Spring has sprung in British Columbia! While Mother Nature may have played a joke on us on April 1st by sending a blanket of snow, the animals were still on the move and so were we, here at the Fraser Valley Wetland Wildlife program.
The Oregon spotted frog conservation breeding population began showing breeding behaviour back in February, even though there was still ice on the water. As soon as the days began to shorten in the fall, males seek out females and attach themselves to the females’ backs in a pre-breeding position called amplexus. They will stay in this formation until the female lays eggs, sometime in March or early April. The males have black pads on their thumbs, appropriately called nuptial pads, which help them get a strong grip around the female’s neck. Here they are positioned perfectly to allow for external fertilization of the female’s eggs as she releases them into the water.
Ever wonder how such a relatively small frog lays such a large amount of eggs? The eggs are much smaller inside the female and once they are released into the water they swell, reaching their final size. Our frogs will lay eggs throughout April and a month later the eggs hatch. We were off to a great start with 16 egg masses laid at the beginning of April.
Our recovery strategy is to hold back a portion of the tadpoles to raise them over the summer in our facility. This allows us to monitor their growth rate alongside tadpoles we have collected from the wild. We want to ensure that our captive bred tadpoles develop along a similar timeline and produce healthy animals. The rest of the tadpoles will be released to wild populations and restoration sites to bolster the number of individuals in future breeding seasons.
The warm spring weather has also awoken our tiny Taylor’s checkerspot butterfly larvae. These larvae entered diapause (like hibernation for larvae) in mid-August and have not moved all winter. Now they are out and about eating as much as they can. We released 135 larvae to the remaining wild population on Denman Island, keeping back 100 to breed and lay eggs in our program this year. They will shed once or twice more before forming a chrysalis and completing metamorphosis. Once emerged as adults, they have about 4 weeks to breed and lay the next generation of larvae.
Both our frogs and butterflies have a lot they need to accomplish in our short spring and summer, and it seems like they are eager to get going!