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​Volume 30 No. 1 Winter 2005

A Long Winter's Nap

Amphibians & Reptiles Sleep It Off

Surviving winter’s chill requires special adaptations for animals whose body temperatures fluctuate with the environment. At this time of year you can walk across the surface of a lake on thick, hard ice and your feet crunch in the cold snows of deep winter. Ice and snow – these solid forms of water hide from our view the animals that lie dormant in the cold.

A Very Cool Community

Beneath the frozen surface of Wisconsin’s lakes and in the snow-covered forests and swamps sleeps a very cool community of amphibians and reptiles. Their disappearance is hardly noticed for it is easy to forget about these silent "cold-blooded" critters during the winter months. But they are biding their time, quietly waiting out the months when frigid air and water temperatures slow their metabolic rate to a standstill. Hibernation (from the Latin word hiberna meaning "winter") is the word used to describe the wintertime inactive stage of both warm-blooded and cold-blooded animals. Amphibian and reptile hibernation (sometimes called "brumation") is possible because of marvelous adaptations. Some amphibians and reptiles are even able to withstand freezing! How do they cope with these severe winter conditions? Not every Wisconsin amphibian or reptile species overwinters in the same way, but there are some general patterns.

As autumn sunlight dwindles and temperatures start to fall, frogs such as the leopard frog, green frog, and mink frog feel the urge to swim to the bottoms of ponds and lakes. They rest on the bottom or may even partially burrow into the mud. Their highly specialized skin allows them to breathe by taking in oxygen through their skin and giving off carbon dioxide in the same way. The moist film on their thin skin allows respiratory gases to dissolve and diffuse in and out of the blood capillaries. These deepwater hibernators need to have water deep enough so that the ice will not freeze all the way to the bottom and the water must contain just enough dissolved oxygen to meet their needs. Their metabolic rates are so low that they do not feed, but very slowly use a reserve of stored energy.
Occasionally there are "winter kills" of frogs where the oxygen levels at the pond bottom are insufficient to sustain them.

Another Wisconsin amphibian that spends winter in deep water is a large aquatic salamander called a mudpuppy. Unlike some frogs, this strange looking amphibian remains relatively active and even feeds during the winter. People ice-fishing occasionally catch them!
Reptiles such as the painted turtle, snapping turtle, and Blanding’s turtle also spend their winters under deep water. They too require oxygen, but their skins are not as capable of exchanging gases as the amphibians. A turtle survives this dilemma by taking water into its mouth and cloaca (the termination of the urinary and digestive systems). Here, the skin lining the throat and cloaca is capable of exchanging enough oxygen and carbon dioxide to sustain the low metabolism.

Hibernation Hiatus

Some amphibians hibernate on land by digging their way down below the frost line to avoid freezing. In autumn, the American toad burrows his way down by pushing earth with his hind feet. Down, down, down to three feet or more. The spotted, blue-spotted, and tiger salamanders go deep too, but they tend to use abandoned burrows or other natural holes. These salamanders are sometimes called "mole salamanders" because of their propensity to use burrows. Once they are deep enough, they go dormant and wait until the warming soils of spring signal the end of their rest. These deep-soil hibernators, like the deep-water hibernators share a common trait: if they freeze they die. Changing climates with less snow to insulate the soil, and cold temperatures could impact these deep-soil hibernators.

Frozen Frogs

A few frogs native to Wisconsin have the amazing ability to withstand freezing. The wood frog, chorus frog, spring peeper, gray treefrog, and Cope’s gray treefrog can simply freeze solid! As late fall approaches, individuals of these species lay on the forest floor, under leaves and debris. When the temperatures dip for extended periods to below freezing, much of the water in their bodies (more than fifty percent) will freeze. During this time the frog does not breathe nor does its heart beat. Brain activity is immeasurable. The frog appears to be dead and rock-solid. Despite this apparently terminal condition, as temperatures warm, the frog awakens to spring. This feat is accomplished by an intricate metabolic process that results in high levels of sugars and sugar alcohols in the frog’s tissues. This sugary mix acts as an antifreeze agent protecting the delicate cells in the body. Ice forms around the outsides of the frog’s organs, but the thicker fluid in the individual cells does not freeze, and the fragile cellular structures remain intact.

As scientists have studied the freeze tolerance phenomenon, they’ve discovered that some reptiles also have this capability. Delicate hatchling painted turtles overwinter on land by surviving freezing. Garter snakes are freeze tolerant too, although they are not quite as hearty as their amphibian cousins when it comes to long bouts of freezing. Of course, a huge variety of invertebrate animals (such as insects, spiders, and slugs) are freeze tolerant, but that’s another article.

