Greater Short-horned Lizard - Phrynosoma hernandesi
The body of the Greater Short-horned Lizard is broad and flattened. The back is spiny, with an especially noticeable single row of scales fringing each side of the body. The spines at the back of the head are about as long as they are wide at the base. The coloration of the back usually blends cryptically with the soil and can vary somewhat from region to region and at single localities. The maximum total length is about 15 centimeters. In males, there is a swelling at the base of the tail, and the tail is proportionally longer than in females. Newborn young have the broad and flattened body shape, and are about 2.0 to 2.5 centimeters snout-vent length and up to 3.8 centimeters by the time of first hibernation.
The broad, flattened body separates this lizard from the other three lizard species regularly documented in Montana, and the range overlaps only with the Common Sagebrush Lizard. The Pygmy Short-horned Lizard has been reported from extreme southwestern Montana, in the Centennial Valley, Beaverhead County (Maxell et al. 2003), but adults of this species are much smaller than Greater Short-horned Lizards, the small horns on the back of the head project almost vertically rather than horizontally, and they lack the wide notch between the horns on the back of the head that gives the head of Greater Short-horned Lizards a "heart-shaped" appearance when viewed from above (St. John 2002).
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
No information currently exists regarding the migration patterns of Greater Short-horned Lizards in Montana.
Habitat use in Montana is poorly described, but appears to be similar to other regions. Reports mention individuals on ridge crests between coulees, and in sparse, short grass and sagebrush with sun-baked soil (Mosimann and Rabb 1952, Dood 1980). On the southern exposures of the Pryor Mountains, Carbon County, individuals occur among limestone outcrops in canyon bottoms of sandy soil with an open canopy of limber pine-Utah juniper, and are also present on flats of relatively pebbly or stony soil with sparse grass and sagebrush cover (Paul Hendricks, personal observation).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: mtnhp.org/requests
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
This species is an invertivore. The diet of Greater Short-horned Lizards includes mostly ants and beetles, as well as other insects, spiders, snails, sowbugs, and other invertebrates. Individuals may sometimes gorge themselves on a single type of prey (Hammerson 1999). The diet in Montana is virtually undescribed; stomach contents of three individuals from coulees near the Marias River in Toole County included mostly ants with a few beetles, grasshoppers, and spiders (Mosimann and Rabb 1952).
Adult Greater Short-horned Lizards are diurnal and active during the warmer daylight hours. Specific information for Montana is limited, but information from other areas within their range indicates they may appear as early as late March (Hammerson 1999), with most surface activity in the northern parts of the range occuring from mid-April to mid-September. Extreme records in Alberta extend from April 1 to November 10 (Powell and Russell 1998), but most have disappeared by the mean date of the first fall frost. Young-of-the-year are generally not active during mid-day hours, and small lizards appear more dependent on air temperatures than on substrate temperatures, while large ones are more dependent on substrate temperature. Predators of this species are mostly unknown, but Striped Whipsnake (Masticophis taeniatus) and Burrowing Owls (Speotyto cunicularia) have been reported (Hammerson 1999), and birds have been identified as the primary predatory group (Russell and Bauer 1993). The annual period of activity in Montana is poorly defined, and no predators have been reported.
No studies of the life history and reproduction of this species have been conducted in the state. In extreme southern Montana, young about 3.0 to 3.5 centimeters snout-vent length have been observed in early August and early September (Hendricks 1999).
Based upon information gathered from other areas within the species' range, adult Greater Short-horned Lizards mate shortly after emerging from hibernation in late March to early June, depending on location, and young are born about two or three months after eggs are fertilized. The Greater Short-horned Lizard is viviparous, giving live birth to 5 to 36 young (3 to 15 in the Pacific Northwest) during July to September (Nussbaum et al. 1983, Stebbins 2003). The size of 8 litters from Alberta, born in late July to early August, ranged from 6 to 13 young (Laird and Leech 1980, Powell and Russell 1998) and 5 litters in Colorado ranged from 14 to 18 young (Hammerson 1999). A litter of 13 young was born in southern Wyoming in early August (2.3 to 2.4 centimeters snout-vent length at birth) and consisted of two color morphs (Ashton and Ashton 1998); 4 young were stillborn. Sexual maturity is reached in at least two years (Nussbaum et al. 1983, Hammerson 1999).
