Paper Birch Seeds Dispersing
Paper Birch (Betula papyrifera), also called White Birch, produces separate male and female flowers on the same tree, both in the form of catkins (cylindrical clusters of flowers). The catkins form in the fall and overwinter in a dormant state. In the spring they mature as the leaves develop, becoming pendulous. Male catkins are 2-4 inches long, whereas female catkins are usually 1–2 inches long. Both male and female flowers lack petals, enhancing wind pollination. After fertilization occurs, the male catkins wither away, while the female catkins droop downward and become cone-like.
The mature female catkins consist of tiny winged nutlets that are located behind three-lobed, hardened, modified leaves called bracts. Both winged seeds and bracts are usually dispersed by the wind during the fall and early winter. Birch bracts are species-specific — different species of birch have different-shaped bracts, allowing one to identify the species of birch that a bract comes from. Those of Paper Birch (pictured) look somewhat like soaring birds.
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Unusual Beaver Activity
Beavers are known for their ever-growing incisors which allow them to cut trees down, eat the cambium (a nutritious layer just beneath the bark) and cut what’s left into pieces they are able to haul and use as building material for dams and lodges. More often than not, it’s straight forward work.
Occasionally not every step is taken – you can find standing trees that had the bottom three or four feet (as high as the Beaver could reach) of cambium removed without the trees being felled. You can find de-barked logs that have been left where they fell and not carried or floated to the dam or lodge as construction material. It’s also not unusual to find standing trees where several times a Beaver has attempted but failed to cut all the way through.
Recently John Twomey brought to my attention a tree felled by Beavers unlike any other I’ve ever seen: one or more Beavers had cut down a Paper Birch and eaten the cambium layer, leaving the tree clean of bark. At some point they cut into the tree every 18 inches or so, not quite severing the pieces, but leaving them connected by a core of wood that ran the length of the tree. If any readers have seen anything similar to this, or if you have an idea as to why Beavers would have cut the tree in this fashion, Naturally Curious would love to hear from you. (Photo by Prentice Grassi of his sons investigating said tree earlier this spring.)
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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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Yellow-bellied Sapsuckers Have Varied Diet
Yellow-bellied sapsuckers are just starting to arrive on their northern breeding grounds. As you might assume from their name, these birds feed on the sap of trees. Their horizontal lines of drilled holes are a familiar sight, especially in trees such as paper birch, yellow birch, sugar maple, red maple and hickory, all of which have a high concentration of sugar in their sap.
In addition to sap, yellow-bellied sapsuckers also eats insects (primarily ants), and spiders, probing underneath bark to find them. They’ve even been observed “hawking”– taking off from a branch and scooping up insects in the air.
Lesser known is the fact that sapsuckers also consume vegetation, including the inner bark and cambium layers of trees, the buds of trembling aspen, and a variety of fruits and seeds. The recent cold snap had the pictured male yellow-bellied sapsucker scarfing down crab apples before the sun set. (The next NC post will be on 4/11/15.)
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Paper Birch Catkins: Winged Nutlets & Bracts Dispersing
Paper birch (Betula papyrifera) produces separate male and female flowers on the same tree, both in the form of catkins (cylindrical clusters of flowers). The catkins form in the fall and overwinter in a dormant state. In the spring they mature as the leaves develop, becoming pendulous. Male catkins are 2-4 inches long, whereas female catkins are usually 1 – 2 inches long. Both lack petals, enhancing wind pollination. After fertilization occurs, the male catkins wither away, while the female catkins droop downward and become cone-like.
The female catkins consist of tiny winged nutlets that are located behind three-lobed, hardened, modified leaves called bracts (yesterday’s blog post) and are usually dispersed by the wind during the fall and early winter. Birch bracts are species-specific — different species of birch have different-shaped bracts, allowing one to identify the species of birch that a bract comes from.
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