As you sit in front of a warm fire in your den this winter, take a moment to marvel at how amphibians and reptiles pass their time during this frigid season. Before long, the first spring peeper choruses will alert us that the season has changed. Leopard frogs will once again snag passing damselflies and painted turtles will crawl up on logs to capture the sun’s warmth. Their adaptations have allowed survival through another long season of freezing temperatures.

By Dean Premo, President and co-founder, White Water Associates, Inc.

Dean has a doctorate degree in zoology with an emphasis in herpetology (the study of amphibians and reptiles). With his wife and two children, Dean performs folk and traditional music as the family band White Water.

Hats Off to Crew V

Crew members of the fifth Wisconsin Lake Leaders Institute completed their training this fall with a memorable graduation at the Aldo Leopold Shack near Baraboo. DNR Secretary Scott Hassett, Interim Dean of UW-Stevens Point College of Natural Resources Christine Thomas, and WAL vice president Jim Abbs all attended the graduation.

This group of lake stewards spent six days together over the past year learning about lake ecology, local and state government, and leadership skills.

Since its inception, 160 participants have graduated from the Lake Leaders Institute and have made significant contributions in resolving a host of diverse water management issues.

Meet these Crew V graduates and other lake leaders at this year’s Lakes Convention in Green Bay. More about the Lake Leaders Institute and those who have participated in Crews I through V can be found online at
Join us in congratulating these special leaders of Crew V who are willing to make a commitment to Wisconsin lakes, participate in the decision-making and assist with our state’s water issues...

Larry Bresina, LeAnn Colburn, Lisa Conley, Dennis Cullen, Reesa Evans, Ann Heuschele, Derek Hoffman, Mary Jo Knauf, Mary Knipper, Chris Krieg, Terri, Lyon , Sam Lewis, Emily Lund, Barry McLeane, Paul Maulberg, Meg Marshall, Peter Murray, Cyndi Neeb (Crew IV), Jim Neeb (Crew IV), Don O’Keene, Dave O’Malley, Marlo Orth, Gordon Philip, Scott Porter, Carolyn, Scholl, Teresa Scollon, Susan Sharkey, Dennis VanderWerff

Mixing Milfoil

Eurasian & Northern Water Milfoil Create a Hybrid

There is an aquatic plant that most people who like lakes have heard of…a plant that can cause apprehension...Eurasian water milfoil (EWM). Now there is another wrinkle in the life of this tenacious plant. It seems to have developed a hybrid with Northern water milfoil, one of the "good plants."

Researchers know that water milfoils produce seeds, but they believe that most of these seeds do not germinate. It is considered even less likely that a seedling would live long enough to produce a viable plant. Somewhere, somehow, Northern water milfoil and Eurasian water milfoil cross-pollinated and viable seeds were produced. Thus a hybrid plant came into existence.

Researchers do not know where this hybridization took place or how it is spreading. DNA testing in 36 Wisconsin lakes found the hybrid living in sixteen of them. In the case of Pine Lake in Forest County, it has probably been there for years. The hybrid does not seem to be aggressive and is not forming large beds.

Since water milfoil spreads via plant fragments, we may be transporting hybrid fragments from one lake to another or maybe the hybridization is occurring in many lakes at the same time. If all the hybrids are of the same genetic stock, it would be convincing evidence that the plant is being spread via transportation as a fragment. If there is genetic variability in the hybrids, it would lead us to believe hybridization is happening on its own in different lakes.
DNA testing is the only sure way to tell if you have the hybrid milfoil. The hybrid does not canopy like EWM. In fact, researchers have not found specific characteristics that fit only the hybrid – it seems to have a combination of characteristics of both parent plants. Because of factors that can be unique to an individual lake such as nutrient levels, water clarity, and water depth, even the same species of water milfoil often look different from lake to lake. To make it even more confusing, water milfoils, like many plants, display variances even on the same plant. Looking at a single water milfoil plant you will find that the leaves often have different counts of leaflets depending upon where you pull the leaf from the stem. It is quite common for the lower leaves to have fewer leaflets per leaf. That is why there are ranges on leaflets in the plant taxonomy keys. EWM has leaves with "more than" 12 leaflets on each side of the leaf. Northern water milfoil has "11 or fewer" leaflets on each side of the leaf. These are general guidelines, however, and you can certainly find Eurasian water milfoil plants with less than 12 leaflet pairs and Northern water milfoil plants with more than 11 leaflet pairs per leaf.

