Calvin the Salamander Returns!
Calvin and his kin depend on two things for their survival: forest and fishless ponds.
Most evenings in April find me pondside, observing the behaviour of spotted and Jefferson salamanders. This year I did metaphorical backflips when I encountered Calvin the piebald salamander once again. I wrote about Calvin last year – a striking piebald spotted salamander now at least 14 years old.
I mused in last year’s column about Calvin’s ability to find his pond every year. As a spotted salamander he may walk 500 metres or more to get there. I wondered if Calvin used scent or magnetic fields to find his way. Calvin’s homing ability is incredibly precise for he returns not only to the same pond every year, but to precisely the same spot in that pond – an area no larger than a typical bedroom. I’m baffled.
Calvin, a male spotted salamander, deposits bright white packets of sperm on the pond bottom to be picked up by a female salamander in her anal vent or cloaca. These salamanders practise safe sex – no intimate contact for them. The females then lay beautiful egg masses, with each embryo surrounded by a distinct protective membrane.
Larvae hatch in about a month and become voracious ambush predators on the pond bottom. They are easily distinguished from frog tadpoles by the prominent feathery gills on the sides of their heads.
Then in mid to late summer, if a drying pond hasn’t claimed their lives, they transform into air-breathing juveniles and leave the water to live on land. Two or three years later, they return to the pond as adults to breed for the first time. As Calvin has taught me, they may reprise this incredible annual journey for more than a decade.
Calvin and his kin depend on two things for their survival: forest and fishless ponds. Where these exist in concert, you’ll find salamanders. For Calvin’s sake, and for the welfare of myriad other animals, we need plenty of both.