Is Mitigation Translocation an Effective Strategy for Conserving Common Chuckwallas?

Mitigation translocation remains a popular conservation tool despite ongoing debate regarding its utility for population conservation. To add to the understanding of the effectiveness of mitigation translocation, in 2017 and 2018 we monitored a population of protected common chuckwallas (Sauromalus ater) following translocation away from the area of construction of a new highway near the South Mountains, Phoenix, Arizona, USA. We removed chuckwallas from the construction right-of-way, paint-marked and pit-tagged them, and then released them in a nearby municipal preserve. We deployed very high frequency radio-telemetry transmitters on a sub-sample of 15 translocated adult chuckwallas. We monitored the radio-marked chuckwallas once a day at 1- to 3-day intervals for up to 46 days to document survival, body mass, and post-release movements. The average distance moved following translocation was 359 ± 53 m. Using minimum convex polygons, the average home range size of translocated lizards was 0.9 ± 0.3 ha, which was 18–45 times larger than expected for the species. Following translocations, we surveyed the translocation sites 1 month later and again 1 year later to determine the presence of translocated chuckwallas. Translocated individuals were rarely observed a second time: in 2017, only 11 of 160 translocated chuckwallas were seen again, and in 2018, only 11 of 192 translocated chuckwallas were detected. In the light of low recapture rate, consistent loss of body mass, and large movements of marked lizards, we conclude that survival of translocated chuckwallas was low over a single year. In the future, efficacy of mitigation translocation could be better evaluated by assessing the spatial ecology of both resident and translocated individuals simultaneously using radio-telemetry