Thursday, February 22, 2018

Otters Dig Through Beaver History

This is the first chapter of my memoir of watching beavers and otters. I am slowly writing it and putting other chapters on my blog at Memoir of Three Valleys

  Otters Dig Through Beaver History

Beavers are shaped like the history they make, like their ponds, triple oblongs: head, body, tail. It may be true that no man is an island unto himself, but don't pin that on a beaver. Otters are shaped like their dream, like the fish they chase. Get a long line of otters together and you might fairly say you have a river with fish running through.

Otters on the shore of the Big Pond
Beavers and otters are about the same size, say a yardstick long including tail with the small end of the otter's tail exceeding that limit. Neither is that type of furry animal which impresses you with how light they are when you pick one up. They don't fluff out in a show. Their fur is the nonpareil. When such things mattered scientists rated the durability of furs. Otter fur rated 100, the standard for all others, beaver fur 90, everything else hardly bumped 50, mink and skunk made 70. So they are heavy animals for their size which attests to their strength of their muscles.

They have muscles where we and most other animals don't; muscles that make their tails blur not just wag. Since the fall of 1997 I have taken videos of beavers. Their usual reaction to my being there is to slap their tail. Almost every time they do that, the camcorder jerks. Their pancake shaped tail is hinged to their body the better to thwack the water with always surprising force.

A beaver prepares to slap its tail

No mammal's tail is more a part of the body than the otter's cone shaped tail and in that respect it is almost as fearsome as an alligator's. Yes, it can wag in the air when an otter dives but its the motive whip and rudder when the undulating otter swims underwater. In the relatively shortened spaces of a beaver pond it is clear that thanks to its strong tail there is no corner of it that an otter cannot get to almost instantly.

An otter's tail catches up to the wake it made
Beavers are fast swimmers too but their tail is for steering. Their two large webbed hind feet propel them through the water. 

Back feet and tail of beaver (another beaver probably took a bite out of the tail_

Both animals can stay under water 10 minutes at a time easily. Both animals are equally adapted to operating under water using their mouth and fore paws to catch and eat fish or dig and cut roots.

Both have sensitive whiskers that extra sense humans can't begin to fathom especially since beavers and otters use that sense under water. Otter whiskers sense bullheads sleeping in the muddy bottom. As well as for finding roots under water, I think beavers use their whiskers when they're gnawing almost to the middle of the trunk of a tree 30 feet taller than they are. At the twitch of a whisker dancing on the wood, get your head out!

a beaver's whiskers

The fallen trees around a beaver pond attest to the strength of a beaver's jaws and teeth. When they aren't gnawing deeply into the trunks of trees, beavers are rather modest about the strongest part of their body. They have a receding lower jaw and contrary to all the cartoons of them, their four large front incisors also recede and are half covered with flab. You almost never see their teeth even when they are eating. But you hear their gnawing even if you're at the next pond up or down from the pond where they are dining.

A beaver skull
The bullet shape of an otter's head keeps their jaws and show of teeth from being as obvious as a snarling dog's. But they communicate the strength of their jaws and teeth in two ways. When eating a fish they often hold their head ups and gnash the fish with their teeth in full view. 

When they do that you can hear the attention grabbing crack of fish bones. A literal translation of one Indian word for otter is bone-cruncher. Yes, the sentimental depictions of them are also true. They can loll on their back, hold a fish in their front paws and more daintily pick at the meat but in some 16 years of watching them, I saw that once.

Like most animals they both have good hearing, but they are soft spoken. The beavers “hmmmm”; the otters “huuuuuh.” The beaver's angry hiss is scarcely audible and my usual reaction to the screech of a vexed otter is you got to be kidding. (Otters do have a call almost as loud as that from hungry cattle about to be fed but that call is meant only for other otters or God in heaven. It is at once that insistent and ethereal.)

Both are awkward on land. The beaver's gallop is a bit of a thump  – that big flat tail! 

A beaver runs toward a hole in the Big Pond's ice
The otter's gallop is more like a dance but a bit clumsy.

A otter runs up from Beaver Point Pond dam

However on ice and going down snow covered slopes the otter is faster then any mammal except the mink. (That much smaller mammal of the same mustelidae family can give the illusion of sliding uphill in the snow – at least to me and I can't explain it.) The beaver doesn't slide in the snow or ice.

So the interesting thing about the co-evolution of beavers and otters is that they are evenly matched. But since the more agile otter eats flesh, the general assumption is that a beaver should be careful around an otter, especially in the winter.

 Beaver well exposed in East Trail Pond March 2003

Not to worry, beavers are the champion co-evolvers. The ponds they make are welcoming habitat for otters, minks, muskrats, snapping turtles, any kind of turtle but the snapper is the one to look out for, snakes, frogs, herons, common terns, I've even seen cormorants in beaver ponds, etc. Ecologists designate beavers as a keystone species because so many other species depend on beaver ponds. If that wasn't credit enough, the "hydrological-beaver- paradigm" credits beaver dams for retaining water in a way the restores watersheds and even fights climate change.

However, I am not qualified to write much about co-evolution and hydrological paradigms. This book is a history. I take co-evolution and beneficent paradigms as short-hand for problems solved. You put two different species together in a pond and you assume that since they've co-existed for a few million years there's no problem. Both have been dealt genes to allow them to survive and their habitat to sustain itself.

