influence on the decrease in the species population number. Conservation The total estimated breeding population is less than 3,000 individuals. In 1994 when the species was listed, only six of the 22 extant populations south of Ventura were known to contain more than a dozen adults. It has been extirpated from an estimated 75% of its former range in the U.S. The most important threats to the arroyo toad stem from human activities. These activities include encroachment by agriculture, construction of roads, off-road vehicle use, grazing by livestock and mining. All can result in substantial habitat destruction and/or alteration of river hydrology. Other smaller threats are due to introduced non−native predators such as bullfrogs and predatory fish, non−native invasive plants, drought, wildfire and wildfire suppression, unseasonal water releases from dams, and light and noise pollution from adjacent developments. The arroyo toad has been the subject of litigation related to its conservation status. In 2000, developer Rancher Viejo, which wished to build on a site that the toads used as a habitat, sued the Secretary of the Interior over whether the Department was constitutionally authorized to apply the Endangered Species Act to prevent the development in order to protect a species that never crossed state lines. The developer's challenge to the law failed, but in his dissent to the ruling then-Judge and later-Chief Justice John Roberts famously expressed his puzzlement that "regulating the taking of a hapless toad that, for reasons of his own, lives its entire life in California constitutes regulating 'commerce...among the several states'." On March 27, 2014, the Department of Fish and Wildlife recommended the arroyo toad's status be downgraded from Endangered to Threatened. The agency stated that the arroyo toad still faces "significant threats", in particular operation of dams and water diversions, urban development, introduced predator species, and drought. However, they felt that conditions had improved, saying, "The overall magnitude of threats impacting the arroyo toad has decreased since the time of listing, due in part to implementation of conservation and management actions." References Further reading Biologicaldiversity.org: Arroyo toad (Anaxyrus californicus) Mitrovich, Milan J., et al. "Habitat Use and Movement of the Endangered Arroyo Toad (Anaxyrus californicus) in Coastal Southern California." Journal of Herpetology 45.3 (2011): 319-328. Pauly, G. B., D. M. Hillis, and D. C. Cannatella. (2004) The history of a Nearctic colonization: Molecular phylogenetics and biogeography of the Nearctic toads (Bufo). Evolution 58: 2517–2535. Sahagun,