Conservation

Turtle Nesting

These are the most commonly asked questions by people during the active turtle season. Answers to these and other questions are found below.

♦Is that turtle lost?
♦What is it doing away from water?
♦Why do turtles lay their eggs on the shoulders of roads?
♦How do I protect the eggs from being eaten by predators?
♦How long does it take for turtle eggs to hatch?
♦Is there anything we can do to help stop turtles from being hit on our highways?
♦Is it legal to collect turtles in Wisconsin?

From late May to early July, female aquatic turtles leave the water to seek an upland site to nest and deposit their eggs. Some map and painted turtles may do this twice a year, while Wisconsin’s other species only nest once a year.  Turtles have a keen sense of direction. They may travel further than 1.5 miles from water to find that “special place” to deposit their valuable cargo.  To think that they are lost simply because they are away from water is incorrect. Some female turtles return to the sites at which they hatched (i.e. their natal nesting sites) to nest themselves after maturing.  Five to 20 years may have lapsed, depending on the species, and the landscape may have changed significantly since they hatched. When human development forces female turtles to look for a new nesting site, they may wander about for hours or even days until they find one that suits them.  Turtles may be opportunistic nesters, taking advantage of freshly disturbed soils where digging is easy. They are even known to use dirt, gravel or mulch piles that are temporarily located on driveways or in constructions areas! In many cases, turtles end up nesting, or attempting to nest, along roadway shoulders.  The results can be disastrous for mom and her hatchlings.

Most turtle nest polishes looks like this
Snapping Turtle nests are messy, so smooth them out before protecting them


It can take some time to learn to detect a finished turtle nest as most species spend considerable time trying to disguise the site by making it blend with the surroundings.  A finished nest will have a circular flat surface called a nest polish that the female creates by pulling soils back into the nest and compacting it over the eggs using the bottom of her shell.  A fresh polish will have claw marks at the outer edge  Snapping Turtle nests are usually quite sloppy, having no polish but having a long mound of soil behind where the eggs are deposited.  The mound is often interrupted by the turtle’s long thick tail.  

If you see a turtle nesting but later find only holes or depressions in the soil, it probably means the female abandoned the site before laying her eggs. She may have left the site if digging conditions did not allow her to complete the nest cavity or because she was scared off by an intruder.  It is best to stay well away from turtles while they nest so they don’t abandon the attempt and waste valuable energy trying to nest again later, which could mean an additional trip across a road.  

Turtle egg clutches can contain few to many eggs.  The endangered Ornate Box Turtle, Wisconsin’s only terrestrial (strictly land) turtle, usually lays 3-4 eggs per year.  Common Snapping Turtles have been known to lay as many as 83 eggs in a single clutch, although 30-50 is more typical. Once laid in their flask-shaped nest cavity, the eggs develop over a period that ranges from about 65-90 days or longer.  The length of incubation is dependent on temperature, with cooler temperatures slowing development. Nests laid in open sunlight hatch sooner than those laid in partial shade. Hatchlings from nests laid later in the nesting season or laid in cool summers may not emerge from the nest until the following spring, actually over-wintering just a few inches below ground level.  The young turtles, fully formed and hatched by fall, produce a glycol-like substance that serves as an antifreeze, and helps prevent freezing of their cells in winter, although their body fluids may freeze. If you find hatchling turtles on land in spring (late April into May), they likely emerged from a nest that overwintered. All other age classes of aquatic turtles must overwinter under water, but can freeze to death during severe winters when prolonged freezing results in excessive cell damage.

Abandoned turtle nest cavity

A remarkable fact about most Wisconsin turtles is that their sex is determined by the average incubation temperature during the middle part of their development.  Warmer temperatures (e.g. >82 degrees F) produce more females while cooler temperatures (e.g. <77 degrees F) produce more males.  It is interesting to note that most turtle populations have a 50/50 adult sex ratio, indicating that warm and cool seasons end up balancing out the sex ratio over time, although other factors likely play a role in this as well.  How climate change may affect this “balance” is unknown. It has also been demonstrated in Wisconsin and elsewhere in the USA that adult turtle sex ratios have been altered (skewed toward more males) by high road mortality of females, which travel on land to nest.  This problem is most evident in areas with high road densities. The Wood Turtle is the only Wisconsin turtle whose sex is not determined by incubation temperatures. Instead, its sex is related to genetics.

Once a female turtle finishes nesting, she returns to the water, leaving her eggs unguarded.  The eggs are extremely vulnerable to predation, especially during the days immediately following nesting.  Once hatched, baby turtles must fend for themselves. They rely on instinct and environmental cues to locate water and food.

Roads- Wolves in Sheep’s Clothing

Roads pose serious threats to turtles.

If you are wondering why roads are so attractive for turtle nesting, the answers are quite simple.  Gravel or sandy roads and gravel road

shoulders that experience a lot of sunshine can be a plus where natural nesting sites are lacking, especially on east-west oriented roads where the sun hits much of the day.  The adjacent pavement of the road surface absorbs heat from the sun and helps elevate the temperature of the adjacent shoulder gravel. Increased heat results in shorter hatching times for turtle eggs, but there is also a risk that the eggs will overheat and die or will be flooded by prolonged days of heavy rain that can also lead to embryo death.  Most Wisconsin lakes, rivers and wetlands have roads nearby, affording a close and “convenient” nesting site.

The downside to nesting on or along roads, or crossing them to find suitable nesting habitat, is obvious to anyone who travels in June and sees the carnage of dead female turtles on our state’s roadways.  The few hatchlings that do manage to hatch have an even tougher time crossing roads on their way to water.

