Pygmy Short-horned Lizard
Scientific Name: Phrynosoma douglasii
Other/Previous Names: Pigmy Short-horned Lizard ,Pygmy Short-horned Lizard (British Columbia population)
Taxonomy Group: Reptiles
Range: British Columbia
Last COSEWIC Assessment: April 2007
Last COSEWIC Designation: Extirpated
SARA Status: Schedule 1, Extirpated
Image of Pygmy Short-horned Lizard
Like all horned lizards, often referred to incorrectly as horned toads, the Pygmy Short-horned Lizard has a round and flat trunk with short legs. This squat form makes it difficult for them to move quickly or with agility in a cluttered environment, but does allow them to have large stomachs and to accommodate a large number of embryos; it also creates a large dorsal surface area for basking in the sun. The Pygmy Short-horned Lizard is the smallest of the horned lizards. It rarely exceeds 6 cm from snout to tail, the female being slightly larger than the male. Compared to other ornately armoured horned lizards, the Pygmy Short-horned Lizard has relatively small horns on its head and body. Colour and pattern are variable within the species. The lizard's colour blends with its environment so that it is very difficult to detect when it is motionless. The dorsum is typically grey with about 12 dark blotches, and the ventral surface is pale. When the Pygmy Short-horned Lizard is cool, it tends to be darker, which allows greater absorption of solar heat, and it becomes paler as it warms. The tail of the Pygmy Short-horned Lizard is short and is incapable of regrowth if lost, unlike the tails of many other lizards. Newborns resemble adult lizards but they are a mere 2.2 cm from snout to tail and have no horns.
Distribution and Population
The Pygmy Short-horned Lizard inhabits the Great Basin and surrounding areas from northern California and Nevada through eastern Oregon and Washington, most of southern and eastern Idaho and into the extreme south-central part of British Columbia, in the Okanagan and Similkameen valleys. In Canada, the only confirmed sightings of the Pygmy Short-horned Lizard were in the Osoyoos region of the Okanagan Valley. However, nearly 20 anecdotal observations have been reported since the first specimens were collected from Osoyoos in 1898. The unconfirmed sightings were reported in the Similkameen Valley, from Chopaka at the international border north to Keremeos, and from Osoyoos at the international border north to Kaleden. The abundance of Pygmy Short-horned Lizards in Canada, either historically or currently, is entirely unknown. Four surveys within the past 20 years have not revealed any individuals. However, the public has reported at least 18 anecdotal observations, the most recent of these in 2004. The Pygmy Short-horned Lizard is considered to be extirpated (locally extinct) in Canada, as no confirmed observations have been made in the last 50 years.
The habitat requirements of the Pygmy Short-horned Lizard are poorly understood; however, it appears that a broad range of habitats are used. Generally, the species resides in deep-soiled desert basins and shallow-soiled slopes and ridges. Consistent features are well-drained sites with exposed ground and access to friable soils for burrowing, thermoregulating and foraging. Vegetation must be adequately sparse to allow basking and unencumbered movement. However, vegetation is selectively used for shade in very hot weather. Friable soils suitable for burrowing are needed somewhere within an individual’s home range, although the area can be dominated by very shallow or coarse-textured soils. The Okanagan and Similkameen valleys still appear to have suitable habitat for this species, and some of this habitat is currently protected. However, the distribution of potentially suitable habitats in the Okanagan is currently highly fragmented. The remaining suitable habitat in the Similkameen is more contiguous, but the soils are typically less friable.
Unlike some other lizards that lay eggs, the Pygmy Short-horned Lizard is viviparous: it gives birth to fully developed live young. Viviparity is a strategy employed by many reptiles in cooler climates or where seasons of activity are shorter. Mating occurs in spring, soon after the Pygmy Short-horned Lizards have emerged from their hibernation site. Sexual maturity in females usually occurs in their third year. After a gestation period of approximately three months, they give birth to about 15 live young. Longevity is unknown but is at least five years in the wild. Pygmy Short-horned Lizards are the most cold-tolerant of the horned lizards; they must nonetheless seek shelter during the cold winters. During hibernation, which occurs in shallow burrows, their metabolism significantly slows down. In areas such as the Okanagan and Similkameen valleys that often have little or no snow cover during cold periods in the winter, these lizards must find deeper refuge or else many of them will not survive. Pygmy Short-horned Lizards emerge from winter hibernacula in late March to early June. The primary prey of all horned lizards is ants, especially harvester ants. Adults most commonly also feed on other invertebrates such as beetles, grasshoppers and snails. Foraging starts after the lizards have warmed in the morning sun and continues until the heat of the afternoon drives them to seek refuge in shade or in a burrow. Horned lizards are well adapted to dry conditions; it is believed that they do not require waterholes. Their water requirements are probably met by licking dew or collecting rainwater that they translocate to their mouth from the bony scutes (plates) on their back. Water is also provided by the prey they ingest. Pygmy Short-horned Lizards have many potential predators, including birds, snakes and coyotes. The lizards’ camouflage colour and ability to remain perfectly still often lets them go unnoticed. They will flee slow-moving predators or inflate their body and make intimidating gestures. Their horn-like projections are minor deterrents but can be effective against predators like snakes that have to swallow them whole.
Reasons for extirpation
Habitat loss has been extensive in the Okanagan Valley and to a lesser extent in the Similkameen Valley. Although this habitat loss is likely a contributing factor to the species’ extirpation, it appears that Pygmy Short-horned Lizards were already rare by the early twentieth century. The rarity of the species in Canada may have also been a result of the high mortality rate during hibernation. Unlike most other temperate-zone reptiles, the Pygmy Short-horned Lizard seeks only shallow subterranean refuge during winter. In years of low snowfall, extreme or prolonged cold could cause widespread mortality. If the species were reintroduced, current potential threats would include extensive habitat loss, road mortality, and predation by native and exotic animals. Pygmy Short-horned Lizard populations tend to be localized and are therefore susceptible to local extinction if the area becomes unsuitable. The restricted mobility of horned lizards also curbs their ability to leave an area. In addition, Pygmy Short-horned Lizards require an uncluttered environment to navigate through and to thermoregulate. Certain invasive plants choke interstitial spaces between native vegetation. This may make much of the habitat unusable by restricting movement. Finally, predation may be increased by greater populations of natural predators such as ravens, crows and kestrels, and by the introduction of domestic cats.
Federal ProtectionThe Pygmy Short-horned Lizard is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
In the event it is rediscovered, the Pygmy Short-horned Lizard is protected under the Wildlife Act (1990) and the Wildlife Amendment Act (2004) of British Columbia.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Pigmy short-horned lizard (Phrynosoma douglasii)
Status Preliminary draft received by leads
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
8 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (1 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2007 (2007)2007 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
Recovery Document Posting Plans
- Date modified: