In late February and early March, bald eagle pairs either built a new nest or added to a nest from previous years. The nests were built in large, tall trees near water, with white pines being favorites. They were made with large sticks and now average about four feet wide and three feet deep, with the heaviest weighing almost 3 tons!

During this week, many female eagles are now laying two white eggs. Both parents will take turns incubating these eggs and protecting them from predators. In about forty days, the eggs will hatch, and the tiny eaglets that emerge will be fed bits of meat by both their parents.

Did you know? It’s not easy being an eagle chick! The first chicks to hatch aggressively fight for the most food, and have been known to attack their younger siblings. If the eaglets survive to three months of age, they will take their very first flight.

Learn more: Cornell Lab of Ornithology

Click here to check out a live eaglecam in Maine.

Geese are monogamous (have one mate) and will sometimes pair for life. Male and female geese have very different roles in raising their family. The geese (females) choose the nesting site, build the nest, and incubate the eggs, while the gander (male) defends the territory.

The goose will build her nest along shorelines using twigs, grasses, and moss. Next, she will lay 4-6 white eggs and line the nest with her own down feathers to keep them warm. The eggs will be incubated for about a month before they hatch, and then both parents will protect the goslings. Young geese are able to swim and feed themselves a mere 24 hours after hatching! In about 2 months, they are ready to fly. The family will migrate together in the fall and co-exist for almost a year.

Did you know? Canada geese eat aquatic vegetation, grasses, roots, and sprouts, but will also eat corn and grain from farm areas. An adult goose eats about a 1/2 pound of food a day!

Learn more: Cornell Lab of Ornithology

The big brown bat is the most widespread bat in the United States. It is a winter hibernator whose body stays just above freezing in attics, mines, and caves. Their heartbeat drops from 400 beats per minute when they are awake, to 25 beats while hibernating!

These bats are amazing insect eaters that love beetles. They mate in late summer and early fall, but delayed fertilization means that the female doesn’t actually become pregnant until April. She will then give birth to twins in June. Females live in maternal colonies that can number in the hundreds.

Did you know? Young big brown bats learn to fly at 18-35 days old, and may live up to 19 years!

Learn more: Animal Diversity Web

As water temperatures approach 50 degrees, the first frogs of spring announce their presence. Listen closely near the frog pond and you may hear several species: chorus frogs, spring peepers, and wood frogs. These species spent the winter buried under leaf litter on land. Their bodies underwent special chemical changes that allowed them to actually freeze solid during the winter. Now that they have thawed, they are making their way to ponds and lakes to breed.

Become a frog call expert by clicking on the species below to access more information from the Seagrant Website: 

Chorus Frog “cree-ee-ee eek”

Spring Peeper “peep!”

Wood Frog “quack, quack, quack”

Learn more:

Some amazing footage of a wood frog thawing: Nova

A calendar of when Wisconsin frog species call: Frog and Toad Survey

These interesting birds are found in many spots at CWES, but they prefer wooded areas near water. Phoebes will soon be building their nests on cliffs, bridges, and under the eaves of buildings. These nests are made of mud and moss cemented to structures, and then lined with fine grasses and hair. In early May, 2-6 white eggs (sometimes speckled with red) will be laid in this nest.

Watch the buildings at CWES for signs of phoebe nests and listen for their raspy call of “fee bee” which sounds quite a bit like them saying their name.

Did you know? The Eastern phoebe was the very first bird to be banded! One was banded in 1804 by John James Audubon when he attached a silver thread to its foot to track it.

Learn more: Cornell Lab of Ornithology

Painted turtles spent this winter hibernating underwater in nearby lakes. They burrowed into the mud where they breathed through the skin in their mouths. Once they emerge they will mate, and in early summer the female will lay 3-9 small white eggs in a hole she will dig on land. She will choose a location that is sunny and near water, and then bury her eggs to protect them from predators such as squirrels, skunks, foxes, raccoons, and snakes. After about ten weeks these eggs will hatch, and may live as long as thirty years.

Amazing!!! The sex of a turtle is determined by the temperature of the egg it develops in. Lower temperatures will result in male turtles, and higher temperatures will result in females. Male painted turtles are slightly smaller and flatter than females, and have longer front claws.

