CLBMON-37. Kinbasket and Arrow Lakes Reservoirs: amphibians and Reptile Life History and Habitat Use Assessment. Year 6 Annual Report – 2016

Author: V.C. Hawkes, B. McKinnon, C. Wood

In 2016, through a variety of survey methods (egg mass surveys, visual encounter surveys, auditory surveys, radiotelemetry), we documented the presence of four species of amphibians and five species of reptile in the drawdown zone of Kinbasket and Arrow Lakes Reservoirs. Species documented in Kinbasket included Western Toad (Anaxyrus boreas), Columbia Spotted Grog (Rana luteiventris) and Western Terrestrial Garter Snake (Thamnophis sirtalis). The Long-toed Salamander (Ambystoma macrodactylum) and Western Painted Turtle (Chrysemys picta) were not detected in 2016 (but were in 2015). Western Painted Turtle has been detected from only one location in the drawdown zone (at the KM88 study location in 2015). A Western Painted Turtle was outside of the town of Valemount in 2016, the first record of this species in the region. Although the location of the observations was > 4km away from Kinbasket Reservoir, this detection taken with that of 2015 raises questions about the known distribution of Western Painted Turtle in the region. Species documented in the drawdown zone of Arrow Lakes Reservoir include Western Toad, Columbia Spotted Frog, Pacific Chorus Frog, Western Terrestrial Garter Snake, Common Garter Snake (T. elegans), Western Painted Turtle, Northern Alligator Lizard (Elgaria coerulea), and Western Skink (Plestiodon skiltonianus).

In Kinbasket, Western Toad and Columbia Spotted Frog were the most commonly encountered species, usually in wetlands within wool-grass–Pennsylvania buttercup, Kellogg’s sedge or willow-sedge habitats. Pond characteristics varied by species with Columbia Spotted Frog using ponds situated at higher elevation and with a higher abundance and per cent cover of aquatic macrophytes compared to Western Toad. Western Toad breed in ponds as low as 734 m ASL in ponds that are typically devoid of vegetation or woody debris. It appears that the water physicochemical parameters measured (dissolved oxygen, conductivity, pH, temperature) do not affect distribution, occurrence or development of either species. In Arrow Lakes, Western Toad and both species of garter snake were the most commonly detected species; these species all use a wide variety of habitats and occur at overlapping elevations (434 to 440 m ASL).

Most amphibians and reptile detections were distributed within an elevation range of 744 to 754 m ASL for Kinbasket Reservoir and 435 to 445 m ASL for Arrow Lakes Reservoir. The influence of reservoir operations on the availability of habitat in the DDZ was evident; as reservoir elevations increased, the amount of available habitat decreased and the changes in habitat availability was similar in both reservoirs in 2016. In Kinbasket, a subtle difference in reservoir operations was observed, with a decrease in available habitat earlier in June and subsequent lower reservoir levels through August and September, thus more habitat was available during the late season period than in 2010, 2012, and 2014. In 2016 in Arrow Lakes, it was a slightly different year for reservoir operations with reservoir levels reaching an early peak in June and subsequent decrease, which led to increased available habitat in the late summer and fall as compared to 2012 and 2014. Although more habitat was available later in the season, this did not necessarily benefit amphibians as the crucial period for successful breeding is in June when reservoir levels were high (i.e., breeding habitat was inundated). The continued presence of amphibians and reptiles of all life stages in the drawdown zone in consecutive years suggests that these species are not adversely affected by reservoir operations. However, we do not know if populations of these species are affected relative to non-reservoir populations, and we won’t know that unless suitable non-reservoir populations are studied.

Radiotelemetry was used in 2016 to determine how Common Garter Snakes use habitats in the drawdown zone and the locations of any overwintering sites in the Valemount Peatland area of Kinbasket Reservoir. The results obtained suggest that Common Garter Snakes use marsh areas within the drawdown zone for summer foraging and thermoregulation and then move into upland habitats for overwintering during September. Data obtained from Common Garter Snakes indicate that there are core areas of use that correspond to locations associated with high densities of amphibians (e.g., Pond 12). More data are required to better assess seasonal habitat use by garter snakes in the drawdown zone of Kinbasket Reservoir.

