Sunday, October 25, 2009

Anatomy of a Food Cache

In Finishing the Food Cache I talked about how beavers arrange their food cache to maximize the space available. Yesterday I got this close up picture of a small food cache made up almost entirely of willow branches. Click on the photo to see the fine branch tips radiating out from the underwater core of the cache.

The beavers anchored the branches butt-first into the mud and the branches are interwoven with each other. A skilled floral arranger couldn't have done a better job!

The second picture shows the small lodge near the food cache. Based on the grass on the lodge and the minimum amount of mud I think this was an older lodge that has been renovated. This colony is probably a pair of young 2 year old beavers that met and bonded this summer and are now getting ready to spend their first winter together. If all goes well this winter they may start raising a family next year.

Happy Creek Forest Fire!

I just got back from a run on the Happy Creek Trail. A little before 5:00 PM MST I came across a forest fire east of the trail on the east side of the creek. The location is about 1.5 km south of Maxwell Lake. The fire was about 20 m x 20 m and blazing almost to the treetops. Another 10 minutes of running brought me to the Beaver Boardwalk where I borrowed a cell phone and called 911 to report the fire.

Now I'm home and writing this post! The government folks are on their way out to the fire. I don't expect it will do much. It's pretty cool and not much wind. I'll get a picture of the aftermath and post it here in the next several days.

November 16, 2009 update

It turned out the fire I saw was an old cabin that was fully ablaze. The SRD folks went up the next day. They hauled in some fire hoses to soak the site and they cut down some scorched trees. Here's a photo of the aftermath.

The fire started in or around the cabin, which was completely destroyed. Fortunately the weather was cool and the forest was moist, so the fire didn't spread.

Beaver Trails

Most of the year beavers don't stray too far from the safety of water. All that changes in the fall when they strart putting up their winter food supply. Then it's necessary to travel overland to the groceries. Travelling the same routes each time and dragging back branches forms recognizable trails. Sometimes these are hard to capture in a picture. Yesterday I lucked out and found this trail network highlighted by a light covering of snow - in fact it was snowing when I hit the shutter button.

The second picture shows the overall layout of this beaver colony. The view is looking downstream from a road. I added arrows showing a dam, a bank lodge, and the location of the food cache. Click on the picture for a larger view. The open water in the upstream pond is being kept open by beaver activity, not water flow. Soon the cold will win and this colony will be iced in to just the lower pond, which is maintained by another lower dam not visible in the picture.

Friday, October 23, 2009

The Outdoor Classroom

Hexagon in shape, the outdoor classroom commands the best corner on the original phase of the Beaver Boardwalk. The idea here was to provide a larger area for small groups to use. Maybe it's a little small for a full school class, but that doesn't seem to matter. And who might have imagined what innovative uses might occur? I've personally seen yoga, a game of chess, and a watercoulor artist at her easel. Hinton Town Council has held meetings there, and someone told me that it was used once for wedding pictures. And yes, it's used by school groups. That's all great - just the kind of things I had in mind.

There's a story behind the hexagon shape. I thought that shape would be interesting and more efficient for talking to a group. The construction of a hexagon was another matter altogether. Fortunately for me, Mark Schoenberger and some of his kids volunteered just when I was trying to figure out the framing. Mark has a lot of carpentry experience and with his knowledge between the two of us we got the framing done in record time. Not bad considering there was about 6" of water on top of mud and ice at the time, which made for treacherous footing and more than one pratfall by both of us. We finished muddy and triumphant. Another great day building the boardwalk!

The Waterdeck

When we designed the 3rd phase of the Beaver Boardwalk I wanted to extend a short section into Maxwell Lake and build in seating so people could relax and enjoy nature. Originally I thought it would have to be a floating structure because I thought the lake bottom would be too soft to support posts. But that assumption was wrong, so the waterdeck is supported by pressure-treated posts just like most of the boardwalk is.

So for those who didn't notice, a little secret. I didn't want the waterdeck to be a great height above the water (remember my "close to nature" desire above). Turns out that I should have been a little more careful with my estimation. When spring came and the lake level began to rise it was pretty obvious the new waterdeck was soon going to be the underwaterdeck. There was nothing to do but admit error and raise the deck, which ended up being an enjoyable Saturday's work. I unscrewed everything and raised the whole structure by the width of a 2 x 8, which turned out to be just about right.

