Center for Biological Diversity behind the request
The U.S. Fish and Wildlife Service, announced that after a 12-month finding on a petition to list the Tucson shovel-nosed snake as an endangered or threatened species, the listing is unwarranted. “The Tucson shovel-nosed snake as an endangered or threatened species is not warranted, and, therefore, we are removing this subspecies from our candidate list,” according to the announcement.
The U.S. Fish and Wildlife Service received a petition, dated December 15, 2004, from the Center for Biological Diversity requesting that the Service list the snake as an endangered or threatened species throughout its range and designate critical habitat within its range in the United States.
According to the Service, “The petition, which was clearly identified as such, contained detailed information on the natural history, biology, current status, and distribution of the Tucson shovel-nosed snake. It also contained information on what the petitioner reported as potential threats to the subspecies from urban development, agricultural practices, collecting, inadequacy of existing regulations, drought, and climate change. In response to the petitioner’s requests, we sent a letter to the petitioner, dated September 7, 2005, explaining that, due to funding constraints in fiscal year 2005, we would not be able to address the petition in a timely manner.”
On February 28, 2006, the Center filed a 60-day notice of intent to sue the Department of the Interior for failure to issue 90-day and 12-month findings, and a proposed listing rule, as appropriate, in response to the petition as required by 16 U.S.C. 1533(b)(3)(A) and (B). ‘In response to the notice of intent to sue, we announced our intention to submit a 90-day finding to the Federal Register as expeditiously as possible,” advised the Service.
On July 29, 2008, the Service published in the Federal Register (73 FR 43905) its 90-day finding that the petition presented substantial scientific information indicating that listing the Tucson shovel-nosed snake may be warranted. On March 31, 2010 the Service published a 12-month finding on the December 15, 2004, petition to list the Tucson shovel-nosed snake as an endangered or threatened species.
In the 12-month finding, the Service found that listing the Tucson shovel-nosed snake as an endangered or threatened species was warranted but precluded by
higher priority actions. Upon publication of the 12-month finding, the Service added the Tucson shovel nosed snake to the candidate list.
“The Tucson shovel-nosed snake remained a candidate through all of our subsequent annual candidate notices of review (75 FR 69222, November 10, 2010; 76 FR 66370, October 26, 2011; 77 FR 69994, November 21, 2012; and 78 FR 70104, November 22, 2013). On September 9, 2011, the Service entered into a settlement agreement regarding species. As required by the settlement agreement, the Service is required to submit a proposed rule or a not warranted 12-month finding to the Federal Register for the Tucson shovel-nosed snake in Fiscal Year 2014, which ends September 30, 2014. The 12-month finding fulfills that requirement, according to the Service.
The following is a summary of the results and conclusions from the SSA Report:
The Tucson shovel-nosed snake is a small, non-venomous snake (250–425 millimeters (mm) (9.84–16.73 inches (in)) total length) in the family Colubridae, with a shovel-shaped snout, an inset lower jaw, and coloring that mimics coral snakes (Micrurus spp.) (Mahrdt et al. 2001, p. 731.1). The Tucson shovel-nosed snake is a subspecies of the western shovel-nosed snake (Chionactis occipitalis).
The western shovel-nosed snake consists of four subspecies: Colorado Desert shovel-nosed snake (C. o. annulata), Mohave shovel-nosed snake (C. o. occipitalis),
Nevada shovel-nosed snake (C. o. talpina), and Tucson shovel-nosed snake. The range of the western shovel-nosed snake extends from southern Nevada and southern California, across southwestern Arizona, and into Mexico. Snakes of the family Colubridae, which includes all shovel-nosed snakes, tend to be abundant in their respective habitats, widely distributed, and chiefly nonvenomous; the family includes the kingsnakes, gartersnakes, and watersnakes. The Tucson shovel-nosed snake has been recognized as a subspecies of the western shovel-nosed snake since 1941.
However, the original subspecies description was based on one color pattern variation compared to the other subspecies. More recent genetic studies, explained in detail below, have clarified that the identification of the subspecies based on color patterning is inaccurate and leads to under-representation of the actual extent of the subspecies’ population.
