Queensnake evaluation

Committee on the Status of Species at Risk in Ontario (COSSARO) Assessed June 2010 by COSSARO as Endangered

Part 1: COSSARO candidate species at risk evaluation form – June 2010 Queensnake (regina septemvittata)

Current designations:

GRANK – G5 (Secure)
NRANK Canada – N2 (Imperiled)
COSEWIC – Endangered (April 2010) - placed in a higher risk category after reassessment (previous status was Threatened in 2000).
SARA – Endangered Schedule 1
General Status Canada – At Risk (2005)
ESA 2007 – Threatened
SRANK – S2
General Status Ontario – At Risk (2005)

Distribution and status outside Ontario:

Relatively widespread in eastern North America, primarily east of the Mississippi River. It ranges as far north as southwestern Ontario and an isolated population in northern Michigan, and south to the Gulf of Mexico from the Florida Panhandle to eastern Mississippi. Its range extends almost as far east as the eastern seaboard in Delaware, and west to Illinois and an isolated population in Arkansas. The Canadian distribution of the Queensnake is limited to scattered and isolated populations in southwestern Ontario west of the Niagara Escarpment (COSEWIC 2010).

Eligibility criteria

Native status

Yes – There are several Ontario records from the late 1800s, and no suggestion that it is not a native species.

Taxonomic distinctness

Yes – There is some controversy around the composition of the genus Regina, due to its apparent polyphyletic nature based upon DNA sequence data. Recent molecular studies have suggested that there may be 2-3 evolutionarily independent lineages within the genus, and that a taxonomic re-evaluation of the genus is warranted. However, as only one species occurs in Canada, it is unlikely that these potential taxonomic revisions will affect the conservation status of Queensnakes (COSEWIC 2010). No Designatable Units (DU) have been identified. Although most populations in Ontario appear to be isolated with little opportunity for genetic exchange due to the species' restriction to shorelines, there is no evidence to suggest more than one DU (COSEWIC 2010).

Priority-setting criteria

Recent arrival in Ontario

No – Known in Ontario since at least the late 1800's.

Non-regularly occurring species

No – A regularly occurring species in Ontario.

Primary criteria (rarity and declines)

1. Global rank

   Not in any category – Ranked G5 globally.

2. Global decline

   Threatened – The following information is referenced from the NatureServe (2010) website, and has been interpreted to suggest a noncyclical decline of greater than 30% of global range and an unquantified but generally recognized serious regional population decline:

   • “Global Short Term Trend: Stable (unchanged or within +/- 10% fluctuation in population, range, area occupied, and/or number or condition of occurrences) Global Short Term Trend Comments: Currently, extent of occurrence, area of occupancy, number of subpopulations, and population size probably are relatively stable or declining at a rate of less than 10 percent over 10 years or three generations.

   • Global Long Term Trend: Moderate decline to relatively stable (25% change to 50% decline)

   • Global Long Term Trend Comments: Area of occupancy, number of subpopulations, and population size appear to have declined in some parts of the range, but the degree of decline is unknown.” (NatureServe 2010)

3. Northeastern North American ranks

   Special concern - Highly ranked (S1, S2, SH or SX) in 4 of 12 northeastern jurisdictions in which it occurs natively and is ranked (33%). See Appendix 1.

4. Northeastern North American decline

   Not in any category - Little information available to support quantitative declines in the core of its range. Identified as a “state species with conservation status” for only 3 states – Delaware, New Jersey and New York (PARC 2004). Most available reports of decline appear to be limited to more northerly jurisdictions, e.g.:

   • Serious declines in New York (Blais No date - most recent cited reference was 1991);
   • Large population decrease in Wisconsin over past 30 years (Wisconsin Department of Natural Resources 2005);
   • Disappeared from many areas of Pennsylvania due to extirpation of local crayfish populations (McCoy 1982, cited in Austen and Oldham 1999);
   • Numbers have declined in many areas of its Great Lakes range due to habitat degradation (Harding 1997, cited in NatureServe 2010).

