Tuesday, October 20, 2009

Your Long-toed Neighbors

Presenting the handsome, long-toed salamander -- probably the most common amphibian in western Montana. What, you've never seen one? Well that's probably due to your unusual habitat use. You evolved to live above ground and be active during the daytime ("diurnal"), just the opposite of our four-inch long, subterranean and nocturnal neighbors. As a result, we don't notice each other very often.

Adult long-toed salamander (c) John Ashley
As adults, long-toed salamanders spend most of their lives burrowed below ground. They live in moist niches like decaying logs, rock fissures and small animal borrows. On summer nights, they'll climb to the surface to eat worms, spiders, insects, and other tasty morsels. Here in Montana, they hibernate through the winter, apparently burrowing down deeper.

In early spring, they'll often migrate across snow to reach their breeding ponds, marshes and lakes. Determined salamanders will converge on the breeding sites from up to half a mile away, but an estimated 95% of adults live within 200 meters of their breeding pond. (Dispersals, on the other hand, can sometimes cover great distances. Genetic research from southwestern Montana has shown that salamanders are capable of moving between ponds that are seperated by mountain ridges.)

The first ones to reach the breeding ponds are adult males, who then court the females as they arrive a week or so later. The handsome male will rub his chin on hers -- in that seductive, salamander way -- encouraging her follow him and pick up a spermataphore that he then deposits in the shallows. How could she resist?
Fertilization is internal and she'll soon lay several hundred eggs in multiple masses, anchored to plant stems in water 2-3 feet deep. The adults return to land and, in 3-4 weeks, larval salamanders hatch out, spread out, and hide out in the aquatic plants and debris along the pond bottom.

This aquatic, larval stage may last from several months to several years, depending on water conditions and food availability. These youngsters are about two inches long and look like tadpoles with legs. They sport three pairs of feathery gills branching out from either side of their rather large head.

During metamorphosis, the larval gills are absorbed and the salamanders emerge from the water as air-breathing juveniles. They move uphill during rainy nights, away from the pond. These juveniles will reach sexual maturity 1-2 years after metamorphosis.

Montana's long-toed salamanders may live for 5 or 6 years, while lifespans of up to 10 years have been reported in warmer parts of their range. The species ranges from southern Alaska to northern California, between the Pacific coast and the Rocky Mountains. The spotty populations have managed to occupy a wide range of habitats, from semi-arid sagebrush deserts to sub-alpine meadows.

Canadian road signSalamanders must negotiate a wide range of obstacles, both natural and man-caused. For example, severe drought can cause 100% larval mortality if the breeding pond goes dry. The predators of larval salamanders include fish, dragonfly larvae and (non-native) bullfrogs. Adults are eaten by voles, garter snakes and Kingfishers.

Non-native fish introductions cause big problems for Montana's little salamanders. Over the years, more than 50 species of non-indigenous fish have been introduced to our state. Almost half of our 1,650 high elevation ponds and lakes -- waters that were historically fish-free -- now contain non-native salmonoids. These fish now dominate areas where larval salamanders used to be the top of the aquatic food chain. While introduced fish have extirpated native salamanders in some Montana lakes, salamanders have also recolonized a few lakes after non-native fish were removed.

Another potential problem for salamanders is maintaining a migration route between upland habitat and breeding areas. A good example of this occurred in Glacier's sister park, Waterton National Park.

Salamander tunnel in Waterton National Park (c) Parks CanadaA population of long-toed salamanders went unnoticed in Linnet Lake, until concrete curbs were added to the adjacent road in 1990. The following spring, hundreds of salamanders migrating downhill towards the lake couldn't climb the curbs, and they became trapped in the road. During one week in April 1992, community volunteers manually lifted more than 2,000 salamanders over the curbs during cool, rainy nights. So the considerate Canadians -- having evolved much further along in their wildlife ethos -- lowered the curbs and built four salamander crossing tunnels under the road. As a result, salamander mortality from cars fell from 44% to 0%.

Happily, that population of long-toed salamanders has gone back to being virtually unnoticed by their diurnal neighbors.

Behind the lens: We had some help noticing this salamander during migration, about 75 feet from the lake. When we first met him, he was halfway down the throat of a 12-inch long, writhing garter snake. On seeing us, the snake dropped the salamander and disappeared. The salamander didn't appear too injured, so we hid him under some woody debris near the water's edge, and wished him well.

Note that, unless it just fell out of a snake's mouth, you should avoid picking up or touching wild animals.