The Surprisingly Varied Diet of Beavers
It is common knowledge that beavers are herbivorous but the extent of their herbivory is not always appreciated. Examining their skull would tell you that their massive four front incisors (as well as the muscles attached to their jaws) are designed to do some serious chewing. And serious chewing does take place, especially in the fall. Poplars, birches, alders, willows, maples and many other deciduous trees as well as a few conifers are felled in order to reach and consume the inner bark, or cambium layer. (The de-barked logs and branches are subsequently used to repair dams and lodges). Not only do Beavers need to meet their daily nutritional needs but they must cut enough trees to last them through the winter.
However as spring approaches and they can access land, their diet changes from the woody branches they’ve been eating all winter (from their winter food pile under the water) to a diet that consists mainly of herbaceous plants. Ninety percent of their time is spent eating non-woody plants, often skunk cabbage, water lily rhizomes and grasses in the early spring. As summer progresses, they seek out aquatic plants, ferns, sedges and a variety of flowering plants. Usually it’s not until late summer/early fall that their incisors are once again given a good workout.
The pictured Beaver had the good fortune of having a large patch of tasty Jewelweed (Impatiens capensis) growing on and adjacent to its lodge.
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Monarchs Splitting Exoskeleton For The Fifth And Final Time
In the Northeast there appears to be an amazingly large number of Monarch larvae this year, and most of these larvae will complete their metamorphosis by transforming into a beautiful green chrysalis. Once mature, the larva, or caterpillar, wanders about and finds a suitable spot (usually protected and stable) to spend the next two weeks hanging precariously in the wind. It then spins a silk mat in this location, and puts a silk “button” in the middle of the mat. It clasps the button with its last set of prolegs (it has three pairs of true legs, and five pairs of so-called prolegs) and spends about 18 hours hanging in a “J,” with its head down, preparing to split its exoskeleton for the last time and reveal the chrysalis within it.
Ba Rea, a Monarch specialist (and publisher of my children’s book, Milkweed Visitors), informs her “Monarchchaser’s Blog” (https://monarchchaser.wordpress.com/about-monarchs/) readers that even though the visible changes between the larval and pupal (chrysalis) stages of a Monarch are sudden, inside the caterpillar these changes are taking place gradually and long before we can see them. “The parts that will transform the caterpillar into a butterfly are present from the time that the egg hatches. Inside the caterpillar are “imaginal disks.” As wonderfully fanciful as the word imaginal sounds, it is actually referring to the adult stage of the monarch which is called the imago. These disks are the cells that will become the butterfly’s wings, legs, proboscis and antennae, among other things. By the time the caterpillar is half an inch long its butterfly wings are already developing inside it. “
After eight to fifteen days, the adult Monarch emerges from its chrysalis and heads towards Mexico (butterflies that emerge after the middle of August migrate). It is the great grandchildren and great great grandchildren of these migrating monarchs that will return next summer. (Photo: Monarch hanging in a “J” from Jewelweed, also known as Touch-Me-Not — not the sturdiest of plants to hang from!)
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Beavers Consuming Herbaceous Plants
One associates Beavers with a fairly strict diet of bark and twigs. While their winter diet consists primarily of woody plants, they consume a variety of herbaceous and aquatic plants (as well as woody) during the spring, summer and fall months. Shrubs and trees make up roughly half the spring and autumn requirements, but as little as 10% of the summer diet when herbaceous plants such as sedges and aquatic plants become available.
Recent observation of a local active Beaver pond revealed that Interrupted Fern (Osmunda claytoniana), Jewelweed/Touch-Me-Not (Impatiens capensis) and grasses are high on the list of preferred foods of one Beaver family during the summer, although woody plants such as poplars (Populus spp.) and Paper Birch (Betula papyrifera) have also been consumed in fairly large quantities. All too soon Beavers in the Northeast will be limited to the bark of branches they’ve stored under the ice. Until this time, they take advantage of the accessibility of more easily digested herbaceous plants. (Thanks to the Shepards and Demonts for photo op.)
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