near their nesting site and where food was provisioned by conservation managers, but occasionally these condors made longer exploratory movements. During the breeding seasons, the home ranges of this pair intersected closely as the birds often flew together during courtship, mating and chick rearing activities. This is the first time that a 3D movement-based utilization distribution for wildlife has been visualized over time.

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