General Distribution
The tree lizard is narrowly distributed in California along the Colorado River and adjacent
areas. It frequents elevated situations such as cliffs, rocks, ledges, bushes and trees. It
prefers moister habitats and reaches greatest abundance in desert riparian, desert wash, and
dense stands of shrubs. It is active in spring and summer, occasionally in early fall, but not in
winter (Stebbins 1954, Milstead 1970, Vitt 1974, Martin 1977). Habitat Requirements
This lizard spends much of its time climbing in vegetation or rocks. It shelters in
vegetation, under rocks, and in rock crevices (Stebbins 1954, Milstead 1970, Vitt 1974). Reproduction
Courtship begins in early April and proceeds through the summer. An
average of 8 eggs is laid per clutch (range 5-12), and as many as 6 clutches may be
produced (Stebbins 1954, Fitch 1970). This lizard has a high reproductive potential and
seems to respond to increased rainfall, and presumably increased insect availability, by
producing multiple clutches of eggs. Daily/Seasonal Activity
This lizard is diurnal and will usually feed during the entire day. It
becomes active in early spring and remains abroad until early fall. In winter it forms wintering
aggregations (Stebbins 1954, Vitt 1974).
These lizards move to local wintering aggregations in the
fall and spend the winter there. They move away from these aggregations in the spring.
Movements are local (Vitt 1974). Diet and Foraging
This species feeds on spiders and insects such as beetles, ants, termites,
lepidopterous larvae, hemipterans, homopterans and grasshoppers (Stebbins 1954, Milstead
1970). It commonly feeds in shrubs and trees and also on rocks, by sitting on an elevated
perch and waiting for a prey item to approach. Territoriality/Home Range
Nothing has been reported on the home range of this species. Any
estimate would be complicated by the tendency to climb and incorporate the vertical
dimension into activity areas.
Males defend territories. This lizard has a complicated social system that has
not been completely studied (Milstead 1970). Predator-Prey Relations
This species is eaten mainly by avian predators. Literature Cited
Fitch, H. S. 1970. Reproductive cycles in lizards and snakes. Univ. Kans. Mus. Nat. Hist.
Misc. Publ. 52:1-247.
Martin, R. F. 1973. Reproduction in the tree lizard (Urosaurus ornatus) in central Texas:
drought conditions. Herpetologica 29:27-32.
Martin, R. F. 1977. Variation in reproductive productivity of range margin tree lizards.
Copeia 1977:83-92.
Milstead, W. W. 1970. Late summer behavior of the lizards Sceloporus merriami and
Urosaurus ornatus in the field. Herpetologica 26:341-357.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill,
New York. 536pp.
Vitt, L. J. 1974. Winter aggregations, size classes and relative tail breaks in the tree lizard,
Urosaurus ornatus (Sauria: Iguanidae). Herpetologica 30:182-183.
Information gathered from California DFG - California Interagency Wildlife Task Group
