Phrynosoma cornutum - (Harlan, 1825)
Texas Horned Lizard
Other English Common Names: Texas horned lizard
Taxonomic Status: Accepted
Related ITIS Name(s): Phrynosoma cornutum (Harlan, 1825) (TSN 173938)
Unique Identifier: ELEMENT_GLOBAL.2.105969
Element Code: ARACF12010
Informal Taxonomy: Animals, Vertebrates - Reptiles - Lizards
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Reptilia Squamata Phrynosomatidae Phrynosoma
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
Concept Reference Code: B90COL01NAUS
Name Used in Concept Reference: Phrynosoma cornutum
Taxonomic Comments: Reeder and Montanucci (2001) examined phylogenetic relationships of horned lizards (Phrynosoma) based on mtDNA and morphology.
Conservation Status
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NatureServe Status

Global Status: G4G5
Global Status Last Reviewed: 06Jul2005
Global Status Last Changed: 26Aug1998
Rounded Global Status: G4 - Apparently Secure
Reasons: Widespread and still relatively common in some areas of the south-central U.S. and northern Mexico; declines have been noted in portions of the range, but doing well in many areas; apparently moderately threatened by fire ants, insecticides, loss of habitat, and overcollecting.
Nation: United States
National Status: N4N5 (05Oct1996)

U.S. & Canada State/Province Status
United States Alabama (SNA), Arizona (S3S4), Arkansas (S2), Colorado (S3), Georgia (SNA), Kansas (S4), Louisiana (SX), Missouri (S2), New Mexico (S5), North Carolina (SNA), Oklahoma (S2), Texas (S4)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles)
Range Extent Comments: The range extends from extreme southwestern Missouri and central Kansas to southeastern Colorado, and south and west throughout most of Oklahoma and Texas (including coastal barrier islands), eastern and southern New Mexico, and southeastern Arizona to northeastern Sonora, Chihuahua and Durango east of Sierra Madre Occidental, Coahuila, Nuevo Leon, Tamaulipas, San Luis Potosi, and Zacatecas (Price 1990). Native eastern limit is uncertain; records for Missouri and Arkansas have been questioned (now extirpated from Arkansas; Trauth et al. 2004), and possibly the species is not native to Louisiana (Price 1990). This species has been introduced and is established in several areas in the southeastern United States, including North Carolina (Herpetol. Rev. 20:12), Florida (Jensen, 1994, Herpetol. Rev. 25:165), and elsewhere (see Price 1990 for references).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: This species is represented by hundreds of collection sites throughout the historical range in the United States and by well over 100 sites in Mexico (Prices 1990). Many historically occupied sites still support populations (e.g., Hammerson 1999).

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: Total adult population size is unknown but surely exceeds 10,000 and likely exceeds 100,000. This species can be locally abundant in undeveloped areas with appropriate habitat (Carpenter et al. 1993, Hammerson 1999).

Number of Occurrences with Good Viability/Integrity: Many to very many (41 to >125)

Overall Threat Impact: Medium
Overall Threat Impact Comments: Declines may be related to the spread of fire ants, use of insecticides to control fire ants, heavy agricultural use of land and/or other habitat alterations, and overcollecting for the pet and curio trade (Price 1990, Carpenter et al. 1993, Donaldson et al. 1994).

This species is extremely vulnerable to changes in habitat, especially the loss of harvester ants (Carpenter et al. 1993). Harvester ants comprise up to 69% of the diet (Pianka and Parker 1975), and fire ants are thought to out-compete native harvester ants for food and space (Henke and Fair 1998). This threat may be significant in parts of Texas but probably not elsewhere. Intensive agriculture (plowing) could destroy adults and their eggs (Carpenter et al. 1993, Donaldson et al. 1994) but, according to Henke and Fair (1998), reports of declines due to loss of habitat caused by urbanization, suburban sprawl, and conversion of native rangeland to agricultural crops are mostly unsubstantiated (Henke and Fair 1998).

The widespread use of broadcast insecticides is also thought to contribute to declines. Insecticides can be detrimental by directly causing illness or death or indirectly by severely reducing or eliminating harvester ants (Henke and Fair 1998).

In the past, this lizard was collected for the pet trade, by boy scout troops for trading at jamborees, for the curio trade, and by tourists (Donaldson et al. 1994, Henke and Fair 1998).

