ABSTRACT

Two studies were conducted to determine the suitability of the Westron Corp. self-ballasted mercury vapor lamps in the captive maintenance of the chuckwalla lizard, Sauromalus obesus. Initially, preference for basking under either a Westron lamp or an incandescent flood lamp was measured in a separate enclosure involving five individuals selected from a group of eight juveniles. Following this, the eight chuckwallas were divided into two groups and maintained for fifteen months in indoor enclosures illuminated with either an incandescent flood lamp and fluorescent Sylvania 350 BL combination or a single Westron self-ballasted mercury vapor lamp. Snout-to-vent length (SVL), body mass, and cloacal body temperatures were measured every two weeks. After nine months, the lizards were radiographed to assess bone density and blood was collected for assay of 25-hydroxyvitamin D. No significant differences in SVL and body mass growth rates, cloacal body temperatures or bone densities were observed between the two groups. The serum 25-hydroxyvitamin D concentrations for lizards exposed to the incandescent lamp/Sylvania 350BL combination were significantly less than those measured in lizards exposed to the Westron lamp and wild-caught lizards. Furthermore, the Westron lamp maintained 25-hydroxyvitamin D at levels comparable to those observed from a wild-caught sample. Observations support a preference for basking under a Westron lamp. These data suggest that the Westron lamp is at least as effective as an incandescent/blacklight combination in maintaining desert dwelling chuckwallas and that either setup may result in adequate vitamin D production sufficient to sustain healthy bone density.