Threats to this species in Montana are speculative, due to lack of study and poor survey coverage. The Greater Short-horned Lizard was considered the most abundant reptile along the Missouri River in Montana in the late 19th Century (Cope 1879), second only to the Western Rattlesnake, but it is no longer thought common anywhere in the state, with the possible exception of southern Carbon County (Maxell et al. 2003). The relatively few records in recent years parallel the pattern for Colorado (Hammerson 1999), but inadequate survey coverage makes conclusions regarding trends in Montana tenuous. Habitat loss due to the conversion of prairie to cropland has undoubtedly contributed to the apparent decline, but livestock grazing is probably not a serious threat to any population, judging from reports in other regions. However, clearing of sagebrush to increase grass production for livestock could have detrimental impacts on local populations of Greater Short-horned Lizards. Off-road recreational vehicle traffic and increased traffic associated with road building to oil and gas developments in eastern Montana could also have negative impacts on some populations. Indiscriminant use of insecticides to control some insect species could also affect the food supply of this lizard. No management activity for this species in Montana is currently underway, nor is any proposed at this time, but the conversion of native prairie to cropland or other use will contribute to the decline of this species in the state. Collecting of animals for commercial purposes including export to the pet trade is prohibited. Within the range of the Greater Short-horned Lizard in Montana where sagebrush control is planned, some sage should be left in a network of patches to insure population persistence of these lizards. Given the small home range size of the species, thinning of sagebrush or removal in small patches is probably a better management guideline than removing sagebrush entirely or in large patches.
- Literature Cited AboveLegend: View Online Publication
- Ashton, K.G. and K. L. Ashton. 1998. Phrynosoma douglasii (short-horned lizard). Reproduction. Herpetological Review 29(3):168-169.
- Cope, E. D. 1879. A contribution to the zoology of Montana. American Naturalist 13(7): 432-441.
- Dood, A.R. 1980. Terry Badlands nongame survey and inventory final report. Montana Department of Fish, Wildlife, and Parks and Bureau of Land Management, Helena, MT. 70 pp.
- Hammerson, G.A. 1999. Amphibians and reptiles in Colorado. University Press of Colorado & Colorado Division of Wildlife. Denver, CO. 484 p.
- Hendricks, P. 1999. Amphibian and reptile survey of the Bureau of Land Management Miles City District, Montana. Montana Natural Heritage Program, Helena, MT. 80 p.
- Laird, M. and R. Leech. 1980. Observations on the short-horned lizard in southeastern Alberta. Blue Jay 38(4): 214-218.
- Maxell, B.A., J.K. Werner, P. Hendricks, and D.L. Flath. 2003. Herpetology in Montana: a history, status summary, checklists, dichotomous keys, accounts for native, potentially native, and exotic species, and indexed bibliography. Society for Northwestern Vertebrate Biology, Northwest Fauna Number 5. Olympia, WA. 135 p.
- Mosimann, J.E. and G.B. Rabb. 1952. The herpetology of Tiber Reservoir Area, Montana. Copeia(1): 23-27.
- Nussbaum, R.A., E.D. Brodie, Jr. and R.M. Storm. 1983. Amphibians and reptiles of the Pacific Northwest. University of Idaho Press. Moscow, ID. 332 pp.
- Powell, G.L. and A.P. Russell. 1998. The status of short-horned lizards (Phrynosoma douglasi) and (P. hernandezi) in Canada. Canadian Field Naturalist 112(1):1-16.
- Russell, A. P. and A. M. Bauer. 1993. The amphibians and reptiles of Alberta. University of Calgary Press. Calgary, Alberta. 264 p.
