This column originally appeared in the April 8, 2007 issue of the Poughkeepsie Journal.

Muddy roads, melodious birds, and swelling buds are all traditional signs of approaching spring. Yet, another harbinger receives comparatively little notice ? the awakening of local amphibian life.

During the winter months, wood frogs (Rana sylvatica) and spring peepers (Pseudacris crucifer) persist in a near?frozen state, waiting for the warmth of April. Unlike some other amphibians, these species don't excavate tunnels below the frost line to escape winter's chill.

Instead, the cold?blooded animals drop their body temperature to near freezing levels, and glucose in their tissues acts as an anti?freeze. Now, the rise in temperature is prompting a meltdown.

In mid? April, the high, thin peep of the aptly named spring peeper is the first conspicuous sign amphibians have awakened. Yet, by the time peepers emerge, most wood frogs have already concluded their spring nuptials. Milk?chocolate brown with a black Zorro mask, wood frogs have a subtle call. Unlike the strident tones of the peeper or the bellowing "jug?o?rum" of the bullfrog, their call resembles a throaty chuckle or low quack.

Also early to emerge are yellow spotted salamanders (Ambystoma maculatum). These voiceless animals congregate at local ponds and vernal pools for courtship and breeding. This event may span only a few short nights, and conditions must be exact. Forest?dwellers, salamanders wait for the first mild and rainy evening, when snow has melted and the temperature ranges between 35 and 45 degrees Fahrenheit.

Yellow spotted salamanders are faithful to their traditional breeding sites, returning to them year after year. If moved to another location, captured animals will ignore the new site and return to their home pools. Their spring migration to vernal ponds often requires negotiating a treacherous route. Many salamanders and frogs are killed crossing roadways, which cut through formerly forested landscapes.

In recent years, for reasons not fully understood, many amphibians have shown dramatic population declines. With their permeable skin, these animals are particularly susceptible to the pesticides and herbicides in runoff. Some of these chemicals can affect the development of young frogs at concentrations of less than one part per billion. Acid rain is also suspect, especially when acidified snowmelt alters the chemistry of breeding ponds.

Except in spring, we may not see or hear many amphibians, but we should not overlook their importance.

Arrival of spring's warmth stirs amphibians back to life

Each frog or toad consumes an enormous number of insects during the summer months, reducing our exposure to mosquito bites and the diseases they may transmit.

When we see changes in amphibian populations, we should ask what may tell us about changes in our environment. If frogs in our freshwaters are declining in number or developing abnormally, might there be a consequence for humans?

Interested in learning more about frogs? On April 14, the Institute of Ecosystem Studies is offering Voices of Spring, a free weekend education program. The event will feature a slide presentation and hands?on exploration at a nearby pond.

If you can't attend, but still want to indulge in the melodies of spring, plan a visit to our Millbrook campus. The grounds are open for the season and the Fern Glen is a wonderful place to investigate amphibian life.

Judy Sullivan manages the Fern Glen, an assemblage of native plants surrounding a woodland pond at the Institute of Ecosystem Studies.

If you go:
What: "Voices of Spring," a free weekend education program. The event will feature a slide presentation and hands-on exploration at a nearby pond. A flashlight and rubber boots are recommended.
When: 6 p.m., Saturday, April 14.
Where: Institute of Ecosystem Studies.
Cost: Free.
Where to call: Seating is limited; please call early to reserve your space. Contact Pamela Freeman at 845-677-7600 ext. 121.
The Institute is open from 9 a.m. to 6 p.m. Monday to Saturday and 11 a.m. to 6 p.m. Sunday.
Visit: www.ecostudies.org/visitor_information.html for information.