COSEWIC Assessment and Status Report on the Queensnake Regina septemvittata in Canada – 2010
Table of Contents
- COSEWIC Assessment Summary
- COSEWIC Executive Summary
- Species Information
- Name and classification
- Morphological description
- Genetic description
- Designatable units
- Global range
- Canadian range
- Habitat requirements
- Habitat trends
- Habitat protection/ownership
- Life cycle and activity patterns
- Food preferences
- Interspecific interactions
- Population Sizes and Trends
- Search effort
- Fluctuations and trends
- Rescue effect
- Limiting Factors and Threats
- Loss and degradation of habitat
- Persecution and disturbance
- Diet specialization
- Special Significance of the Species
- Existing Protection or Other Status Designations
- Technical Summary
- Acknowledgements and Authorities Consulted
- Information Sources
- Biographical Summary of Report Writer
List of Figures
List of Tables
- Table 1. Conservation Status of the Queensnake throughout its North American Range
- Table 2. Most Recent Queensnake Reports at All Known Element Occurrences
Queensnake Regina septemvittata
Endangered – 2010
COSEWIC -- Committee on the Status of Endangered Wildlife in Canada
COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:
COSEWIC. 2010. COSEWIC assessment and status report on the Queensnake Regina septemvittata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 34 pp.
COSEWIC. 2000. COSEWIC assessment and status report on the Queensnake Regina septemvittata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 28 pp.
Smith, K. 1999. COSEWIC status report on the Queensnake Regina septemvittata in Canada, in COSEWIC assessment and status report on the Queensnake Regina septemvittata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1–28 pp.
COSEWIC would like to acknowledge James Kamstra for writing the status report on the Queensnake Regina septemvittata in Canada, prepared under contract with Environment Canada. This report was overseen and edited by Ronald J. Brooks, Chair of the COSEWIC Amphibians and Reptiles Specialist Subcommittee.
For additional copies contact:
c/o Canadian Wildlife Service
Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur la couleuvre royale (Regina septemvittata) au Canada.
Queensnake -- Photo by Scott Gillingwater.
© Her Majesty the Queen in Right of Canada, 2010.
Assessment Summary – April 2010
Reason for designation
This species has a restricted and shrinking distribution in southwest Ontario. It consists of scattered small populations which are isolated due to habitat fragmentation and the species’ limited dispersal capacity. Over the last decade, the number of extant locations has declined and the species’ riparian and riverine habitat has continued to be lost and degraded. The species is limited by its extremely specialized diet and threatened by decline in its prey of freshly moulted juvenile crayfish. Other threats include persecution and effects of invasive Zebra Mussels and Common Reed.
Designated Threatened in April 1999. Status re–examined and confirmed in May 2000. Status re–examined and designated Endangered in April 2010.
Queensnake Regina septemvittata
The Queensnake is a slender, medium sized, semi–aquatic snake. Its average snout–vent length is about 40–50 cm, with total length averaging 40 to 60 cm to a maximum of about 90 cm. The dorsal colour is brown or dark olive with three narrow black stripes running down the midline and along each side. The belly is pale yellow or cream with four dark brown to black longitudinal stripes, often becoming mottled with age.
The Queensnake is relatively widespread in eastern North America, ranging from southeastern Pennsylvania, western New York and southwestern Ontario, west to southeastern Wisconsin and south to the Gulf Coast from the Florida panhandle to eastern Mississippi. The Canadian range is highly localized and sporadic and is restricted to southwestern Ontario. The Queensnake occurs west of the Niagara Escarpment, from the northern portion of the Bruce Peninsula, south to Lake Erie and west to Essex County.
Queensnakes are most commonly associated with rocky streams and rivers, but are also occasionally found in marsh, pond, and lake shore habitats. This highly aquatic species is usually found within 3 m of the shoreline and only at sites where there is an abundance of crayfish, its primary food source.
Queensnakes feed almost exclusively on freshly moulted crayfish. In Ontario, they are generally active from late April to late September and likely hibernate communally. In parts of the U.S., female Queensnakes reach sexual maturity in 3 years, and males in 2 years. Mating can occur in either spring or early autumn. The Queensnake is viviparous, with 5 to 23 young usually being born in late August or September.
Population sizes and trends
Only one Ontario population has been surveyed thoroughly enough to estimate population size. Thus overall abundance in the province is difficult to estimate. Of the approximately 29 known populations (Element Occurrences or EOs) in Ontario, 14 have been reconfirmed since 1990, and 15 are “historic” (no confirmed records in past 20 years) or extirpated. Targeted recent efforts to locate Queensnakes at 14 of these 15 sites have failed to find any specimens. No snakes have been observed at nine EOs in over 30 years and these nine populations are considered extirpated. One additional EO has no sightings recorded since 1997 despite repeated surveys from 2002 to 2010. Thus, significant losses appear to have occurred in many parts of the known Canadian range of this species. Queensnakes have been found at four previously unknown sites since 2000, but these are unlikely to represent newly established populations.
Limiting factors and threats
Loss, fragmentation and degradation of habitat and decline in prey abundance represent the most significant threats to Queensnakes in Ontario. The narrow fringe of riparian habitat necessary for Queensnakes’ survival has been greatly reduced in both quality and quantity. Urbanization surrounding riparian habitat has decreased water quality and increased fortification of banks, water diversion and removal, spread of exotic vegetation, and threats from human presence. In agricultural areas, livestock with free access to riverbanks, farming to the edge of waterways, and clearing of vegetation and debris along shorelines have further degraded shoreline and aquatic habitats and added silt and contamination from increased erosion. Natural and artificially induced plant succession (non–native species), most notably of large woody vegetation and invasive Phragmites, has also reduced habitat quality and abundance at historic Queensnake sites. Additionally, direct human persecution and accidental mortality through human recreational activities further contribute to losses.
The Queensnake’s specialized diet makes it exceptionally vulnerable to declines in prey (crayfish) populations. Any factors that negatively impact crayfish will similarly affect Queensnakes. In many areas, the larger non–native Rusty Crayfish (Orconectes rusticus) is displacing native crayfish, though the impact of this introduced crayfish on Queensnakes is currently unknown. Similarly, occupation of Queensnake habitat by Zebra Mussels (Dreissena polymorpha), Round Goby (Neogobius melanostomus), Common Carp (Cyprinus carpio) and invasive, non–native vegetation may threaten some populations.
Special significance of the species
The Queensnake reaches the northern limit of its range in southern Ontario, and therefore snakes in this region may have genetic characteristics distinct from more centrally located populations. In the few Ontario watersheds where the Queensnake occurs, the species may serve as an indicator of environmental quality because its aquatic habits and specialized diet may make it particularly susceptible to water and prey contamination. In addition, its crayfish prey is vulnerable to contamination and increased silt in the water, and declines in crayfish numbers will be reflected in the viability of Queensnake populations. The highly specialized feeding behaviour of the Queensnake make it an interesting species from ecological and evolutionary perspectives.
The Queensnake is legally protected under the Ontario Fish and Wildlife Conservation Act as a specially protected reptile, which prohibits the collection, hunting, possession or sale of reptiles except under authority of a licence. As a provincially Threatened species, it is protected under the Ontario Endangered Species Act (2007) and its habitat will be legally regulated. Because the majority of Queensnake habitat in Ontario occurs within the floodplains of streams and rivers, the habitat is afforded some protection from development through the Conservation Authorities Act. The Provincial Policy Statement (PPS) issued under Section 3 of the Planning Act states that development and site alteration will not be permitted in the significant habitat of endangered and threatened species. Additionally, the Fisheries Act prohibits harmful alteration, disruption or destruction of fish habitat, and therefore could provide indirect protection for aquatic Queensnake habitat as well. In 2002, the Queensnake was designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). The species is currently listed on Schedule 1 of the federal Species at Risk Act (SARA), which protects its habitat on federal lands.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal–Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.
COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non–government science members and the co–chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.
- Wildlife Species
- A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.
- Extinct (X)
- A wildlife species that no longer exists.
- Extirpated (XT)
- A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.
- Endangered (E)
- A wildlife species facing imminent extirpation or extinction.
- Threatened (T)
- A wildlife species likely to become endangered if limiting factors are not reversed.
- Special Concern (SC)*
- A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.
- Not at Risk (NAR)**
- A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
- Data Deficient (DD)***
- A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.
* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006.
The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.
COSEWIC Status Report on the Queensnake Regina septemvittata in Canada – 2010
The Queensnake Regina septemvittata (Say) is a member of the Colubridae, a large family that includes most Canadian snakes. Some recent authorities divide Colubridae into smaller families, placing the Queensnake in the Natricidae (Center for North American Herpetology 2009). The Queensnake was originally named Coluber leberis by Linnaeus in 1766 (Smith and Huheey 1960), but later designated Regina leberis by Baird and Girard (1853). Because the original description by Linnaeus was in error, the first true description was by Say (1825), who named it Coluber septemvittata. Previously placed in the genus Natrix (Natrix septemvittata) with other water snakes (Smith 1961, Conant 1960), the Queensnake has since been included in the genus Regina and has maintained the current accepted name of Regina septemvittata for the past 40 years. However, Alfaro and Arnold (2001) examined the molecular phylogenetics of snakes in the genus Regina, including R. septemvittata, and their evolutionary relationship with other thamnophine snake species. Based on DNA sequence data, Regina was recognized as being grossly polyphyletic (Alfaro and Arnold 2001) and due for major revision (Crother et al. 2008). Almost since its erection, the composition of the genus Regina has been controversial. Scale colouration, hemipenial morphology, osteology, visceral morphometrics, and cranial myology have been used to support Regina monophyly. However, more recently, allozymes (Lawson, 1987) suggest that there are two to three evolutionarily independent lineages subsumed in the genus. DNA sequences reveal a major split among the four species of Regina with R. grahami and R. septemvittata closely allied with the Nerodia (watersnake)group. Furthermore, maximum likelihood and maximum parsimony trees suggest that no pairs of Regina species are sister taxa. Given that only one species occurs in Canada, however, these potential taxonomic revisions will not affect the conservation status of Queensnakes.
There are no recognized subspecies of Queensnake in Canada or throughout its more extensive range in the eastern United States (Crother et al. 2008). Neill (1963) described a distinct subspecies from Alabama, but this subspecies has generally not been accepted as valid.
The Queensnake is a slender, small to medium sized, semi–aquatic snake. Its dorsal colour is brown or dark olive with three narrow black stripes running down the midline and along each side on the fifth and sixth scale rows. The dorsal stripes are less apparent in older individuals. The belly is pale yellow or cream with four dark brown to black longitudinal stripes: two narrower central stripes and a broader lateroventral stripe on each side (Smith 1961; Conant and Collins 1998). The belly stripes often become mottled with age. The head is distinctly bi–coloured, with the cream throat extending to the upper lip, contrasting with the darker top of head. It is the only North American snake with a longitudinally striped belly. The striped belly and lack of light coloured, mid–dorsal stripe distinguishes it from brownsnakes (Storeria dekayi), gartersnakes, and ribbonsnakes (Thamnophis spp.) which are superficially similar. The Queensnake can attain a total length of approximately 90 cm (snout to tip), but is more commonly in the range of 40 to 60 cm (Conant and Collins, 1998). Snout–vent length is about 40–50 cm (Hulse et al. 2001). The scales are strongly keeled and the anal plate is divided. There are 19 scale rows midbody and 17 posteriorly (Anderson, 1965) and the number of ventral scales ranges from 133 to 154 (Wright and Wright, 1957).
In southern Ontario, no studies of inter– or intra–population genetic variation have been undertaken. Most populations appear to be isolated from one another with minimal opportunity for genetic exchange between locales. Populations are confined to small segments of a few watersheds where suitable habitat remains. This isolation has been exacerbated by the extent of agricultural conversion, urban development, recreational use, road networks, and plant succession within the portion of Ontario where the species occurs. Queensnakes are rarely found more than 3 m from water (Campbell and Perrin 1979; Smith 1999), although movements to hibernacula can exceed 10 m (Gillingwater, 2009). Presumably, individuals rarely cross between watersheds due to inhospitable terrain between areas of suitable habitat. Opportunities for recolonization of suitable habitat, therefore, are seriously limited and most populations are likely reproductively isolated.
All Queensnakes in Canada are a single species with no subspecies recognized. They all occur in the same ecozone and there is no evidence of deep (or any) genetic divergence or natural disjunction to justify more than one Designatable Unit (DU).
The Queensnake is relatively widespread in North America east of the Mississippi River, though it is sporadically distributed and at risk in many regions (Figure 1; Table 1). Its range extends from southeastern Pennsylvania, western New York and southwestern Ontario, west to southeastern Wisconsin and south to the Gulf Coast from the Florida panhandle to eastern Mississippi. Isolated records also exist from northern Michigan, southwestern Mississippi, and Arkansas (Conant and Collins, 1998). The Queensnake is apparently extirpated in New Jersey and Missouri (NatureServe, 2009). The S ranks in all states and provinces where it occurs are in Table 1.
Information obtained from NatureServe, 2009.
The current Canadian range is highly scattered and restricted to southwestern Ontario, west of the Niagara Escarpment, from the northern portion of the Bruce Peninsula, south to Lake Erie and west to Essex County (Figure 2). The former range may have extended east to Toronto, as there is an unsubstantiated 19th century literature report (Ure, 1858), but no reports have come from this area since the mid–1800s (Campbell and Perrin, 1979). Approximately 5% of the species’ global range is in Canada.
Ontario populations are concentrated along selected sections of several of the larger river systems where habitat conditions are suitable, notably the central portion of the Grand, middle and lower sections of the Thames, the Ausable, and the lower Maitland Rivers. There are also several shoreline records along Lake Erie such as Long Point, and on Fighting Island in the Detroit River, Walpole Island in the St. Clair River and the eastern shore of Lake St. Clair. There were several historic records from the Lake Huron Shore and the Bruce Peninsula. More recently, Queensnakes have been found on the Bruce Peninsula near Emmett Lake and at Baptiste Harbour (Jalava, 2009). The Natural Heritage Information Centre (NHIC) database (2008) has 27 Element Occurrences and approximately 200 records of Queensnakes in the province. Two EOs are reported here that are not in the NHIC database (see Table 2).
The Extent of Occurrence in Canada comprises roughly 30,000 km², but the Index of Area of Occupancy is only about 80 km². This IAO estimate assumes that most of the extant Element Occurrences comprise 4 km² each. To determine the current IAO, an assumption was made that any EOs where no Queensnakes have been reported in over 30 yrs are no longer extant. On this basis, 20 EOs are extant and 9 have been extirpated (Table 2). Queensnakes typically occur along narrow strips of shoreline that may be less than 100 m in length, so the actual AO may be much less than 80 km².