- St. John, A.D. 2002. Reptiles of the northwest: California to Alaska, Rockies to the coast. Lone Pine Publishing, Renton, WA. 272 p.
- Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. 3rd Edition. Houghton Mifflin Company, Boston and New York. 533 p.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- [OEA] Olson Elliot and Associates Research. 1985. 1983-1984 Wildlife monitoring report for the CX Ranch project. Olson Elliot and Associates Research. Helena, MT.
- [PRESI] Powder River Eagle Studies Incorporated. 1998b. Spring Creek Mine 1997 wildlife monitoring studies. Powder River Eagle Studies Incorporated. Gillete, WY.
- [USFWS] US Fish and Wildlife Service. 1994. Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species. Federal Register 59(219): 58982-59028.
- [VTNWI] VTN Wyoming Incorporated. No Date. Second year's analysis of terrestrial wildlife on proposed mine access and railroad routes in southern Montana and northern Wyoming, March 1979 - February 1980. VTN Wyoming Incorporated. Sheridan, WY. 62 p.
- [WESCO] Western Ecological Services Company. 1983b. Wildlife inventory of the Southwest Circle known recoverable coal resource area, Montana. Western Ecological Services Company, Novato, CA. 131 p.
- Allen, J. A. 1874. Notes on the natural history of portions of Dakota and Montana Territories, being the substance of a report to the Secretary of War on the collections made by the North Pacific Railroad Expedition of 1873. Proceedings of the Boston Society of Natural History. pp. 68-70.
- Baxter, G.T. and M.D. Stone. 1985. Amphibians and reptiles of Wyoming. Second edition. Wyoming Game and Fish Department. Cheyenne, WY. 137 p.
- Benson, K.R. 1978. Herpetology of the Lewis and Clark expedition 1804-1806. Herpetological Review 9(3): 87-91.
- Brunson, R.B. 1955. Check list of the amphibians and reptiles of Montana. Proceedings of the Montana Academy of Sciences 15: 27-29.
- Bureau of Indian Affairs, Department of the Interior. 1981. Draft Environmental Impact Statement. Unpublished report for the Crow/Shell Coal Lease, Crow Indian Reservation, Montana.
- Burroughs, R. D. 1961. Natural history of the Lewis and Clark expedition. Michigan State University Press, East Lansing. 340 p.
- Carlson, J. (Coordinator, Montana Animal Species of Concern Committee). 2003. Montana Animal Species of Concern. Helena, MT: Montana Natural Heritage Program and Montana Fish, Wildlife, and Parks. In Press. 12p.
- Chandler, J.D. 1965. Horned toad record. The Blue Jay 23(2): 92.
- Cooper, J. G. 1869. Notes on the fauna of the Upper Missouri. American Naturalist 3:294-299.
- Cooper, J. G. 1869. The fauna of Montana Territory. II. Birds. American Naturalist 3:31-35, 73-84.
- Cooper, J.G. 1860. Report upon the reptiles collected on the survey. In: Reports of explorations and surveys to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean. Volume 12, Book 2, Part 3, Number 4. pp. 292-306, +14 pls. 36th Congress, 1st session, House Executive Document Number 56. Serial 1055.
- Cooper, S.V., C. Jean, and P. Hendricks. 2001. Biological survey of a prairie landscape in Montana's glaciated plains. Report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, MT. 24 pp. plus appendices.
- Cope, E.D. 1872. Report on the recent reptiles and fishes of the survey, collected by Campbell Carrington and C.M. Dawes. pp. 467-469 In: F.V. Hayden, Preliminary report of the United States geological survey of Montana and portions of adjacent territories; being a fifth annual report of progress. 538 pp. 42nd Congress, 2nd Session, House Executive Document Number 326. Serial 1520.
- Cope, E.D. 1875. Check-list of North American Batrachia and Reptilia; with a systematic list of the higher groups, and an essay on geographical distribution. Based on the specimens contained in the U.S. National Museum. U.S. Natioanl Museum Bulletin 1: 1-104.
