@article{ref1,
title="Potential mortality effects of off-highway vehicles on the flat-tailed horned lizard (Phrynosoma mcallii): a manipulative experiment",
journal="Environmental management",
year="2009",
author="Grant, Tyler J. and Doherty, Paul F.",
volume="43",
number="3",
pages="508-513",
abstract="Southern California desert public lands receive especially high levels of off-highway recreation due to large population centers nearby and popular riding environments such as sand dunes. Controversy has developed over the flat-tailed horned lizard (Phrynosoma mcallii), previously a candidate for listing under the Endangered Species Act. Some evidence suggests lower lizard abundance in areas of higher recreational use than in areas with low or no use. We designed a manipulative experiment to ensure maximum inference in evaluating the direct impact of recreational riding of off-highway vehicles on lizards. Thirty-six lizards, in situ, were treated with an off-highway vehicle treatment during hibernation season in three treatment groups: high impact, low impact, and control. Treatments consisted of timed riding by off-highway vehicles. In all treatment groups survival was 100%, despite hibernation of lizards at very shallow depths. Consequently, indirect effects of off-highway vehicles deserve increased attention. The relative importance of direct versus indirect (i.e., degradation of lizard habitat) impacts caused by off-highway vehicles remains unknown. These indirect effects may include the altering of vegetation, substrate, and prey. We recommend that a manipulative approach be adopted to investigate these possibilities.<p /> <p>Language: en</p>",
language="en",
issn="0364-152X",
doi="10.1007/s00267-008-9217-0",
url="http://dx.doi.org/10.1007/s00267-008-9217-0"
}