5. Ontario occurrences

   Special concern – 27 documented Element Occurrences (EOs) in the NHIC data base (2 ranked X [extirpated], and 13 ranked H [historical; no records in 20+ years])(https://www.biodiversityexplorer.mnr.gov.on.ca/nhicWEB/speciesDetailReport.do?elID=180776) [link inactive], although status report author notes 29 EOs (COSEWIC 2010). Most extant Ontario occurrences are from a small number of rivers including the Grand, Maitland, Thames, Ausable, St. Clair and Detroit (COSEWIC 2010).

6. Ontario decline

   Threatened – Absent from greater than 50% of documented Ontario sites. Of 29 known EOs in Ontario, 13 (44.8%) are considered historic where the species has not been recorded in more than 20 years. Twelve of the 13 historic sites have received considerable search effort since 1990 without success (COSEWIC 2010). An additional two EO's have not been reconfirmed since last being reported in 1990 and 1999 despite repeated searches. Queensnake has been confirmed at the remaining 14 EOs since 1990. This reflects a 51.7% decrease in documented EOs. Based upon NHIC data, of the 27 EOs, 2 are ranked X (extirpated) and 13 are ranked H (historical; no records in 20+ years), representing a 55.5% decline.

   It should be noted that this is a cryptic species that has always had a limited Ontario range, has never been considered common, and is often missed even in deliberate searches. The COSEWIC status report cites examples where no individuals have been observed for decades and then were found again. In spite of extensive searching, only three new EOs have been documented since 2000. These are believed to be newly located but long-established populations rather than newly colonized areas (COSEWIC 2010).

7. Ontario’s conservation responsibility

   Not in any category – Ontario range much less than 10% of global range.

Secondary criteria (threats and vulnerability)

1. Population sustainability

   Insufficent information – No information available on population viability analysis, or reproductive or recruitment failures. “All Ontario Queensnake studies suggest low population density, localized distribution, and limited potential for individuals to migrate among populations” (COSEWIC 2010).

2. Lack of regulatory protection for exploited wild populations

   Not in any category – Queensnake receives protection from harm, harassment and take under the Endangered Species Act 2007 and the Fish and Wildlife Conservation Act.

3. Direct threats

   Endangered - At risk of disappearance or severe decline at >75% of EOs in Ontario due to demonstrated threats. Major threats include habitat loss, fragmentation and degradation (COSEWIC 2010). Queensnake is sensitive to a wide range of aquatic habitat and adjacent shoreline degradation activities including shoreline alteration, sedimentation, water control structures, water contamination, intensive agriculture and livestock impacts; habitat alteration can also fragment and isolate populations. There are several reports of Queensnake being killed intentionally and unintentionally by near-shore anglers. (COSEWIC 2010).

   The indirect effects of invasive species are a significant concern. Negative effects of Zebra Mussel (Dreissena polymorpha) and Round Goby (Neogobius melanostomus) on Queensnake populations have been documented (COSEWIC 2010). The impact of displacement of native crayfish by expanding Rusty Crayfish (Orconectes rusticus) populations is unknown, but is of potential concern.

   Most Queensnake habitat in Ontario is privately owned, with fewer than 25% of Ontario EOs within protected areas (Austen and Oldham 1999). These EOs receive some protection through a range of variable protection designations (e.g. conservation areas, provincial parks, national wildlife areas, environmentally sensitive areas and floodplain regulations; Austen and Oldham 1999, Smith 1999).

4. Specialized life history or habitat-use characteristics

   Threatened - Queensnake is generally found adjacent to rocky shorelines of primarily rivers and some lakes, rarely being found more than 3 m from the shoreline, and has a highly specialized diet, feeding almost exclusively on freshly moulted crayfish (Cambaridae) (COSEWIC 2010). If habitat conditions are not suitable for healthy crayfish populations, or become degraded, Queensnake will not be present or will not persist. It is thus very sensitive to changes in both shoreline habitat and crayfish abundance.

