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Uma inornataCoachella Valley Fringe-toed Lizard

By Tyler DeVos

Geographic Range

Uma inornata is found only within the Coachella Valley and San Gorgonio Pass in California. (Behler and King, 1979)

Habitat

Uma inornata is found in a desert-type habitat. The distribution of this species is heavily affected by sand characteristics (such as grain size and compaction), and the lizard is only found in areas of windblown sand (as opposed to compacted sand dunes). Various studies have confirmed that Uma inornata requires sand grains with diameters of between 0.1 mm and 1 mm, and that the lizard heavily favors areas with deep, loose sand. Due to the need for windblown sand, Uma inornata tends to avoid areas of high plant density, instead preferring a habitat with sparse, shrub-like vegetation—primarily Larrea divaricate, Franseria dumosa, Dalea emoryi, Dicoria canescens, and Astragalus lentiginosus. Within the small geographic range across which Uma inornata is found, temperatures vary from 50°C in the summer to -7°C in the winter, and the mean annual rainfall is about 15.24 cm. (Barrows, 1997; Mayhew, 1965; Turner, et al., 1984)

Physical Description

Uma inornata is a medium sized lizard species with a flattened body and granular scales, along with a characteristic fringe of pointed scales on the back edges of its toes. The body is a grey color, and patterning consists of dark bands under the tail, dark spots and lines over the shoulders, and diagonal dark lines on the throat. Some individuals display smaller black spots on the belly, and the sides of both sexes may turn pink during breeding season (late April until August). Size (measured from snout to vent) varies considerably with both age and gender; juveniles range from 0 to 5 cm, immature females from 5.1 to 6.9 cm, immature males from 5.1 to 7.9 cm, adult females from 7 to 9.9 cm (mean 8.1 cm), and adult males from 8 to 12.2 cm. (mean 10.2 cm). All males possess two enlarged post-anal scales, while the majority of females (though exceptions do exist) lack these scales. (Behler and King, 1979; Mayhew, 1965)

  • Sexual Dimorphism
  • male larger
  • Range length
    7 to 12.2 cm
    2.76 to 4.80 in

Development

Uma inornata displays no unusual developmental characteristics.

Reproduction

The courtship display of Uma inornata involves a male rapidly nodding his head and waving (alternately) each of his front legs as he approaches either a female or another male. After finishing a successful display, the male will attempt to commence courtship by grasping the female by the skin of the neck or shoulder and partially inverting the base of his tail under her cloaca. If the male has performed his display for an unreceptive female or another male, the unreceptive individual will either flee or lift and wave its tail toward the head of the performing male as a signal of rejection. (Carpenter, 1963)

Most individuals are capable of reproduction starting during the second summer following hatching. Males are capable of breeding from mid-April until mid-August, while females are able to breed from late April until early September (resulting in an actual breeding season that ranges from late April until mid-August). Females are believed to lay more than one clutch per year—though this has not been closely studied—with clutches typically containing two to four eggs (average egg size is 21.8 by 11.8 mm). The gestation period is unknown. Male reproductive success has been found to be influenced heavily by precipitation and food supply; in years of low winter precipitation and inadequate nutrition, testes of Uma inornata do not become reproductively active. (Behler and King, 1979; Mayhew, 1965)

  • Breeding season
    The Coachella valley fringe-toed lizard breeds from late April through mid-August
  • Range number of offspring
    2 to 4
  • Range time to independence
    0 (high) minutes
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

There is no mention in any literature of parental care in the species Uma inornata.

  • Parental Investment
  • no parental involvement
  • precocial

Behavior

While this species is not communal, a hierarchy will develop among individuals forced to coexist within a confined space; dominance is established through aggression displays and fighting, and results in a hierarchy in which a single dominant male has several equal subordinates, with additional tiers of less dominant individuals below the subordinates. At night Uma inornata may rest in small rodent burrows, but more frequently bury themselves under the sand (both of these behaviors may also be used when fleeing predators). When resting on hot sand during the daytime, Uma inornata typically raise their toes, body, and tail above the substrate surface. (Horchar, 1993; Carpenter, 1963)

  • Range territory size
    437 to 1070 m^2

Home Range

Both male and female Uma inornata maintain home territories; the territory of an average adult male is about 1070 square meters, while that of an average adult female is about 437 square meters. Territory size has been found to be proportional to snout vent length, with younger lizards maintaining proportionally smaller territories than their adult counterparts. (Horchar, 1993; Carpenter, 1963)

Communication and Perception

Communication in the species Uma inornata includes several different types of behavioral displays used to convey aggression or submission to conspecifics. Challenge displays take place between two individuals, and involve a characteristic face-off position in which lizards present their lateral sides to one another, facing in opposite directions. Both challengers will then raise their bodies parallel to the ground, distend both the dewlap and the side of the belly facing the opponent (to increase body surface area), and engage in a series of rapid, push-up like motions. Both this challenge display and the assertion display (a slightly fragmented and less intense version of the challenge display) are forms of aggression used to assert dominance and defend territory, and can often lead to fighting. If the conflict reaches this stage, the two challenging individuals will begin to move in a shifting circle, lunging at one another and trying to avoid being bitten. Males may bite opponents near the base of the tail, the head, or the body, and eventually the more aggressive challenger will emerge from the interaction as the dominant individual. At this point, the subordinate individual may flee (and is often chased by the aggressor), or display its submission by flattening its head and body to the ground while holding its legs close to its sides (the aggressor will not attack as long as this position is maintained).