- Cope, E.D. 1900. The crocodilians, lizards, and snakes of North America. Report of the U.S. National Museum 1898: 153-1270.
- Corn, P.S. and L.J. Gingerich. 1987. Phrynosoma douglassii brevirostre (eastern short-horned lizard). Herpetological Review 18(1): 20.
- Coues, E. and H. Yarrow. 1878. Notes on the herpetology of Dakota and Montana. Bulletin of the U.S. Geological Geographic Survey of the Territories 4: 259-291.
- Crother, B.I. (ed.) 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico. SSAR Herpetological Circular No. 37:1-84.
- Dammann, J. 1949. Birth of eighteen young Phrynosoma douglassi Hernandes. Herpetologica 5: 144.
- Dumas, P.C. 1964. Species-pair allopatry in the genera Rana and Phrynosoma. Ecology 45(1): 178-181.
- Farmer, P. 1980. Terrestrial wildlife monitoring study, Pearl area, Montana June, 1978 - May, 1980. Western Technology and Engineering, Inc. Helena, MT.
- Farmer, P. J. 1980. Terrestrial Wildlife Monitoring Study, Pearl Area, Montana, June, 1978 - May, 1980. Tech. Rep. by WESTECH for Shell Oil Co.
- Gates, M.T. 2005. Amphibian and reptile baseline survey: CX field study area Bighorn County, Montana. Report to Billings and Miles City Field Offices of Bureau of Land Management. Maxim Technologies, Billings, MT. 28pp + Appendices.
- Gibbons, J. W., and 10 others. 2000. The global decline of reptiles, déjà vu amphibians. BioScience 50:653-666.
- Goldberg, S.R. 1971. Reproduction in the short-horned lizard Phrynosoma douglassi in Arizona. Herpetologica 27(3): 311-314.
- Guyer, C. 2006. Phrynosoma douglasii (pigmy short-horned lizard) copulatory position. Herpetological Review 37(1):91-92.
- Guyer, C. and A.D. Linder. 1985a. Growth and population structure of the short-horned lizard (Phrynosoma douglassi) and the sagebrush lizard (Sceloporus graciosus) in southeastern Idaho. Northwest Science 59(4): 294-303.
- Guyer, C. and A.D. Linder. 1985b. Thermal ecology and activity patterns of the short-horned lizard (Phrynosoma douglassi) and the sagebrush lizard (Sceloporus graciosus) in southeastern Idaho (USA). Great Basin Naturalist 45(4): 607-614.
- Hammerson, G.A. and H.M. Smith. 1991. The correct spelling of the name of the short-horned lizard of North America. Bulletin of the Maryland Herpetological Society 27(3): 121-127.
- Hanauska-Brown, L., B.A. Maxell, A. Petersen, and S. Story. 2014. Diversity Monitoring in Montana 2008 – 2010 Final Report. Montana Fish, Wildlife & Parks. Helena, MT. 78 pp.
- Hendricks, P. and J.D. Reichel. 1998. Amphibian and reptile survey on Montana refuges: 1996. Montana Natural Heritage Program, Helena, MT. 19 p.
- Hornbeck, G.E. and J.E. Green. 1990. A reconnaissance field survey of the eastern short-horned lizard and its habitat in Samedan Manyberries 9-13-4-5 W4M. Delta Environmental Management Group Ltd. Calgary, AB. 27pp.
- Hornbeck, G.E. and J.E. Green. 1991. Year two of a reconnaissance field survey of the eastern short-horned lizard and its habitat in Samedan Manyberries 9-13-4-5 W4M. Delta Environmental Management Group Ltd. Calgary, AB. 17pp.
- Humphris, Michael., 1993, Wildlife Monitoring Report. Spring Creek Coal Company 1993 Mining Annual Report. Appendix I. April 11, 1993.
- Humphris, Michael., 1994, Wildlife Monitoring Report. Spring Creek Coal Company 1994 Mining Annual Report. Appendix I. April 1994.
