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Cambium

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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Yellow-bellied Sapsuckers Have Varied Diet

4-6-16 yellow-bellied sapsucker mael 471 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.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.