Saturday, November 17, 2007

The Perforated Pine

This is the trunk of a shore pine, freshly excavated by a Red-breasted Sapsucker, a bird with a funny name and an important role in our coastal ecosystem. The sapsucker is a small woodpecker with a bright red head, nape, throat and breast, and a black body with white patches on the wings and rump. It drills neatly-spaced rows of shallow holes, or wells, through bark into the actively growing layer of trees, causing sap to leak out. The birds eat the sap and those insects that are attracted to and become mired in it.

The sapsucker has been referred to as a "keystone species," because its activities provide some of the necessities of life for other species. The oozing sap and trapped insects are also consumed by other birds. It is not uncommon to see songbirds trailing sapsuckers from tree to tree, intent on robbing the wells. The Rufous Hummingbird is one of our earliest migrants. It arrives in southern BC in March, sometimes before nectar-bearing flowers have opened. The presence of sapsucker wells can mean the difference between life or death to these tiny, calorie-burning birds in unpredictable or harsh March weather. At least thirty species of birds, a number of butterflies, and several mammal species have been recorded as sapsucker well-robbers.The nesting habits of sapsuckers are also exploited by others. Many birds nest in tree cavities but relatively few are able to excavate their own. Each year a pair of sapsuckers a makes a new nest hole, allowing other species, including wrens, certain swallows, bluebirds and other woodpeckers to inhabit their previous homes. The presence of sapsuckers increases the reproductive rates of other species.

The Red-breasted Sapsucker is a year-round resident in the lower mainland and can be found from sea level up to 1200 m, although it may temporarily flee from higher elevations during heavy snowfalls. They can be noisy - mewing or laughing calls reveal their presence. When hammering away at a tree they can be approached closely, seemingly almost oblivious to humans.
Once, walking on a trail on Mount Seymour, I came across one that had died mysteriously, as though it had dropped from the sky. It didn’t seem to be injured in any way. The person with me said, "It looks like a Christmas tree ornament." It did, so bright and perfect.

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