Did you know? The top of a turtle’s shell is called the carapace. The bottom half of a turtle’s shell is called the plastron.

Painted turtles are omnivores and eat duckweed, algae, tadpoles, small fish, insects, and crayfish.

Learn more: Animal Diversity Web

Coyotes (Canis latrans) are adaptable animals found all over North America. They breed in February and March, and their pups (usually 6) are born during this week. The pups are cared for by both of their parents, and will stay in their den for about a month.

Coyotes often use and enlarge the dirt dens of woodchucks and badgers to raise their pups in. These dens will be used year after year, and usually have several entrances.

Once the pups are weaned (at one month) they are fed regurgitated food by both of their parents. When they are able to hunt for themselves they will catch mostly small mammals, but may also eat snakes, birds, large insects, and carrion. The maximum lifespan for these nocturnal hunters is ten years in the wild.

Learn more: Animal Diversity Web

The American mink (Mustela vison) prefers to live in wooded areas near water. They consume small mammals, frogs, crayfish, fish, and even ducks! They hunt mostly at night and sometimes in the water. Their thick fur with oily guard hairs keep them waterproofed and their partially webbed feet are helpful for paddling.

Mink are members of the Mustelidae family which also includes weasels, badgers, skunks, otters, martens, fishers, and wolverines. Minks produce a powerful musk from anal glands to attract mates during the winter breeding season.

Minks have their 1-8 pups in burrows on the banks of rivers and lakes. If the agressive little animals can avoid being hunted by birds of prey, coyotes, and snakes, they usually live 3 years in the wild.

Learn More: Animal Diversity Web

This medium-sized frog spent the winter hibernating in the mud on lake bottoms and breathing through their skin. Listen for this spotted frog’s call which sounds like someone running their finger over a full balloon. Click here for a sample of their call at the Seagrant Website.

Like most frogs, male leopard frogs are smaller than the females. During April and May they mate and lay eggs in clusters of hundreds on aquatic plants. Depending upon water temperatures, the eggs will hatch in 1-3 weeks and the tadpoles will metamorphose into frogs 2-3 months later. Tadpoles eat mainly algae and plant matter. Adult frogs eat insects, earthworms, and even smaller frogs!

Special Skin: All amphibians have sensitive skin that they breathe through in addition to their lungs. They shed this skin from time to time and then eat it. Make sure to wash and wet hands before trying to catch or hold an amphibian!

Do you know why frogs close their eyes when they swallow? They push their eyeballs into the roof of their mouths to help them move their food along!

Leopard frog numbers have been declining in the state due to habitat loss and chemical pollutants.

After breeding, mallard males leave the females to care for their 9-13 white eggs. Drakes (males) have a bright green head, while hens (females) are a drab brown. If you look closely at a drake’s tail, you will find that a few of the feathers are curled.

A hen makes her nest on the ground near water and under the cover of vegetation and brush. The eggs will hatch in about a month, and the hen will then lead her ducklings into the water where they will stay for the rest of the summer.

Did you know? Ducklings are able to feed themselves after they hatch, and eat vegetation, grain, worms, insects, and snails.

Learn more: Cornell Lab of Ornithology

Eastern cottontails may have as many as six litters in a year, with 5-6 young in each litter! Before she has her young, the female will make a nest in a depression in the ground and line it with grasses and fur from her chest. The young kits will leave this nest at 7 weeks old, and the female will have her next litter.

Eastern cottontails are mainly nocturnal and eat a variety of plants. To escape predators such as coyotes, foxes, birds of prey, and weasels, they can leap as far as 15 feet.

Did you know? Cottontails have a short lifespan of about a year and a half, but can mate when they are just 3 months old.

Learn More: Animal Diversity Web

As spring days become longer, special hormones are released in the bodies of bucks. These hormones cause them to grow new antlers and thicken their neck muscles to carry the extra weight…3-9 pounds worth!

Early antlers are covered with fuzzy skin (called velvet) full of nerves and circulating blood. This covering nourishes the antlers as they grow over the next five months. Antlers are very sensitive as they grow, so bucks avoid bumping them.

