Driftless Terroir: An Accidental Tree Frog Eco-Rescue Adventure

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Debi Morton

by Debi Morton

It had been a rainy May and June. My husband, Michael, and a friend were emptying puddles of water to prevent mosquitoes. They went out to our pickup parked in the field borderi

ng the woods next to the solar array, to move it to dump any water that had collected in the bed. The bed of the truck had up to 6 inches of water. Before he got into the truck to move it and dump the water, they noticed hundreds of tadpoles. Thus began our adventure.

The sun was beating down on the black truck bed and the water was 98 degrees. Too hot for the  tadpoles. Michael added cool water slowly over a period of hours so as not to shock the tads. He then put plywood over the truck bed to provide some shade, added netting to prevent access by bird predators, and added a live well aerator for more dissolved oxygen. There was only algae for the tads to eat. He went to a nearby pond and collected buckets of duckweed. The very young tadpoles eat duckweed roots and the duckweed regenerate the roots. We were just buying time to decide what to do with all these potential frogs.

The next morning, Michael went out to the truck to see how everyone was doing and was shocked to see that the duckweed was almost completely gone! Our efforts were reinforced and thus we were drawn into nurturing all these guys. The tadpoles grew rapidly and needed a more substantial food. Microwaved lettuce leaves did the job.

Next step was to create a little more habitat since some of the tads were getting legs and needed ground. Rocks were added and the water levels were watched daily and maintained so there was a deep section and a slopping shallow area. The tadpoles were eating machines and 30 gallons per day of fresh water was required to offset the tadpole manure. Michael being the scientist and engineer that he is, immediately wanted data. I was just having fun watching the tads grow. Michael got out his underwater video mini-cameras and placed them in the deep end. Every book on pond life published in the last century in the United States or the United Kingdom appeared on our table. (The best was from 1930, by Ann Haven Morgan, professor and chair of zoology at Mount Holyoke College. Morgan was one of only two female scientists listed in the 1933 listing of 300 American scientists).

What ensued was amazingly interesting and not at all what we had expected or perhaps anticipated. Over 10 weeks, 1.3 terabytes of high-definition video was collected and edited to add to our understanding of the natural history of an eastern gray treefrog.

An entire ecosystem had emerged full blown with the tadpoles, nearly every native aquatic insect on the water and aquatic insect larva in the water, snails, a variety of plankton and algae. The carbon for the ecosystem had been provided by the detritus of gathering firewood. Tiny snails appeared plus a variety of unicellular plant and animal life. Eventually, tree frogs emerged one to three at a time, day after day, the males first and the females last. Every day we monitored the scene and brought lettuce to replace that which had been eaten. We would watch the video of that day’s developments to experience this underwater world and observe how things were growing. Sometimes the camera would capture a frog swimming directly at the camera and you could see their facial expressions. After about four weeks, tiny tree frogs started climbing the side of the truck bed and sitting on the edge or hanging out on the rocks. After a day the adults would be gone and a new batch would emerge. As the days went by the number of swimmers was diminishing, more adults were waiting their turn to escape the aquarium and find the woodland. Within about eight weeks nothing was left in the water. Magical!

Let us all be reminded how our amphibian friends are critical to our environment and are bellwether to change. Protect the Driftless!

Post Script: During this time, video segments of the aquatic insect life were shared with the University of Wisconsin for species confirmation. With this experience, Michael created a science lesson with his niece, a third-grade teacher, for her students equipped with video and all the paraphernalia required to hatch the frogs. Find the video on YouTube.

Debi Morton lives on the ridge toward Dodgeville and owns Driftless Depot Organic Market, Deli & Café in Spring Green. She is a lifelong foodie, chef and advocate of eating seasonally. Debi and her husband, Michael, are also organic and biodynamic growers of fruits and vegetables — Driftless Area caretakers for 38 years. To contribute to Driftless Terroir, e-mail info@voiceoftherivervalley.com.

The Eastern Gray Tree Frog

Excerpts from “The Natural History of Amphibians and Reptiles of Wisconsin,” by Richard Carl Vogt, 1981

Size: “Largest gray treefrog in Wisconsin. Males range from 4-5 cm. Females slightly larger and lack the vocal pouch. Color varies from gray, brown, light green, dark green with dark blotches and usually one large middorsal blotch, X or star shaped. Dark leg bars are also present. Juveniles tend to be all green with no dark spots. It takes two years to come to full maturity.”

Trill: “A beautiful call. They have a slow melodic trill. Trill rate is 14.8-29.0/sec at 18-26 degrees C. The warmer the temperature, the faster the trill rate. Summer rains induce calling.”

Range: “Covers most of eastern United States from Ontario and southern Maine to the Gulf of Mexico.”

Habitat: “Abundant in southern mesic hardwoods, southern and northern lowland forests, boreal forest and northern mesic and dry-mesic hardwoods.

Habits: “Females lay up to 2,000 eggs or in loose clusters of up to 30 eggs attached to vegetation near the surface of ponds. Eggs hatch in three to six days. Tadpole metamorphosis six to eight weeks. Then disperse into the fields and surrounding woodlands up to 10 m off the ground foraging, feeding on small invertebrates.”