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Uta stansburiana

Page history last edited by PBworks 16 years, 8 months ago

Uta stansburiana, Side-Blotched Lizard

Tetrapoda: Amniota-Sauropsida-Diapsida-Squamata-Iguanians-Iguanidae

(pic 1)




The Side-Blotched lizard is a small lizard with very granular scales.  Also, has gular fold on its throat and a large interparietal scale on top of its head.  The dorsal side is grey to tan in color with small black dots.  Males often have orange sides and necks especially during breeding seasons.  The most obvious characteristics of the Side-Blotched lizards is a darkish blue strip behind the fore limbs (pic 2).  This is most apparent on Males, but can still be seen on females and juveniles (pic 3).  In general Females and Juveniles are less bright in color than males.  In Idaho, Side-Blotched lizards are the smallest lizards with adults getting to a total length of only 130 mm. 


(pic 2 Male Side-Blotch lizard with distinct bright colors with orange coloration on head and blue side-blotch)



(pic 3 Female Side-Blotch with less distinct side blotch and dull colors)




Side-Blotched lizards can be found from the State of Washington south to the Baja pennisula and Northern Mexico and east into Colorado and Texas. 


In Idaho, They can be found in the southwestern part of the state mainly along the Snake River plain. (fig 1)


(fig 1 Idaho distribution of Side-Blotch lizard)


Ecology and Behavior


Side-Blotched lizards in habit arid to semi-arid regions with desert shrubs and Pinon-jupiner trees.  They can be found in sand, gravel, and rocky substrates.  In Idaho, Side-Blotched lizards inhabit areas usually of a lava rock terrain dominated by desert brush.  The Side-Blotched lizard is a diurnal species that can be active year round, but will usually hibernate, sometimes in aggragates, in their northern ranges.  In summer, they are usually active in mid-morning and late afternoon.  Will often be found at bases of shrubs or in rocky washes.  They will often climb on top of low rocks in order to bask. 


The Side-Blotched lizards are opportunistic forager that will usually wait for prey to wander by them.  They usually feed on a large variety of insects including grasshoppers, beetles, ants and termites.  They also feed on ticks, mites, spiders and scorpions.  They will sometimes even cannabalize young lizards. 


They are plygynous in mate selection and mate usually in spring and early summer.  However, they are often found in male-female pairs.  In Idaho the mating season usually is between March and August.  Females lay clutches of eggs of 2 to 5 and hatchlings will start to emerge in June.  Juveniles will reach sexual maturity after about 1 to 2 years.


Scientific Study


Life-History Strategies Near the Limits of Persistence: Winter Survivorship and Spring Reproduction in the Common Side-Blotched Lizard (Uta stansburiana) in Eastern Oregon:


This study focuses on the life histories and what adaptations ectotherms make in order to survive the colder winter climates of the northern regions.  The study focused on the survivorship and breeding oppurtunities of Uta stanburiana in eastern Oregon.  The lizards were collected from the field in eastern Oregon and seven to eight individuals were placed in one of six enclosures that had 100 m2 of area, and of similar habitat of which they were collected.  A total of 47 (14 males and 33 females) individuals were placed in the enclosures in the fall of 2003.  In may of 2004, the individuals in the enclosure were recaptured as well as another 73 females and 8 males were collected from the field.  These individuals than were put in one of nine enclosures where they remained until they produced yolk or shelled eggs.  These females were than collected and placed in individual cages until they layed their clutch of eggs.  They were than returned to their field enclosures after laying their eggs.   


The results of winter survivorship found that 10 males and 19 females survived the winter or a total of about 61%.  This winter survivorship is higher than previously expected.  The data also showed no relationship as to age, sex, or body size had increased survivorship over the winter.  Also, unlike more southern biotypes, the lizards were found to only lay one clutch of eggs in a season as compared to multiple clutches that are laid by the more southern biotypes.  It was also found that only a third to one half of females actually laid a clutch of eggs, of which most yearling females did not lay eggs.  Unlike southern biotypes which lay multiple clutches of eggs in their first year of life.  This shows that the northern biotypes lay less eggs in a season and require more years to grow and lay clutches of eggs.  However, survivorship and average life appear to be higher and longer among the northern biotypes allowing for them to still reproduce and survive just as well as the southern biotypes. 


More studies are needed into why there is increased survivability and average life in the northern biotypes as compared to the southern biotypes.




Zani PA, 2003. Life-History Strategies Near the Limits of Persistence: Winter Survivorship and Spring Reproduction in the Common Side-Blotched Lizard (Uta stansburiana) in Eastern Oregon. Journal of Herpetology. vol 39 issue 1 (march 2005) pp 166-169.







Created by: Matthew Knoff


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