In the field with Dr. Allison

In early March, we set up automated call recorders in six amphibian study sites where we are monitoring the amphibian response to oak woodland restoration, and working to expand wood frog reintroduction to three restored sites using translocation of egg masses. The call recorders can be programmed to record sounds for three hours after sunset. The recorder data are in the form of spectrograms that show us the frequencies and duration of sounds in the environment. We can use these spectrograms to determine which frog species are calling on a given date.

We began sampling for amphibians migrating to the breeding ponds in mid-March. The challenge is that wood frogs are “explosive breeders,” so they may call for between two nights to about seven or eight nights. Their emergence time varies with location, year, and site conditions, so while we typically await those warm spring rains, some ponds are heavily shaded and take longer to thaw. Wood frogs overwinter in little burrows called “forms” in the substrate beneath the leaf litter. If the soil stays frozen in a more shaded site, it will take longer for the frogs to emerge and arrive at the breeding pond. Because all of the activities of amphibians are dependent on ambient temperature, we have different pond arrival dates across study ponds depending on forest canopy cover and pond canopy cover.

We have a new intern, Melissa, working with us to sample amphibians and help collect data for the reintroduction effort. In her first week (3/22-3/26), wood frog breeding commenced so we have had our hands full conducting photo-recapture and measuring all frogs and salamanders encountered. We began egg mass surveys this week, and we will be conducting egg mass translocation to reintroduction sites next week. We place the translocated eggs in pop-up laundry hampers to obtain hatching rates, and survival rates of tadpoles to metamorphosis.

One interesting observation (included as a photo here) are the gartersnakes cueing in on the amphibian breeding activity. We often see the newly emerged gartersnakes, still muddy from overwintering, patrolling around the breeding ponds where there is a lot of frog activity. The snakes will swim through the pond and position themselves on logs to catch frogs as they are distracted by calling or breeding.