History is a bit of that too but also the ups and downs of muddling through which at the end can leave you asking what the hell happened. To be sure, in this history I did most of the muddling. Beaver can make mud dance to any tune they want. Beavers write their history on the land more legibly than any other animal other than man which is why after 19 years sporadically hiking on the western end of Wellesley Island I knew something about the beavers there even though I had never seen one.

Although I did fall on my face trying to follow 5 otters, I got up and went up to the Big Pond where I saw two of the otters fishing. One otter “hrummphed a lot” seemingly at me. But even though I noted it in my journal, I didn't have any sense that I was seeing history. I assumed otters using the pond was twas-ever-thus stuff and no need to put it on a timeline.

When I first got a measure of them, my sense of how beavers made history could be a bit blunt. Just before moving up to the island, I noticed that beaver dam flooding the road that came down from the private land to South Bay. A year later in April 1995 while watching the beavers in the pond behind that dam, I heard two ATVs roar around the South Bay trail, turn up toward the flooded road, stop, and deflate into an impatient putt-putt. I heard one driver yell “Damn Beavers!” They turned and roared away. I thought the beaver in the pond gave me a knowing look.

But as I continued to watch beavers, continued to bother beavers, I soon came to the conclusion that they see right through us, actually hardly see us at all. Their eyes discern shadows showing them where to direct their nose and ears. They put up with the terror we inflicted on them. What saved them from extinction was not flooding roads but finding the heart of the swamp and lying low. What had them making history again was not their effort to contest our control of the island but a pursuit of their own idea of perfection. If that sounds like sweetened hogwash, than you've never seen several acres of water brimming a long beaver dam.

Otter Hole Pond dam
The Lost Swamp Pond dam was the pinnacle of beaver engineering but the dam pictured above, a double S-curve of mud and logs afforded me my most pleasurable 230 feet of walking and pondering from the ridge beside it. If the pink granite plateau was my top of the world, this dam created a new world.

If beavers wrote their history with their dam, otters entered that history in March 1996. They dug a hole through the middle of the long dam that in what I began calling Otter Hole Pond. I wasn't an eyewitness to history, to the actual breach. That took place under about 6 inches of ice and a foot of snow. But I should have been on the banks to hear the gnawing.

Before moving I anticipated that our winters would primarily be an attempt to steal exercise from the challenging weather. We all got cross country skis. I followed the beavers as closely as I could until the ponds all froze over in early December. The Christmas before we moved up Leslie gave me Hope Ryden's Lily Pond, an excellent four year study of a family of beavers in the Catskills. I took a page from Hope Ryden's book and said goodbye to the beavers like she did and got out my skis. I assumed the beavers would stay under the pond ice eating the bark of branches they sank in front of the lodge thus assuring their safety against coyotes. I didn't expect to see them again until March. A week later I saw them and continued to see them throughout the winter because they made holes in the ice and continued to forage up the wooded ridge for trees.

The beavers' hole in the ice and path up the ridge

When we moved up to the island I assumed that the animals I would see were fairly well understood. I pictured myself finding the music of their lives, the vibrations arising from their well understood behavior. Voila! seeing the beavers not go by the book was just the music I was looking for, a special adaptation to a relatively warm winter in a pond where the bank lodge the beavers wintered in was built too late to be well provided with food.

The Lowest Pond lodge seemed unprepared for winter

And we learned to keep an eye on the swamps during winter and not just try to keep our knuckles from getting white on the state park ski trails. 

Next winter, 1995-96, I got the hang of tracking otters in the snow and following their tracks kept me walking across several ponds. Just as the Lowest Pond beavers did, I noticed other beavers in other ponds came out from under the ice to forage for trees. In mid-February I even noticed that there was a small hole in the top of soon to be Otter Hole Pond dam that had lowered the pond water level about a foot. The slides on the dam convinced me that otters made the small hole. There were also several holes in the pond ice.  I got into the habit of walking on the ice and looking into every hole noticing how wide the gap was between the pond water and the ice. Then for good reasons I lost track of what was happening.

A week before I saw the big hole in the dam, I reported a trapper illegally trapping beavers on state land. He trapped the Big Pond and Lost Swamp Pond, both partially on private land. He came from a bump in the road 5 miles south of the river called Omar and had the land owner's permission but crossed the property line. He also trapped in the small pond just below the Big Pond where I discovered his traps. I saw two sticks coming out of a hole in the ice. I stopped following otter slides and just made sure there were no foot prints or ATV trails on the ponds. 

On Saturday March 10 walking up to the ponds from the South Bay trail we saw a guy standing on the ice behind the dam. Fearing he was a trapper we hurried up and met a photographer who had just taken photos of a beaver swimming in a large pool of open water behind the dam. We didn't see the beaver but we saw a hole three feet in diameter in the middle of the dam. The photographer had no idea how it got there. I saw fresh otter slides and large black scats, unmistakably from the fish-eating otters, all around the hole. 

The otter-made hole it what I began calling Otter Hole Pond 

I went back twice the next week to check on the dam thinking that if I saw an otter there it would be a confession. Then we had a bit of a thaw and when we went back to check on the dam the Saturday after we saw the huge hole, we saw what seemed like endless water rushing through the hole making a deep stream straight through the snow and ice below. Deep and too wide, this was a thrilling and completely unexpected anticipation of spring. Even watching a muskrat diving in the water below the dam didn't keep me from having an uneasy feeling that this wasn't right.