The extra benefit to that beautiful day was the chance to talk with a couple from Austria and a family from England who were enjoying the boardwalk and wanted to know what I was doing. They were very interested in natural history and I enjoyed chatting with them.

By the way, it's called the waterdeck because of a great suggestion by Beth MacCallum. She didn't think we should call it a wharf or a dock because we didn't want to encourage watercraft use of Maxwell Lake. Voila - the waterdeck!

Tuesday, October 20, 2009

Finishing the Food Cache

Warmer weather in the past week has opened up most of Maxwell Lake again, and the beaver colony is really working hard to get their lodge and food cache in top shape for the winter. I've given them a full pickup load of aspen each of the last 3 evenings. Normally it takes them 2-3 days to float that much aspen down to the lodge but lately they've been topping thier own accomplishments. Their rate of food removal has increased to a pickup load a day. All of the 11 beavers help build the food cache but the kits can't take larger branches - only the adults can handle those.

So besides the incredible work capacity of these amazing animals there's another marvel. How do they manage to cram 24 pickup loads of aspen branches into a compact pile that seems to take up no more room on the surface than a single pickup load of loose branches? Of course 11 beavers working so hard must need a lot of food, so it's not all in the winter food pile. But a lot of it is. Someday I want to go snorkeling around one of these food caches in the late fall. I'll bet there's an interesting sight to see.

By the way, I've been giving the beavers some pretty large logs just to see what they can handle. I don't know if they might cut some of these into smaller pieces or take them as they are, but logs of 8" diameter and about 8' long have disappeared. That's a pretty fair weight for me to lift, and I'm over 200 lbs. Even considering the log is floating in the water, for a 45 lb beaver to wrestle it with no problem demonstrates awesome strength.

Lake Tower

The 2nd observation tower was built in spring 2009 at the east end of Maxwell Lake as part of the 3rd and final constuction phase of the Beaver Boardwalk. This lake tower has two stories, with a separate section of boardwalk accessing the ground floor and an elevated ramp to the upper floor. The ramp ended up being considerably longer than planned to keep it on Town of Hinton property and still support wheelchair access. An unintended benefit turned out to be the birding in the willow canopy along the ramp. There were great views of many small birds such as this family of yellow warblers (photograph by Paul Higgins) that are often very difficult to see in the dense shrubbery.

So why two levels? Like the pond tower, the upper floor on the lake tower is for nature observation. The ground floor (actually it's the water level floor) is also for use by skaters in the winter. Skaters will have a place to sit and put on their skates or get out of the wind, and somewhere to stash their gear.

A few people have asked me why you can't get from the upper floor to the lower floor without going the long way around. I did think about putting in stairs (and I had a dream about a fireman's pole, which would have been fun!) but I abandoned those ideas pretty quickly. I couldn't see any way to connect the two floors without creating a safety issue. Wood stairs in the winter covered in snow aren't my idea of a safe undertaking. Take the time to visit each level - you won't be disappointed.

Saturday, October 17, 2009

Lumberjack Beavers

There's one drawback to providing so many pickup loads of aspen branches to the beavers each fall. Because they don't cut their own trees, nobody gets to see the results of their normal behaviour. Fortunately all one has to do is hike the Happy Creek Trail to see one of the active colonies upstream in action. This photo taken this afternoon shows a large aspen that the beavers have been working on. We counted more than a dozen large trees that were either felled or showing evidence of serious gnawing.

The second photo shows a large lodgepole pine cut about half through. Beavers don't normally cut conifer trees because they prefer deciduous species like aspen, balsam poplar, paper birch, and willows. In fact, cutting conifers might indicate not enough preferred food. Most of the aspen close to the upper Happy Creek ponds has long since been cut. Beavers will travel further from water, but this increases the risk they will be killed by a predator. There may be another reason to cut conifers though. I've noticed over the years that sometimes conifers and other non-preferred species like alder are placed on top of the food cache. This weighs down the preferred species that are stuffed underneath. When the pond freezes the ice isolates the capping and keeps the good stuff available below.

Beaver Lodge Armour

In the last week or so the beavers have plastered a thick coat of fresh mud on their lodge. The frozen mud will provide an impenetrable barrier to protect the beaver family during the winter. It would be pretty hard for a wolf or a late-hibernating bear to break through. More importantly, the mud seals air leaks and provides extra insulation so the body heat of the beavers can keep their lodge warm. OK, warm is a relative term. The recorded temperature inside one lodge in the depth of winter was 0.8-1.0 °C, or just about the same temperature as the water beneath the ice. Compared to outside though, which might be -30 °C or colder, it's a tropical resort. The beavers always leave a small area at the top of the lodge as a breathing hole. On a cold winter day one can see the warm air rising up through the hole, indicating all is well with the beavers below.