Mortality from road traffic is an important local threat in some areas. Males are particularly vulnerable during May-June in Arizona-New Mexico (Sherbrooke 2002). A high level of road mortality may lead to significant local declines.

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: This species apparently has declined in area of occupancy and population size near the northeastern margins of the range in Texas, Oklahoma, and Kansas, but it is doing well in most the range. According to Price (1990), the Texas horned lizard has virtually disappeared from Texas east of a line from Fort Worth through Austin and San Antonio to Corpus Cristi (formerly widespread and abundant in that area); it has also declined in range and/or abundance in areas where it was formerly common in parts of north-central Texas, the Texas Panhandle, and parts of Oklahoma. Price's conclusions are supported by more recent surveys in Texas, Oklahoma, and Kansas. A 1992 Texas survey found the greatest declines in east Texas (where no individuals were found) and apparent declines also in central Texas; the species appeared to be doing well in northern and western Texas (Donaldson et al. 1994). Bartlett and Bartlett (1999) stated that the decline may have halted in at least some parts of Texas; they found numerous individuals in areas where searches in several previous years yielded few. A 1999 survey in Texas was unable to determine if the decline has halted or if it continues today (Henke 2003). A 1992 Oklahoma survey found the species to be rapidly disappearing in eastern areas of Oklahoma where it was once known to be abundant (Carpenter et al. 1993). A 1993 survey of the northern Flint Hills of Kansas suggested that populations were possibly declining (Busby and Parmalee 1996), and local collectors reported declines in the southeastern portions of Kansas (Bill Busby, pers. comm., 1998). In Colorado no trend information is available, but recent surveys indicate that the species appears to be locally common and stable (Siemers, pers. comm., 1998; Hammerson 1999). According to Rosen (Herp Diversity Review 1996), populations are thriving and plentiful in extreme southeastern Arizona. New Mexico densities have not changed historically, and populations are considered stable (Charles Painter, pers. comm., 1998). Status is unknown in Sonora, Mexico (Andres Villareal Lizarraga, pers. comm., 1998).

Long-term Trend: Decline of <50% to Relatively Stable

Intrinsic Vulnerability: Moderately vulnerable

Other NatureServe Conservation Status Information

Inventory Needs: Determine the number of populations and abundance. Monitor selected populations across the range to determine trends. Determine threats and monitor the spread of fire ants and their effect.

Distribution
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Global Range: (200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles)) The range extends from extreme southwestern Missouri and central Kansas to southeastern Colorado, and south and west throughout most of Oklahoma and Texas (including coastal barrier islands), eastern and southern New Mexico, and southeastern Arizona to northeastern Sonora, Chihuahua and Durango east of Sierra Madre Occidental, Coahuila, Nuevo Leon, Tamaulipas, San Luis Potosi, and Zacatecas (Price 1990). Native eastern limit is uncertain; records for Missouri and Arkansas have been questioned (now extirpated from Arkansas; Trauth et al. 2004), and possibly the species is not native to Louisiana (Price 1990). This species has been introduced and is established in several areas in the southeastern United States, including North Carolina (Herpetol. Rev. 20:12), Florida (Jensen, 1994, Herpetol. Rev. 25:165), and elsewhere (see Price 1990 for references).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States ALexotic, AR, AZ, CO, GAexotic, KS, LAextirpated, MO, NCexotic, NM, OK, TX

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted.