No one I talked to would accept that otters put a huge hole in the dam, except Leslie who saw the hole too. The initial reaction to a huge hole in a beaver dam is that one of those high percentage of people “intolerant” of beavers or a trapper must have done it.

Leslie behind the hole in the dam
Unfortunately I had just been made aware of trappers and their ways. They don't cover their trails. The trapper I reported didn't put any traps on the dams which is illegal, as is damaging a beaver dam in any way. Ten days after the breach, I caught another trapper in the park by tracking his prints in the snow. He lived on the island and I was somewhat familiar with his small footprint. I saw no prints before the breach.

There was no reason for the Nature Center staff to breach a dam to protect any trails. Bob Wakefield had retired and his replacement ended the war with beavers by changing the East Trail so it no longer crossed the wetlands. The new trail was far from and never threatened by the breached dam. (We missed Bob. He battled the beavers over excellent wetland trails. With him gone, there were none in the park.) Talking with the DEC officer, I was pleased to learn that in the State of New York beaver dams are sacrosanct. Even if the state park people wanted to breach the dam they would have needed a permit from DEC.

When I mentioned the otters making a hole in the dam to Joe Lamendola in the Watertown DEC office, I got a blank stare. Maybe he was worried that since beaver dams were sacrosanct the hole had to be investigated.

I drew a blank when I looked Hope Ryden's Lily Pond and other books for any mention of otters breaching beaver dams. I could see why. All books about beavers celebrate the beavers' dams, the keystone in the paradigm of the keystone species. Confidence in the permanence of beaver dams has led scientists to speculate that in some cases beaver engineering has endured for millenniums. Beavers abandon ponds because they run out of food to forage not because otters harassed them. What the beavers leave behind is a marvel too, a meadow of exceptional fertility.

Second Swamp Pond meadow in August 2011

The dam builder paradigm is so convincing that a scientific paper which describes and all but proves that otters commonly breach beaver dams takes pains not to tarnish the paradigm. Instead the paper suggests that beavers are trapped in a paradigmical Catch 22. A Swedish study had shown that beavers have a Pavlovian reaction to flowing water. They have to stop it. They have to make the dams that are so beneficial to so many species. But when otters breach dams in the winter, the beavers living in a lodge packed with frozen mud and swimming under the ice don't hear the water running. Hence they momentarily lose the water in the pond. By fall and usually much sooner, they repair the dam; the pond is restored; the paradigm endures.

But in my case, I was sure the beavers heard the water flowing. They weren't fast a sleep and had their ears above the water and the ice. They cut down a large tree near the dam and cut small trees just below the dam. Meanwhile the water level below the ice was low enough that the ice had collapsed in places. That must have inspired the otters to dig the hole deeper down into and through the dam.

The beavers repaired the dam by April 4, 1996, twenty five days after I first saw the hole in it. They used their characteristic engineering skill making a small dam below the hole that backed up water into the hole so that their repairs wouldn't be washed away. Then they pushed a large log into the hole perpendicular to the dam and then filled the hole with small sticks and mud. In a sense, the beavers wiped the historical slate clean. Something happened but nothing changed.

 Otter Hole Pond in the Spring after the Dam Was Repaired
But could the beaver paradigm be so fragile? I hoped not.
The swampy shrubby scrubby lowlands that we had bulled and wiggled our way through twice or thrice a year for 19 years to sunbathe on high granite rocks had metamorphosed from an inchoate scribble into not just a landscape but a panorama. I suppose we can blame the great painters for making us think beautiful landscapes are eternal. Pick your perspective on water rising in a series of ponds. Sitting beside the dams afforded a view of the wooded ridges, spectacular in the fall. Seen from the ridges the ponds reflected clouds of migrating ducks that flew up when they heard a foot fall. 

 Lost Swamp Pond in October
I wanted the officials in charge of naming geographical features to name the bigger beaver ponds and put them on the map for good. Name the ponds after the private landowner's grandchildren. The family would never hire a trapper again.

I had much to learn about beaver ponds.

Beaver ponds conceal as much history as they make, especially Otter Hole Pond. A drought in the spring and summer of 1999 allowed me to piece together how the beaver made the magnificent pond. To cross those suddenly exposed almost dried out flats I had to look for any high ground to keep out of the mud. So I discovered the old dams behind the long dam that the otters breached.

The creek that seeped through the electrified dam that turned Wakefield's East Trail wetland into the East Trail Pond joined the creek that seeped through the venerable Second Swamp Pond. Beavers made Otter Hole Pond dam about 50 yards below the confluence of the two creeks. 

Map I made in October 1997 of Otter Hole Pond 

But before that they made two small dams below the Second Swamp Pond dam that were soon flooded over by water backed up by Otter Hole Pond dam.

The Second Pond dam, my Mother of All Dams, was a classic dam taking advantage of two granite outcrops on opposite sides of the valley. The outcrops narrowed the valley by about a third of its width and left about 70 feet to dam. Below the dam the valley was twice as wide and flatter. But the beavers managed to make little ponds below the big dam.

Dam just below Second Swamp Pond restored by beavers 

The first was behind a small dam off a slight bank on the north side of the valley just below the big dam. If their main pond gets too deep, beavers often build a small pond below to get at the cattail rhizomes, that redolent word is apt for the thick roots of cattails growing in the wet ground below the dam. They also built a small lodge beside the slight bank that anchored the dam.

The beavers did the same thing below the Big Pond in the First Valley. That valley narrows and dam-making all the way down to South Bay was easy. The beaver that stood up before me in 1994 did so in a narrow pond half way between the Big Pond and South Bay. (I called it Middle Pond.)