Observations of feeding behavior in Uma inornata have suggested that this species is able to sense organisms moving beneath the surface of the sand. It has been suggested that hearing may be the sense responsible for this ability, though further research is needed to confirm this supposition. (Carpenter, 1963)

Food Habits

Uma inornata is an omnivorous species, feeding on various arthropods, flowers, leaves, and occasionally hatchling lizards. In addition, individuals will consume both their own shed skin and that of other species if encountered. The diet of the fringe-toed lizard varies on an annual cycle, with a primary diet of flowers and plant-dwelling arthropods during the spring and a primary diet of ground-dwelling arthropods and leaves during the summer. During the month of May (the peak of the breeding season) male and female diets differ significantly, with females specializing in energy maximizing foods (anything with high nutritional value) and males specializing in time minimizing foods (usually easily located flowers and plant matter).

Plant species consumed by Uma inornata include Petalonyx thurberi, Psorothamnus arborescens, Tiquilia plicata, and Dicoria canescens, while arthropod species consumed include Veromessor pergandei, Macrobaenetes valgum, Apis melifera, Eremoblatta subdiaphana, and various species of the genera Agallia and Eleodes. Phrynosoma platyrhinos, Callisaurus draconoides, Dipsosaurus dorsalis, and Cnemidophorus sexlineatus hatchlings may also be consumed, along with occasional instances of cannibalism.

Fringe-toed lizards have been observed digging prey out from under the sand, and seem to be able to detect the presence of underground arthropods. Though this species has not been observed to climb plants in order to feed on their flowers, individuals will jump in order to pull down flowers that are out of reach. In one instance, an individual was even observed running and leaping from the top of a sand hill in order to capture a slow flying bee. (Carpenter, 1963; Durtsche, 1995)

  • Animal Foods
  • reptiles
  • insects
  • Plant Foods
  • leaves
  • flowers

Predation

Anti-predation behavior of Uma inornata mainly consists of fleeing from perceived threats. A frightened lizard may either retreat into a nearby rodent burrow or dive beneath the sand. In addition, lizards in the genus Uma have been observed running bipedally over the sand when fleeing predators at high speeds. Cryptic coloration also aids Uma inornata in remaining hidden from predators.

The main documented predators of Uma inornata are Falco sparverius and Lanius ludovicianus. (Horchar, 1993; Carpenter, 1963; Barrows and Allen, 2007)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The Coachella-valley fringe-toed lizard is commensal with many species of burrowing rodents that live within its ecosystem. While such rodents are generally unaffected by the presence of Uma inornata, the lizard benefits greatly by using rodent burrows for both shade and protection from predators.

In addition, a mutualistic relationship may exist between Uma inornata and the plants Dicoria canescens and Salsola tragus. Both of these plants provide Uma inornata with shade and a valuable foraging habitat, while the habit of Uma inornata of feeding upon arthropods found on the leaves and stems of the plants (along with also digging up those which live near the roots) likely helps to protect the plants from consumption by insects. However, the fringe-toed lizard is also known to feed on the leaves of Dicoria canescens, so the costs and benefits of this relationship must be studied more thoroughly in order to confirm whether it is truly mutualistic.

More general roles of Uma inornata within the Coachella Valley ecosystem include serving as a source of food for large avian predators and contributing to control of the insect population through feeding. (Barrows and Allen, 2007; Barrows, 1997)

Species Used as Host
  • Burrowing rodents
Mutualist Species
  • Dicoria canescens
  • Salsola tragus

Economic Importance for Humans: Positive

Due to the relatively small, desert-like area in which it is found, the positive effects of Uma inornata on humans are minimal. The fringe-toed lizard’s diet includes ants, though its contribution to the control of this pest population is likely small because of the high variety of other insects on which it also feeds. (Durtsche, 1995)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

The listing of Uma inornata as a threatened species ultimately resulted in the creation of the Coachella Valley Preserve System in 1986, which may have had small negative economic effects on humans living near the preserve. Five percent of the total area available was ultimately protected, making this land ineligible for human development. In addition, a conflict of interests exists between humans and Uma inornata regarding flooding and wind-blown sand; both flooding and a lack of windbreaks are required in order to maintain suitable habitat, despite the fact that these conditions are generally undesirable for humans living near the preserve boundaries. (Barrows, 1996)

Conservation Status

The Coachella Valley fringe-toed lizard is listed on the U.S. Endangered Species Act List as threatened, and on the IUCN Red List as endangered (Uma inornata is not listed on the CITES appendices). Causes of the fringe-toed lizard's status are numerous, and include habitat fragmentation, drought, and scouring. Construction of Interstate 10 in the 1950’s was a serious issue for the fringe-toed lizard, as it divided the lizard’s habitat and required the construction of large windbreaks which blocked the movement of windblown sand. A constant influx of this sand is crucial for the success of Uma inornata, so construction of windbreaks (or structures that channel wind and blow sand away from habitat areas) can be detrimental. Continued human development has resulted in a loss of 80 to 90% of the fringe-toed lizard’s original habitat. Naturally occurring droughts have also been observed to negatively affect populations of Uma inornata.