Range Map Compilers: NatureServe, 2005


U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Cochise (04003), Graham (04009)*, Greenlee (04011), Pima (04019)
CO Baca (08009), Bent (08011), Crowley (08025)*, Kiowa (08061), Las Animas (08071), Lincoln (08073), Otero (08089), Prowers (08099), Pueblo (08101)
KS Barber (20007), Geary (20061), Kingman (20095), Morton (20129), Riley (20161), Stanton (20187), Stevens (20189)
MO Barry (29009), Henry (29083), McDonald (29119)*, Stone (29209)*, Vernon (29217)*
NM Dona Ana (35013), Otero (35035)
OK Beaver (40007), Beckham (40009), Blaine (40011), Bryan (40013), Caddo (40015), Canadian (40017), Carter (40019), Cherokee (40021), Cimarron (40025), Cleveland (40027), Comanche (40031), Cotton (40033), Creek (40037), Custer (40039), Ellis (40045), Garfield (40047), Garvin (40049), Grady (40051), Greer (40055), Harmon (40057), Haskell (40061), Hughes (40063), Jackson (40065), Jefferson (40067), Kay (40071), Kingfisher (40073), Kiowa (40075), Lincoln (40081), Logan (40083), Major (40093), McClain (40087), McIntosh (40091), Muskogee (40101), Noble (40103), Oklahoma (40109), Okmulgee (40111), Osage (40113), Pawnee (40117), Pontotoc (40123), Pottawatomie (40125), Roger Mills (40129), Seminole (40133), Sequoyah (40135), Stephens (40137), Texas (40139), Tillman (40141), Tulsa (40143), Wagoner (40145), Washita (40149), Woods (40151), Woodward (40153)
TX Atascosa (48013), Brewster (48043), Brown (48049), Cameron (48061), Coke (48081), Collingsworth (48087), Concho (48095), Cottle (48101), Donley (48129), El Paso (48141), Hidalgo (48215), Hockley (48219), Hudspeth (48229), King (48269), Kleberg (48273), La Salle (48283), Lubbock (48303), McCulloch (48307), Menard (48327), Runnels (48399), Taylor (48441), Terrell (48443), Terry (48445), Val Verde (48465)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
10 Upper Kansas (10270101)+, Middle Kansas (10270102)+, Marmaton (10290104)+*, South Grand (10290108)+
11 Beaver Reservoir (11010001)+*, James (11010002)+, Upper Arkansas-Lake Meredith (11020005)+, Apishapa (11020007)+, Horse (11020008)+, Upper Arkansas-John Martin (11020009)+, Purgatoire (11020010)+, Rush (11020012)+, Two Butte (11020013)+, South Fork Ninnescah (11030015)+, Cimarron headwaters (11040001)+, Upper Cimarron (11040002)+, North Fork Cimarron (11040003)+, Sand Arroyo (11040004)+, Bear (11040005)+, Upper Cimarron-Liberal (11040006)+, Lower Cimarron-Eagle Chief (11050001)+, Lower Cimarron-Skeleton (11050002)+, Lower Cimarron (11050003)+, Upper Salt Fork Arkansas (11060002)+, Lower Salt Fork Arkansas (11060004)+, Chikaskia (11060005)+, Black Bear-Red Rock (11060006)+, Caney (11070106)+, Bird (11070107)+, Lake O' the Cherokees (11070206)+*, Elk (11070208)+*, Lower Neosho (11070209)+, Lower Canadian-Deer (11090201)+, Lower Canadian-Walnut (11090202)+, Little (11090203)+, Lower Canadian (11090204)+, Upper Beaver (11100101)+, Middle Beaver (11100102)+, Coldwater (11100103)+, Lower Beaver (11100201)+, Lower Wolf (11100203)+, Middle North Canadian (11100301)+, Lower North Canadian (11100302)+, Deep Fork (11100303)+, Polecat-Snake (11110101)+, Dirty-Greenleaf (11110102)+, Lower Prairie Dog Town Fork Red (11120105)+, Upper Salt Fork Red (11120201)+, Lower Salt Fork Red (11120202)+, Middle North Fork Red (11120302)+, Lower North Fork Red (11120303)+, Elm Fork Red (11120304)+, Groesbeck-Sandy (11130101)+, Blue-China (11130102)+, Middle Pease (11130104)+, Farmers-Mud (11130201)+, Cache (11130202)+, West Cache (11130203)+, North Wichita (11130204)+, Northern Beaver (11130208)+, Lake Texoma (11130210)+, Washita headwaters (11130301)+, Upper Washita (11130302)+, Middle Washita (11130303)+, Bois D'arc-Island (11140101)+, Blue (11140102)+, Muddy Boggy (11140103)+, Clear Boggy (11140104)+