Wood (1949) stated that three general conditions were deemed necessary for the persistence of Queensnakes in a given area: a) a permanent still or flowing body of water with temperatures at or above 18°C for most of the active season; b) an abundance of cover material, such as flat rocks along the bank; and c) a large population of crayfish. These features are present at most sites occupied by Queensnakes in Ontario, but at outer Long Point, Walpole Island and Lake St. Clair, rocky cover of this sort is rare or absent, and the species may use crayfish (Cambarus diogenes and Fallicambarus fodiens) burrows for cover.
Queensnakes feed almost exclusively on crayfish, so their habitat must include features that support substantial populations of these crustaceans. Queensnakes are most commonly associated with stream or river habitats with rock or gravel in the channel and along the adjacent banks (Duellman, 1951; Conant, 1960; Oldham, 1986; Gillingwater, 2002). This highly aquatic species is strongly associated with water, rarely venturing far overland, and usually confined to within 3 m of a shoreline (Campbell and Perrin, 1979; Gillingwater, 2008). Of 185 Queensnake captures along the Thames River by Piraino and Gillingwater (2007), 177 (96%) were within 5 m of the river’s edge and the others were up to 15 m from the water at a hibernaculum. Streambed substrates commonly associated with Queensnakes include limestone (Wood, 1949) and slate (Triplehorn, 1949).
Even though Queensnakes are most commonly associated with rocky stretches of river and usually absent from intervening areas lacking stones, Judd (1955) has located this species along mudflat shoreline habitat. Even in areas of extensive rocky cover, Queensnakes are often localized and separated from other populations (J. Rowell pers. comm. 2009). The species may be less commonly found in other habitats such as marshes (Conant, 1960), ponds (Wood and Duellman, 1947), lake shores (Duellman, 1947; Bekker, 2007), and quarries (Mattison, 1995). Some Ontario records include the shorelines of large lakes such as Long Point on Lake Erie and Baie du Doré on Lake Huron, though these areas generally have smaller adjacent ponds and wetlands and the snakes occur in the extensive inland marshes and not along the Lake Erie shore itself. In addition, one population on the Bruce Peninsula occurs among rocky meadow marsh shorelines on small inland lakes which may dry up in summer (Jalava, 2009).
These snakes are sometimes associated with shrubs and trees along the shores of rivers and streams, where they will bask on overhanging branches (Campbell and Perrin 1979, Layne and Ford, 1983; Ernst and Barbour, 1989; Gillingwater, 2008). Campbell and Perrin (1979) found Ontario Queensnakes in close association with willow (Salix spp.) and Eastern Cottonwoods (Populus deltoides) as well as herbaceous meadow marsh species, but snakes avoided shorelines with a heavy canopy. One section of the Thames River harbouring a Queensnake population was open to sunlight for approximately 8 h a day. At this site, rocks covered portions of the shore along with open clay areas, low–lying broad–leafed plants, grasses, and scattered shrub willow (Gillingwater and Piraino, 2002). Queensnakes used geotextile mats (introduced for erosion control and creation of habitat for the snakes) for cover and for thermoregulation, including during gestation.
A suitable hibernation site is critical for survival overwinter (Bauchot, 1994; Mattison, 1995). In Ontario, one communal hibernation site, believed to contain a significant portion of the local population, was located along the Thames River. It occurred in a seepage area on an open south–facing clay slope above the river’s high water mark; small mammal burrows were present which provided access to the hibernaculum (Gillingwater, 2008). Further research at this site in 2009 has also identified access points at the base of woody vegetation (Gillingwater 2009). This is the only hibernation site known from Ontario. The species appears to hibernate communally and is thought to use anthropogenic structures such as bridge abutments, cracks in rock outcrops, and crayfish burrows (Campbell and Perrin 1979).
Most Queensnake populations occur along river systems in southwestern Ontario, where dwindling narrow corridors of riparian habitat remain in an area of intensive agriculture. Agricultural activities may encroach on rivers and creeks by removing riparian vegetation and allowing livestock access to the streams along some stretches. These actions lead to direct loss of habitat, as well as bank erosion that contributes to increased sediment, silt and turbidity in the waterway. The snakes also occur, or historically occurred, in urban centres along the Thames and Grand Rivers, both of which have undergone considerable urban expansion in recent decades. Queensnake habitat lies below the top of the bank where development has been relatively restricted, but channel reconfiguration and fortification of river shorelines to prevent erosion continue to affect the snakes negatively and reduce their remaining habitat. In addition, increased use of shorelines by the general public has further reduced vegetative cover and increased the level of disturbance. Another threat may come from storm water management that can lead to rapid changes in water flow.
Cottage development increasingly affects shoreline areas along Lake Huron. It is difficult to quantify the amount of habitat lost given the limited observations of Queensnakes in this area; however, there is a recent report of Queensnakes at Baptiste Harbour (Jalava, 2009) where new cottage development is occurring. Some residences have been recently built in close proximity to Queensnake habitat along the Ausable River (J. Kamstra, pers. obs.) and the Canard River (S. Gillingwater, pers. comm.). Within the often isolated areas of existing Queensnake habitat, natural and artificially induced succession are also occurring. Natural succession generally includes the expansion of native woody canopy cover. Such succession could eliminate necessary open habitat and, without adjacent habitat to colonize, the local snake population may be at risk of extirpation. To some extent, other natural processes such as erosion and storms could counter this succession by creating open areas. Artificially induced succession includes invasive exotic plant species such as Manitoba Maple (Acer negundo), Common Reed Phragmites australis australis, and other species that can overtake sensitive marsh, river and creek shoreline habitat. At Long Point and along the wetlands of Lake St. Clair, Phragmites is currently invading important snake and turtle habitat within the interior ponds. Manitoba Maple is tolerant of spring flood conditions and continues to spread along the shoreline of rivers and creeks throughout southern Ontario (Gillingwater 2009).
Currently, Queensnakes are known to occur in some protected areas, although the degree of protection varies. National parks, for example, afford a higher level of protection than conservation areas. At some of these protected areas, Queensnakes have not been observed for several decades, or records are so few that it is not known if they contain extant viable populations. These protected areas include:
- Bruce Peninsula National Park
- Long Point National Wildlife Area
- Big Creek National Wildlife Area
- St. Clair National Wildlife Area
- App’s Mills Conservation Area (Grand River CA)
- Rock Glen Conservation Area (Ausable River CA)
- Fanshawe Conservation Area (Upper Thames River CA)
- Komoka Provincial Park
The Queensnake hibernates through late fall and winter, emerging in spring. In Ontario, the active season generally extends from as early as mid–April to as late as mid–October (Piraino and Gillingwater, 2008; J. Kamstra, pers. obs.). In warmer, more southern portions of their range, the active season is extended. In Indiana, Queensnakes have been recorded from March 20 to November 7 (Wright and Wright, 1957). In Ohio, activity has been reported from April to September (Conant, 1938b). Extremely cold winters cause mortality in some other snake species during hibernation (Bauchot, 1994; Mattison, 1995; Porchuk, 1996) and may also affect Queensnakes. Movement from terrestrial hibernacula to shoreline habitats extends throughout April and into early May. By mid–May, Queensnakes begin to enter the water on a regular basis as water temperatures increase (Gillingwater 2009).
Queensnakes likely hibernate communally, but they may also hibernate singly, depending on site conditions. In Ontario, aggregations of Queensnakes have been reported in late autumn (Neill, 1948; Wood, 1944; Wood and Duellman, 1950) and in early spring (Gillingwater, 2008; Piraino and Gillingwater, 2003) and may indicate communal hibernation.
