Breeding behaviour of Temperate Zone amphibians is influenced by environmental variables, but the initiation of calling (phenology) and influences on calling activity may vary with species and region. We investigated the influence of the timing of ice melt, water temperature, and photoperiod on the breeding phenology of the Northern Leopard Frog (Lithobates pipiens (Schreber, 1782)) in southern Alberta, Canada, using automated recording units. We also examined the influence of wind speed, relative humidity, water temperature, and time of day on calling activity. The initiation of calling varied by 13 days at our three sites, suggesting that calling was influenced more by water temperature and timing of ice melt than photoperiod. Calling was first observed 8–11 days after ice melt at water temperatures of 7.5–8 °C at our sites. No calling was detected at water temperature <5 °C. We recorded nocturnal and diurnal calling at all sites; >50% of calling was diurnal, even on days with warm overnight temperatures. Calling activity was influenced by time of day, water temperature, wind, and relative humidity. Our results suggest that date of initiation of calling varies considerably among breeding ponds and that the time of day of peak calling varies with both site and water temperature.
Effect of glucocorticoids on expression of cutaneous antimicrobial peptides in northern leopard frogs (Lithobates pipiens)