COSSARO criteria met (primary/secondary)

The number of primary and secondary criteria met in each status category is as follows:

• Endangered – 0/1
• Threatened – 2/1
• Special concern – 2/0

Summary

Queensnake (Regina septemvittata) is a medium-sized semi-aquatic snake that is restricted in distribution to isolated fragments of shoreline habitat in southwestern Ontario west of the Niagara Escarpment. Although this species is apparently secure in its core range in the eastern United States, there is some indication of declining populations in more northern jurisdictions, including Ontario. A cryptic species that is difficult to locate and survey, Queensnakes are apparently no longer present in up to one-half of its known historical EOs. Queensnake has a specialized life history, living within 3 m of rocky shorelines and feeding almost entirely on recently moulted crayfish. It has a conservation status of concern in approximately one-third of northeastern North America. Threats in Ontario relate primarily to human uses and activities that degrade shoreline habitat, impair water quality, or otherwise affect the quality of habitat for both Queensnake and their crayfish prey. Invasive species such as Zebra Mussel, Round Goby and Rusty Crayfish are also significant concerns. Given these considerations, Queensnake has been designated as Endangered in Ontario.

Information sources

Austen, M. J. and M.J. Oldham. 1999. COSSARO candidate V, T, E species evaluation for Queen Snake (Regina septemvittata). Unpub. report. Ontario Ministry of Natural Resources, Peterborough ON. 8 pp.

Blais, D.P. No date. Species Dossier – Queen Snake. State of New York Endangered Species Working Group. 6 pp. http://www.gflrpc.org/Publications/GenRiverActionStrategy/Species/QueenSnake.pdf [link inactive]

COSEWIC. 2010. Update COSEWIC Status Report on Queensnake Regina septemvittata. Committee on the Status of Endangered Wildlife in Canada, Ottawa. Two-month Interim Report (Feb. 2010). 33 pp.

Harding. J.H. 1997. Amphibians and reptiles of the Great lakes region. University of Michigan Press, Ann Arbor MI. xvi + 378 pp.

McCoy 1982. Amphibians and reptiles in Pennsylvania. Carnegie Museum of Natural History Special Publication no. 6.

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. http://www.natureserve.org/explorer. (Accessed: May 13 2010).

PARC 2004. National State Wildlife Agency Herpetological Conservation Report. Draft report. Partners in Amphibian and Reptile Conservation. 130 pp. http://www.parcplace.org/documents/PARCNationalStates2004.pdf [link inactive]

Smith, K. 1999. COSEWIC status report on the queen snake Regina septemvittata in Canada, in COSEWIC assessment ad status report on the queen snake Regina septemvittata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-28 pp.

Wisconsin Department of Natural Resources 2005. Queen Snake. Pp. 3-258 & 3-259 in Wisconsin’s strategy for wildlife species of greatest conservation need. http://dnr.wi.gov/org/land/er/wwap/plan/ [link inactive]

Appendix 1: Northeastern North America rank, status and decline

Occurs as a native species in 14 of 29 northeastern jurisdictions Srank or equivalent information available for 13 of 14 jurisdictions = (93%) S1, S2, SH, or SX in 5 of 13 = (38.5%)

Part 2: Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

No. Does not meet Criterion A as size of decline unknown (COSEWIC 2010)

Criterion B – small distribution and decline or fluctuation

Yes (endangered). Meets Criterion B2 as the index of area of occupancy is estimated to be less than 500 km² (~80 km²); meets criterion B2.a as the Ontario population is considered severely fragmented.

Criterion C – small population size and decline

Yes (endangered). Meets Criterion C as the provincial population (mature individuals) is estimated to be less than 2500; meets Criterion C2.a(i) as population is observed and projected to be in decline, and no population is estimated to contain more than 250 mature individuals.

Criterion D – very small or restricted

No. Does not meet Criterion D as population estimated to exceed 250 mature individuals.

Criterion E – quantitative analysis

N/A – No population viability analysis has been conducted on Ontario’s population.

Rescue effect

1. Some populations occur close to apparently secure populations along the US border or across the Great Lakes shoreline. However, rescue effect is unlikely because of the species' isolated and fragmented distribution in Ontario, and its limited ability to disperse because of its reliance on nearshore areas with suitable forage.