|Our favorite amphibian pond in daylight hours|
Last night Glen and I went on a herp walk. “Herp" refers to herpetology, the study of reptiles and amphibians: in this case, salamanders and frogs. We wrote in our blog at Thanksgiving about our driving ambition to see a big night: one of those special times when herds of salamanders and/or frogs migrate into the breeding ponds for the spring. We haven’t had a big night yet, but we are definitely seeing signs of movement.
In pursuit of this obsession, we’ve been going out about once a week, whenever the weather looks promising. Last night’s weather was primo: temperature 51 degrees, half an inch of rain in the last 20 hours and when we left the house, coming down in sheets. This is amphibian migration weather.
We drove out to one of our favorite sites not far from our house: on the east side of this country road are some healthy freshwater ponds, while on the west side of the road is a dense patch of evergreen trees. Many of our local amphibians live a two part life; in fall and winter they hide out in sword ferns, under rocks or rotten wood or in rodent burrows deep in these evergreen forests. But come mid-late winter, with warming temps, increasing daylight and a Pineapple Express rain storm right out of tropical Hawaii, the amphibians are lured out of their winter homes and head across the road to the breeding ponds. These seasonal migrations lured us too, out of our warm house on a nasty winter night.
Bundled up in rain gear, layers of fleece, reflective vests and juggling flashlights, we walked the road between the woods and the breeding ponds. Right away we saw our first amphibian; a Northwestern Salamander Ambystoma gracile leaving the woods and heading across to the pond.
|Northwestern Salamander Ambystoma gracile|
You can identify this salamander by several key field marks: it is a uniform dun brown on top and white-gray underneath. It has fat parotoid glands at the base of the jaw on either side: these glands have a concentration of pores capable of excreting a milky mixture of poisons and irritants as a defense against predators. Northwestern Salamanders are also quite stout and have strongly marked grooves along their ribs.
We turned it over to check its gender: it squirmed and did not make the job easy but we saw that it was a male by the swollen genitalia at the base of the tail.
|Northern Red-legged Frog Rana aurora|
Further on Glen was surprised to see our first frog of the season. This was a Northern Red-legged Frog Rana aurora . It played possum as we walked up, but was docile and cooperative as we moved it off the road and over the pond. Up until a couple of years ago, I thought our only local species was the Pacific Chorus frog. When we saw our first Northern Red-legged frog a couple of years ago, it was a real thrill. This frog reminded us of that first sighting.
We continued to walk down the road. This road is well-traveled and on this night, we had to move aside for more than 20 cars ( I was very happy for our reflective vests). It’s obvious that cars are heavy users of this road: we counted 25 or more carcasses of amphibians that failed to make a safe crossing. We saw one squashed Northwestern salamander female; we knew she was a female because as she was hit she extruded a jellylike mass full of unfertilized eggs.
Northwestern salamanders may live five years. They show site fidelity, which means they like salmon always return to the same waters to breed and produce young. Twice a year they must make these migrations: from woods to ponds and back again. This means as many as ten crossings in their lifespan. For “our” salamanders at this pond, this is an incredibly risky lifestyle. As we walked this road and kept a watchful eye, Glen remarked on the depressing nature of this field work and I concurred.
|Amherst MA, Henry Street Salamander Tunnels|
The night got darker and wetter. We returned to our warm house, where I sat by the furnace and watched steam rise from my sodden clothes. I thought of the amphibians we had seen, who heed the ancient call of their kind, leaving the safety of the woods for the breeding ponds and for future generations. On these dark nights, I pray for their safe passage.
• Northwestern salamander photo by D. Hagin from Washington Herp Atlas, (The Washington Heptofaunal Atlas Project).
• Northern Red-Legged Frog photo by Nancy Partlow
• California Herps - Salamander Life History, Amphibians and Reptiles of California
• Searching for Salamanders and Frogs, by Rob Schanz, Chehalis River Council, Rob surveys for amphibians for Stream Team.