12 Yellow House Draw (12050001)+, Upper Clear Fork Brazos (12060102)+, Lost Draw (12080001)+, Upper Colorado (12080008)+, Middle Colorado-Elm (12090101)+, North Concho (12090104)+, Concho (12090105)+, Middle Colorado (12090106)+, Pecan Bayou (12090107)+, San Saba (12090109)+, Middle Nueces (12110105)+, Lower Frio (12110108)+, Atascosa (12110110)+, Baffin Bay (12110205)+, South Laguna Madre (12110208)+
13 El Paso-Las Cruces (13030102)+, Jornada Draw (13030103)+, Rio Grande-Fort Quitman (13040100)+, Maravillas (13040206)+, Dry Devils (13040303)+, Tularosa Valley (13050003)+, Salt Basin (13050004)+, Independence (13070010)+, Lower Pecos (13070012)+, Elm-Sycamore (13080001)+, Los Olmos (13090001)+, Lower Rio Grande (13090002)+
15 Upper Gila-Mangas (15040002)+, San Simon (15040006)+, Willcox Playa (15050201)+, Upper San Pedro (15050202)+, Rillito (15050302)+, Brawley Wash (15050304)+, Whitewater Draw (15080301)+, San Bernardino Valley (15080302)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A wide-bodied spiny lizard.
General Description: A flattened, wide-bodied lizard with long spines on the head (the two central ones are longest), a short snout, and dark lines radiating from the eye on each side of the face; dorsum mainly brown, yellowish, tan, reddish, or gray, with sooty or dark brown blotches on neck, back, and tail (rear edge of blotches white or yellow); middorsal stripe present (beige or white); row of enlarged scales on each side of throat; two rows of pointed fringe scales on each side of body; adult snout-vent length 6.2-12.5 cm (Stebbins 1985).
Diagnostic Characteristics: Differs from P. SOLARE in lacking four large horns with bases that touch at the back of the head. Differs from P. CORONATUM in having one (vs. 2-3) rows of enlarged scales on each side of the throat. Differs from P. PLATYRHINOS in having a double row rather than a single row of pointed fringe scales on each side of the body. Other horned lizards have either much smaller horns or a dark middorsal stripe rather than a pale one. See Stebbins (1985).
Reproduction Comments: Lays clutch of 14 to 60 eggs, May-July. Eggs hatch in about 6 weeks (Behler and King 1979).
Ecology Comments: Desert populations cycle in abundance, possibly following similar cycles of their primary prey (POGONOMYRMEX harvester ants) (Price 1990).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: Home range size and movements seem quite variable. Munger (1984a) found that single-season home range size in southern Arizona averaged 1.3 ha in females and 2.4 ha in males. Home range length extended up to about 400 m but often was 100-300 m, and some individuals that were observed more than 30 times moved over an area less than 55 m across. Some individuals tended not to remain in a limited area. Overlap of home ranges occurred but was not extensive.