Here's the process. A beaver dives to the pond bottom and scoops up a big dollop between it's front legs, chest, and chin. Then it walks up the lodge on it's hind legs using the tail as a brace and balance. At the chosen spot the beaver slaps the load down and smooths it out with it's front paws. Then it's back to the pond, this time on all fours, to get another load. In this photo the wet line on the right side of the lodge is the path recently followed by a wet beaver.

In their book Wild Alberta at the Crossroads Marian and Robin White have a great picture of a beaver carrying mud.

Hooded Merganser Visit

This evening a male hooded merganser visited the beaver pond. He decided to preen on the food cache located beside the beaver lodge. I couldn't get a sharp photo and this one is the best of a blurry lot. Hoodies are pretty uncommon in the Hinton area and we usually only see them during spring and fall migration. Our area is near the northern limit of their Alberta distribution.

This second-smallest member of the merganser tribe feeds on small fish. By now he's probably full of brook sticklebacks from the pond. Hooded mergansers nest in tree cavities located near small woodland ponds. There are about a dozen pileated woodpecker cavities in the area, which would make good nesting sites. We also will be putting up nest boxes this winter. Wouldn't it be great to someday see a brood of hooded mergansers on Maxwell Lake?

There's a postscript to this story. When we came by 2 hours later there were 3 beavers around the lodge, and one youngster was curious about the stranger fishing beside the food cache. It followed the somewhat distraught duck around until he decided to escape by climbing out onto the food cache.

Wednesday, October 14, 2009

Berry Cold Birds

The interesting story this week is the many birds that got caught by the unseasonably cold and snowy weather we're "experiencing". The last laggards of the bird species known as short-distance migrants were still here when the Arctic blast arrived. Short-distance migrants don't head for Florida or more southern climes. They just go as far as they need to, which is why the greater Vancouver area (for example) has a lot of robins in the winter.

Now the stragglers are surviving on mountain ash berries, crabapples, apples, and the berries of the May bush. Most of them will quickly move on if the weather warms up as it's supposed to do in the next several days.

Rocky Morin took this "frozen moment" photo of a male American robin about to swallow a mountain ash berry. Other species spied in the past few days at the mountain ash U-pick are varied thrush, hermit thrush, and Bohemian waxwing.

Monday, October 12, 2009

Witch's Butter

Halloween is coming soon, so this picture I took of the witch's butter fungus on a dead pine log near the Beaver Boardwalk seems like a fitting subject. Apparently this jelly fungus, probably Dacrymyces palmatus, got it's common name because if it appears on decaying wood at your house you are supposedly under a witch's spell.  Witch's butter is actually a parasite of other wood-decaying fungi and gets no help from supernatural sources, but it does appear very suddenly after fall rains, as if by magic.

Most of the jelly fungi are reported to be edible, but I've never tried this one and I wouldn't recommend it or any other fungus unless an expert is involved in identification and assurance. Mushrooms and other fungi don't have much nutrition value, so never take a risk unless you are sure. You won't starve without them, and you could get very ill or even dead with them.

Sunday, October 11, 2009

A Beaver Family Who's Who

A question I hear often is "How many beavers are there?' Before I answer that let's look at beaver social structure, which is built around a family, also called a colony. A colony consists of an adult male and female plus their offspring from the past 2 years. When young beavers reach their second birthday they leave the parent colony and wander far and wide seeking a mate and a place to set up their own colony.

Back at the home colony, the adult female produces a new litter of usually 3-4 beaver kits every year. The number of kits depends on the body condition and age of the adult female. If she is young or in poor condition fewer or no kits will be born. I know the Maxwell Lake beaver colony had at least 4 kits in both 2008 and 2009 because I saw 4 kits at one time in both years.

The next consideration is the fact that beavers are very territorial. All members of the colony defend their territory against any strange beaver, so all beavers seen in Maxwell Lake and upstream and downstream along Happy Creek for a few hundred meters are members of the Maxwell Lake colony. There are several other colonies further up Happy Creek above the powerline crossing .

Now we have all the pieces to answer the question. Assuming all the kits survived, there are at least 10 beavers in the Maxwell Lake colony. I've personally seen 7 at once in 2009. There could be more than 10, but that's my best estimate.

