Tuesday, November 29, 2011

November 18 to 24, 2011

November 18 just over a week ago we saw the beaver in the Deep Pond dive into one of the burrows along the high slope of the pond, and because of our trip south, I didn’t have a chance to walk over and look over that burrow until today. The typical beaver pond often creates the illusion that things in it or along its far shore are bigger than they are. Looking across the pond from the dam, it looks like the beaver had done a good bit of work protecting the shore above the burrow. Standing above that section of the slope, I could see that the beaver hasn’t done much at all, save push up a bit of mud and two logs.

In other years beavers here have had cache piles in the pond outside the burrows and in places there is quite a collection of old beaver cut logs on the bottom of the pond, which drops off quickly. The logs pushed into the slope look relatively fresh, but I have seen no evidence that this beaver has cut any trees of that size since it has been in this pond.

As I walked around the pond I looked for trails into the woods, and now that the leaves are down I can see most of the trees. The beaver has some wide trails,

But they all peter out when they read the woods. The only woody vegetation I saw that the beaver cut was a little bit more honeysuckle.

I saw no signs of where the beaver took those honeysuckle branches. With the pond higher and the vegetation in it sinking as it dies back, I can’t tell if the beaver is still eating lily pads and rhizomes. However, there are more stalks of taller grasses floating in the pond.

But the muskrat I saw in the pond, and it might be eating that.

November 19 we have had a warm fall and because of that deer ticks seem to be everywhere in the woods and fields. Leslie has had a few bites. I’ve picked two off my skin before they dug in. Luckily, we can get to the East Trail by largely staying on relatively wide trails where we are less like to get ticks. So we took a break from the ticks today and went to the East Trail Pond even avoiding our usual shortcuts through woods and fields. Plus Leslie wanted to see the otter scent mound of which, in my journal entry for the 16th, I opined that the otters built solely to send a message to the beavers. Looking at my edited photos of the scent mound and lodge, Leslie immediately jumped to the same conclusion. Staying on the trail, we could easily see the beavers’ work along the south shore of the pond. I noticed that the bitternut hickory the beavers resumed cutting had fallen but was hung up on another tree.

It was easy to see that the beavers have resumed using the far west end of the pond. That area was all muddy and from the trail I took a photo of it as I overlooked the maple on the ledge that the beavers had almost completely stripped.

I took a photo of the large red oak next to the maple. They had girdled the oak now it looked like they were gnawing into it in hopes of eventually cutting it down.

In the 10 years I’ve watched this beaver family, they’ve always cut down large red oaks but never one quite that large. Of course, it is difficult to account for the intentions behind any given beaver gnaw. For example, a small twinned oak has been well gnawed around the trunk. It would be easy work for a beaver to cut both, but it has only cut one and seems more intent on gnawing rather than cutting the tree down.

Across the trail, an ash tree they cut a few weeks ago fell into other trees. The beavers cut off a log from the bottom of the trunk and the ash danced farther down the slope, and the beaver has started another cut higher up the trunk. Meanwhile in the cluster of trees where the ash once stood there are three trees in the process of being cut down.

Then the trail goes between a huge oak that the beavers have almost girdled and a smaller oak that they’ve almost cut.

Given all this wood work, I am not sure why the west end of the pond is so muddy. Over the years these beavers have been prone to dredge all their channels so perhaps they are deepening this area in preparation for winter.

Last fall the beavers cut several trees west of the pond, but haven’t been back this year, until this week. They have almost cut down a small tree and have girdled a larger one -- the typical pattern of these beavers.

Then we walked up the trail along the ridge north of the pond. An oak log the beavers have been working on is now in the middle of the trail.

The number of trees the beavers cut in the fall can’t help but strike humans as wasteful. For example, the beavers have started cutting other large trees even as an even larger tree they cut fell conveniently into the pond. But after trimming the branches off that tree, the beavers have not gnawed any bark on the trunk.

But that shows what the beavers want at this time of year, branches to cache near their lodge. To get the branches they have to cut trees down, and tall trees with their long branchless trunks do not sate their appetite for branches. Despite the number of photos I took, since I didn’t leave the trail, we got around the pond quickly and quietly enough so that we sat on the ridge overlooking the pond in case a beaver or otter was in it.