We will need more studies to better understand the hybrid. Researchers will look at the effect of chemicals on the hybrid, how easily EWM plants cross-breed with Northern water milfoil, and if the water milfoil weevil will control the hybrid. We do not know if the hybrid is more or less aggressive than the native Northern water milfoil. History has shown that human impacts on aquatic systems (such as the introduction of EWM) can have major consequences…with luck this milfoil hybrid will prove harmless.

AIS Workshop Opportunity

With the growing concern over the spread of aquatic invasive species to Wisconsin’s inland lakes, many lake association members and other concerned citizens are looking for ways to get involved.

To address this need, the Wisconsin Lakes Partnership is offering workshops through their Clean Boats, Clean Waters Volunteer Watercraft Inspection Program. In 2004, over 350 volunteers were trained to perform watercraft inspections to educate boaters on how and where invasive species are most likely to hitch a ride into waterbodies.

How can you get involved?

For more information about the Clean Boats, Clean Waters Watercraft Inspection Program visit For more information on the following workshops contact Laura Felda-Marquardt at or 715-365-2659.

Workshop Dates and Locations

April 9 - Spooner, 8:30am-noon, Agriculture Research Station, Washburn County
April 13 - Crandon, 6-9pm, Crandon Library, Forest County
April 16 - Barnes, 8:30am-noon, Barnes Town Hall, Bayfield County
April 23 - Mercer, 8:30am-noon, Mercer Community Center, Iron County
April 28 - Green Bay, 6-9pm, KI Convention Center, Brown County (see page 14)
April 30 - Green Bay, 8-11am, KI Convention Center, Brown County (see page 14)
May 4 - Manitowish Waters, 6-9pm, North Lakeland Elementary School, Vilas County
May 10 - Rhinelander, 6-9pm, Nicolet College, Oneida County
May 14 - Ashland, time TBA, Great Lakes Visitor Center, Ashland County
May 17 - Amherst Junction, 5-8:30pm, Lake Emily County Park, Portage County
May 19 - Elkhorn, 4-7:30pm, Government Center, Walworth County
May 21 - Waukesha, 8:30am-noon, DNR Service Center, Waukesha County
May 26 - Eagle River, 6-9pm, Northland Pines Middle School, Vilas County
June 2 - Minocqua, 6-9pm, Nicolet College-Lakeland Campus, Oneida County
June 11 - Florence, 8:30am-noon, Resource Center, Florence County
June 16 - Madison, 2-5pm, location TBA-Big Splash Angler Ed. Program, Dane County
June 18 - Barron, 8:30am-noon, location TBA, Barron County
June 21 - Eagle River, 1-4pm, Trees For Tomorrow-Big Splash Angler Ed. Program, Vilas County
June 23 - Cable, 1:30-5pm, Telemark Lodge-Northwest WI Lakes Conference, Bayfield County
July 9 - Ladysmith, 8:30am-noon, location TBA, Rusk County

Additional workshops may be added, please check the website for the latest details:

Grant Rules

Guides for Aquatic Invasive Species Control Grants

There is a growing realization of the potential effects of aquatic invasive species (AIS) on Wisconsin’s waters and therefore, on our economy. This concern has helped to generate state financial support in the struggle to control AIS and limit their spread in our waters.

To assist in guiding the work that will be done with these grant dollars, rules are now in place which will help people interested in managing invasive species in their lakes or rivers. The Wisconsin legislature directed the Department of Natural Resources (DNR) to write rules (NR 198) that establish procedures to award cost-sharing for Aquatic Invasive Species Control Grants. These grants are available to public and private entities for up to 50% of the costs of projects to control invasive species. These monies are available to conduct projects on all waters of the state, including lakes, rivers, streams, wetlands and the Great Lakes. The grant projects are broken down into three major groupings:
  • Education, prevention and planning
  • Early detection and rapid response
  • Controlling established infestations

Eligible Sponsors

Any entity that is eligible for a Wisconsin Lake or River Planning or Protection Grant is also eligible for an AIS Control Grant. This includes units of local government, tribes, lake protection and rehabilitation districts, qualified lake associations, qualified river management organizations, nonprofit conservation organizations and qualified school districts. However, first priority will go to units of local government.

The state will pay up to 50% of the cost of a project, with caps of:
  • $75,000 for education, prevention and planning
  • $10,000 for early detection and rapid response
  • $75,000 for controlling established infestations
The remaining 50% must be provided by the local organization in the form of cash, time, services, or "in-kind" items. These grants operate on a reimbursement basis.


Applications for education, prevention and planning projects and established infestation control projects are due by the first of February and August of each year. Early detection and rapid response grants are offered continuously on a first-come, first-served basis, funded in order of approval.

