HERPETOLOGY OF ZUNI MOUNTAINS — GEHLBACH 257 



Its elevational range is about equal to that of S. undulatus, but the 

 two species are separated ecologically in all life belts. As suggested 

 by its fewer lamellae, S. undulatus is primarily terrestrial, while U. 

 ornaius is distinctly scansorial and saxicolous. At the same locality 

 S. undulatus is found on the ground or on fallen or leaning tree trunks 

 (rarely on vertical trunks), and U. ornatus inhabits rock outcrops, 

 boulder piles, and cliffs. U. ornatus maintains body temperatures 

 that are two to three degrees higher than S. undulatus or S. graciosus 

 (P. Licht, in litt.). It frequents situations with greater exposure 

 (table 2). 



Table 2. — Niche relationships of adult lizards in the Zuni region {species are 

 arranged from most scansorial to most terrestrial, top to bottom of table) 



S. graciosus also is predominantly terrestrial and does not occur 

 in ecological sympatry with U. ornatus. It has more lamellae than 

 S. undulatus and fewer than U. ornatus; its vertical range and center 

 of abundance are quite different (fig. 3). S. graciosus was found 

 only in the vicinity of big sagebrush or saltbush on loose soil. In 

 contrast, S. undulatus rarely was seen on such a substrate and was 

 taken commonly on hard-packed clay or broken sandstone in the 

 pinyon-juniper savanna. While these edaphic factors may separate 

 partially the two species of Sceloporus, marked terrestrialism in S. 

 graciosus belies the obvious adaptive significance of having more 

 lamellae. This character actually may have little to do with local 

 ecological segregation, or it could permit more effective locomotion 

 on loose soils. 



P. douglassi has the lowest lamellae count among the iguanids con- 

 sidered here and is characteristically the most terrestrial (table 2 ; fig. 

 4). Although the two species of Sceloporus sometimes climb in rock- 

 piles, bushes, and trees, P. douglassi was never observed off the ground. 

 It has the greatest elevational range of any species in the Zunis and is 

 more sedentary in habit and more abundant above 7200 feet (fig. 3). 

 The vertical distribution and lamellae count of E. multivirgatus are 

 most like those of P. douglassi ; however, this skink typically inhabits 

 dense vegetative cover (table 2). Bogert (1949) and Fitch (1956b) 

 have shown that low body temperatures are more typical of Eumeces 

 than either Sceloporus or Cnemidophorus. 