Both the 3,709 acre Coachella Valley National Wildlife Refuge and the adjacent 16,405 acre Coachella Valley Preserve have been established to protect the remaining areas in which Uma inornata still occurs. In addition, concerns about movement of sand off from protected habitat areas are being addressed through the Coachella Valley Multispecies Habitat Conservation Plan and the Conceptual Area Protection Plan. Both of these projects aim to purchase additional sand sources and sand transport corridors in order to maintain the viability of Uma inornata habitats located within the preserves. ("Uma inornata", 1980; Hammerson, 2007; Vandergast, et al., 2015)

Other Comments

A study of genetic variation among individual Coachella Valley fringe-toed lizards found that populations in different areas of the Coachella Valley have begun to accumulate distinct genetic differences. This has led to speculation that habitat fragmentation may be isolating small groups of lizards and initiating the speciation process. However, it has also been argued that genetic diversity within each of these populations is declining, which could eventually result in inbreeding-related problems. (Vandergast, et al., 2015)

Contributors

Tyler DeVos (author), Northern Michigan University, Travis Moe (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

threatened

The term is used in the 1994 IUCN Red List of Threatened Animals to refer collectively to species categorized as Endangered (E), Vulnerable (V), Rare (R), Indeterminate (I), or Insufficiently Known (K) and in the 1996 IUCN Red List of Threatened Animals to refer collectively to species categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU).

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

1980. "Uma inornata" (On-line). ECOS Environmental Conservation Online System. Accessed March 17, 2017 at https://ecos.fws.gov/ecp0/profile/speciesProfile.action?spcode=C02I.

Barrows, C. 1996. An Ecological Model for the Protection of a Dune Ecosystem. Conservation Biology, 10: 888-891. Accessed January 31, 2017 at http://www.jstor.org/stable/pdf/2387113.pdf.

Barrows, C. 1997. Habitat Relationships of the Coachella Valley Fringe-Toed Lizard (Uma inornata). The Southwestern Naturalist, 42: 218-223. Accessed January 31, 2017 at http://www.jstor.org/stable/pdf/30055264.pdf.

Barrows, C., M. Allen. 2007. Community complexity: Stratifying monitoring schemes within a desert sand dune landscape. Journal of Arid Environments, 69: 315-330. Accessed January 31, 2017 at http://www.sciencedirect.com/science/article/pii/S0140196306002928.

Barrows, C., M. Allen. 2007. Persistence and local extinctions of endangered lizard Uma inornata on isolated habitat patches. Endangered Species Research, 3: 61-68. Accessed January 31, 2017 at http://www.int-res.com/articles/esr2007/3/n003p061.pdf.

Behler, J., F. King. 1979. National Audubon Society Field Guide to Reptiles and Amphibians of North America. New York, USA: Alfred A. Knopf, Inc..

Carpenter, C. 1963. Patterns of Behavior in Three Forms of the Fringe-toed Lizards (Uma-Iguanidae). Copeia, 1963: 406-412. Accessed January 31, 2017 at http://www.jstor.org/stable/pdf/1441361.pdf.

Durtsche, R. 1995. Foraging Ecology of the Fringe-Toed Lizard, Uma inornata, during Periods of High and Low Food Abundance. Copeia, 1995: 915-926. Accessed January 31, 2017 at http://www.jstor.org/stable/pdf/1447040.pdf.

Hammerson, G. 2007. "Uma inornata" (On-line). The IUCN Red List of Threatened Species 2007. Accessed March 17, 2017 at http://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T22727A9380224.en.

Horchar, V. 1993. "Home range dynamics of the Coachella Valley fringe-toed lizard" (On-line pdf). ResearchGate. Accessed January 31, 2017 at https://www.researchgate.net/publication/35546657_Home_range_dynamics_of_the_Coachella_Valley_fringe-toed_lizard.

Mayhew, W. 1965. Reproduction in the Sand-Dwelling Lizard Uma inornata. Herpetologica, 21: 39-55. Accessed January 31, 2017 at http://www.jstor.org/stable/pdf/3890706.pdf.

Turner, F., D. Weaver, J. Rorabaugh. 1984. Effects of Reduction in Windblown Sand on the Abundance of the Fringe-Toed Lizard (Uma inornata) in the Coachella Valley, California. Copeia, 1984: 370-378. Accessed January 31, 2017 at http://www.jstor.org/stable/pdf/1445193.pdf.

Vandergast, A., D. Wood, A. Thompson, M. Fisher, C. Barrows, T. Grant. 2015. Drifting to oblivion? Rapid genetic differentiation in an endangered lizard following habitat fragmentation and drought. Diversity and Distributions, 22: 344-357. Accessed January 31, 2017 at http://onlinelibrary.wiley.com/doi/10.1111/ddi.12398/full.

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