by Bill Glass

In the Chicago Wilderness certain animal harbingers of spring are seldom seen, though they've been making pilgrimages on spring nights across the landscape for thousands of years. These elusive creatures are salamanders.

The blue-spotted salamander (Ambystoma laterale) comes in size Medium, adults being 3-5 inches from snout (nose) to tip of the tail. It tends to have a dark background color (dark brown, black or blue-black) with bluish flecks. This salamander is a northern species; its southern range includes the hardwood forests, woodlands, and savannas of Chicago Wilderness.

Blue-spotted salamanders are seldom found above ground except at night during the breeding season. During the day, they stay under cover, in burrows in the ground, under leaves, or under logs in the forests. On warm evenings during breeding season, blue-spotted salamanders can be found migrating to breed in vernal ponds, temporary pools that dry up each year during the summer months. This drying up is important for amphibians like the blue-spotted salamander; it keeps predators such as fish and larger frogs from getting established in the ponds. During the day salamanders hang out near their breeding ponds in moist areas under logs or leaf litter.

The males arrive first at the pond, usually by late March depending on weather conditions. After the females arrive, a sweet little courtship occurs. The male holds the female with his front legs and rubs his chin over her head. Next he deposits a packet of sperm, or spermatophore, on the pond bottom and tries to position the female over it. If all goes well, she will pick up the spermatophore in her cloaca (urogenital opening), and the eggs are then internally fertilized. She lays eggs singly or in small groups on sticks or on vegetation in the pond. The adults leave the ponds and go back to their subterranean existence.

After three-to-four weeks, the eggs hatch into larvae that look somewhat like frog tadpoles, but have a longer body and external gills. After a short period of time, front and rear legs will develop. Over several months the larvae get larger feeding on worms, crustaceans, and insects. Towards the end of their larval period they go through a metamorphosis, lose their external gills, and start to resemble an adult salamander. The actual timing of this transformation depends on food availability and competition. Blue-spotted salamanders are amazingly flexible and transform at different body sizes and varying lengths of larval life. If food is scarce, they'll transform more rapidly. This very strategy allows them to breed in temporary pools. And yet, however long it takes them to transform into adults, they must do it before the pond dries up. In some dry years, they may not make it in time and reproduction will need to wait until the next year or beyond. With a life history strategy like this, the adults must be able to live for a few years to make sure some of them successfully breed.

Some long-time naturalists in this region remember mass migrations of salamanders years ago. In the Palos Forest Preserves of Cook County, hundreds could be seen on some nights crossing the roads and many of these were blue-spotted salamanders. Sadly, these vast migrations seem to be a thing of the past. Many species of amphibians, including the blue-spotted salamander, have decreased in numbers. There are many reasons given for this decline, but habitat loss or habitat degradation is probably the primary one. Recently, there's renewed interest in monitoring the health of amphibians in the Chicago Wilderness area. [For information about becoming a frog monitor, call the Habitat Project at (847) 965-9239.]

This spring, keep an eye out for temporary ponds. Explore the woods nearby slowly and carefully, and you may be rewarded with the discovery of an elusive creature lurking under a log &endash; the blue-spotted salamander. Your neighbor and mine.

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