Editing Horned lizard (section)

==Population decline==
[[File:Phrynosoma douglasii 4220.JPG|thumb|upright|''[[Phrynosoma douglasii]]'']]
A [[University of Texas]] publication notes that horned lizard populations continue to disappear throughout their distribution despite protective legislation. Population declines are attributed to a number of factors, including the fragmentation and loss of habitat from real estate development and road construction, the planting of non-native grasses (both suburban and rural), conversion of native land to pastureland and agricultural uses, and pesticides. Additionally predation by domestic dogs and cats place continued pressure upon horned lizards.<ref name=Pianka>{{cite web|last1=Pianka|first1=Eric|last2=Hodges|first2=Wendy|title=Horned Lizards, Part 2|url=http://uts.cc.utexas.edu/~varanus/phryno2.html|website=uts.cc.utexas.edu|publisher=University of Texas|access-date=March 1, 2015|archive-url=https://web.archive.org/web/20150426033805/http://uts.cc.utexas.edu/~varanus/phryno2.html|archive-date=April 26, 2015|url-status=dead}}</ref>

Fire ants (''[[Solenopsis invicta]]''), introduced from South America via the nursery industry's potted plants, pose a significant threat to all wildlife including horned lizards. ''Phrynosoma'' species do not eat fire ants. Fire ants kill many species of wildlife, and are fierce competitors against the native ants, which horned lizards require for food (with their specialized nutritional content). Fire ants have given all ants a bad reputation, and human attempts to eradicate ants, including invasive species and the native species on which the lizards prey, contribute to the continued displacement of native ant species and the decline of horned lizards.<ref name=Pianka/>

The Texas horned lizard (''[[Phrynosoma cornutum]]'') has disappeared from almost half of its geographic range. Their popularity in the early to mid-20th-century pet trade, where collectors took thousands from the wild populations to sell to pet distributors, without provision for their highly specialized nutritional needs (primarily formic acid from harvester ants), resulted in certain death for almost all the collected lizards. In 1967, the state of Texas passed protective legislation preventing the collection, exportation, and sale of ''Phrynosoma'', and by the early 1970s, most states enacted similar laws to protect and conserve horned lizards in the USA. As recently as the early 2000s, though, the state of [[Nevada]] still allowed commercial sale of ''Phrynosoma'' species. Despite limited federal protection in [[Mexico]], horned lizards are still offered in Mexican "pet" markets throughout the country.<ref name=Pianka/>

In 2014, the [[Center for Biological Diversity]] in Tucson petitioned the [[Oklahoma Department of Wildlife Conservation]] to have the Texas horned lizard put on the endangered species list due to the massive decline of its population in Oklahoma, where it was once plentiful. The center said it may later seek protection for the animal on a federal level; it also said that reptiles in general are dying off at up to 10,000 times their historic extinction rate, greatly due to human influences.<ref>{{cite news|url=https://newsok.com/article/5378004/center-for-biological-diversity-wants-texas-horned-lizard-declared-an-endangered-species-in-Oklahoma|title=Center for Biological Diversity wants Texas horned lizard declared an endangered species in Oklahoma|last=Godfrey|first=Ed|work=[[The Daily Oklahoman]]|date=December 20, 2014|access-date=November 5, 2018}}</ref>