More detailed information on lake Grants can be found at
The DNR can provide help with applications and technical guidance. Private consultants can also assist you. A list of consultants, without endorsements, can be obtained from UW-Extension, College of Natural Resources, University of Wisconsin, Stevens Point, WI 54481 (715/346-2116 or or your DNR Regional Lakes Coordinator.

AIS Control Grants - Qualifying Projects

There are many types of projects that qualify for the Aquatic Invasive Species (AIS) Control Grants. The following list gives you a flavor of what they might be. Details and the actual rule (NR 198) can be found at the UWEX Lakes website at

1. Education, Prevention and Planning
  • Educational programs and distribution of information about AIS. (Note: Projects will be reviewed for consistency with the DNR statewide education strategy and the use of existing publications and outreach materials).
  • Monitoring, mapping and reporting of data about the presence or absence of AIS to provide baseline information and monitor trends in a water body or water bodies.
  • Development of plans for the prevention and control of AIS.
  • Studies or assessments that will aid in the prevention and control of AIS.
  • Watercraft inspection and education projects.

2. Early Detection and Rapid Response
  • Identification and removal, by approved methods, of small pioneer populations of AIS in the early stages of colonization or re-colonization.
  • Control of a re-colonization following the completion of an established infestation control project.

3. Controlling Established Infestations
DNR-approved control activities recommended in a management plan adopted by the sponsor for the control of AIS.
Experimental or demonstration projects following a DNR approved plan.
Purple Loosestrife bio-control projects (no plan approval required).

Help With Your Newsletter

Are you always looking for good articles and pictures for your lake newsletter? Check out the UWEX Lakes website at and click on Editor’s Corner. You will find dozens of articles from past issues of Lake Tides, photos and website resources for your use. Also feel free to call our staff if you have questions about newsletters.


February 23, 2005 - Watershed Planning Conference - Milwaukee. A day focusing on the health of local watersheds and Lake Michigan. For more information: 414-272-5100 or

March 10, 2005 - Early bird deadline for the 2005 Wisconsin Lakes Convention. See pages 8-14 for details and registration information.

March 11-12, 2005 - Wisconsin Aquaculture Annual Conference - A registration packet can be found online at (click on Register Online and scroll down to Wisconsin Aquaculture Conference).
For registration questions, please contact CALS Conference Services at 608-263-1672.

March 30-31, 2005 - Shallow Lakes Forum - Arrowood Resort, Alexandria, MN. The event will focus on the impacts of shoreland development on shallow lakes, subsequent surface water and land use changes, and the policy that goes along with these issues. For more information: or contact Shannon Fisher at 507-359-6073.

April 1, 2005 - Deadline for 2005 Wisconsin Lakes Stewardship Award nominations. See for details.

April 22-24, 2005 - Lake Home & Cabin Show - for details call 888-471-1192 or go to

April 28-30, 2005 - 27th Annual Wisconsin Lakes Convention - Water in Our Veins: Celebrating Lake Volunteers - KI Convention Center, Green Bay.

May 1, 2005 - Grants Deadlines
Lake Protection and Lake Classification Grants
River Planning Grants
River Management Grants


The Wood Frog (excerpt)

I am a frozen frogsicle.
I froze beneath a logsicle.
My mind is in a fogsicle
Inside this icy bogsicle.
My temperature is ten degrees.
I froze my nose, my toes, my knees.
But I don’t care, I feel at ease,
For I am full of antifreeze.
- Douglas Florian
lizards, frogs and polliwogs (2001)
Douglas Florian is a nationally known children’s author and illustrator. His latest book is zoo’s who.

Lake Tides -- 905032

College of Natural Resources
University of Wisconsin
800 Reserve Street
Stevens Point, WI 54481
Volume 30 No. 1
Winter 2005
Wisconsin Lakes Partnership

Published Quarterly
Phone: 715-346-2116
Editors: Mary Pardee, Robert Korth, Tiffany Lyden
Design Editor: Amy Kowalski
Contributing Editor: Carroll Schaal, DNR
Photos by: Robert Korth (unless otherwise noted)
Illustrations by: Carol Watkins, Chris Whalen
The contents of Lake Tides do not necessarily reflect the views and policies of UW-Extension, UWSP-CNR, the Wisconsin DNR or the Wisconsin Association of Lakes. Mention of trade names, commercial products, private businesses or publicly financed programs does not constitute endorsement. Lake Tides welcomes articles, letters or other news items for publication. Articles in Lake Tides may be reprinted or reproduced for further distribution with acknowledgment to the Wisconsin Lakes Partnership. If you need this material in an alternative format, please contact our office. No state tax revenue supported the printing of this document.

©1993- University of Wisconsin-Stevens Point