Branson and Baker (1974) found that female Queensnakes in Kentucky normally reproduce for the first time in their third year, whereas males mature in their second year. Because Ontario is at the northern limit of the species’ range, it may be that reproduction begins a year or two later due to shorter active seasons. Mating may occur in both spring and fall (Branson and Baker, 1974); however, no solid data are available on reproductive frequency. Ford (1982) describes courtship, in which the male made a series of vertical oscillations with its head and neck to align with the female’s posterior before copulation.
The Queensnake is viviparous, with young being born between July and September (Behler and King, 1988; Campbell and Perrin, 1979). In Ontario, neonates were found at parturition sites in late August and early September (Gillingwater 2009). Litter size ranges from 5 to 23, but is usually no more than 12 (Logier, 1958; Triplehorn, 1949). Two Ontario females captured by Campbell (1977) gave birth to 10 and 15 young and litters located just after birth along the Thames River ranged in size from 8 to 14 (Gillingwater 2009).
Viviparous reproduction has benefits for survival of young but results in a high energy cost for the female and increased susceptibility to predation during gestation (Greene, 1997; Shine 1985). Females must spend a considerable portion of the active season at a suitable gestation site that provides a sufficiently warm microclimate to promote rapid embryo development and some protection from predators. A nearby secure parturition site is also necessary for birthing, though gestation sites may sometimes be used for parturition. Such sites provide cover during parturition, are adjacent to the water’s edge, maintain high humidity and appear to provide protection from excessive heat and predators (Gillingwater, 2009).
Queensnakes are prey specialists, feeding almost exclusively on freshly moulted (post ecdysis) crayfish. Over 99% of the diet of 45 Queensnakes in New York was crayfish (Raney and Roecker 1947), and 98.6% of the diet of 120 snakes from Kentucky was crayfish (Branson and Baker, 1974). Only crayfish were found in the stomachs of five Queensnakes caught along the Thames River in Ontario (Judd 1955). The three other species of Regina also feed almost entirely on crayfish (Ernst and Barbour, 1989).
The Queensnake has infrequently been reported to consume other prey items, including small fish (LeRay, 1928; Conant, 1938a; Wood, 1949; Adler and Tilley, 1960), toads (Surface, 1906), and dragonfly larvae (Raney and Roecker, 1947). Feeding behaviour has rarely been observed in the wild and Queensnakes feed poorly in captivity (Logier, 1958; Campbell and Perrin, 1978). The Queensnake forages among stones and detritus in shallow water, taking crayfish from under cover (Raney and Roecker, 1947). Ernst and Ernst (2003) observed Queensnakes flush freshly moulted crayfish and consume them tail first. Wood (1949) observed a Queensnake scavenge a dead crayfish. Foraging behaviour observed in Ontario was similar with snakes probing in and among submerged rocks in relatively calm shoreline water (S. Gillingwater pers. comm.).
In much of their range, Queensnakes feed largely on crayfish of the genus Cambarus (Conant, 1960; Raney and Roeker, 1947; Wood, 1949). Cambarus is not common in Ontario or in other locations in the northern portion of the Queensnake’s range (Hamr, 1998). In Kentucky, Queensnakes feed almost exclusively on the crayfish Orconectes juvenalis, which is much more abundant than Cambarus there. Penn (1950) recorded several populations of Queensnakes in New York, Pennsylvania and Virginia feeding primarily on Orconectes obscurus. In Ontario, the most abundant crayfish at many Queensnake sites is Orconectes propinquus, and this species presumably is the Queensnake’s main prey (Campbell and Perrin, 1979; Crocker and Barr, 1968; Judd, 1962). All identified disgorged crayfish from captured Queensnakes in a recent Ontario study were Orconectes propinquus (S. Gillingwater, unpubl. data). Cambarus and Fallicambarus crayfish are more common in wet meadow/prairie habitats (e.g., Long Point, Walpole Island) (Hamr 1998) and may be more important prey for Queensnakes in these areas.
It is likely that Queensnakes will feed on whichever native crayfish species is locally most abundant. It is not known whether Queensnakes could feed on the non–native Rusty Crayfish.
Hamr (1998) has documented the recent decline of Orconectes propinquus throughout much of southern Ontario, perhaps partially due to competition with the larger, more aggressive, non–native Rusty Crayfish (Orconectes rusticus). The decline also results from degraded water quality. Crayfish populations are likely not significantly impacted by Queensnake predation, especially in Ontario where snake populations are generally quite small.
Being relatively small, the Queensnake is potentially susceptible to predation by a number of larger animals. In the U.S., hibernating and juvenile Queensnakes were vulnerable to predation by crayfish (Branson and Baker, 1974). With the replacement of native crayfish by the larger Rusty Crayfish, juvenile snakes may be more susceptible to predation. Hibernating snakes were also preyed upon by mice (Wood, 1949; Branson and Baker, 1974). Swanson (1952) recorded that an Eastern Milksnake (Lampropeltis triangulum) consumed a Queensnake in captivity, and this might occasionally occur in the wild as Queensnakes and Eastern Milksnakes share cover material along river shorelines at some locations in Ontario (S. Gillingwater, pers. obs.). Shoreline predators such as American Mink (Mustela vison), River Otter (Lontra canadensis), Raccoon (Procyon lotor), Great Blue Heron (Ardea herodias), and gulls probably prey on Queensnakes. In some areas of southwestern Ontario, relatively high densities of both American Mink and Raccoon occur along Queensnake habitat. At one site along the Thames River, American Mink have been found beneath cover materials used by Queensnakes (Gillingwater, 2009). It is not known how predation affects snake populations. Unnaturally high predator populations in human influenced environments (e.g., Raccoons) may reduce Queensnake populations in urban areas or in heavily used parks.
Branson and Baker (1974) examined thermoregulation and body temperature in Kentucky Queensnakes. They found that body temperatures averaged 25.6 °C, ranging from 12.2° to 30.4 °C when the snakes were active. Body temperatures were up to 6 °C higher than ambient. The critical thermal maximum was about 44 °C for adults and 40 °C for juveniles. Queensnakes appear particularly sensitive to increased temperatures, quickly showing signs of heat stress when handled during warm days (S. Gillingwater pers. obs.). Queensnakes are thought to have the most water permeable skin of any other North American snake, and would be vulnerable to dehydration on land (Stokes and Dunson 1982).
Few data exist on Queensnake dispersal as no radio–telemetry studies have been conducted on the species to date. Localized distribution along certain stretches of stream, and complete absence from others, implies that Queensnakes generally do not move far. Their close association with water and their permeable skins may make Queensnakes reluctant to move inland and disperse across watershed boundaries. Living on rivers with currents and regular floods, however, has the potential for carrying some individuals downstream for considerable distances within watersheds and some “dispersal” may occur that way.
Branson and Baker (1974) conducted a mark–recapture study and found that Queensnakes had small home ranges. Most individuals did not move more than 30 m from their original point of capture, although one individual moved 122 m in 2 weeks. At one Ontario site on the Thames River, movements of 100 m have been observed between hibernation and gestation sites (Gillingwater, 2009).
As discussed above, probably the most important interspecific interaction for Queensnakes involves their prey. Queensnakes only occur where there is an abundant population of crayfish.
Queensnakes normally do not occur with other snake species, but Bekker (2008) found them living in similar habitat to Northern Watersnakes (Nerodia sipedon) and Eastern Foxsnakes (Pantherophis gloydi) along a stretch of Lake Erie in northwestern Ohio. Branson and Baker (1974) also noted that they sometimes occur under rocks in the company of Northern Watersnakes. In Ontario, Queensnakes are sometimes found sharing cover objects with Northern Brown Snake, Eastern Milksnake, and Eastern Gartersnake as well as with Green (Lithobates clamitans) and Leopard (Lithobates pipiens) Frogs, and American Toad (Anaxyrus americanus) (S. Gillingwater unpubl. data).