The geographical western extent of snakes with this distinguishing color pattern variation was never documented; therefore, the exact range of the subspecies was never described and was thought to be substantially smaller than our current understanding of the range as described below.
At the time of the 2008 90-day and 2010 12-month findings, we accepted the taxonomic status and distribution of the subspecies as described by Mahrdt et al. (2001, entire). The range supported by Mahrdt et al. (2001, entire) encompassed approximately 1,149,367 hectares (ha) (2,840,147 acres (ac)) and extended from Phoenix, Arizona, to Tucson, Arizona. A large intergrade zone was thought to exist where the Tucson shovel-nosed snake’s and Colorado Desert shovel-nosed snake’s ranges overlapped; an intergrade zone is defined as an area of overlap between the ranges of two subspecies where individuals may possess intermediate characters (attributes or features that distinguish a subspecies, such as coloration) or traits of both subspecies. Snakes within the intergrade zone between Tucson shovel-nosed snake and Colorado Desert shovel-nosed snake possessed color patterns characteristic (or intermediate) of both subspecies. Following our 90-day finding (July 29, 2008; 73 FR 43905), genetic studies involving mitochondrial DNA were conducted to help inform the taxonomy and genetic structure of the Tucson shovel-nosed snake and the intergrade zone. The data from this genetic study initially suggested that the Tucson shovel-nosed snake was not a valid subspecies. Therefore, we
requested peer review and input in September 2008 on the issue of taxonomic classification and distribution of the snake. Four out of six peer reviewers believed that, based on genetic work by Wood et al. (2008, entire), the subspecies did not warrant taxonomic recognition; however, the peer reviewers also recognized that more conclusive genetic studies, including microsatellite data, were needed.
These genetic studies were not complete until after our 2010 12-month finding. Our 2010 12-month finding for the Tucson shovel-nosed snake (March 31, 2010; 75 FR 16050) acknowledged the uncertainty of the taxonomy of the snake, but recognized the best available scientific information continued to recognize the Tucson shovel-nosed snake as a subspecies. In the 2010 12-month finding, we continued to recognize the Mahrdt et al. (2001) representation of the range (which was limited to 1,149,367 has (2,840,147 ac)) with a large intergrade zone with the Colorado Desert shovel-nosed snake subspecies) and description as the best available science at that time. The 2010 12-month finding concluded that listing of the Tucson shovel-nosed snake was warranted but precluded by higher priority listing actions.
Since the publication of our 2010 12-month finding (March 31, 2010; 75 FR 16050), additional genetic work has been conducted for the Tucson shovel-nosed snake. This new genetic work supports that the Tucson shovel-nosed snake is a valid subspecies and that the subspecies occupies a much larger range than previously believed. A U.S. Geological Survey study used both mitochondrial DNA and 11 microsatellite loci to assess whether patterns of population genetic structure follow the spatial structuring of phenotypic variation (variation in observable characteristics such as shape, color pattern, or even behavior) that originally led to the subspecies description and included samples from all subspecies of the western shovel-nosed snake throughout its range. The results and data from this study were made available to us prior to development of this SSA Report.
We now understand that the western boundary of the estimated range of the Tucson shovel-nosed snake is almost 322 kilometers (km) (200 miles (mi)) west of the range described by Mahrdt et al. (2001) and used by the Service to represent the range of the snake in our 2010 12-month finding (see Figure 3 of the SSA Report). The estimated range supported in the U.S. Geological Survey study includes approximately 2,000,655 ha (4,943,728 ac) more than the range we identified in our 2010 12-month finding; this represents a 274 percent increase in our understanding of the estimated range of the subspecies. We recognize that there is considerable color pattern variation throughout the range of the Tucson shovel-nosed snake; however, the genetic data indicate that, despite the color pattern expressed, snakes previously thought to be a different subspecies within this range are genetically Tucson shovel-nosed snakes. Based on this new information, the current estimated range of the snake encompasses 3,150,022 ha (7,783,875 ac) of land.