Middle Pond dam in 1995

To dam farther down the Second Valley was more difficult. The beavers made another small dam anchored on a small granite outcrop on the south shore. This dam flooded water back to the edge of the woods and they built a more substantial lodge where the land began to inch up a bit higher. Extending their first small dam would have mirrored the large dam behind it. Extending this second small dam to span the valley's widest point would have been pointless hard work since it would miss damming the creek coming down from the East Trail Pond which flowed about 100 feet below that second low dam. 

Remnant of long dam below Second Swamp Pond during a drought
I could kick myself for not seeing all these dams made, but I learned that it is almost impossible to see long low dams being built. Unlike humans beavers don't clear the area before they build. They work under the cover of the tall grasses and low shrubs. In the late summer of 2010 I had vantage points both below and behind where they were building a low and long dam in a wetland, the middle of Wakefield's East Trail wetland to be exact. For a few weeks there was a progression of glubs and water slowly rising behind a still invisible line. 

I had to part the cattails and find firm ground to see the beginning of a long dam that I would soon be able to walk on.

Back to 1996: the Second Valley narrows a bit where the creeks merged. The creek coming down from the Mother of All Dams cuts lower and the beavers anchored what would become a 230 foot long dam at the south end of a 10 foot high granite cliff, the north face of the Second Ridge, which was about 60 feet from the creek.

While it took me several years to piece together that history of the creation of Otter Hole Pond, the otters could have deduced it in a matter of minutes as they swam from Otter Hole Pond dam all the way up to the Second Swamp Pond dam. As they looked for fish otters could swim through the flooded over small dams between the two big dams. The beavers made trenches in the dams when the water from the big dam below backed over the smaller dams. If the otters didn't realize that beaver dams could be breached, beavers showed them that it was possible.

The beavers also built the dam at just that spot, north of a granite ridge, affording otters a place to den close to the new dam. There are two ways to look at granite. It's a cold round rock that diminishes through exfoliation caused by eons of freezing and thawing. It's also a slowly burning rock (very, very slowly burning!) that along the edges of ridges that aren't rounded can bear a striking resemblance to the grid of glowing embers on the last big log you put on a fire. Like the embers of that log, the granite breaks off in square chunks. If water half covers the granite chunks, otters often find a good place to den. Somewhere on all the islands there are fronts of granite that are slowly burning so otters are familiar with such venues for possible dens.

The slow "burn" of pink granite

While beavers make lodges to sleep in, otters look for spaces they can move into, ideally with an underwater entrance and a dry bed above well concealed from anything sniffing about on the shore. Beavers lodges are perfect; rock dens work fine too. Otters denning in the rocks beside Otter Hole Pond would sleep closer to the dam than the beavers in their lodge.

 Granite wall behind Otter Hole Pond dam during drought of 1999

otter den inside the granite wall

It's presumptuous to suggest that the beavers made a mistake. But I did wonder how the beavers would react when otters came to the pond. So far I had only seen otters in the fall and slides in the winter snow. I only expected to see beavers in the summer and now and then I did see them. I couldn't miss seeing their new dam building. Were they trying to correct their mistakes or at least make any otter dam busting less disruptive?  

When water poured out of the hole in the dam it coursed through a small pond created by a dam the beavers built in the fall of 1995 about 70 yards farther down the valley where a rounded granite outcrop divided the valley. They dammed the south side of the outcrop just high enough to back water to the foot of Otter Hole Pond dam flooding a stand of trees just the size beavers can conveniently cut down. 

2003 view of Beaver Point  Pond dam from the granite knoll

After Otter Hole Pond dam was breached in March 1996, in the late summer they built a dam on the north side of the granite outcrop below Otter Hole Pond. I laughed when I first saw their small dam because the only water it held back was in the holes the beavers dredged to build up the dam.

The start of the north end of Beaver Point Pond dam 

Usually I never saw what was coming until it happened. Fall rains created a huge pond Otter Hole Pond. I noticed that the younger beavers rather enjoyed the granite outcrop in the middle of the two small dams and I began calling the pond Beaver Point Pond.

In September otters reappeared in the ponds or I should I finally saw them. They were there. I just didn't know where to look. I saw an otter mother and two pups on September 14, and again on the 16th and 18th at the Lost Swamp Pond and Second Swamp Pond. Finally our 9 year old son saw an otter. That was a big deal. That summer he had played one of the otters in a play that I wrote for kids about the animals in the swamp.

But we didn't get a good look at the otter. The Second Swamp Pond was shallow and swimming otters were often concealed by grasses. The only good ridge to watch them from was on the north shore. Crossing the dam to get there would scare any otters in the pond. The Lost Swamp Pond's west shore was all ridges but the pond had a dog leg shape and was a football field long.

 A rough sketch map of the ponds

Then in mid-October he and I were at Otter Hole Pond and heard growling from the lodge. He thought it was a coyote, then a large otter got into the pond and swam below us. Otter Hole Pond had the best sight lines for seeing anything in it.

After a brief look at us, the otter dived and disappeared. We were standing on top of the ridge just behind the jumble of granite where otters might den. We heard a growling purr from the lodge and couldn't tell if it came from the other side of the lodge or the inside. Beavers don't growl or purr.

The beavers were still in that lodge. They didn't make a lodge in Beaver Point Pond despite the amount of time they spent down there. 