By early fall, the antlers stop growing and the bone in them dies. At this point the velvet dries up and comes off, and the antlers are no longer sensitive. The bucks will then use their antlers to spar with other bucks over does. In early winter, as the days shorten, hormone levels in the buck’s body make them lose or shed their antlers. If they can make it through the winter, they will begin the whole process again next spring.

Did you know? The size of a buck’s antlers depend upon both genetics and nutrition. 

Learn More: Animal Diversity Web

Round-lobed hepatica blooms from April to May in wooded areas. Many woodland wildflowers bloom early in the spring, which allows them to take advantage of full sunlight before the trees produce leaves and shade the forest floor. Hepatica leaves used to be boiled into a tea for liver disorders, simply because the leaves were shaped like a liver. Luckily, this type of diagnosis is no longer in practice!

Garlic mustard is an alien invader from Europe that produces hundreds of seeds per plant. It will completely take over an area, eliminating the native wildflowers there. Its leaves appear in early April, and its small white flowers bloom from May to June.

The plant is a biennial, which means that it has a two-year lifecycle. The first year it only produces leaves, and in the second it also produces flowers. It likes shaded, moist woods and wooded edges, and its leaves and stems smell like garlic when crushed.

Did you know? This plant has become a large problem in many areas of the state, and parks and wildlife areas have begun organizing “pulling parties” in which volunteers work to remove it. Garlic mustard seeds can remain viable (able to grow) in the soil for 5 years, making it difficult to completely get rid of.

Learn More: Freckmann Herbarium

This week you may hear male toads trilling, which can last a full 30 seconds! To hear their call, click here and listen.

Toads lay their eggs in the water in long strands of 3,000-20,000 eggs! When the toad tadpoles hatch they swim together in schools, something that frog tadpoles usually don’t do.

Did you know? Toads have thicker skin than other amphibians, so they can live further from water. The large “warts” behind a toad’s eyes are called paratoid glands. These glands make a toxin that can inflame the mouth of a predator and make them feel queasy. Predators include birds, small mammals, and snakes. In turn, adult toads eat all sorts of insects–even slugs!

Learn more: Click on the link for the Upper Midwest Environmental Sciences Center to hear the call of the eastern American toad and 10 additional species of frogs in the Upper Midwest Amphibian Research and Monitoring Initiative.

Last fall, these animals ate until their body weight increased by an incredible 120%. They then spent the winter taking long naps and using up those fat reserves. Now that spring has arrived they are ready to have their young–4 kits. After mating, only the female raccoon will care for the kits in hollow trees and caves.

Two months from now the kits will start hunting at night wtih their mom, looking for fruit, nuts, crayfish, insects, rodents, frogs, fish, and bird eggs. They’ll also have to keep an eye out for coyotes, wolves, and large birds of prey. If they are careful they may live up to 19 years (average age is about 5)!

Did you know? Raccoons weigh 12-35 pounds, with the males being larger!

Learn more: Animal Diversity Web

If you are walking near Minister Lake, you are likely to hear this bird. They prefer open, shrubby places near water. Song sparrows snack on fruit, seeds, and insects. Like several other species, the males have arrived before the females to scope out and defend a territory this spring.

These amazing vocalists can sing 20 different tunes with many variations which they learn from neighboring birds. The more advanced their song, the more appealing they are to females. Once a male finds a mate, the two will build a cup-like nest of grasses and weeds on the ground. They may then have as many as 3 broods (batches) of eggs over the summer.

Did you know? Some birders say the song sparrow sounds like “Hip, hip, hip hurray boys, spring is here.” Click here to see if you agree.

Learn more: Cornell Lab of Ornithology

Fiddleheads are the young, coiled leaves of ferns (which look like the curved end of a fiddle). Some species of fiddleheads, like those from the ostrich fern, are edible when cooked and taste a bit like asparagus. Other species can be toxic if eaten. Keep an eye out as new oak ferns unfurl in the woods of CWES, and sensitive ferns appear near Minister Lake.

Learn more: Cofrin Center for Biodiversity

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