Asynchronous breeding and variable embryonic development period in the threatened Northern Leopard Frog (<em>Lithobates pipiens</em>) in the Cypress Hills, Alberta, Canada: conservation and management implications

Abstract

. 2014. Asynchronous breeding and variable embryonic development period in the threatened Northern Leopard Frog (Lithobates pipiens) in the Cypress Hills, Alberta, Canada: conservation and management implications. Canadian Field-Naturalist 128(1): 50 -56. understanding breeding phenology is critical for establishing monitoring strategies, comprehending population dynamics, and developing conservation actions for at-risk species, such as the Northern Leopard Frog (Lithobates pipiens). The timing of spawning and hatching in the Northern Leopard Frog may be highly variable depending on regional environmental conditions, which can make establishing the timing of surveys difficult. In spring 2006, eggs were laid over 30 days (24 April to 23 May) and hatching occurred over 2 weeks (14-28 May) at three neighbouring ponds in Cypress Hills, Alberta, Canada. Although spawning occurred over a month, all eggs hatched within a 2-week period, indicating variable embryo development rate. Among 26 egg masses, eggs laid later in the season developed approximately four times faster than those laid earlier, and Akaike information criterion-ranked models suggested that both Julian date and water temperature were important predictors of embryo development rate: later spawning date and warmer water were associated with faster rates. some egg masses survived colder temperatures than previously reported for this species. Asynchronous breeding and variable development rates reveal the need to conduct multiple surveys over the breeding season, even within a small geographic area, to document reliably the presence of egg masses and identify breeding habitat. Identification of key breeding habitat is necessary to mitigate human-caused disturbances of such regionally imperiled species.

Environmental DNA surveys can underestimate amphibian occupancy and overestimate detection probability: implications for practice

“…We surveyed 68 wetlands for northern leopard frogs and boreal chorus frogs during spring breeding season (30 Apr–3 Jun) using 3 different survey methods: environmental DNA (eDNA), automated recording units (ARUs), and time‐constrained visual encounter surveys (VESs). In Alberta, the breeding season for both species typically lasts from late April to June (Russell and Bauer 2000, Kendell 2002, Randall et al 2014). Nighttime auditory surveys and daytime VESs are 2 common amphibian survey methods used by researchers collecting data on population dynamics and for government‐regulated assessment of wetlands (Dodd 2010, Environment and Sustainable Resource Development 2013, Partners in Amphibian and Reptile Conservation 2013).…”

Effects of environmental variables on the calling behaviour of Northern Leopard Frogs (Lithobatespipiens) in Alberta, Canada

“…The breeding calls of L. pipiens consist of a complex series of snores, grunts, and chuckles 1 (Larson 2004) and males usually call while floating in the water (Russell and Bauer 2000). In Alberta, breeding typically occurs in mid-April to late May and occasionally into early June (Russell and Bauer 2000;Kendell 2002;Randall et al 2014). Oviposition typically begins 2-3 days after the initiation of calling (Corn and Livo 1989).…”

Using Decision Analysis to Determine the Feasibility of a Conservation Translocation

“…Conservation translocation programs often involve difficult decisions regarding how and when to act in response to threats impacting at-risk species and ecosystems. Translocation programs typically require considerable resources (e.g., staffing, captive breeding program development and maintenance, postrelease monitoring; Canessa et al 2014, Kissel et al 2017, Hilbers et al 2019; for a discussion of costs specific to this assessment, see Randall et al 2021) and invariably result in those resources not being allocated to other conservation actions or species (Martin et al 2018). Therefore, a proactive evaluation of likelihood of success prior to investing in a conservation translocation is a critical, but generally lacking, step in deciding whether conservation resources should be devoted to translocation of a particular species.…”

“…We undertook a decision-analytic process to assess the feasibility of northern leopard frog reintroduction in northern Idaho (Randall et al 2021). The assessment was initiated in 2019 but the bulk of the work occurred primarily in winter 2020/spring 2021 over a period of six months.…”