Truth be told, back then I was more eager to see otters than beavers. They make the heart beat faster. It was also more convenient to hike out looking for otters. I generally saw otters during the day even in the morning. Beavers came out toward evening. There are reasons for that. Brown bullheads, the otters' biggest meal in the ponds, were active at night. They were easier to catch in the day by swimming over them as they slept in the silt of the pond bottom. The otter's whiskers could sense where they were.

Why beavers generally come out when it is getting dark is a matter of controversy. Since beavers hear and smell more acutely than they see, they feel safer when winds are calmer. Trees release pollen at night and are easier to smell. Also in felling trees, they often cut a tree to a tipping point and wait for the stronger daytime winds to blow it down. 

 beavers gnaw to a point and let the wind do the rest

When raising kits during the long summer days, they keep them in the lodge until it is dark and the winds calm down. Hence they grow up being comfortable in the dark. All that said, I often saw beavers out alone in the broad daylight, more on that later.

But one foggy late afternoon in November 1996 when I hoped to see otters in Otter Hole Pond, the beaver family was out instead and I was reminded of how interesting it is watching them. “I was treated to a working beaver family.” I am quoting my journal now which can serve as a specimen of how I viewed beavers then. I only took our camera out occasionally when the light was good, but I did have binoculars: "At first I focused on a medium size beaver gnawing beside the lodge - the side where I couldn't see him - then one large beaver swam out and went over the dam. I lost him in the fog. A medium size beaver swam out along the brush pile, looked over at me but did not see me and instead climbed up on ice to nose around the brush pile up there. Not very exciting." 

Then I heard a crunch and crash below the dam which seemed to resolve itself into distant gnawing. It was still light enough for the binoculars to pierce the fog and "a big brown hulk in the fog" resolved into a beaver up on his hind legs making short work of  a tree trunk about 6 inches in diameter. "He first gnawed from above and the side, then tucked his head under to gnaw the bottom of the limb. Once he cut it he grabbed the end of the trunk with his jaws and dragged it with powerful lunges two or three times and then went back to trim the branches holding it up. As he trimmed each branch, he lugged it up to the dam, over, and to the brush pile."

I would see this a hundred times in the next twenty years and can't explain the dumb excitement of seeing a beaver haul a branch into a pond. Some branches he tucked up in the pile of branches over the ice and with others he dived to sink them under the pile. He went promptly back to the tree, tugged some more and then trimmed and brought the next piece back. He dragged straight branches about 8 feet long up and over and you could see where he trimmed the smaller branches. Such a display of grit, sagacity, and virtue, yes, virtue. But none of the other beavers helped. Then another beaver did come up and work on the same tree alternating with the other beaver in dragging branches up.

"Meanwhile a little beaver came out of the lodge floating like two segments of a tootsie roll." From my perch on the ridge, I was still condescending. But the little beaver was the only beaver that noticed me. He "uhuhed" at an adult but got no response. Then it dived and swam toward me. I followed its air bubbles and then it swam right under the ice in front of me. Evidently it made one fast grand circle before surfacing again at the lodge. When a working beaver came back with another branch, the baby whispered with authority and on his way back to the dam the big beaver glared in my direction but went back to work. I began to ease myself back up the ridge and the big beaver let out two tremendous tail thwacks near the lodge. 

Next time I went out with our camera but the beavers didn't come out. I did capture the image of a mink dancing on the ice.
Looking from Otter Hole Pond at expanding Beaver Point Pond below, and mink dancing in the ice

Thanks to all the chickens minks have killed after sneaking into chicken coops, they have a reputation for being heartless killers. Otters are about five time bigger than minks and possess the same killing talents. Both species eat fish. Knowing that otters were likely in Otter Hole Pond again, perhaps even in the beaver lodge, much as I loved the lively otters, I worried about the virtuous beavers not to mention their dam.

The twain met a few weeks later out in the half frozen pond. "As I came down to Otter Hole Pond a small beaver swam away, head up but empty mouthed, all the way back to the lodge, coasting the ice that still covered most of the pond. Then I heard big branches being pulled into the north shore of the pond. I walked quietly up to the little cliff overlooking the pond to hear and see up pond better. Then two small otters swam out from their den in the rock below me and looked up at me without reacting."

The beaver began to swim back toward me but then thought better of it and stayed by the lodge. "The two otters climbed up on the ice - tussled with each other then broke the ice and dived back into their den purposefully - finally seeing me or was it bedtime? At last a tail splash came from the other side of the pond." 

It didn't cross my mind that the otters might have been afraid of the beavers.

I set seeing otters slide in the snow as my goal for the winter. I achieved that goal before Thanksgiving. The early freeze was a false start to winter and the much of the ice behind Otter Hole Pond dam melted. I saw three otters fishing between the lodge and the dam. They snorted when they saw me but didn't hide. "About 50 yards up from the dam they climbed out on the ice and did their slides! as well as played a little. They nuzzle their chin down, pull up their front legs and then push into a slide with their rear legs." Unfortunately they were soon back in the water."

While I didn't see the beavers do it, I did see the results of their preparations for winter: mud on their lodge for warmth and protection from coyotes, mud on their dams to keep them from leaking and capture more water before the final freeze, and more branches and logs to sink beside their lodge. They did the humdrum work of perfecting the paradigm assuring themselves, and other species that depended on them, of surviving a long winter under the ice of the pond.