In 2016, through a variety of survey methods (egg mass surveys, visual encounter surveys, auditory surveys, radiotelemetry), we documented the presence of four species of amphibians and five species of reptile in the drawdown zone of Kinbasket and Arrow Lakes Reservoirs. Species documented in Kinbasket included Western Toad (Anaxyrus boreas), Columbia Spotted Grog (Rana luteiventris) and Western Terrestrial Garter Snake (Thamnophis sirtalis). The Long-toed Salamander (Ambystoma macrodactylum) and Western Painted Turtle (Chrysemys picta) were not detected in 2016 (but were in 2015). Western Painted Turtle has been detected from only one location in the drawdown zone (at the KM88 study location in 2015). A Western Painted Turtle was outside of the town of Valemount in 2016, the first record of this species in the region. Although the location of the observations was > 4km away from Kinbasket Reservoir, this detection taken with that of 2015 raises questions about the known distribution of Western Painted Turtle in the region. Species documented in the drawdown zone of Arrow Lakes Reservoir include Western Toad, Columbia Spotted Frog, Pacific Chorus Frog, Western Terrestrial Garter Snake, Common Garter Snake (T. elegans), Western Painted Turtle, Northern Alligator Lizard (Elgaria coerulea), and Western Skink (Plestiodon skiltonianus).

In Kinbasket, Western Toad and Columbia Spotted Frog were the most commonly encountered species, usually in wetlands within wool-grass–Pennsylvania buttercup, Kellogg’s sedge or willow-sedge habitats. Pond characteristics varied by species with Columbia Spotted Frog using ponds situated at higher elevation and with a higher abundance and per cent cover of aquatic macrophytes compared to Western Toad. Western Toad breed in ponds as low as 734 m ASL in ponds that are typically devoid of vegetation or woody debris. It appears that the water physicochemical parameters measured (dissolved oxygen, conductivity, pH, temperature) do not affect distribution, occurrence or development of either species. In Arrow Lakes, Western Toad and both species of garter snake were the most commonly detected species; these species all use a wide variety of habitats and occur at overlapping elevations (434 to 440 m ASL).

Most amphibians and reptile detections were distributed within an elevation range of 744 to 754 m ASL for Kinbasket Reservoir and 435 to 445 m ASL for Arrow Lakes Reservoir. The influence of reservoir operations on the availability of habitat in the DDZ was evident; as reservoir elevations increased, the amount of available habitat decreased and the changes in habitat availability was similar in both reservoirs in 2016. In Kinbasket, a subtle difference in reservoir operations was observed, with a decrease in available habitat earlier in June and subsequent lower reservoir levels through August and September, thus more habitat was available during the late season period than in 2010, 2012, and 2014. In 2016 in Arrow Lakes, it was a slightly different year for reservoir operations with reservoir levels reaching an early peak in June and subsequent decrease, which led to increased available habitat in the late summer and fall as compared to 2012 and 2014. Although more habitat was available later in the season, this did not necessarily benefit amphibians as the crucial period for successful breeding is in June when reservoir levels were high (i.e., breeding habitat was inundated). The continued presence of amphibians and reptiles of all life stages in the drawdown zone in consecutive years suggests that these species are not adversely affected by reservoir operations. However, we do not know if populations of these species are affected relative to non-reservoir populations, and we won’t know that unless suitable non-reservoir populations are studied.

Radiotelemetry was used in 2016 to determine how Common Garter Snakes use habitats in the drawdown zone and the locations of any overwintering sites in the Valemount Peatland area of Kinbasket Reservoir. The results obtained suggest that Common Garter Snakes use marsh areas within the drawdown zone for summer foraging and thermoregulation and then move into upland habitats for overwintering during September. Data obtained from Common Garter Snakes indicate that there are core areas of use that correspond to locations associated with high densities of amphibians (e.g., Pond 12). More data are required to better assess seasonal habitat use by garter snakes in the drawdown zone of Kinbasket Reservoir.