In southern New Mexico, home range size was about 1 ha or less (Worthington 1972). Whitford and Bryant (1979) recorded movements of 9-91 m per day (average 47 m) in New Mexico. Individuals followed a zig-zag course and rarely crossed their own path.

In Colorado, Montgomery and Mackessy (in Mackessy 1998) reported that a juvenile moved approximately 100 m in two days. Another juvenile was recaptured 480 m from its original capture location after 47 days.

In Texas, total area of use varied from 291 sq m (25 days) to 14,690 sq m (116 days); weekly home ranges appeared to be mobile (Fair and Henke 1999). Annual adult survival rate was between 9 and 54 percent.

In Oklahoma, average individual daily linear movements for all lizards was 45.0 m (range 10-220 m); males moved significantly farther than females in but not after May when their average daily movements were very similar; average individual daily activity area for all lizards was 232.8 square meters (range 1.7-3011.4 sq m); males covered drastically larger areas in a day during May than did females (Stark et al. 2005).

Terrestrial Habitat(s): Desert, Grassland/herbaceous, Shrubland/chaparral
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris
Habitat Comments: This lizard inhabits open arid and semiarid regions with sparse vegetation (deserts, prairies, playa edges, bajadas, dunes, foothills) with grass, cactus, or scattered brush or scrubby trees (Degenhardt et al. 1996, Bartlett and Bartlett 1999, Hammerson 1999, Stebbins 2003). Soil may vary in texture from sandy to rocky. When inactive, individuals burrow into the soil, enter rodent burrows, or hide under rocks. Sheffield and Carter (1994, Herpetol. Rev. 25:67-68) reported individuals that climbed 1-2 m up tree trunks when soils were wet after heavy rains. Eggs are laid in nests dug in soil or under rocks (Collins 1982).
Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food Comments: Eats mainly ants but also other small insects (Stebbins 1985).
Adult Phenology: Diurnal, Hibernates/aestivates
Immature Phenology: Diurnal, Hibernates/aestivates
Phenology Comments: Active April to September in north (Collins 1982, Hammerson 1982). Sometimes found on warm roads at night (Hammerson 1982).
Length: 18 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Management Requirements: Based on abundance of harvester ants, McIntyre (2003) found no evidence that Conservation Reserve Program plots planted in exotic grasses are significantly poorer habitat for P. cornutum than native grass plantings.
Monitoring Requirements: See Fair and Henke (1997) for information on different capture/survey methods.
Population/Occurrence Delineation
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Group Name: Phrynosomatid Lizards

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy highway or highway with obstructions such that lizards rarely if ever cross successfully; major river, lake, pond, or deep marsh; urbanized area dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Phrynosomatid lizards have small home range sizes, usually less than 0.5 ha (often much less) and rarely more than 1 ha (see examples in BCD EO Specs). In a study that documented exceptionally large home range size for a phrynosomatid, Munger (1984a) found that single-season home range size of Phrynosoma cornutum in southern Arizona averaged less than 2.5 ha. Dispersal distances are poorly known, and most studies have not been designed to detect long distance movements. The separation distance for suitable habitat is a compromise between the typical sedentary habits of these lizards, their physical ability to cover fairly large distances in a short period of time, their tendency to occur throughout patches of suitable habitat, and the likely low probability that two occupied locations separated by less than several kilometers of suitable habitat would represent independent populations.
Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .2 km
Date: 21Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 06Jul2005
NatureServe Conservation Status Factors Author: Hammerson, G., and M. K. Clausen
Element Ecology & Life History Edition Date: 06Jul2005
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Bartlett, R. D., and P. P. Bartlett. 1999a. A field guide to Texas reptiles & amphibians. Gulf Publishing Company, Houston, Texas. xviii + 331 pp.

  • Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.

  • Busby, W. H. and J. R. Parmalee. 1996. Historical changes in a herpetofaunal assemblage in the Flint Hills of Kansas. American Midland Naturalist 135: 81-91.

  • Carpenter, C. C., R. St. Clair, P. Gier, and C. C. Vaughn. 1993. Determination of the distribution and abundance of the Texas horned lizard (PHRYNOSOMA CORNUTUM) in Oklahoma. Final Report to Oklahoma Department of Wildlife Conservation, Federal Aid Project E-18.

  • Collins, J. T. 1982. Amphibians and reptiles in Kansas. Second edition. Univ. Kansas Mus. Nat. Hist., Pub. Ed. Ser. 8. xiii + 356 pp.

  • Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.

  • Conant, R. and J. T. Collins. 1991. A field guide to reptiles and amphibians: eastern and central North America. Third edition. Houghton Mifflin Co., Boston, Massachusetts. 450 pp.

  • Conant, R., and J. T. Collins. 1998. A field guide to reptiles and amphibians: eastern and central North America. Third edition, expanded. Houghton Mifflin Co., Boston, Massachusetts. 616 pp.

  • Crother, B. I. (editor). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84.

  • Crother, B. I. (editor). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84. Online with updates at: http://www.ssarherps.org/pages/comm_names/Index.php

  • Crother, B. I. (editor). 2012. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 7th edition. SSAR Herpetological Circular 39:1-92.

  • Degenhardt, W. G., C. W. Painter, and A. H. Price. 1996. Amphibians and reptiles of New Mexico. University of New Mexico Press, Albuquerque. xix + 431 pp.

  • Dixon, J. R. 2000. Amphibians and reptiles of Texas. Second edition. Texas A & M University Press, College Station. 421 pp.

  • Donaldson, W. A., A. H. Price, and J. Morse. 1994. The current status and future propects of the Texas horned lizard (PHRYNOSOMA CORNUTUM) in Texas. Texas Journal of Science 46:(7-113).

  • Fair, W. S., and S. E. Henke. 1997. Efficacy of capture methods for a low density population of PHRYNOSOMA CORNUTUM. Herpetological Review 28:135-137.