- James J.D., A.P. Russell, and G.L. Powell. 1997. Status of the eastern short-horned lizard (Phrynosoma douglassii brevirostre) in Alberta. Alberta Environmental Protection, Wildlife Management Divison, Wildlife Status Report No. 5, Edmonton, AB. 1-20.
- Lewis, M., Clark, W., and Members of the Corps of Discovery. (2002). The Journals of the Lewis and Clark Expedition (G. Moulton, Ed.). Lincoln: University of Nebraska Press. Retrieved Oct. 1, 2005, from the University of Nebraska Press / University of Nebraska-Lincoln Libraries-Electronic Text Center, The Journals of the Lewis and Clark Expedition web site: http://lewisandclark journals.unl.edu/
- Linder, A.D. 1989. Short-horned lizard Phrynosoma douglassi. Rare, sensitive, and threatened species of the greater Yellowstone ecosystem. Tim W. Clark, Ann H. Harvey, Robert D. Dorn, David L. Genter, and Craig Groves, editors. pp. 50-51.
- Martin, P.R. 1980a. Terrestrial wildlife habitat inventory in southeastern Montana. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena MT. 114 p.
- Martin, P.R. 1980b. Terrestrial wildlife inventory in selected coal areas of Montana. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena, MT. 84 p.
- Martin, P.R., K. Dubois and H.B. Youmans. 1981. Terrestrial wildlife inventory in selected coal areas, Powder River resources area final report. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena, MT. No. YA-553-CTO- 24. 288 p.
- Matthews, W.L. 1979. Wibaux-Beach wildlife baseline study - nongame species. Bureau of Land Management, Miles City, MT. 93 p.
- Matthews, W.L. 1981. Broadus-Pumpkin Creek baseline inventory - wildlife. Bureau of Land Management, Miles City, MT. 83 p.
- McEneaney, T. and J. Jensen. 1974. The reptiles and amphibians of the Charles M. Russell National Wildlife Range - 1974. Charles M. Russell National Wildlife Refuge. Lewistown, MT. 3 p.
- Milner, B.J. 1979. Northern short-horned lizard in southeastern Alberta. Alberta Naturalist 9: 90-92.
- Moll, E.O. 2004. Patronyms of the pioneer west. IX. Phrynosoma hernandesi (Girard, 1858) greater short-horned lizard. Sonoran Herpetologist 17(6):58-61.
- Montanucci, R.R. 1979. Notes on systematics of horned lizards allied to Phrynosoma orbiculare (lacertilia: iguanidae). Herpetologica 35(2): 116-124.
- Montanucci, R.R. 1981. Habitat separation between Phrynosoma douglassi and P. orbiculare (lacertilia: iguanidae) in Mexico. Copeia 1981(1): 147-153.
- Montanucci, R.R. 1984. Breeding, captive care and longevity of the short-horned lizard Phrynosoma douglassi. International Zoological Yearbook 23: 148-156.
- Montanucci, R.R. and B.E. Baur. 1982. Mating and courtship-related behaviors of the short-horned lizard, Phrynosoma douglassi. Copeia 1982(4): 971-974.
- Moulton, G.E. editor. 1983. The Journals of the Lewis & Clark Expedition. University of Nebraska Press, Lincoln & London.
- Nero, R.W. 1957. Records of the horned toad in Saskatchewan. Blue Jay 15: 119-120.
- New, E.R. 1991. Drilling in short-horned lizard country. Abstract presented at the CADE/CAODC Spring Drilling Conference, April 10-12, 1991. CADE/CAODC Conference Publications, Calgary, AB.
- OEA Research. 1985. Wildlife Inventory:Monitoring Report for the CX Ranch Project. 1983-1984. Unpublished report for Consolidation Coal Company, Pittsburgh, Pennsylvania.
- Pack, H.J. 1918. Some habits of the pygmy horned lizard. Copeia 1918(63): 91-92.
- Phillips, J.A. and H.J. Harlow. 1981. Elevation of upper voluntary temperatures after shielding the parietal eye of horned lizards (Phrynosoma douglassi). Herpetologica 37(4):199-205.