None was. Then we went down to look at the scent mound and compare it to the beaver lodge out in the pond. Of course, the mere comparison doesn’t prove my assertion that the scent mounds represent the otters sending a message to the beavers. But it does show that if the otters want to, if they look from their scent mound toward the middle of the pond they can see the top of the beaver lodge.

The otters first built a scent mound low on this slope. My crazy idea explains why they built another one up high on the rock. I took a photo at a different angle in that ever vain hope that another image might bolster my point. The other day I saw how difficult it is for beavers to get on top of their lodge since they otter proofed it with many logs crisscrossing the top. So I am not suggesting that the otters think that the beavers climb up their lodge and then are struck by an otters’ imitation of it. But one day I saw a beaver lurking in the pond below the scent mound keeping an eye on an otter on the shore above.

Anyway, fun to think in my weird fashion that I am overhearing a conversation of sorts between otters and beavers. As we headed back around the pond, I noticed that the beavers are back gnawing into the trunk of another lodge tree standing in the water just off the north shore.

We both got a tick or two on our pants that were easily removed.

November 21 I did some work at our land, cutting maple logs in the valley the beavers vacated, which was a bit melancholy. Of course we checked on the Deep Pond to see what the beaver has been up to. We are not having much rain, but it seems the beaver makes a point to push up a bit of mud now and then. I assume the different colors of the two mud heaves reflect a 24 hour lapse in time between each heave, and that the light color is more recent.

The middle section of the dam is well built up, at least a foot higher than the water behind the dam.

Nonetheless, here too, the beaver pushed up some mud, and as usual some still green vegetation was dredged up along with the mud.

Back on the island, after lunch, we took some friends for a hike to the East Trail Pond. After lecturing about beavers, I broke away to check the latrine below the ridge for fresh otter scats. Strangely, few people seem eager to join me in that quest. There was nothing new there, and the smell of their last round was unsniffable. I took another photo of the big scent mound. Now that I think that the otters made this scent mound to mock the beaver who otter proofed their lodge with logs on top, I over interpret what I see. Why are there so many pieces of wood near the scent mound….?

It got cold enough last night to freeze some of the pond, and there was still some patchy ice on the shady south side of the pond.

I went down the ridge to the north shore of the pond and got a photo looking up the broad trail the beavers are making up the ridge.

They have several projects on the way up beginning with stripping the bark off what remains of a thick red oak trunk. That so much of the gnawing is on the underside of the trunk encourages me to believe that there is a kit or two in the family. An adult beaver could easily gnaw the top of the trunk.

Instead of walking up the trail I continued along the shore of the pond and took a photo of the big tree that fell into the pond. It’s not an accurate photo since the sunlight on the trunk gives the impression that the bark has been gnawed off at spots, which is not the case. The beavers have just trimmed the branches off the tree.

I am familiar with many of the tree-cutting projects on the south slope of the pond, but generally I look down on them. Today I looked up and saw a nice juxtaposition of the beavers’ levels of work: a thin tree cut down but the trunk not segmented and hauled away, a middle size tree cut sufficiently to fall but hung up in other trees, and a huge trunk being girdled.

How much work has gained how much nutrition? Sounds like a simple calculation, and may be for humans because biologists have saddled us with a notion that every animal has to eat so much every day to survive. But whatever calculus beavers used which stretches over such a different sense of time than our own is difficult for me to fathom. The clutter of branches in the crown of the downed maple on the ledge have been simplified. Three remain, but I suppose the beavers have taken all they will off this tree on which they did about all they could without falling over the ledge.

Staying along the shore I checked the ice in front of the burrow, but there were no bubbles under it today.

I almost walked by a maple that fell since the last time I was here. This twinned tree had been gnawed by fits and starts over the last year, so the stump of the half that just fell looked like old work.

I didn’t notice before, but this tree had been topped years ago. The beavers quickly took the remaining branches on the lower trunk.

Beavers are always showing me things about trees that I didn’t notice before. The hardest lesson remains trying to figure out why they keep trying to girdle the big oaks. I walked around one twinned red oak and saw gnawing at all levels.

I wish I could say that this proved that a family big and small had been working on it, but I’d have to see it to be sure. But I am giving the impression that a spent time contemplating all that I was seeing. Actually I hurried off to catch up with Leslie and our friends on the trail. I took a photo of the ash trunks hung up but dancing down the ridge as the beavers cut more logs off the bottom.