  • Fair, W. S., and S. E. Henke. 1999. Movements, home ranges, and survival of Texas horned lizards (PHRYNOSOMA CORNUTUM). Journal of Herpetology 33:517-525.

  • Hammerson, G. A. 1982b. Amphibians and reptiles in Colorado. Colorado Division of Wildlife, Denver. vii + 131 pp.

  • Hammerson, G. A. 1999. Amphibians and reptiles in Colorado. Second edition. University Press of Colorado, Boulder. xxvi + 484 pp.

  • Henke, S. E. 2003. Baseline survey of Texas horned lizards, Phrynosoma cornutum, in Texas. Southwestern Naturalist 48:278-282.

  • Henke, S. E., and W. S. Fair. 1998. Managment of Texas horned lizards. Wildlife Management Bulletin of the Caesar Wildlife Research Institute, Texas A & M University-Kingsville, Bull. No. 2. 7 pp.

  • Herp Diversity Review Board. 1996. Herp Diversity Review Species List Final Rankings. Unpublished report to the Arizona Natural Heritage Program, Arizona Game and Fish Department.

  • Johnson, T. R. 2000. The amphibians and reptiles of Missouri. Second edition. Missouri Department of Conservation, Jefferson City. 400 pp.

  • Mackessy, S. P. 1998. A survey of the herpetofauna of southeastern Colorado with a focus on the current status of two candidates for protected species status: the massasauga rattlesnake and the Texas horned lizard. Final report to the Colorado Division of Wildlife.

  • McIntyre, N. E. 2003. Effects of Conservation Reserve Program seeding regime on harvester ants (Pogonomyrmex), with implications for the threatened Texas horned lizard (Phrynosoma cornutum). Southwestern Naturalist 48:274-313.

  • Mirarchi, R.E., editor. 2004. Alabama Wildlife. Volume 1. A checklist of vertebrates and selected invertebrates: aquatic mollusks, fishes, amphibians, reptiles, birds, and mammals. The University of Alabama Press, Tuscaloosa, Alabama. 209 pages.

  • Mount, R. H. 1975. The reptiles and amphibians of Alabama. Auburn University Agricultural Experiment Station, Auburn, Alabama. vii + 347 pages.

  • Munger, J. C. 1984. Home ranges of horned lizards (Phrynosoma): circumscribed and exclusive? Oecologia 62:351-360.

  • Pianka, E. R., and W. S. Parker. 1975. Ecology of horned lizards: a review with special reference to PHRYNOSOMA PLATYRHINOS. Copeia 1975(1):141-162.

  • Price, A. H. 1990. PHRYNOSOMA CORNUTUM. Cat. Am. Amph. Rept. 469.1-469.7.

  • Reeder, T. W., and R. R. Montanucci. 2001. Phylogenetic analysis of the horned lizards (Phrynosomatidae: PHRYNOSOMA): evidence from mitochondrial DNA and morphology. Copeia 2001:309-323.

  • Sherbrooke, W. C. 2002. Seasonally skewed sex-ratios of road-collected Texas horned lizards (Phrynosoma cornutum). Herpetological Review 33:21-24.

  • Stark, R. C., S. F. Fox, and D. M. Leslie, Jr. 2005. Male Texas horned lizards increase daily movements and area covered in spring: a mate searching strategy? Journal of Herpetology 39:169-173.

  • Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.

  • Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.

  • Trauth, S. E., H. W. Robison, and M. V. Plummer. 2004. The amphibians and reptiles of Arkansas. University of Arkansas Press.

  • Webb, R. G. 1970. Reptiles of Oklahoma. University of Oklahoma Press, Norman. 370 pp.

  • Whitford, W. G., and M. Bryant. 1979. Behavior of a predator and its prey: the horned lizard (Phrynosoma cornutum) and harvester ants (Pogonomyrmex spp.). Ecology 60: 686-694.

  • Whiting, M.J., J. R. Dixon, and R. C. Murray. 1993. Spatial distribution of a population of Texas horned lizards (PHRYNOSOMA CORNUTUM: PHRYNOSOMATIDAE) relative to habitat and prey. Southwestern Naturalist 38:150-154.

  • Worthington, R. D. 1972. Density, growth rates and home range sizes of Phrynosoma cornutum in southern Dona Ana County, New Mexico. Herpetological Review 4:128.

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Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2017. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

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