Update October 20, 2009 This evening I saw 5 kits at the same time, so I'm upping my estimate to 11 beavers for this year: 5 kits, 4 yearlings, and 2 adults.

The best time of year to count beavers is from June-August after the kits are born and are active around the lodge. That's when the size difference between the adults, yearlings, and kits is most pronounced and a minimum count of each category is most reliable. Dave Conlin took a great photograph of a Saskatchewan beaver family with 8 members. Check it out and make your own estimate for the Maxwell Lake beaver colony in 2010!

Thursday, October 8, 2009

Maxwell Lake on a Snowy October Day

The first photo was taken this afternoon just after I gave the beavers yet another load of aspen branches. I've lost count but I think that's number 16 for this year. I marvel at how they tow off all those branches and pack them into a compact food cache pile at their lodge. This evening there were 3 beavers there waiting, and even me tossing the branches into the lake didn't dissuade them.

One big beaver couldn't wait. A few seconds after the lake photo was taken, it dragged a good sized branch down to the lake (second photo) and towed it off. Free food is great, but a busy beaver doesn't wait if the load is a little late. The instinct to store food is very strong. The colony members will keep storing food until the lake freezes over and they are locked into their winter routine by a shell of impenetrable ice.

Do Beavers Eat Wood?

Trick question - it depends on what your definition of wood is. Let's take an aspen branch for example. The beavers absolutely love the leaves, small twigs, and bark. But as soon as the twigs get to the diameter of a baby pinky finger the beaver starts to peel the bark off, leaving the white twig behind, as shown in the 2nd photo. So the answer is more or less no, they don't eat wood. This makes sense when one looks at what food value wood has to a beaver. The wood is mostly indigestible cellulose bound together with lignin. Great fare if you're a termite, but not so much if you're a beaver who has trouble digesting cellulose.

Are the leaves, twigs, and bark much better? Well yes they are. They contain most of the nutrients in the aspen branch and there is much less cellulose. Probably they taste better too, at least to a beaver. A beaver's stomach has lots of bacteria that help to digest their food but even so it's a tough job to digest coarse plant material. The first time through the digestive system produces a soft pellet which the beaver eats. A second digestion pass extracts more nutrients before the final pellet is produced.

Sunday, October 4, 2009

Happy Creek Trail

The Beaver Boardwalk is located where Happy Creek and Maxwell Lake come together. The Happy Creek Trail was built by West Fraser about 15 years ago. It starts on either side of Happy Creek off the gravel Town of Hinton Trail near the Pond Tower, loops upstream over 3 km along a series of beaver ponds, crosses the creek on a footbridge, and returns downstream. The Happy Creek Trail is well used by walkers, runners, and mountain bikers.

Working with West Fraser, the Hinton Mountain Bike Association helps to maintain the trail and signs. For single-track bike enthusiasts it's a challenging trail. I'm told only a few local expert bikers are able to ride the entire trail without getting off their bike. Personally I love to run it. There are lots of ups and downs, roots to trip over (which keeps me on my toes - most of the time), and a micro-wilderness experience on the outskirts of Hinton. Combine that with at least 3 active beaver colonies and the dams and ponds they maintain and you can't beat it.

Mallard reflection

Every visit to the Beaver Boardwalk is a chance to see a special moment in nature. Last week I spent an enjoyable 15 minutes watching this mallard hen preening on a log. Although I was only 10 m away she clearly thought keeping her plumage in good shape was more important than worrying about me.

I snapped a series of photographs and took a couple of short videos. Although it's not as sharp as I'd like, this photo showing her reflection in the cold pond water was most pleasing to my eye.

Grand Opening Summary

On a warm September 15, 2009 we celebrated completion of the Beaver Boardwalk after 3 years of dedicated effort by a lot of folks. The kick-off was at the Reimer Drive trailhead where the partners congratulated all who contributed funds, time, and support to make the project a reality. We also announced the winners of the children's colouring contest (more about that in another post) and Beth MacCallum and I led a walking tour of the new sections.

After the tour I gave a talk on beavers at the Hinton Library attended by about 50 people. Then the day was topped off by several dozen people watching the beavers munching on fresh aspen at Maxwell Lake. At one point I counted 42 people there, and all the while up to 6 beavers were tucking into supper. The photo shows the watchers - the beavers are over the bank in the centre right.