Surveying and Trapping

Surveyors looking for egg masses.

.. and the frogs are finally out!

They're late this year, given the late late spring. Frogs started breeding at one of the wetlands around March 14th, about as late as it gets. Breeding season means that surveyors are out in full force, searching for and counting egg masses in known breeding locations and new.

The main egg masses you'll see in a wetland at this time of year are northwestern salamander egg masses and red-legged egg masses. If you know where to look, you might even find some Oregon spotted frog egg masses.

Oregon spotted frogs in amplexus (male on top).

This year, we're doing some really exciting work to get a good idea of exactly how large the frog populations are: a mark-recapture study at two sites. This project is being run by Amanda Kissel, a graduate student at SFU in the lab of Dr. Wendy Palen. Amanda and her field crew have been out daily for over a week trapping frogs in amphibian traps, marking them individually with Passive Integrated Transponder tags (like the microchip in a dog). By recapturing a proportion of the frogs each day, she'll be able to determine an approximate size of the entire population. Up until now, we've had to rely on counts from egg masses to determine the number of breeding females in a population. This year, we'll be able to approximate the number of males in the population and as long as we keep trapping in future years, the estimates will get more and more accurate. So far, they've captured over 80 frogs - larger than our original population estimate!