Big Pond lodge in November - ready for winter

Praise them from whom all blessings flow, but my red letter day during our third winter on the island was January 29, 1997: “at Otter Hole Pond dam, yes!, otter tracks with pooh on the dam and hole through the dam. Pond level already down a foot or two.”

By February there were two large holes in the dam. By mid April both were patched. I must be seeing history since history repeats. But I didn't realize it was a history worth recounting and analyzing until the next winter when otters didn't put a big hole through the dam: do beavers take charge in Chapter Two?

Tuesday, April 15, 2014

Otters and Beavers Share a Winter Pond

Although I began winter tracking in 1994, I didn't get any inkling of how beavers and otters share the same pond until March 1996 when I saw a huge hole in a dam that I thought could only have been made by otters. I saw their prints, slides and scats in the snow all around it.

In the fall of 1997 I saw how a mother otter used beaver ponds to raise her pups, teaching them how to catch fish and live in an ever expanding range encompassing the ponds of several beaver families. Then for most of 1998 it seemed as if my schooling by otters ended. I tracked otters from pond to pond in January and otters seemed to make themselves at home just behind the same dam they breached the year before, but they didn't breach it again and soon moved on.

In 1997 I saw otters on 15 different days, usually up to a half hour at a sitting. I only saw them 5 times in 1998. The beavers seemed as active as usual both years. Their main lodge in what I soon called Otter Hole Pond grew larger even though the beavers spent a good bit of time in the pond just below it. The water of that lower pond which I called Beaver Point Pond lapped up to the downstream side of Otter Hole dam. 

In late November 1998, I saw 4 beavers out in the pond working on and around the lodge, preparing it for winter. 

I noticed an increase of otter scats around the ponds in December, and some possible otter slides on the pond ice. There was no snow on the ice making it hard to see otter slides but easy to see how the ice of each pond brimmed the tops of the dams holding back more water than I had ever seen in those ponds. 

As is often the case on the island, winter struck hard on New Year's Day as the high temperature hovered around 0F. Beavers react to the bitter cold by hunkering down in their lodge after a long autumn of overeating. You seldom even hear beavers in their lodge unless the temperature is 20F much less see them up on the ice. But I've tracked otters for miles when it's 0F. 

We had snowfall and, of course, it became easy to see where the otters were active. I saw otter slides going from granite boulders where I knew they liked to den heading straight to the beaver lodge.

That same day, January 5, I saw that there were cracks in the ice,

The ice of the beaver pond was buckling as it collapsed behind the dam.

I've learned in the years since that beavers also breach their dams in the winter but I had no doubt that the otters made that hole in the dam in early January 1999. When I looked up at the dam from the pond below, I could see an otter slide from the dam to a pool of open water in the ice below that the water flowing through the hole in the dam created.

Soon there were holes in the ice behind the dam along the shore of Otter Hole Pond. I saw fresh otter scats around the holes on January 5, 6, 7, 12 (with 3 fish heads), 17, 20 (with fish entrails), 21, 22, 25 (with 5 fish head including one of a grass pickerel).

It wasn't easy keeping track of this. We had five more inches of snow; then freezing rain; then rain; then more cold. Then after a night bottoming out at -18F, we had a foot of snow bringing our snow pack to 22 inches, with much of the lower strata rather icy. On the 18th we had a thaw accompanied by heavy rains. I expected to see that the beavers in Otter Hole Pond had come out to forage for bark, but they didn't. I did hear mewing in their lodge.

I usually checked the ponds in the afternoon when it's warmer. But in late January the temperatures were consistently warmer night and day so on the morning of the 27th I went out at dawn determined to see the otters.

I had a ringside seat atop the granite rocks where they had their den. I heard some cracks of ice - thumps really and got the feeling that somebody was there, but ice does crack as the morning warms up. Well, I did not have to wait long. I heard noise below me and then an otter came out. I had a good view as it squirmed in the snow stretching for all it was worth.

Then it got up and rather directly centered its behind over the previous day's scats and let fly. Tail was out, up, and firm, the rest of the body did a rhumba and twitch.

At the same time I heard a splash, so there were two otters. I soon saw an otter below me again and again it let fly with a scat and disappeared back into the rocks. Then all was quiet below me and I focused on the hole by the dam. Soon enough there was the sound of cracking ice and then a head popped out from a hole a few yards further down the dam. The otter's head was hard to see

and no action on the ice. I heard chirping, the usual sound otters make to connect with other otters. Then I got the great idea of going on the ice and standing midway between the dam hole and the cliff holes. I heard the beavers mewing in the nearby lodge and I heard otter splashes, I presumed, under the ice. Then I heard snorting right under me. The otter either saw me through the foot thick ice or smelled me. I heard more snorts and then I saw an otter head poke up out of a hole near the cliff, snorting right at me.

I made believe that it didn't see me. The otter ducked, soon swam under me and snorted at me again. It wanted me out of there. So I left.

As for the beavers mewing in the nearby lodge, I was not as great an interpreter of beaver mewing as I was of otter snorts. However, I had never and have never heard otters make sounds like beavers. When I've seen beavers stressed by otters, I never heard them make a sound -- they slapped their tails. When beavers have been stressed by my presence I've heard a huffing but nothing like the growl or screech made by an otter stressed by a beaver or me. All to say, I was pretty confident that the beavers were in the nearby lodge and reacting to my presence and the otters' with apparent equanimity.