Queensnakes appear to have limited adaptability, given their strong dependence on crayfish and specialized habitat needs. They are almost never found more than a few metres from water. This restriction may be related to the Queensnake’s permeable skin and greater susceptibility to desiccation than most other snake species. Queensnakes do show some ability to adapt to a broader range of wetlands than just rocky streams, as they sometimes inhabit lakeshore wetlands, flooded quarries, and marshes.
Recent Queensnake surveys have been conducted by several observers. Past surveys may not have been rigorously standardized, but they were conducted in a similar manner. These searches entail carefully checking riparian vegetation for basking snakes and overturning submerged and exposed rocks and other cover items, generally within 3 m from the shoreline (Judd, 1955; Campbell and Perrin 1979; Spurr and Smith, 1979; Gartshore and Carson, 1990; Lamond, 1994; Piraino and Gillingwater, 2003, 2004). For example, 11 field days of survey were conducted along 7 km of the Maitland River in 2008 and two Queensnakes were found (S. Bowles, pers. comm. 2008). In 2002, on a middle section of the Thames River, 140 person hours were spent searching which included overturning 21,649 rocks. Nine Queensnakes were found, all confined to an isolated 100–m stretch of the river (Piraino and Gillingwater, 2003).
Ontario Ministry of Natural Resources (OMNR) biologists conducted surveys along Whiteman’s Creek, a tributary of the Grand River on 12 and 18 August in 2003, finding 23 snakes (R. Tervo, pers. comm.). OMNR also conducted surveys along the Ausable River on several days in the summer of 2004 with limited success (D. Jacobs, pers. comm.) and surveys along the Bayfield River with no success (Gillingwater, pers. comm. via K. Vlasman OMNR). On the Bruce Peninsula, surveys for Queensnakes were commissioned by Parks Canada in 2006, 2007, and 2008 following the discovery of a Queensnake on an inland lake in 2005 (Brinker, 2007; Jalava, 2009).
Over 10 days from mid–August to early September 1979, Campbell and Perrin (1979) searched 16 Ontario sites known to have Queensnakes in the past. Six researchers intensively searched many of the same locations as Campbell and Perrin over the spring and summer of 1997 (Fletcher and Gillingwater unpubl. data 1997; Smith 1999) with only 38 specimens being located (6 – Maitland River, 19 – Upper Thames River Watershed, 6 – Canard River, 4 – Grand River Watershed, 2 – Ausable River Watershed). During this survey, no Queensnakes were located at most of the known historic Thames, Grand, Maitland, and Ausable sites and no snakes were located at any historic sites along the Bayfield River, Nanticoke Creek, Long Point NWA, Otter Creek, Big Creek NWA, St. Clair NWA, or the Bruce Penninsula. Despite the intensity of surveys, the species appeared absent from, or scarce in, the majority of historic locations
The Queensnake has always had a limited range and has never been considered common in Ontario (LeRay, 1928; Mills, 1948; Logier, 1958; Campbell, 1977; Oldham, 1986; Lamond, 1994). It is relatively abundant in some sites, yet absent from other areas of seemingly suitable habitat (Spurr, 1978; Gillingwater 2008). Queensnake abundance, behaviour, and habitat use in a given area are also subject to change throughout the active season as snakes move between hibernacula, foraging grounds and thermoregulation/gestation sites (Gillingwater, 2002; Piraino and Gillingwater, 2003–2004), making estimation of abundance less reliable. The overall scarcity, elusive behaviour, aquatic lifestyle, and adaptation to rocky habitats of this species make it difficult to derive robust population estimates. Intensive surveys at a large number of historic sites suggest that at all but one location, the species was either present at low densities or absent (Fletcher and Gillingwater 1997 unpubl. data). Subsequent surveys in the Upper Thames River Watershed have revealed extremely low densities in all but one location, where densities were moderate (Gillingwater, 2009).
Only one location has been sampled intensively or consistently enough for even a rough estimate of population size. At this location, a 200–m section of the North Thames River, the Queensnakes were subjected to a 3–year capture–mark–recapture study (Gillingwater, 2002; Piraino and Gillingwater, 2003–2004). The population size was estimated at about 50 adults using the Lincoln Index for population estimation. The study employed intensive timed surveys and PIT tagged all captured adults. Recapture rates and population estimates were “consistent” but confidence limits were not calculated. At a site along Lake Erie in northern Ohio, a mark–recapture study estimated a population of 359 Queensnakes along 2 km of shoreline (Bekker, 2007). No Canadian survey has revealed population sizes even close to as large as Bekker’s estimate. Based on the best available information from historic and recent Ontario surveys and from NHIC data, combined with evidence of declining habitat quality, documented loss of historic populations, and decline in crayfish, it is highly unlikely that such sizable populations occur in Ontario. All Ontario Queensnake studies suggest low population density, localized distribution, and limited potential for individuals to migrate among populations. Even at sites with less human–altered habitat, such as the Maitland River and the Bruce Peninsula, high snake densities or extensive ranges have not been reported either anecdotally or through active surveys.
The Queensnake is one of the least reported snake species in Ontario (based on the number of records in the NHIC database). Recent surveys suggest a decline of Queensnake numbers and loss of some Ontario populations, and, as noted above (Search effort), recent dedicated surveys found few or no Queensnakes at most historic locations.
Between 2002 and 2009, Deb Jacobs (pers. comm. to S. Gillingwater), and Gillingwater (2002, 2009), Piraino and Gillingwater (2003, 2004, 2007) also surveyed for Queensnakes along all known sites in the Upper Thames River watershed, visiting all these sites on several occasions over this period. Of these five historic Upper Thames River locations, only two have had confirmed Queensnake observations in the past 10 years. A breakdown of these sites follows:
Thames River, north London
This site maintains the most thoroughly studied population in Canada and contains approximately 50 adults based on mark recapture efforts from 2002 to 2006 (see below), with its habitat at serious risk of loss due to recreation, succession, and unnatural flooding;
Thames River, Komoka PP
This site had two observations of Queensnakes in the past decade. It has little habitat remaining (few areas of cover, encroaching woody growth, unnatural flooding);
North Thames River, Plover Mills
This site appears to have good habitat and high crayfish densities, but no Queensnakes have been observed in over 30 years;
Thames River, Dorchester
This site has limited habitat with no Queensnake sightings for more than 20 years;
Medway Creek, City of London
This site has declining habitat quality (increased traffic and recreation, increased woody canopy cover, increased upstream disturbances, unnatural flooding), and no Queensnake observations since 1997 despite yearly surveys from 2002 to 2010 (historically Queensnakes were reported from this location from the 1950s to 1990s).
