Clutch Size in the Great Basin Spadefoot (Spea intermontana), South Okanagan Valley, British Columbia, Canada

Breeding wetlands and upland terrestrial habitat used by the Great Basin Spadefoot (Spea intermontana) are under intense pressure from the expansion of agriculture, urban development, and loss of grasslands throughout the species range (AmphibiaWeb 2012). At the northern edge of the Spea intermontana geographic range, the British Columbia population of the Great Basin Spadefoot is designated as a threatened Species At Risk (BC Southern Interior Reptile and Amphibian Recovery Team 2007; Committee on the Status of Endangered Wildlife in Canada [COSEWIC] 2007). In the South Okanagan Valley, British Columbia, approximately 90% of wetlands have been lost (Lea 2008). In the lowland Valley (,450 m elevation), metamorphic success of Spea intermontana has been observed in natural ephemeral wetlands, small agricultural ponds, and diverse anthropogenic sites (Ashpole and others 2012). Spadefoot developmental adaptation (either a delay or an increased rate of metamorphosis) in response to the larval habitat has been attributed to resource availability and consequently fitness (see overview by Morey and Reznick 2004). Morey and Reznick (2004) report wild populations of Spea intermontana development ranging from 36 to 60 d. In a comparative resource study, Spea intermontana metamorphic development was slowest (41 d) in individuals with the lowest food availability (Morey and Reznick 2004). Spea intermontana clutches are described in standard field guides as containing few eggs (5 to 40 eggs/clutch) in a randomly shaped grape-sized cluster, where 1 egg can easily be detached from the group (Corkran and Thoms 1996; Cannings and others 1999; Jones and others 2005; Matsuda and others 2007). Here we describe large clutch sizes of Spea intermontana not previously documented in the scientific literature or field guides. Egg clutches were oviposited in 3 human-made ‘ephemeral’ breeding sites, including a swimming pool (Site A), a constructed agricultural retention pond (Site B), and a cement irrigation ditch (Site C). Additionally, road kill samples of Spea intermontana provide a broader range of possible fecundity rates, and skeletocronology suggests that reproductive maturity occurs at 1 y of age.