Flat-tail Horned Lizard
Encyclopedia
The Flat-tail Horned lizard (Phrynosoma mcallii) is named for Colonel George A. M'Call. M'Call collected the first specimen in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
in the 19th century. They occupy a small range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
in the Sonoran Desert
Sonoran Desert
The Sonoran Desert is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest...
of southwestern California, southwestern Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, and extreme northern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. Over time, horned lizard populations have adapted to climate, food, and predators, causing them to in some ways be distinct from one another. "A medium-sized flat-bodied lizard with a wide oval-shaped body and scattered enlarged pointed scales on the upper body and tail. The back skin is smooth with small spines. 8 horns extend from the back of the head. The two central horns are long, slender and sharp. Long and narrow spines on the lower jaw and two rows of fringe scales on the sides of the body, the bottom row scales smaller than the upper." They are threatened by development, agriculture, and other man-made intrusions into their small range. The majority of their remaining habitat in the U.S.A. is administered by the Bureau of Land Management (BLM). The species(Phrynosoma mcallii), frequently coexists with sources of natural gas, oil, geothermal energy, and minerals which can found in their habitat. In 1982, the U.S. Fish and Wildlife Service declared the P. mcalli as a Candidate 2 Category for the list of threatened and endangered species due to concerns over potential threats to their habitat which could further diminish the population. P. macalli has also been given special status in both California and Arizona, which prevents their collection. Experiments have been conducted in order to attempt to explain the "fluctuations in populations of flat-tailed horned lizards, Phrynosoma mcallii, in the Coachella Valley, California. This species has the smallest range of any horned lizard in the United States. Within portions of its range, there are potentially conflicting activities, such as suburban development, agriculture, off-road recreation, and activities along the international border."“Between 1978 and 1980 the Bureau of Land Management supported investigations of the status of P. mcallii in California. The purpose of this work was to determine the local distribution and relative abundance of P. mcallii, to correlate these parameters with various habitat attributes, and to gather information on the structure of the populations and mobility and food habits of individual lizards.” In addition,"the distribution and abundance of the flat-tailed horned lizard (Phrynosoma mcallii) was examined throughout Arizona. The species is restricted to 650-700 km 2 of desert lands in the extreme southwest corner of Arizona. Relative abundance was correlated with numbers of western whiptail (Cnemidophorus tigris) and active black harvester ant nests (Veromessor pergandei). Areas in which galleta grass (Hilaria rigida) was among the dominant perennial plants or in which surface soils were sand had relatively high abundance indexes.".