The past two days have been very busy for the Oregon Spotted Frog Program in Vancouver. The summer of 2016 did not provide us with warm enough temperatures at the right times to allow our frogs to grow large enough for release in the fall. As a result we kept them back and had frogs that had grown an extra season to release this spring. About half of our frogs that we overwintered at the Greater Vancouver Zoo, 100 individuals, got released into the restored wetland in Thursday March 23. Our field team and their two enthusiastic spring break students came to the zoo to help mark frogs and then released them to the wetland that afternoon.
We will be marking the remaining frogs, approximately 100, in the next couple of week and releasing them as well. The extra time spent in captivity served the frogs well. Last fall they were on average under 3 grams, and by this spring they averaged 9 grams! This additional size will give them a better chance of survival versus if we had released them in the fall.
We were also excited the following morning, after the release, to arrive to the zoo to see our first Oregon spotted frog egg mass laid by our captive adult population of frogs. These frogs were retained from 2015 and kept to form the base of a breeding colony at the zoo.
This year marks the first year these animals will be old/large enough to breed. We have seen many animals in amplexus over the past few weeks, which is breeding posture for frogs. We were very happy to see these first eggs. The eggs look very healthy and over the next few weeks we will be able to assess their fertility and watch the embryos develop. Stay tuned for some blog entries about Gosner staging, which is a system we used it to track frog development!