Of the 29 element occurrences (EOs) in Ontario (Table 2 (N=29); NHIC 2008 (N=27)), 15 are “historic” (not seen in more than 20 years) and 14 have been confirmed since 1990, although one of these latter EOs has not had a confirmed sighting since 1997 (Medway Creek) despite repeated surveys from 2002 to 2010 (Table 2). Queensnakes were last observed at three of the EOs well over 50 years ago and at 12 other EOs between 1960 and 1990 (Table 2). Concerted efforts to confirm the presence of Queensnakes at 14 of these 15 historic sites have had no success: Thames River (Gillingwater (2002); Piraino and Gillingwater (2003, 2004, 2007); Gillingwater unpubl. data; Fletcher and Gillingwater unpubl. data 1997, Smith 1999); Ausable River (Gillingwater pers. comm. via D. Jacobs OMNR 2004; M. Fletcher and S. Gillingwater unpubl. data 1997; Smith 1999); Bayfield River (S. Gillingwater pers. comm. via K. Vlasman OMNR 2004; M. Fletcher and S. Gillingwater, unpubl. data 1997); Nanticoke Creek (S. Gillingwater pers. obs. 2008, M. Fletcher and S. Gillingwater, unpubl. data 1997; Smith 1999); Bruce Peninsula (Jalava, 2009; Brinker, 2007); Grand River (Smith 1999); Big Creek National Wildlife Area (S. Gillingwater unpubl. data 2003–2008; Smith 1999); Long Point National Wildlife Area (S. Gillingwater unpubl. data); Lake St. Clair wetlands (M. Fletcher and S. Gillingwater unpubl. data 1997). The 15th site was not surveyed as it now lies in the heart of the City of Toronto and is certainly extirpated if it ever was a valid record.
The records of Queensnake in the Ontario Herpetofaunal Summary (OHS) and NHIC database (Table 2; Oldham and Sutherland, 1986; Oldham, 1988; Oldham and Weller, 1989; OHS data now with NHIC 2009) have been used to describe further the population trends in Ontario (below), unless otherwise indicated. The first Queensnake reported for the province was in 1858 in Toronto (Ure, 1858), but the species has never been recorded anywhere near Toronto since. J.H. Garnier recorded several individuals in wetlands on the east side of Lake St. Clair in the early 1880s. The last sighting for the southeast side of Lake St. Clair at Bradley’s Marsh was in 1973. Bradley’s Marsh was temporarily drained in the 1970s; therefore that population has almost certainly been extirpated. A Queensnake was collected in 1880 on the east side of Lake St. Clair south of Mitchell’s Bay (LeRay, 1928). There had been no records in that vicinity for over 120 years until 2003 when one was found in the St. Clair National Wildlife Area. Rattlesnake Creek and the Bayfield River have not had reported sightings since the late 1970s. The Bayfield River appears to provide suitable Queensnake habitat (Gillingwater, 2008), but repeated searches there during the 1980s (Smith, 2000), in 1997 and in 2005 (Gillingwater, 2008) have failed to find any snakes. Nanticoke Creek, north of Lake Erie, has not had any reports of Queensnakes since the mid–1980s, suggesting that population may now be extirpated. There are very few observations of Queensnakes from near the tip of Long Point, despite many visits by naturalists and biologists each year. However, after an absence of records for decades, one was found there in 2004. Additionally, portions of suitable habitat along the St. Clair, Long Point and Big Creek National Wildlife Areas and Nanticoke Creek are becoming increasingly colonized by Phragmites a. australis, a possible threat to the species (S. Gillingwater pers. obs.).
Queensnakes have been consistently located along the Thames, Grand, Ausable, and Maitland River watersheds, albeit in small numbers and in isolated locales. Some Queensnake populations within the Thames River Watershed may have been lost as recently as 2002 (Gillingwater, 2002). Queensnakes were first reported from the Canard River in 1985 (Oldham, 1986), with sightings in 2002 (G. Waldron Consulting Ecologists, 2003) and more recent observations on nearby Fighting Island in the Detroit River in 2009 (R. Jones, pers. comm., D. Noble/J. Choquette pers. comm.). Francis and Campbell (1983) rediscovered Queensnakes in the Waterloo region after a 50–year absence of recorded sightings. This finding is more likely the result of inadequate or infrequent surveys over the time interval, rather than ‘recovered’ populations.
Some Queensnake populations on the Bruce Peninsula may have been lost, in particular at Scugog Lake where the species has not been reported since 1927, and at Baie du Doré where it was last seen in 1969. Surveys were also conducted at the historic EO locations of Scugog Lake and Cameron Lake over the same period without success (Jalava, 2009). In 2005, however, a Queensnake was encountered near Emmett Lake in the central part of Bruce Peninsula National Park. Subsequent surveys conducted in 2006, 2007, and 2008 resulted in discovery of a small number of individuals (Brinker, 2007; Jalava, 2009). In addition, a Queensnake was reported at Baptiste Harbour on the northwest end of the Bruce Peninsula in 2003. Jalava and others also searched that area in 2008, but found none.
|EO Number||Location||First Observation||Last Observation||Recent|
|1332||Grand River – Whiteman's Creek||1926–05–23||2009–06||1997 Fletcher and Gillingwater; 2003–2007 Tervo||Yes|
|1334||Maitland River – Lower||1967||2008–07–04||1997 Fletcher and Gillingwater; 2008 McKichan||Yes|
|1336||St. Clair River – Walpole Island||1881||1990–09–07||Yes *|
|1338||Nanticoke Creek||1987–08–01||1987–08–01||1997 Fletcher and Gillingwater; 2008 Gillingwater. None found in either survey||* ?|
|1339||Thames River – Medway Creek||1955–07||1997–05–13||1997 Fletcher and Gillingwater; 2002–2010 Gillingwater. None found in all surveys||No ?|
|1340||Detroit River – Canard River||1985–10–07||2009–05–01||2002 Waldron|
2009 Russ Jones
|1342||Ausable River – Rock Glen||1961–06–24||2008–09–12||2004 Jacobs|
|1343||Grand River – Glen Morris||1963||2009–07–03||2009 Kamstra||Yes|
|1346||Grand River – Bannister Lake||1988–06–06||1988–06–18||Yes *|
|1347||Grand River – Cambridge||1975–09–19||2001–08–03||1997 Fletcher and Gillingwater||Yes|
|13758||Lake Erie – Long Point||1961||2004–08–25||Gillingwater 2005||Yes|
|13766||Thames River – Plover's Mills||1887–05–30||1976–08–10||2002–2010 Gillingwater||No *|
|13767||Lake St. Clair – Bradley's Marsh||1880||1973–05–15||Fletcher and Gillingwater 1997||No *|
|13768||Lake St. Clair – Mitchell's Bay||1880–07–11||2003–06–07||2003 Woodliffe||Yes|
|13769||Thames River – Chatham||1882–07–09||1882–07–09||No *|
|13770||Spring Creek, Bruce||pre 1977||pre 1977||2006–2008 Jalava||No *|
|13771||Scugog Lake, Bruce||1927–08–02||1927–08–02||2006–2008 Jalava||No *|
|13772||Lake Huron – Baie du Doré||1969||1969||No *|
|13774||Thames River – North London||1882||2010–05–20||2002–2010 Gillingwater||Yes|
|13779||Thames River – Dorchester||1990–09–06||1990–09–06||2002–2010 Gillingwater. None||No *|
|13780||Bayfield River||pre 1977||pre 1977||Fletcher and Gillingwater 1997, OMNR 2004||No *|
|13782||Lake Erie – Big Creek NWA||1960||1988||Gillingwater 2003–10||No*|
|13783||Otter Creek||pre 1979||pre 1979||Fletcher and Gillingwater 1997||No *|
|13800||Toronto||pre 1858||pre 1858||No *|
|67887||Grand River – Paris||2001–07–17||2001–07–17||1997 Fletcher and Gillingwater;||Yes|
|91993||Cameron Lake, Bruce||1989–07–20||1989–07–20||2006–2008 Jalava||Yes *|
|92409||Andrew and Emmet Lakes, Bruce||2005–08–25||2008–08||2006–2008 Jalava||Yes|
|Thames River – Komoka||2004–08–26||2004–08–26||2004 Jacobs||Yes|
|Lake Huron – Baptiste Harbour||2003–06||2003–06||2006–2008 Jalava||Yes|
Queensnakes have been frequently reported at some sites such as on the middle section of the Thames River, Ausable River, and along some parts of the Grand River watershed. Only the North Thames River population has been sampled intensively or consistently enough for even a rough estimate of population size. The site is approximately 200m long, and is negatively affected by human recreational use that has resulted in snake injuries and mortality as well as loss/destruction of habitat. Additionally, water diversion structures, high levels of silt and sediment and ongoing plant succession threaten this relatively well–studied population of Queensnake.
