Friday, June 21, 2013

Primary Providers

Northern Flickers (Colaptes auratus) are one of the primary excavators here in the western forests. A pair will often chisel more than one nesting cavity each spring before choosing where they'll raise their young. And in subsequent years, they'll nest within 100-200 meters of their previous year's nest site, sometimes even in the same tree, but seldom in the same cavity.

Female Red-shafted Northern Flicker (c) John Ashley
Red-shafted Northern Flicker female tending to her hungry youngsters
There is quite a bit of competition for these extra Flicker cavities among the other forest birds and mammals living here at the end of the road, as most of them are unable to excavate a home of their own. Several of the small owls species use old Flicker cavities for roosting and nesting, as do Kestrels. Chickadees also use the thermally stable cavities for wintertime roosts.

But it's the use of new Flicker cavities by European Starlings (Sturnus vulgaris) that is causing problems in most areas. Starlings wait until the new cavity is done, then they move in and force the Flickers out, even if the Flickers have eggs laid. As the non-native Starlings have expanded across the continent, Flicker populations have declined.

The three forms of Flickers in North America were lumped into a single species back in 1973, based on the fact that they interbreed along the boundary where they overlap. They were later split back into two species, Northern and Gilded, based on differences in habitat use. Gilded Flickers live in the Sonoran Desert while Northern Flickers cover most of the rest of North America.

The Northern Flickers were further divided into subspecies based on the color of their feather shafts - yellow or red. In the photo above, these red shafts are visible in the primary wing feathers that are folded over the bird's tail. Flicker shaft color is derived from the foods they eat, with the Red-shafted apparently better able to oxidize pigments to turn them red. The red deepens with age for male Flickers, but not females, though this difference is imperceptible to us. The underwing colors are used for pairing and defensive displays.

In general, yellow-shafted Flickers live east of the Continental Divide, red-shafted live west of the Rockies, with a bulbous band of intergrades occurring along this margin, from northern Texas to southern Alaska. Here in Montana, red-shafted Northern Flickers live year round in the west, and the rest of the state is in the intergrade zone.

Nationwide, Breeding Bird Surveys (years 1968-1991) show a 19% decline in red-shafted numbers and a 52% decline in yellow-shafted Flickers. Christmas Bird Counts (years 1959-1988) show a steady 2% average annual population decline across North America. These declines include the surveys and counts conducted in Montana.

Here at the end of the road, in northwestern Montana, our Flickers prefer to nest in the old larch snags that still stand on the undeveloped side of the lake. Just around the tree trunk from the nest pictured above, female Buffleheads nest each summer in an old Flicker cavity that's located just a few feet higher in the same tree.

Years ago, shortly after we moved into the Flickers' neighborhood and started building our own nest, I photographed the tiny Bufflehead chicks leaping from the old Flicker cavity. That one photo has paid for a big chunk of our nesting materials over the years. So in a roundabout way, nesting Flickers have helped to provide for my family as well - and we are grateful for them.