ABSTRACT
Extraction of oil and gas occurs around the world and associated worksite activity can affect native species, even when some good habitat remains. Understanding the possible negative effects is important for management of protected species. Blunt-nosed Leopard Lizards (Gambelia sila) are a state- and federally listed endangered species in the San Joaquin Desert of California, and part of their remaining range coincides with oil field operations. In 2015 and 2016, we used radiotelemetry to study home ranges and movements of G. sila living in an oil field with limited infrastructure and roads (a light-density oil field constructed from 2011 to 2014) and at a control site of native habitat about 3 km away. We did not find significant differences between the oil field and control site in either home-range size or daily distances moved. We did, however, find that the number of predation events was significantly greater at the oil field site, assuming that known predation occurrences represented all predation. Predation by birds was greater at the oil field site and likely was facilitated by predator perching locations provided by power poles, transmission lines, and other tall vertical structures associated with the oil field. No similar structures or other perching locations for large predatory birds existed at the control site. Only a twin-pole, three-wire transmission line existed adjacent to the oil field prior to its development. Given that G. sila are endangered largely because of habitat loss, their recovery may benefit from minimizing these hazards in oil fields that currently support the species.