It was warm again on February 3. I checked Otter Hole Pond and saw that there was such a large pile of scats at the rock cliff that it was evident that every morning since I last saw the otters they had come out and crapped at that spot. The set-up was so perfect I decided that these otters did not scoot around through the woods to other ponds because they did not need to. The otters seemed to have shaped it just the way they want it. The ice sloping down from the shore afforded two to three feet of air space, a veritable under ice gallery by the shore, and I bet that the way was clear to most of the pond, that big blocks of ice had not collapsed to the bottom of the pond. Meanwhile by the lodge I heard several beavers mewing, harmonizing.

No sooner had I decided that the otters would spend the winter in those two ponds, connected by a hole through a dam, then the next time out I saw two otter slides leaving the ponds. I tracked the otters to the ponds in neighboring valleys and the next few times I came to Otter Hole Pond, I heard mewing, moaning, and gnawing in and around the beaver lodge. It was turning out to be a warm winter. Perhaps that's why the otters became so rambunctious and moved.

But they certainly didn't forget Otter Hole Pond. On February 11 at least one otter was back in the pond. I saw a fresh bullhead head on the ice behind the dam, and on the other side of the dam I saw a fresh scat on the with attendant scrapping.

Finally on February 17 I saw a beaver sitting in some open water in Beaver Point Pond gnawing on a branch. For the past two years, I had often seen beavers swimming up Beaver Point Pond and climbing over the dam into Otter Hole Pond so I suspected the beavers used both pond, but I couldn't be sure. Then on the 18th I saw a beaver on Beaver Point Pond as it dived into the water and disappeared under the ice. I walked up to Otter Hole Pond dam keeping an eye on the open water below it. Finally I saw rippling but the beaver never surfaced. I saw the wake on the surface of the water go into the hole and then when I got near the hole the beaver went through and dived into Otter Hole Pond and I soon heard energetic mewing in the lodge. I got down on my belly and could see the light through the hole. So the beavers were taking advantage of the otter hole. 

On February 21 the temperatures turned colder and most of the open holes were iced over. I found that I had perfect conditions for measuring the holes in Otter Hole Pond dam. As I expected all was more or less quiet in the pond. So with a trusty beaver stick with several knobs to help with measuring - and with my 100 feet of tape, I went to work. 

First the big distances. It was 85 feet from the rock cliff holes where the otters denned to the edge of the beavers' lodge. From the edge of the lodge to the hole in the dam it was 64 feet. The two measurements roughly formed a right angle. 

I got on my belly and eased over the new ice and got my stick into the upstream entrance of the hole which I found was about 23 inches wide. At that entrance the water was about 15 inches deep. There was an 8 inch gap, or clearance, between the water level and the crisscrossing logs of the dam. And above those logs was another hole about 17 inches high. I assumed the otters fashioned that upper hole first and then dug deeper. All totaled that was a hell of a hole.

The upper hole I credited entirely to the otters. It was possible the the lower hole, through which the water was flowing as I measured, might have been widened and deepened by the beavers. The depth of the water at the down stream entrance of the hole was 23 inches.

Because the level of Beaver Point Pond is so high, the level of the two ponds had no more than a 3 or 4 inch difference. Beavers commonly breach upper dams when the pond levels equalize. 

I also measured what I call the open space between upper ice level and the water level. At the rocks I measured three galleries 12 inches, 6 inches, and 15 inches. At the dam I measure one at about ten inches of airspace under the ice. 

The galleries were for the convenience of otters when they fished and I saw a fish head on the ice above one. The beavers used the hole through the dam to get down to Beaver Point Pond dam where I saw that they had stripped one large limb and cut down some trees. Plus there was now a major leak in the dam. I didn't hazard a guess as to who fashioned it. I only saw mink tracks there.

As far as I could tell, when the otters came they preferred Otter Hole Pond. They seemed to abandon their rock dens along the shore and I began to find fresh otter scat outside a smaller, older beaver lodge in the pond, about 50 yards up stream from where the beavers were staying. I thought an otter mother and her three pups lived there in the fall of 1997.

I soon noticed that I had a second hole through the dam to measure - 3 feet from top to bottom and a good 18 inches wide. Also there was a hole directly on the top of it, about the size of a football for an animal to slide through. I assumed this was work done when the pond was buried in snow.

One logical explanation for there being two holes through the dam is that if an otter didn't want to encounter a beaver near one hole, it could us the other, or vice versa though in my experience, in beaver ponds otters try to avoid beavers. But having never seen the course of events in any pond shared by otters and beavers repeat itself from one year to the next, I shy away from suggesting there is a logic involved in the unfolding of events.

Usually I clearly saw a mother otter and two or three of her pups. I could tell because I would see one large slide and one set of larger prints accompanied by two or three smaller slides and prints. In the summer of 1998 I saw a mother and one pup in the pond. I heard stressed chirping when I saw the otters in January. The mother feeds her pups most of the summer and when there is only one pup, it stands to reason that by winter it might be almost as big as its mother.

My usual tension while watching otters in the winter was discovering when the mother and pups separated which could occur between mid-January until March, though in the winter 2010 a mother and her two pups were still together in May. The otters I watched in 1999 didn't seem to make a clear separation. In late February I began to think that there was only one otter in the pond. But in mid-March I was once again sure that there were two. 

Otters usually left the beaver ponds in mid-March. The river around the island thaws well before the beaver ponds. Sitting along the river, I've watched seemingly endless schools of perch. Meanwhile those ponds where the dams have been breached are virtually dry in March. Generally when I've tracked otters in the ponds then, I got the sense that they moved from pond to pond searching for deeper water and more fish. In a word, they seemed restless.

