Thamnophis rufipunctatus

Based on scale ultrastructure, Chiasson and Lowe (1989) suggested that this species be included in the genus Nerodia, but data presented by Blaney (1977) are inconsistent with this suggestion, and available molecular data indicate a closer relationship to Thamnophis than to Nerodia (de Queiroz and Lawson 1994). See Rossman et al. (1996) for further discussion of taxonomy.

Spotty distribution in Arizona, New Mexico, and Mexico; not very abundant; probably at least several dozen occurrences; abundance and number of subpopulations have declined; threatened by loss of habitat, wanton killing, and the introduction of predaceous and/or competitive species; some populations are susceptible to local extirpation with no adjacent populations for recolonization; no known protected populations.

The range includes central and eastern Arizona and west-central New Mexico in the Mogollon Rim area and a larger disjunct area in Mexico in northern Sonora and Chihuahua and southward in the Sierra Madre Occidental to central Durango, at elevations of 700-2,430 meters (Rosen and Schwalbe 1988, Tanner 1990, Rossman et al. 1996, Arizona Game and Fish Department 1997, Stebbins 2003).

The New Mexican distribution includes the Gila and San Francisco river drainages in Catron, Grant, and Hidalgo counties, at elevations of 1,125-2,100 meters (Degenhardt et al. 1996, New Mexico Department of Game and Fish 1997).

In Arizona, this speices occurs in upland drainages in central and eastern Arizona from the White Mountains and along the Mogollon Rim to Oak Creek Canyon, in Apache, Coconino, Gila, Graham, Greenlee, Navajo, and Yavapai counties; good populations found at Oak Creek Canyon and along the East Verde River (New Mexico Department of Game and Fish 1997; Arizona Game and Fish Department, 2002, unpublished abstract compiled and edited by the Heritage Data Management System ). A previously eliminated population from Fort Valley Creek at the Museum of Northern Arizona, Flagstaff, may have been reintroduced (Rosen and Schwalbe 1988).

The number of distinct occurrences or subpopulations has not been determined using consistent criteria but probably there are at least several dozen. The Arizona Natural Heritage Program has recorded at least 51 occurrences, a few of which are believed to be not extant (Sabra Schwartz, pers. comm., 1998). Degenhardt et al. (1996) mapped 27 collection sites in New Mexico. Conservation status in Mexico is poorly known (Rossman et al. 1996). The Sonora, Mexico, Heritage Program estimates over 100 occurrences with possibly 80% of occurrences in good condition (Andres Villareal Lazarraga, pers. comm., 1998). Tanner (1990) mapped six collection sites in New Mexico and 23 collection sites in Mexico.

The greatest threats are introduced predators (bullfrogs, fishes, crayfish), loss of habitat (urbanization, overgrazing, and destruction of rivers and wetlands), habitat fragmentation, and, in some areas (e.g., Oak Creek, Arizona), habitat degradation caused by heavy recreational use (Rosen and Schwalbe 1988, Nowak and Santana-Bendix 2002, Nowak 2005).

There is indirect evidence that the introduction of bullfrogs has eliminated populations in some areas (see New Mexico Department of Game and Fish 1997). Additionally, low densities and historical declines in the White Mountains correlate closely with the history of fish introductions (Rosen and Schwalbe 1988). Populations may also be negatively affected by predation by introduced crayfish, which also may negatively affect the snake's prey base (Rosen and Fernandez 1996, Nowak and Sanatana-Bendix 2002, Nowak 2005).

Habitat alteration can negatively affect high-elevation populations. The greater need to thermoregulate at higher elevations makes optimal basking sites such as shrubs and snags essential. Under such circumstances, channelization or other activities that remove or disrupt bank vegetation may lead to extirpation (Rosen and Schwalbe 1988).

A notable concern is the isolation of the central Arizona populations in Oak Creek Canyon and East Verde River. The absence of a mainstream population makes repopulation of these streams during local extinction events highly unlikely. This also implies that the East Verde and Oak Creek populations are irreplaceable and that further degradation of the main streams of the Salt, Black, and Gila rivers may eventually eliminate most, if not all populations in these drainages (Rosen and Schwalbe 1988).

Needless killing and excessive collecting may be having a negative impact (New Mexico Department of Game and Fish 1997). There are indications of regular killing and removal along Oak Creek Canyon, Arizona. An estimated 44% of annual mortality of non-neonates is attributed to human mortality (Rosen and Schwalbe 1988).

This species is regarded as not very threatened by the Sonora, Mexico, Heritage Program (Andres Villareal Lazarraga, pers. comm., 1998). However, this does not cover all of the Mexican range, and the United States populations appear to be moderately threatened. The degree of threat warrants further investigation.