Tracking solutions to a persistent threat: spatial movement patterns reflect lead exposure in critically endangered California condors

Abstract

Lead contamination, an exclusively human-induced issue, poses a serious threat to the critically endangered California Condor ( Gymnogyps californianus ). Contamination occurs through condors’ ingestion of lead ammunition residues embedded within the remains of shot animals. Detecting lead exposures typically requires resource-intensive and invasive interventions. Here, we explored a minimally invasive alternative, analyzing movement data from GPS-tagged condors in the 30-day period prior to when their blood lead levels were measured. We found spatial, but not temporal, differences in movement patterns. Lead-exposed condors traversed larger areas of the landscape, with ranges more concentrated in a previously identified high-risk zone, and shared space more extensively with one another than unexposed individuals. However, lead-exposed condors did not exhibit declining movement patterns through time when compared to unexposed birds, making movement-inferred post-exposure detection difficult. While GPS-telemetry is a useful tool in understanding condors’ spatial patterns in relation to lead exposure, future research exploring how movement patterns can be used to detect, predict, and provide early warnings of at-risk condors may better inform targeted conservation efforts.

Bibliographic Information