A Booming First Half of Our 10th Year of the Mountain Yellow-legged Frog Program

We thought 2016, our 10th year, was going to be a quiet year for our frogs. We had a big year last year producing more offspring than ever before and a review of previous years’ reproductive data suggested that, well, the female mountain yellow-legged frogs (MYLF) may only invest in producing eggs every other year or possibly every third year. We were wrong. 

This spring, we brought frogs out of hibernation and reproduction was off the charts. As we told you in our last blog, as of the end of May we had over 7600 eggs produced this year and around 2000 tadpoles. Well, the females kept laying and by our final count, we had over 2300 embryos and we expect around 80% survival for a whopping 1850+ tadpoles produced. Frogs are cool!

With all this success we are now in a pickle. They grow fast, I mean lightning fast. And, only weeks after they hatch, if densities in our frog facility are too high, they’ll start eating each other – uhh…  not so cool…. So, we had to make plans quickly for reintroduction. 

Together with our MYLF partners, we released our first group of MYLF into lower Dark Canyon within the San Bernardino National Forest at the end of May. California Department of Fish and Wildlife biologists recently removed introduced trout from the lower reaches of this creek making it ideal habitat for frogs again. This release group was made up of 111 metamorphs that were produced in captivity last year. Metamorphs take up more space than the tads so this release gave bought us time to let the tadpoles grow for a few more weeks before having to release some of them. 

On the morning of the release, we arrived at the frog room at 5:30am to setup, count and get frogs into buckets of ice-cooled water for transport. Tops are zip-tied on to make sure that no one escapes. Once at the site, we look for the best frog pools--those will the deepest water and lots of crevices provide the best chance for the frogs to hide from predators and to have water through the dry months. 

As soon as we selected the pools we divided the frogs and made our way to the water’s edge to acclimate them to the creek water temperature and ph. When temps and ph are similar, we gently dump the frogs into the pool. Waalaa! Now its up to the frogs.

Because the frogs can change color to match their background, they come out of the white buckets very light in color and it’s easy to find them when released, which could make them easy pickings for predators like ravens, scrub jays and raccoons.  The good news… almost immediately they found a crevice, hid in the creekside vegetation, found safety in numbers, or sought out a light background for camouflage.  We’ll be surveying the site several times this summer to assess success. Stayed tuned for more updates on the frog program.