I saw one of the logs cut off the bottom of the trunk, rolled a bit down the hill almost covered with dead leaves.

Then I took a photo of the oak that had been hanging up in other trees. The wind and gravity finally brought it down.

Beavers cut two branches and dragged them away and have several more to cut.

November 22 the temperature went below 20F last night so I was eager to get out to the East Trail pond to see how the beavers managed the ice, with a hope that there might be signs of otters too. I went with Justin, now 24, and as we headed up the East Trail, I gestured toward Otter Hole Pond, now mostly a meadow, where I took Ottoleo and Justin when they were 12, and we saw a family of otters. Here's a long video clip from that halcyon October day in 1999. Ottoleo and I do most of the talking.

We approached the East Trail Pond from the south and could easily see bubble trails under the ice. Those bubbles and the cracked up ice looked characteristic of how beavers relate from below to a frozen pond. But on the ice there were sweeps, I guess they should be called, that I had to take a hard look at.

I decided they looked more like sweeps from a beaver’s tail, rather than the slides of an otter’s belly. That said, after years of watching beavers during the winter, I have never seen “sweeps” like that.

We walked down toward the dam to see if the beavers broke the ice there. On the way I saw that there were bubbles under the ice leading to the bank burrow.

Unlike the last time I saw bubbles here, these didn’t necessarily show an animal swimming directly in and out of the burrow, more like it was poking around under the ice there. I always look for bubbles under the ice expecting to learn a great deal. Then when I see them, I have little idea as to what they mean save that probably a beaver, muskrat or otter was swimming there. Cracks in the ice tell more of a story. However, I got the impression the beavers were quick to get back under the ice after they broke out from under. There were no breaks leading to the shore, no sticks left on the ice.

It was that cold a night. I saw some large bubbles under the ice behind the dam, but no extensive cracking, though I didn’t walk out on the dam to take a close look.

I continued to take photos of the cracked ice since refrozen, but not because I could tell what happened there. I simply think cracked ice makes for a good photo.

There were bubbles under the ice along the north shore of the pond. I got the impression that beavers had kept the water around the big tree that fell into pond open for a relatively long time.

I was a bit disappointed that there were no bubbles or cracks to be seen off the rock where the otters usually latrine. That suggested that neither otters nor beavers swam by the area where I think I saw an otter and a beaver in a standoff a few weeks ago.

I didn’t see evidence that beavers came out of the pond to gnaw wood, but having someone with me, I was not careful to check all their current projects. We headed off to Audubon Pond via the high granite ridge north of the valley. The sun was at an angle to nicely illuminate the snaking channels of Meander Pond.

I thought if I got to the west end of the pond I could look back and see the iced over channels of the rest of the pond just as well, but looking back I lost my illuminating angle on the sun. Still it is an amazing pond to contemplate. The beavers now in the East Trail Pond, spent the winter of 2009-10 here, without much more water than is in the pond now.

Since we approached Audubon Pond from the northeast, I could wade right into the slightly wet ground where the beavers have cut down several ash trees.

In general the woods around this pond are rather clear. This corner is an exception with an old fallen pine tree adding to the congestion of asters and vines.

The beavers could easily go around the tangles but instead it looks like they are enjoying the ins and outs and then finding ash logs to cut and having no trouble dragging them down to the pond.

On the pond side of the thickets, the beavers finally cut down the large choke cherry tree that they tasted a month or so ago.

I should have checked on how many branches the beavers have trimmed off the cherry but we were due home for lunch in less than a half hour, so we hurried over to the bench on the north side of the pond. The middle of the pond was ice free, but along the shore I could see the bubbles the muskrats left as they swam in and out of their burrow under the trail out to the bench.

There were no signs of otter or beaver activity out near the bench. When otters are in the pond they often can’t resist pooping on the bench. The beavers continue stripping the big ash that fell west of the pond as well as girdle another big ash behind that one.

I took a closer look at the ash stump the better to appreciate the artistry of the beavers’ gnawing.

I saw what I am pretty sure is a fisher’s poop. Justin suggested it was bird poop, but that is exactly where stump hopping fishers like to poop. Plus the poop is twisted and a bit large for a mink.