On March 14, I saw an otter in Otter Hole Pond. First I saw tracks around a patch of open water near the upper lodge, and a small hole by low rocks on the upper shore.

then I saw a hole deep through the ice and snow next to the lodge the beavers were in.

Three feet down the hole I could see lapping water. There was an otter scat next to the hole. I also heard beavers mewing inside the lodge. Then I went down to Beaver Point Pond dam and saw that at least one otter had been out in the snow there. 

Suddenly I spotted a mink scampering along the shore heading up to Otter Hole Pond. I followed and that much smaller version of an otter darted up and slid down the rocks where the otters had had their den. Then as I was walking away back down to Beaver Point Pond dam, I luckily turned back and looking over Otter Hole Pond dam, I saw an otter stick its head out of the new hole beside the beaver lodge. 

Was it looking for me, again, or the mink, who after all competed with the otter for fish to eat? And what did the beavers think of all this commotion?

This perhaps sounds more provocative than it really was. Beaver lodges might strike us as tight quarters but I have seen one, not as large as the Otter Hole Pond lodge, accommodate a family of beavers and muskrats as well as a family of otters making a brief visit. In that case, I was sure all the animals were actually in the lodge. The otters used a kind of penthouse apartment. 

I was sure that the hole through the ice and snow did not go into the lodge. Indeed the otter probably fashioned it because the only deep water remaining in the pond that might have fish in it were the dredged channels around the underwater entrances to the lodge. That's probably why the mink was interested in the hole too.

The next day the only sign of an otter was at the far upper end of the pond, not near the lodges or dam. Had the beavers enforced some behavior?

But on the next day there were fresh scats, and blood at the hole beside the beaver lodge - beaver's blood? no, bullhead parts.

The otter got its meal just before another cold front roared through. The hole was well frozen. Only the big lower hole at the dam had running water. There were two otter scats there and also a trough made by a beaver. Thanks to a snowfall the day before I could track one otter leaving Otter Hole Pond and going up a ridge and into another beaver pond about a quarter mile away.

The cold and snow in mid March, not uncommon here, finally eased, and the thaw came quickly. The ice on a beaver pond is usually the last vestige of winter, but the thaw raises the water level and there is no more breathing space under the ice. 

Once during a February thaw I saw an otter managing that with no trouble, breaking up through the ice with a fish in its mouth. 

But that year the otters and beavers didn't breach the dam and drain the pond. In March 1999 the thaw resolved itself into a rush of water down the old creek channel flanked by the snow covered bottom of the drained pond.

I kept checking the pond, more to see the beavers begin to address the dam repairs they had to make, and I did see some logs behind the dam and thought beavers might have placed them there by a beaver to brace the planned repair job. 

I no longer walked on the melting pond ice but stayed up on the shores of the ponds and walked out on the dams. It was harder to spot scat. Then on March 26th, as I walked by Otter Hold Pond lodge and heard a crack from the direction of the lodge, I turned to see a head sticking out of the hole next to the lodge. Big enough, I thought, to be an otter, but on the spot I decided it was a mink especially when the beast crawled out along a stick. Then it walked out onto the snow and I saw that it was an otter. A pup who was no longer under its mother's supervision?

It began nosing around the lodge and slowly went behind it - showing its spade shaped tail. A few minutes after that a lump crawled out on the ice below the dam that I thought it must be a muskrat, but soon that picture resolved itself into a small beaver bent over like an old man squinting into the sun, sitting on his tail, sniffing the air, not in my direction. I wished I had a better camera or a closer vantage for how golden was its fur in the setting sun.

Then the otter popped up onto the top of the dam and I don't think looking at the beaver that was swimming complacently in the water below. The otter pranced on top of the dam pausing now and then to stretched its tail up for a scat.

and then it went over the back of the dam and seemed to knock down a loose stick as if it wanted to get onto the business of patching the hole in the dam.

I returned my attention to the beaver and saw how high it floated in the winter - indicating it was young. I couldn't even be sure that it noticed the otter up on the dam, nor that the otter noticed it. But here were too young animals who shared their first winter together under the ice of a pond....

I waited all of April for the beavers to patch Otter Hole Pond dam. When the ice melted around the lodge about 30 of the now stripped logs that the beavers had cached for winter food floated and collected behind the holes in the dam. 

It was as if the pond was repairing itself. But the beavers never stuffed the logs into the holes. Soon a south wind blew them over to the north shore the pond. 

While my wife, 11 year old son, and I saw beavers frequently in both ponds, the only repair work the beavers did was on Beaver Point Pond dam. They built the dam higher and soon they could float effortlessly from one pond to the other.

On April 15, I saw an otter swim through the hole, too. But  it appeared to be on an entirely different mission than it was during the winter. It wasn't looking for lodging and wasn't interested in food or otter pups. As I stood on a mossy cliff about 15 feet up from the pond, it climbed up a rock below me, gained the mossy flat in front of me, and without any hesitation because of my presence, scatted and stomped on the moss doing what a big male otter does at that time of year, mark his territory. 

He then got into the pond, snorted at me, and then swam up through the dam and far up Otter Hole Pond doubtlessly to mark more of his territory.

Seeing that otter made my heart beat faster and it was good to see him roving, not ice bound. Then I settled down to the pleasures of watching beavers, as placid as usual, dining on bark along the pond shore.