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A Sapsucker's Busy Work

When scanning a cluster of river-side serviceberry bushes through my binoculars on a recent birding excursion, a light honeycomb-shaped mosaic caught my eye. After closer inspection (and a hint from ACES' Naturalist Rebecca Weiss) we decided the grid was the result of a busy Red-naped Sapsucker. The serviceberry trunks in front of us were home to multiple generations of sap-wells: some barely-visible scars of wells from seasons past and others brand-new, still oozing and darkening the bark around them.  

Rebecca began to explain the fascinating details about these sap-wells. They are feeding hot-spots, not only for the Red-naped Sapsucker but also for an array of other species that come to rely on the bird's work. There were two kinds of wells littering the surface of this particular serviceberry stand. The first were the diameter of a quarter and the sap-sucker must continually maintain the holes to keep sap flowing. The others holes and bark scars showed punctures, resembling a Parcheesi board and no wider than a pen, where the sap suckers uses its bill to probe the tree looking for sap. 

The gallery of holes, regardless of size, were all carved in the soft bark of the tree by a bird no bigger than my hand. The Red-naped Sapsucker (Sphyrapicus nuchalis) is a medium sized-woodpecker. These industrious creatures are denizens of lower elevations of the Rocky Mountains. Both male and female boast red feathered throats, perhaps their most identifiable characteristic. However, the red-nape that their name suggests refers to a tiny patch of red at the back of the head/neck. Red-naped Sapsuckers seek out nooks in soft-barked trees like willow, aspen, poplar and fruit trees where decay has softened generous spaces. Sapsuckers develop real estate in their chosen trees over the years: beginning by building out hollows close to the ground and subsequently building spaces higher and higher in the tree. Like all sapsuckers, they eat insects, fruit and sap which flows within trees' cambium layer, the living tissue just beneath the outer protective bark.

 

Insects and other sap-feeding bird life come to rely on sapsucker feeding holes. One might call this crucial behavior characteristic of a keystone species, or an organism in the ecosystem that many other species depend upon for continued survival and support. However the opportunistic sapsuckers will also eat the insects attracted to their wells, doing so with a dramatic fly-catching technique made possible by their small tongues. The sap sucker will use its beak and tongue to poke, pry and tap bark for insects, and its tongue to fly-catch and sip or lick sap. 

 

Next time you hear a slow, irregular tapping in the lowland forests of the Rocky Mountains, keep your eyes peeled for these striking creatures and the feeding hot-spots they create.