Beaver close up

Open water is still in scarce supply at the Beaver Boardwalk, but every day a little more appears. This evening a large adult beaver surfaced from under the ice right beside the boardwalk and posed for this portrait. Then it climbed out of the water and ambled up the dam to cut a willow shoot, which it dragged the rest of the way up the dam. After towing the branch to the lodge the beaver submerged with it's supper, which was no doubt shared with others inside.

Six people were fortunate to see this display of calm nonchalance within a few meters, talking and taking photos all the while. I got a couple of great video clips as well as some good stills. I'm going to set up a YouTlube account and post some of the better videos soon.

Woodpecker stripes

Many people know that denuded tree trunks and piles of bark scales on the ground at the end of winter are the work of woodpeckers, but have you ever noticed the striped scaling pattern on living pine trees created by the king of the scalers, the three-toed woodpecker? This photo, taken yesterday, shows fresh horizontal stripes created by methodical exploration for the larvae of bark beetles. I know they're fresh because the bark scales were  on top of last fall's needlefall. Close examination of the pattern shows a shallow irregular furrow created by the bird's bill striking sideways blows. I've often watched three toed woodpeckers working industiously across and up and down tree trunks. In this case bark beetle galleries and chambers were hard to find, indicating that the woodpecker did a lot of work for little reward.

Once one knows what to look for, pine stripes are actually fairly common in our local forests. For some reason stripes are usually only on one side of the tree, and that side often faces an opening.

This second photo shows what happens when a woodpecker locates bark beetle larvae under the bark. The stripes merge to form large patches, and if you look closely you can usually find larval galleries and chambers with missing larvae - clear evidence that the woodpecker got a meal. Three toed woodpeckers spend the winter finding and feasting on bark beetles that have attacked dead or dying trees. Evidence of their work is everywhere at this time of the year.

And soon, the sound of drumming will announce the start of the woodpecker breeding season. More on that in a future post.

Pileated woodpecker sighting

This afternoon I went back to check out the pileated woodpecker excavation I found on March 28. I don't think the birds have done much since, but I'll keep watching. I also checked a tree used for nesting a decade ago for new sign, because pileateds often reuse old nest trees. Sure enough, there were a few handfulls of fresh chips on the ground. Another one to watch.

Yesterday Diane Renaud saw a pileated woodpecker chiselling holes in the roots of a dead black spruce beside the boardwalk on the upstream loop. The bird was after carpenter ants, which is both the favourite food and diet mainstay of our largest woodpecker. Fresh excavation sign is all over the boardwalk area, which is another sign that the local pair of pileated woodpeckers will nest somewhere in the vicinity this year. During the nesting period pairs pick a nest site and then don't go too far away until the young leave the nest. Lots of sign in an area during the nesting period is a sure indication a nest isn't too far away.

A Raven's Nest

My running route this afternoon went to the top of the Just Giver trail west of Happy Creek, which is where I spied a bundle of sticks in the forked top of an aspen tree that wasn't there last year. Whacking the trunk with a stick rewarded me with the silent exit of an adult raven. Likely the pair is incubating eggs right now. It will be interesting to watch the progression of the raven family over the nesting season.

Ravens, red-tailed hawks, northern goshawks, ospreys, and bald eagles are the main builders of large stick nests in our area. Raven nests are often near openings, sometimes in isolated trees. Goshawks and red-tails are more secretive, locating their nests below the top of the canopy in denser forest. Ospreys and eagles make massive nests, often in the open near water, that they add to year after year.

Other big birds, especially our 2 largest owls, use old stick nests for their own nests - great gray owls and great horned owls are the likely opportunists. You never know what might be on top of that platform. Several years ago a researcher studying American marten sometimes found his radiotagged animals loafing on stick nests on warm days. A nice private breezy place. What more could a snoozy marten want?

Beavers and robins

There's open water around the beaver lodge so I went over after sundown this evening to look for beavers. I saw 3. Two were floating near the lodge and both of these slapped their tails and went under when they saw me. The 3rd beaver was just below the dam and this one submerged silently and swam under the ice. I waited 5 minutes but it didn't come up. Beavers can hold their breath for 15 minutes or more and I'm sure this one just decided to wait me out, as it really didn't have anywhere to go other than back over the dam into the main pond.

While I was waiting for the beaver to reappear a robin started chirping by the observation tower. That is the first robin of the year for me. I got a blurry photo of my bird, a male, sitting on top of a spruce tree. There was another one calling further away toward Maxwell Lake.

Pileated woodpecker nest testing

Pileated woodpeckers in this area often nest in a living aspen infected with a fungus called Phellinus tremulae. The fungus attacks living trees and rots the heartwood inside an outer shell of sound living sapwood. The fungus forms hoof-shaped fruiting bodies on the outside of the tree called conks. Hence the common name for this fungus - the horse-hoof conk. Although they are strong enough to chip away at very hard wood, even pileated woodpeckers don't like to excavate their nest cavities entirely in hard wood. Large aspens with heartrot are their favourite.

Each spring mated pairs explore for possible nest trees. They are well into the process for this spring, and yesterday I found a test excavation behind Maxwell Lake. There were actually 3 test holes on one tree. Perhaps the tree didn't have enough rot, because I couldn't see any fungal conks on the trunk and the chips on the ground were sound. There is dark hardwood at the back of the excavation however, which might mean rot is present. I'll keep watching the tree to see if the woodpeckers agree with me or not.

Sometimes a woodpecker pair will return years later to an old abandoned start and complete it for use as a nest cavity. There's some evidence to suggest that the original test hole might have actually introduced the fungus to the tree, in which case the woodpeckers are helping their own cause. Clearly the original tree met their requirements, but it didn't have enough rot. No problem, just inoculate the tree and come back later. A neat process to ensure a long-term supply of suitable nest trees.

Spruce buds and squirrels

Every year about this time tiny spruce branch tips appear on the ground. What's going on? Red squirrels are clipping the tips to eat the buds, which are starting to swell as spring advances. Squirrels don't have much to eat right now. Their winter cone middens are getting low, and not much new growth has started. The spruce buds are probably both nutritious and tasty, at least until something better comes along.

I've watched squirrels clipping the tips. They're pretty quick, clipping the twig, turning it to bite off the bud, and dropping it almost in one motion. The first time I watched this activity I had a hard time picking up the bud removal part even with binoculars. To complicate things, sometimes the squirrel clips the twig and just drops it. I don't know if that's deliberate, but I suspect it is. Maybe the squirrels can discern whether or not the bud is a good one, or maybe the protective nest of needles on some buds is too much trouble.

I have another theory about the significance of this. Spruce cone crops are variable, with several years of low crops followed by a bumper crop. Red squirrels actually have bigger litters in the bumper year. This makes sense - the young squirrels will have better survival if there's lots of food for them in that difficult first winter. But what signal causes the squirrels to have bigger litters, which are born before the cones ripen in the late summer? Perhaps this twig clipping is a way to measure how many of those buds are normal vegetative buds, and how many are reproductive buds which will form male and female cones. Whatever the mechanism is, the squirrels somehow know when it's time to have lots of kids. Amazing.