The beavers have completely girdled a larger ash nearby and perhaps they are trying to cut it down. If so, they seem to be challenged by a old dead trunk lying next to the tree. When they move around the tree to gnaw a circle around the trunk, they go up on the log so that they wind up making a cut a foot higher than the other one.

My analysis seems critical of the beavers’ skills which I am loath to make. A bit farther back in the woods they are girdling another ash, but I didn’t walk over to take a closer look.

Meanwhile they cut down another large shag-bark hickory near the pond with, once again, the crown falling conveniently into the pond.

So far they have cut one small branch off it.

Shag-bark hickory is not a favorite food of beavers. Even the beaver family now at the East Trail Pond never cut down shag-barks near the Meander Pond. (Well, I should check that. They did taste one of the many there and maybe did cut it down just before they left.) They did expand their meals to include basswoods but not shag-barks. Obviously these beavers have a taste for them, and it looks like they are taking the branches they cut off them to their cache outside their bank lodge in the embankment nearby.

I’ll try to keep an eye on this cache and try to figure out how much of the shag-bark bark the beavers actually eat. I suppose it is possible they are responding to an instinctual imperative to fill up a cache without necessarily thinking through whether they really want to eat the bark, or if they will only eat it when faced with starving. But here I am implying that the beavers don’t know what they are doing, and obviously they do.

November 24 we had snow yesterday, ending late morning, that amounted to about 2 inches, wet and heavy. Fortunately the leaves were down on all but the oaks. I got out this morning before it warmed up enough for the snow to melt. I headed out on Antler Trail and saw the tracks of three hunters and only one deer. A stayed on the East Trail all the way so I could look over the dam, and I saw that, judging by the tracks on the snow and ice, the beavers had been out in all corners of the pond and the at the dam. Continuing down the trail, heading up pond, I saw that they crossed the trail and headed up to the crown of the tree that fell across the trail a few days ago.

While most larger branches in the crown appeared to be cut off, there was a considerable pile of sticks and twigs on the snow beyond the trimmed trunk.

I saw drag marks left by branches the beavers dragged back down to the pond.

There were no worn beaver trails up on the slope. Now and then I could see individual beaver foot prints and I also saw crisscrossing trails.

The snow was not deep enough, and it was melting away as I walked around, for me to conclude that wood chips that appeared to be on top of the snow were gnawed off by the beaver after the snow. But I saw a trail in the snow leading to wood chips by a small oak that the beavers had worked on before the snow. I think I can conclude that the beavers cut the tree down after the snow, or, cut the tree enough so that the wind blew the tree down.

The beavers had not cut any of the branches in the crown of the fallen tree, nor was there any gnawing on the trunk.

I was surprised to see that the trail of a beaver in the snow looped around the largest red oak that they are girdling and the beaver gnawed into the tree some more. Stripping and eating the bark off a big tree is not a simple operation. Beavers commonly gnaw over an area 3 or 4 times and eventually gnaw into wood that, in the considered opinion of humans, has no nutritional value for the beavers.

As surprising as the renewed work on the huge oak, was their gnawing again on a smaller oak that had been cut enough for the tree to fall and get hung up in other trees. I have a theory that beavers avoid getting too close to unstable trees. I see here that a tree once obviously unstable is not avoided until it falls. A beaver came back to gnaw more bark above the cut, I think.

Closer to the pond there were wider trails left in the snow by the beavers going in and out, plus a bit of crisscrossing. The water in the pond where the beavers got out was still open, suggesting that they were about there early this morning, and the water did not have a chance to freeze.

Ten yards down the south shore there was still ice floating where the beavers had come out. The trail in the snow on shore there was not as noticeable as the other opening. Perhaps only one beaver came in and out there, while the other hole in the ice was used more.

However, there were nibbled sticks on the ice around this hole which suggests that this ice was thick enough to support a beaver. So maybe this is where the beavers came out first, and then the other opening was used more as it got warmer. (All this thinking is pointless and fun, and seems to justify taking these photos, which I always find pleasing to look at.)

When ever there has been ice on the pond, I’ve checked the burrow along the shore to see if I can tell what animal is using it based on bubbles or lack of bubbles. Today there were bubbles under the ice, and there was open water right above the burrow. Yet there seemed to be no other commotion, no animal climbed out of the pond there.