- Phillips, J.A., H.J. Harlow, and C.L. Ralph. 1980. Set-point shifts of behavioral thermoregulation in horned lizards after parietal eye manipulation. American Zoologist 20(4): 732.
- 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.
- Powder River Eagle Studies, Inc., Gillette, WY., 1995, Spring Creek Mine 1994 Wildlife Monitoring Studies. 4/94 to 4/95. Spring Creek Coal Company 1995 Mining Annual Report. Appendix I. May 1995.
- Powder River Eagle Studies, Inc., Gillette, WY., 1999, Spring Creek Mine 1998 Wildlife Monitoring. March 1999.
- Powder River Eagle Studies, Inc., Gillette, WY., 2000, Spring Creek Mine 2000 Wildlife Monitoring. March 2000.
- Powell, G.L. 1980. Diet of the short-horned lizard in Alberta. American Zoologist 20(4): 842.
- Powell, G.L. 1982. The eastern short-horned lizard in Alberta: basic field ecology of northern marginal populations. Unpublished M.S. Thesis, University of Calgary, Calgary, Alberta.
- Powell, G.L. and A.P. Russell. 1984. The diet of the eastern short-horned lizard (Phrynosoma douglassi brevirostre) in Alberta and its relationship to sexual size dimorphism. Canadian Journal of Zoology 62(3): 428-440.
- Powell, G.L. and A.P. Russell. 1985. Field thermal ecology of the eastern short-horned lizard (Phrynosoma douglassi brevirostre) in southeastern Alberta. Canadian Journal of Zoology 63: 228-238.
- Powell, G.L. and A.P. Russell. 1985. Growth and sexual size dimorphism in Alberta (Canada) populations of the eastern short-horned lizard, Phrynosoma douglassi brevirostre. Canadian Journal of Zoology 63(1): 139-154.
- Powell, G.L. and A.P. Russell. 1991b. Parturition and clutch characteristics of short-horned lizards (Phrynosoma douglassii brevirostre) from Alberta. Canadian Journal of Zoology 69(11): 2759-2764.
- Powell, G.L. and A.P. Russell. 1992a. A preliminary survey of the distribution and abundance of the eastern short-horned lizard (Phrynosoma douglassii brevirostre) in Alberta. A report submitted to the Recreation, Parks, and Wildlife Foundation, Edmonton, Alberta. 135pp.
- Powell, G.L. and A.P. Russell. 1992b. The staus of the short-horned lizard (Phrynosoma douglassii) in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa, ON. 22pp.
- Powell, G.L. and A.P. Russell. 1993a. The range and status of the Eastern Short-horned Lizard in the Canadian Prairies. Provincial Museum of Alberta Natural History Occassional Paper 19: 279-290.
- Powell, G.L. and A.P. Russell. 1993b. A radiotelemetric study of movement and thermal ecology in an Alberta population of the eastern short-horned lizard (Phrynosoma douglassii brevirostre). A report submitted to the Fish and Wildlife Branch, Alberta Forestry, Lands and Wildlife, 7th Floor, O.S. Longman Building, 6909-116th St., Edmonton, Alberta T6H 4P2.
- Powell, G.L. and A.P. Russell. 1994a. A radiotelemetric study of movement, thermal ecology, and hibernation site selection in an Alberta population of the eastern short-horned lizard (Phrynosoma douglassii brevirostre). A report submitted to Alberta Environmental Protection, Fish and Wildlife Division, 7th Floor, O.S. Longman Building, 6909-116th St., Edmonton, Alberta T6H 4P2.
- Powell, G.L. and A.P. Russell. 1994b. Movement, thermal ecology, seasonal activity, and overwintering behavior in an Alberta population of the eastern short-horned lizard (Phrynosoma douglassii brevirostre). A report submitted to Alberta Environmental Protection, Fish and Wildlife Division, 7th Floor, O.S. Longman Building, 6909-116th St., Edmonton, Alberta T6H 4P2
- Powell, G.L. and A.P. Russell. 1996b. Short-horned lizards (Phrynosoma douglassii brevirostre) in Grasslands National Park: a report on the 1995 field season. Unpublished report, Parks Canada, Val Marie, SK. 74pp.