Three new EOs have been discovered since 2000; two are on the Bruce Peninsula and one additional site is on the Grand River. These are not believed to be newly colonized sites, but instead are likely long established colonies that were previously unknown.
The Queensnake is a cryptic species that is not often encountered except by deliberate searches, and even these may not prove successful. There are several examples of sites (e.g., Long Point, Lake St. Clair, Cambridge) where no Queensnakes have been observed for decades and then were found again. Consequently, assessing populations is difficult and some caution should be exercised before populations are assumed to be extirpated, rather than ‘historical’. Surveys over the past 8 years suggest that at least two of the extant EO’s along the Thames River may no longer be extant (Gillingwater unpubl. data 2002–2009, Table 2).
Queensnakes are widespread and apparently secure in the bordering states of Ohio and Michigan. A few of the Ontario EOs occur close to the U.S. border or along a Great Lakes shoreline (e.g., Fighting Island, Amherstburg, Long Point, Walpole Island and the east side of Lake St. Clair). Other populations lie inland, mostly within 100 km of the border. Nevertheless, given the isolated nature of Queensnake populations and their limited ability to disperse, the possibility of unassisted recolonization in the event of extirpation is low. Assisted recolonization is also limited, as this species does not do well in captivity and movement of such a specialized species from one locale to another may prove difficult as both appropriate habitat and a viable population of native crayfish would be required for success.
Habitat loss, fragmentation, and degradation are the biggest threats to Queensnakes in Ontario (Cook, 1970; Smith, 1999; Gillingwater, 2008), as previously reviewed under “Habitat Trends”. In the intensively cultivated landscape of southwestern Ontario, natural riparian habitat is often eliminated or reduced to narrow fragments along river banks. Habitat has remained only because some of the rivers are associated with steep valley slopes where agriculture has not been possible. In places, livestock has been allowed free access to rivers and streams causing rutting, erosion, sedimentation, turbidity, excessive nutrients, and removal of vegetation cover through overgrazing. Any type of land use that extends to the edge of a waterway can be detrimental if the cover and structure that form important habitat for Queensnakes are removed.
In the vicinity of urban areas, development on tableland surrounding the floodplain increases surface water drainage from storm sewer outfalls. This runoff often degrades riparian Queensnake habitat by sedimentation, erosion, contamination, and greater oscillation in river levels. In addition, more bridges and erosion control structures further limit natural habitat by replacing natural shoreline with gabion baskets, concrete walls, and rip–rap.
The impact of pollution on Queensnakes is not well known, but they are exposed to water contamination from agricultural practices as well as contamination from direct urban runoff from larger cities such as London and Cambridge. Trauth (1991) argued that water pollution contributed to Queensnake decline in Arkansas. Queensnakes have exceptionally permeable skin for a snake, possibly leaving them vulnerable to pollutants within their aquatic environments (Stokes and Dunson, 1982). In addition, crayfish, their primary prey, can bio–accumulate mercury (Vermeer, 1972), which could affect the long–term health of Queensnakes.
Invasive species may also destroy or fragment Queensnake habitat. Common Carp (Cyprinus carpio) erode river shorelines during spawning, both damaging existing habitat and adding sediment to the water. At one site along the Thames River, Zebra Mussels heavily encrust rocks used for cover and foraging by Queensnakes. The mussels create a physical barrier restricting access between and under many large rocks (Gillingwater, 2009). A sizeable Queensnake population along Lake Erie in Ohio virtually disappeared between 2001 and 2004 because of invasion by Round Goby (Neogobius melanostomus) (Bekker, 2007). The goby feeds aggressively on young crayfish (Davis, 2003), effectively reducing the food supply of the snake. Thus Round Gobies are a serious potential threat to Queensnakes in Ontario.
Invasive plants such as Common Reed (Phragmites australis australis) may limit use of current sites in the long term. Common Reed has rapidly expanded through much of southwestern Ontario in recent decades, now dominating many systems including some sites inhabited by Queensnake such as along the St. Clair, Long Point, and Big Creek National Wildlife Areas and Nanticoke Creek (S. Gillingwater, pers. comm.). Common Reed reduced thermoregulation habitat of Queensnakes in Ohio (Bekker, 2007). Even natural plant succession, which creates a heavy canopy cover from large shoreline trees, can shade out existing Queensnake habitat. Trees, such as Manitoba Maple and large willows, invade floodplain areas, creating extensive shoreline shading along the Thames River (Gillingwater 2009).
Queensnakes, although small and usually inconspicuous, are subject to a surprising amount of direct human persecution. In Ontario, several authors have reported that Queensnakes are killed by anglers or other humans (Campbell and Perrin 1979, Spurr and Smith 1979, Gillingwater, 2008 and J. Kamstra pers. obs.) indicating that persecution happens more frequently than might be expected. Most of the rivers and streams where Queensnakes occur are well–known fishing locations, so anglers are likely to encounter them on occasion. Queensnakes use small rocks for cover and are thus easily injured or killed by people walking near the shoreline in Queensnake habitat, such mortality been observed along the Grand and Thames Rivers (Gillingwater, 2008). In the U.S., Harding (1997) notes that Queensnakes are sometimes killed by anglers who believe they are feeding on game fish (presumably excessively tiny game fish), and Ernst and Ernst (2003) report shooting of many Queensnakes by sportspersons.
Because of the Queensnake’s dependence on crayfish as its primary food item, it is highly vulnerable should decline or loss of crayfish occur. In Pennsylvania, significant crayfish declines have been reported, leading to extirpation of some local Queensnake populations (McCoy, 1982). All crayfish species can be negatively affected by poor water quality caused by sediment, silt, and pollution that occur throughout the Queensnake’s Canadian range (Hamr, 1998). The full impact on Queensnakes from the larger Rusty Crayfish displacing native crayfish is not well understood. The Queensnake feeds on a number of crayfish species, but the Rusty Crayfish’s larger size may make it difficult for the snakes to consume, and this crayfish may even kill juvenile snakes.
The Queensnake reaches its northern range limit in southern Ontario; therefore Canadian populations may contain genetically distinct characteristics from central populations of its range, allowing adaptation to a colder climate. The Queensnake is an interesting species because of its extreme prey specialization and its specialized and unusual aquatic foraging habits. In addition, its evolutionary relationships to watersnakes and to other crayfish snakes is of considerable interest, suggesting independent evolution of prey specialization Queensnakes may also act as indicators of environmental quality because of their permeable skins that make them potentially more sensitive to water contamination than other snake species.
The Queensnake is legally protected under the Ontario Fish and Wildlife Conservation Act as a specially protected reptile, which prohibits the collection, hunting, possession or sale of reptiles except under authority of a licence. As a provincially Threatened species, it is protected under the Ontario Endangered Species Act (2007). In 2002, the Queensnake was designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). The species is currently listed on Schedule 1 of the federal Species at Risk Act (SARA), which protects it on federal lands and will protect its critical habitat once it has been defined.