I’m beginning to think a muskrat is using it, even though I haven’t seen a muskrat in the pond since the summer. But muskrats can be very discreet in their ins and outs, so to speak, unlike beavers and otters. There was not a long trail of open ice out in the middle of the pond. Open water snaked 10 or 20 yards from the lodge and then, evidently, the beavers swam the rest of the way under the ice. I’ve beavers swim much farther under ice but usually later in the season when the ice is thicker.

Turning my attention closer to shore again, I was pleased to find an almost perfectly circular hole through the ice.

That hole was on the way to a wider break through the ice and I followed a trail up the slope and saw that a beaver had gone up to begin cutting a larger tree next to the smaller maple they cut down and didn’t strip much off.

Then I saw evidence that beavers respond to pond freezing by making a point of getting out from under the ice and doing some work even in areas they've been ignoring. The beavers have not done much lately in the far corner of the pond just behind the south end of the dam. Last fall they cut, girdled and almost cut many trees here. Today I saw that they came out from under the ice here, made a wide trail around a well gnawed tree they haven’t addressed for months and resumed their gnawing.

That break in the ice didn’t reach the dam, but, again as if everything in the ice had to be aesthetically pleasing, there was a parallel break in the ice that reached the dam farther out along the dam.

I walked out on the dam to that opening and saw where a beaver came out of the pond up on the snow,

The beaver collected some thin branches in the open water, I assume by going over the dam and foraging through the shrubs down there.

As I continued along the dam looking for a beaver trail in the snow going over it, I passed a square cut in the ice. Not that a beaver cut it. The ice probably just broke that way when the beaver's back humped up under it.

Then I saw trail, not well used, with some stalks collected behind the dam,

Evidently foraged from the pool below the dam.

I didn’t see evidence here that any beaver went beyond the small pool of water and into the meadow below the pond. However a few yards farther along, I saw another trail down to a pool below the dam,

and I thought I could see beaver trails going beyond the pool and down into the meadow.

When I got off the dam, I walked through the meadow on the old boardwalk and didn’t have to go far before I crossed a beaver’s trail and saw where it nipped some shoots from a bush.

It nipped larger shoots off that bush last winter.

When I was back on the dam, I took two nice photos. The beavers opened a trail through the ice behind the north end of the dam.

And while on the dam, I looked back and took a photo of the pond. The ice in the middle of the pond was melting, and I assume the beavers opened trails there during the night.

I hadn’t seen any breaks in the ice or trails over the dam that I thought could have been made by otters. There were no signs that the otters had been up on their latrine on the rock on the north shore. However I did see that a beaver walked up the slope through the snow to the left of the rock. It walked right by the otters first big scent mound below the rock without apparently paying any attention to it.

It didn’t go up on the rock but went above it and then made a somewhat circuitous route over to the huge twin trunked red oak they have been gnawing on for over a year. Judging from the wood chips on the new fallen snow, the beaver climbed up into the crotch of the tree to do some gnawing.

Of course, one can suppose a beaver did this without any thoughts of the otters that have been up on this rock off and on during the last month or so, but, on the other hand, why choose a cold damp day to renew old work. Once it saw the otters had not been back, maybe the beaver justified its climb by taking a bite of something however old. Of course, if one of those two huge trunks toppled over there would be plenty to eat. As I walked along the ridge north of the pond, I saw a collection of stripped logs below. This area gets the morning sun early and is the only spot along the shore of the pond where the beavers have been leaving logs like this.

Standing on high, I took a photo showing the areas of open water that mark where beavers had been, including a nice curving trail to the northwest end of the pond.

Sometimes when I am able to watch beavers foraging in a pond for a couple hours, I will see how they work in all corners. But I usually see them working that long in other seasons. In the late fall, cold afternoons and quick sunsets means I am lucky to see beavers move around the pond at all. Beavers can be active during the day in the winter but then where they managed to keep the pond ice open determines where they can go. So today I was lucky to see how the beavers managed to touch every corner of the pond, sample all types of vegetation from small shoots from the base of previously cut shrubs to cuts on huge oaks that they’ve been gnawing for a year. When I got to the end of the East Trail which affords a view of the end of the north cove of South Bay, I saw a muskrat on the ice

It stayed on the ice nibbling a piece of vegetation long enough for me to enjoy the quick ripples in the water made by the muskrat's rapid jaws and sympathetic tail.