- Powell, G.L., A.P. Russell, and P. Fargey. In Prep. The distribution of the eastern short-horned lizard in Saskatchewan, Canada.
- Powell, G.L., A.P. Russell, and P.J. Fargey. 1998. The distribution of the Short-horned Lizard Phrynosoma hernandesi in Saskatchewan, Canada. Northwestern Naturalist 79: 19-26.
- Powell, G.L., A.P. Russell. 1998. The status of short-horned lizards, Phrynosoma hernandesi in Saskatchewan, Canada. Northwestern Naturalist 79: 19-26.
- Powell, G.L., and A.P. Russell. 1991. Distribution of the eastern short-horned lizard (Phrynosoma douglasi brevirostre) in Alberta, Canada. Northwestern Naturalist. 72(1): 21-26.
- Prieto, A.A., Jr. and W.G. Whitford. 1971. Physiological responses to temperature in the horned lizards, Phrynosoma cornutum and Phrynosoma douglassii. Copeia 1971(3): 498-504.
- Rauscher, R.L. 1998. Amphibian and reptile survey on selected Montana Bureau of Reclamation impoundments. Montana Department of Fish, Wildlife and Parks, Nongame Program. Bozeman, MT. 24 pp.
- Reeder, T.W. and R.R. Montanucci. 2001. Phylogenetic analysis of the horned lizards (Phrynosomatidae: Phrynosoma): evidence from mitochondrial DNA and morphology. Copeia 2001(2): 309-323.
- Reeve, W.L. 1952. Taxonomy and distribution of the horned lizard genus Phrynosoma. Kansas University Science Bulletin 34: 817-960.
- Reichel, J.D. 1997a. Amphibian, reptile and northern bog lemming survey on the Rocky Mountain Front: 1996. Montana Natural Heritage Program, Helena, MT. 81 p.
- Reynolds, T.D. 1979. Response of reptiles populations to different land management practices on the Idaho national engineering laboratory site. Great Basin Naturalist 39(3): 255-262.
- Roedel, M.D. and P. Hendricks. 1998. Amphibian and reptile survey on the Bureau of Land Management Lewistown District: 1995-1998. Montana Natural Heritage Program, Helena, MT. 53 p.
- Roedel, M.D. and P. Hendricks. 1998b. Amphibian and reptile inventory on the Headwaters and Dillon Resource Areas in conjunction with Red Rocks Lakes National Wildlife Refuge: 1996-1998. Montana Natural Heritage Program, Helena, MT. 46 p.
- Schowalter, D.B. 1976. New distribution records of the horned lizard in Alberta. Blue Jay 37: 26-27.
- Sherbrooke, W.C. and F. Mendoza-Quijano. 2001. Phrynosoma braconnieri (Short-tailed Horned Lizard). Defensive Behavior. Herpetological Review 36(1):65-66.
- Sherbrooke, W.C. and M.D. Greenfield. 2002. Phrynosoma hernandesi (short-horned lizard). Defensive hiss. Herpetological Review 33(3):208-209.
- Sherbrooke, W.C., E. Beltran-Sanchez, F. Mendoza-Quijano, B. Baur, and G.A. Middendorf, III. 2004. Is there an antipredator blood-squirting defense in the Bull Horned Lizard, Phrynosoma taurus? Herpetological Review 35(4):345-347.
- Sherbrooke, W.C., E.R. Brown, and J.L. Brown. 2002. Phrynosoma hernandesi (short-horned lizard). Successful open-mouthed threat defense. Herpetological Review 33(3):208.
- Skinner, M.P. 1924. The Yellowstone Nature Book. A.C. McClurg Company, Chicago, IL. 221 p.