As the majority of Queensnake habitat in Ontario occurs within the floodplains of streams and rivers, the habitat is afforded some protection from development through the Conservation Authorities Act. Floodplains, valleys, lands below top–of–bank and sometimes additional buffers are protected from development under this act. However, development immediately adjacent to Queensnake habitat could have negative effects through increased access and human recreational activities along shorelines. The Fisheries Act prohibits harmful alteration, disruption or destruction of fish habitat, and therefore provides indirect protection for aquatic Queensnake habitat as well.
The Provincial Policy Statement (PPS) (MMAH, 2005) issued under Section 3 of the Planning Act considers the habitats of threatened and endangered species to be natural heritage features. Under Section 2.1 of the PPS (Natural Heritage), development and site alteration will not be permitted in the significant habitat of endangered and threatened species. Section 3 of the Planning Act requires that decisions affecting planning matters “shall be consistent with” policy statements issued under the Act. However, Section 2.1.7 of the PPS states “Nothing in policy 2.1 is intended to limit the ability of existing agricultural uses to continue”, and agriculture has greatly contributed to changes or loss of Queensnake habitat. Additionally, the Fisheries Act prohibits harmful alteration, disruption or destruction of fish habitat. This legislation, therefore, provides some indirect protection for aquatic habitat of the Queensnake as well.
The snake receives varying levels of protection throughout its range in the United States. It is designated as legally endangered and protected in Wisconsin (Wisconsin Department of Natural Resources, 2009) and New York (Gibbs et al., 2007).
The NatureServe ranking of the Queensnake in Ontario is S2; nationally, it is N2; and globally, G5 (NatureServe 2009). S rankings for the various states are shown in Table 1.
Queensnake – couleuvre royale
Range of occurrence in Canada: ON
population; Using IUCN guidelines (2008)
GT = 1 + AM/AMR =1 + 4/0.5 =9 years. Where
AM = average age at maturity and AMR = annual adult mortality rate. The estimate of AMR is based on limited data. ~9 yrs
decline in number of mature individuals? Inferred, and projected
of mature individuals within [5 years or 2 generations] Unknown
[reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations]. Unknown
total number of mature individuals over the next [10 years, or 3 generations] . Unknown
[reduction or increase] in total number of mature individuals
over any [10 years, or 3 generations] period, over a time
period including both the past and the future. Unknown
Extent and Occupancy Information
Calculated by measuring a polygon from Amhersburg to Maitland River to upper Bruce Peninsula to Grand River and Long Point.
The historic Toronto record was excluded. 30,000 km²
Assumes that each of the 20 “extant” (see Table 2) EOs covers 4 km², even though Queensnakes typically occupy only narrow strips (often no more than 100 m) of habitat along river or lake shorelines. This IAO estimate also assumes that there is no overlap among the 2x2 km² quadrats so it is a maximum value given that there actually is some overlap and some EOs would have < 4 km² of occupied habitat. 80 km²
There are 29 “Element Occurrences”, but 9–10 of these are considered extirpated and a further 6 are “historical” (no records in past 20 yr Table 2). The remainder (see Table 2 and solid red dots in Figure 2) comprise ~8–10 “extant” locations in which EOs are clumped if they share the same watershed (see COSEWIC definition of location). ~8–10
decline in extent of occurrence? Projected and observed decline
decline in index of area of occupancy? Projected and observed decline
decline in number of populations? Projected and observed decline
decline in number of locations? Projected decline
decline in [area, extent and/or quality] of habitat? Observed and projected decline in area and quality
* See definition of location.
Number of Mature Individuals (in each population)
small and even given ~100 adults per EO and a
maximum of 20 EOs, there would be <2500 mature snakes. Unknown but probably < 2500
Threats (actual or imminent, to populations or habitats)
- The major threat is degradation and loss of natural riparian areas and clean flowing streams because of agricultural activities that destroy riparian habitat (by farming to stream edge, allowing cattle or pigs into streams etc), and by increased runoff leading to higher sediment loads that reduce crayfish prey and increase turbidity making it harder for snakes to catch crayfish.
- Destruction of streamside/riparian habitat by expanding urban development, including placement of gabions and other flood and erosion control measures.
- Decline of the species’ major prey, crayfish, from deteriorating stream quality from agriculture and housing and from invasion of the larger introduced Rusty Crayfish.
- Persecution and habitat disturbance from growing numbers of people using Queensnake habitat for recreation and angling.
- Varied effects of other invasive species including non–native Phragmites (Common Reed), Round Gobies, Zebra Mussels and Common Carp.
- Effects of isolation and small population size (severe fragmentation).
Rescue Effect (immigration from outside Canada)
Status and Reasons for Designation
Reasons for designation:
This species has a restricted and shrinking distribution in southwest Ontario. It consists of scattered small populations which are isolated due to habitat fragmentation and the species’ limited dispersal capacity. Over the last decade, the number of extant locations has declined and the species’ riparian and riverine habitat has continued to be lost and degraded. The species is limited by its extremely specialized diet and threatened by decline in its prey of freshly moulted juvenile crayfish. Other threats include persecution and effects of invasive Zebra Mussels and Common Reed.
Applicability of Criteria
Criterion A (Decline in Total Number of Mature Individuals): Does not meet criterion A as size of decline is not known.
Criterion B (Small Distribution Range and Decline or Fluctuation): Meets Endangered B2ab(ii,iii,iv,v) as the IAO is less than 500 km²; the population is severely fragmented, there is a continuing decline in the quality of habitat due to increased silt/sediment in streams and decreased prey abundance (crayfish), and decline in the area of occupancy, number of populations, and number of mature individuals.
Criterion C (Small and Declining Number of Mature Individuals): Meets Endangered C2a(i) as the total number of mature individuals is estimated to be less than 2,500 individuals, the population is observed to be declining and projected to decline further as habitat is degraded, and no population is known to exceed 250 mature individuals
Criterion D (Very Small or Restricted Total Population): Does not meet criterion D as total number of mature individuals exceeds thresholds.
Criterion E (Quantitative Analysis): Not available.
The report writer would like to thank Scott Gillingwater for providing reports, tracking down records and showing him his study site. He would also like to thank Ron Brooks, co–chair of the Amphibians and Reptiles Species Specialist Sub–committee for his enduring patience during the writing of this report. Mike Oldham of NHIC provided the records in the NHIC database. Information on various records was provided by Steve Bowles, Amy Brant, Frank Burrows, Jonathan Choquette, John Haselmayer, Deb Jacobs, Russ Jones, Tom Preney, Jeff Rowell, Rob Tervo and Allen Woodliffe. Sarah Richer assisted with background information. The Amphibian and Reptiles Co–chair (RJB) would like to also thank G. Blouin–Demers, P. Gregory, M. Oldham, J. Rowell and especially S Gillingwater for extremely helpful reviews and comments on several earlier drafts of this report.
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James Kamstra is a terrestrial ecologist with the firm AECOM Canada Ltd. (formerly Gartner Lee Limited.). He has conducted numerous biophysical inventories and environmental impact studies at many sites in southern Ontario, frequently involving reptile species at risk. He has addressed impacts of a residential development proposal on Queensnakes and Soft–shelled Turtles near London. Other environmental impact studies involved Massasauga Rattlesnake, Butler’s Gartersnake, Eastern Hog–nosed Snake, Blanding’s Turtle and Spotted Turtle. James is a member of the Species Recovery Teams for Blue Racer, Eastern Foxsnake and Eastern Hog–nosed Snakes. He has written recovery strategies for the Eastern Fox Snake as well as Northern Cricket Frog.
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