Another disadvantage of nesting along or crossing over roads is that people pick turtles up, either for food or as pets.  Current law prohibits the taking of turtles from the wild, for any reason, from December 1 through July 14 each year. The purpose of this law is to protect turtles from winter and through the nesting season.  The combination of heavy highway mortality and collection of turtles for food and pets has contributed to the decline in turtle populations statewide.

There are some things you can do to help reduce turtle deaths on roads.  Be alert for turtles on roads so you can avoid hitting them, especially during the nesting season (late May to early July).  If it is safe and you won’t put yourself or other people at risk, stop and move the turtle off the road. Always move turtles in the direction they are headed.  If you are not sure which way they were headed, place them on the side where water or wetlands are present, and place them in the water if you can access it.  However, Ornate Box Turtles should never be placed in water. If you find a turtle in the process of nesting along the road, it is best not to disturb it. Disturbing such a turtle can mean another trip across the road.

If you see someone stop to pick a turtle off the road and then drive off with it prior to July 15, please report the activity along with the vehicle license number, to your local Conservation Warden, or call the DNR’s violation hotline at 1-800-TIP-WDNR (847-9367).  If you see someone swerve to kill a turtle along the road please report this also. Intentional killing of this nature is considered a “waste of wildlife” and is punishable by law.

Protection of Turtle Nests

Evidence of turtle nest predation, a serious concern in turtle conservation.

Research shows that turtle nest predation rates have sky-rocketed in recent decades as a result of increased mammal populations, primarily raccoon and fox.  This has resulted in extremely low hatch rates in many areas of the state. Scientists estimate that if this high nest predation continues for a generation of turtles, some of the less common species may decline to levels that are unrecoverable, meaning the species will become extinct in the state, and common species may become much less abundant.  

There are some simple and proven nest protection methods that can be used to improve turtle nesting success.  To protect a nest is often a very easy process involving only a small investment of time and money. If you find a turtle looking for a nesting site or in the process of nesting, be sure to stay well out of sight so the turtle will not abandon the effort.  One challenge is waiting for the turtle to finish its work, which may last from 1-4 hours. Most turtles nest in the evening and may not complete the process for several hours, often after dark. The key is to protect the nest as soon as the turtle finishes refilling and packing the nest.  Nest predators may dig up the nest immediately after the female finishes nesting, although some are bold enough to interrupt the process and may even kill and eat the female. Waiting until the next morning to protect the nest could be too late.

Once the turtle is finished nesting, you may begin your work.  Some turtles will spend minutes to hours creating a nest “polish.”  It is not essential to wait for them to leave the nest site, but be certain they have laid and covered their eggs before moving them off the nest site so you can protect it.  Be very careful when attempting to move Common Snapping Turtles. Pulling them aside by the tail is effective, but avoid lifting them completely off the ground by their tail so you don’t damage the spine.  Once the turtle has been moved or has left the nest site, follow these steps.

  1. Pinpoint the center of the nest.  This can often be determined by finding the center of the nest “polish”.  A fresh nest may also be evidenced by having a nest polish that is damp when the soil around the polish is dry.  Turtle polishes often range in size from 6”-11″ and represent an area that is about 2 inches wider than the length of the turtle’s carapace (top shell).  Be aware that turtles will often dig “test nests” as they search for a suitable site. A completed turtle nest will be smoothly polished and very flat except for Snapping Turtle nests.
  2. Protect the nest.  This can be done in several ways but should always be done with the nest centered under the protection.  

Protection types:

A flat piece of ¼” or ½” hardware cloth (heavy woven-wire mesh) that measures at least 24″ by 24″.

Wire mesh with staples
  1. Center the wire mesh over the nest polish.  If it is a Common Snapping Turtle nest, mark the center of the nest first and then smooth off the uneven surface to match the surrounding ground.  Stake hardware cloth in place using at least three 5″ landscape “staples” along each of the four sides to help keep predators from digging up the nests.  A downside to placing the wire directly on the ground is that it will need to be lifted off the ground an inch or so about 50-60 days after the nest was created.  Simply pull up the wire and stakes one at a time to lift the wire off the ground so hatchlings will not be trapped under the wire. In many instances, vegetation will have grown up through the wire and will help maintain the gap you created when you first raised the wire off the ground.  If no or few plants are present, place a couple of sticks under the wire to maintain a gap of about an inch above the ground. It is helpful to mark your calendar to remind you to elevate the wire. Feel free to lightly sprinkle dead grass on top of the wire to help reduce visibility by humans, but be certain that the soil under the wire gets good sunlight.  You can also paint the wire tan or green using a roller to make it less visible. This is especially important if the nest is in an area that receives a lot of human traffic.
  2. Use a similarly sized piece of 1/4″ or 1/2 ” hardware cloth (as used in A. above) but nail or staple the edges of the wire to a 1×2 piece of wood (actual thickness is 3/4″ X 1.5″) along each edge of the wire.  Cedar wood is inexpensive and will last for years, as will the hardware cloth. Precut the 1×2 so that you have a 1.5″ gap in each corner of the wood frame.
Self-releasing nest protector

 These corner gaps allow the hatchlings to easily exit the protection device, and once in place you do not need to do anything in the future except to look for a nest emergence hole under the wire.  The incubation period is determined by soil temperatures and also varies somewhat by species. Most hatchlings emerge in 70-90 days, but some species may overwinter in the nest as hatchlings and emerge the following spring. usually in late April or early May and often during a warm spell, often just after a good rain.  

Note: You may want to buy these materials prior to the nesting season if you anticipate protecting nests.

*To report turtle crossing and road mortality locations, and to learn about Wisconsin’s turtle regulations, contact the:

Bureau of Natural Heritage Conservation
P.O. Box 7921
Madison, WI 53707
(608) 266-7012

or see: https://dnr.wisconsin.gov/topic/Wildlifehabitat/HerpRegulations.html