- Smith, H.M., K. Adler, D. Chiszar, and F. Van Breukelen. 1999. Phrynosoma hernandesi: correct spelling. Herpetological Review 30(2): 74-76.
- Smith, W. 1993. An assessment of short-horned lizard habitat and use. Manyberries Badlands, Alberta. A report submitted to the Fish and Wildlife Branch, Alberta Forestry, Lands and Wildlife, 7th Floor, O.S. Longman Building, 6909-116th St., Edmonton, Alberta T6H 4P2.
- Snethen, D.G. 1989. An investigation of reptiles of the lower Reynolds Creek area, Owyhee County, Idaho. Journal of the Idaho Academy of Science 25(1/2): 24-25.
- Spring Creek Coal Company., 1992, Wildlife Monitoring Report. Spring Creek Coal Company 1992 Mining Annual Report. Appendix I.
- Stebbins, R.C. 1985. A field guide to western reptiles and amphibians. Houghton Mifflin Company, Boston. 336 pp.
- Taylor, B.N. 2003. Short-horned lizard (Phrynosoma hernandesi hernandesi). Alberta Species at Risk Report 72:154-160.
- Thompson, L.S. 1981. Circle West wildlife monitoring study: Third annual report. Technical report No. 8. Montana Department of Natural Resources and Conservation. Helena, Montana.
- Thompson, L.S. 1982. Circle West Wildlife Monitoring Study. Fourth annual report. Technical report 10. Montana Department of Natural Resources and Conservation, Helena, Montana.
- Turner, F.B. 1951. A checklist of the reptiles and amphibians of Yellowstone National Park with incidental notes. Yellowstone Nature Notes 25(3): 25-29.
- Turner, F.B. 1955. Reptiles and amphibians of Yellowstone National Park. Yellowstone Interpretive Series No. 5. Yellowstone Library and Museum Association. Yellowstone National Park, WY. 40 p.
- Vitt, L.J., J.P. Caldwell, and D.B. Shepard. 2005. Inventory of amphibians and reptiles in the Billings Field Office Region, Montana. Sam Noble Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, Norman, OK. 33 pp.
- VTN Colorado, Inc. Decker Coal Company., 1975, Draft environmental impact assessment for the proposed North Extension of the West Decker Mine.
- Waage, B.C. 1998. Western Energy Company Rosebud Mine 1997 annual wildlife monitoring report December 1, 1996 to November 30, 1997 survey period. Western Energy Company, Colstrip, MT.
- Waage, Bruce C., 1999, Western Energy Company Rosebud Mine, Colstrip, Montana: 1998 Annual Wildlife Monitoring Report; December 1, 1997 - November 30, 1998 Survey Period. February 24, 1999.
- Waage, Bruce C., 2000, Western Energy Company Rosebud Mine, Colstrip, Montana: 1999 Annual Wildlife Monitoring Report; December 1, 1998 - November 30, 1999. February 2000.
- Werner, J.K. 1974. Geographic Distribution. Phrynosoma douglasii brevirostre. Herpetological Review 5(1): 20.
- Werner, J.K. 1974. Phrynosoma douglassi brevirostre. Herpetological Review 5(1):20.
- Werner, J.K., B.A. Maxell, P. Hendricks and D.L. Flath. 2004. Amphibians and Reptiles of Montana. Mountain Press Publishing Company: Missoula, MT. 262 pp.
- Yarrow, H.C. 1882. Check list of North American reptilia and batrachia, with catalogue of specimens in the U.S. National Museum. United States National Museum Bulletin 24. 249 p.
- Zamudio, K.R. 1996. Ecological, evolutionary, and applied aspects of lizard life histories. Ph.D. Dissertation. University of Washington, Seattle, WA. 167 p.
- Zamudio, K.R., K.B. Jones, and R.H. Ward. 1997. Molecular systematics of short-horned lizards: biogeography and taxonomy of a widespread species complex. Systematic Biology 46:284-305.
- Additional Sources of Information Related to "Reptiles"