Wednesday, November 28, 2012

Beaver - America's Largest Rodent

Where did November go?

At the beginning of the month, I had all of these wonderful plans for our mammal studies.  However, a weekend in Boston and five days visiting family in Pennsylvania - while great fun - made the month zip by.  Barb's nature study plans came to the rescue again.  They served to remind me to get outdoors, even for a short time.  They also allowed me to focus on just one thing, which is what I needed this month.

I asked my son which mammal in our area he wanted to learn more about.  Right away, he said, "Beavers."  He was remembering our exciting encounter with a beaver during an afternoon of kayaking at a nearby pond. We had inadvertently come too close to a beaver lodge and were able to witness the warning slap of a beaver's tail.

So this is how we introduced ourselves to beavers.  At the beginning of the month, I organized a hike with our homeschool group at a local park that has a nature center.  During our hike, we saw a pond with a beaver lodge.  At the end of the hike, we visited the nature center where we were able to view a pond diorama containing a stuffed beaver.

We did a little reading about beavers including this section from my Complete Field Guide to American Wildlife by Henry Hill Collins, Jr.:
Hardly another mammal has played so romantic a part in our history. Demand for its beautiful and useful pelt first lured trappers into the North American wilderness, helped found the Hudson's Bay Company, and established the Astor fortune. Excessive trapping extirpated the species over wide areas. Now it is being restocked and creating ponds and wet lands of great value to fishing, wildlife, vegetation, aesthetics, and the water table. For these it is probably worth far more to men each year now than its pelts ever were, even in the best year of their price and popularity in the heyday of Jim Bridger and the Mountain Men of the early West.

Other interesting facts we learned about the beaver:
  • It is the largest rodent in North America.
  • It can weigh up to 60 lbs.
  • It is most active at dawn, dusk, and at night.
  • Their ears and nose are sealed and a membrane covers their eyes when they are underwater.
  • They have a double-layer coat which they waterproof with an oily substance called castoreum that is secreted from scent glands.
  • They can remain underwater for up to 15 minutes.
  • The largest beaver dam is over 1/2 a mile long.

We also learned a new vocabulary word:  fossorial.  Fossorial means the animal is adapted to digging and living underground.

Beavers build dams to raise the water level near their lodges.  Raising the water level serves several purposes one of which is to ensure that the water is deep enough that it does not freeze all the way to the bottom.  The deeper water also extends the waterways into the forest giving the beaver safer access to food and building materials.  It is no wonder, that beavers are often used as mascots at engineering schools.  Had I been thinking about that, I would have searched out the statue of the MIT mascot while we were there for the Splash! program this month.

This week, B and I went on a hike by ourselves around a pond where we had previously seen beaver activity.  It had snowed lightly the day before, so I was hoping we might see some tracks, but no luck there.  We did see the stumps of a few saplings and a large area on a bigger tree that had been gnawed.  As we learned in the videos that Barb had linked to on one of her pages, beavers are active all winter, so I'd like to go back in the winter and see if we have any luck with the tracks then.  Or, since beaver are pretty skittish, see if we can see vapor coming from their lodges.

Picture taken in October.

Picture taken in November.  Definitely more activity.

Beaver lodge on right.

Here are some videos we watched, some of which Barb had linked to on her blog.  They are from the BBC and are hosted by Richard Attenborough:
Beaver Lodge Construction Squad
How Beavers Build a Lodge
Beaver Facts
Beavers in  the Snow

The beaver is a fascinating animal.  I think reading more about how they affected the history of North America would be interesting.

While we didn't do all that I had hoped we would do this month, we did learn a bit more about one specific animal and that is good enough for me.