Wednesday, May 25, 2011

Spring Dune Hike With Some Surprises

Yesterday I hiked from Sable Lake across to Lake Superior. Then I hiked to the edge of the woods on the east side of the dunes, along that transition zone to the foot bridge near Sable Falls, down the trail to the Sable Visitor's Center, and back the cross country ski trail to Sable Lake. It was a bit chilly with temperatures in the mid 40s and a brisk wind from the northeast. But it was a gorgeous sunny spring day. I'll post the pictures over a couple of days.....

First a couple of shots taken while walking across the dunes.

Not far from the shoreline I noticed all of these 4-10 inch holes dug in the sand.  The wind had removed traces of any prints, but I think deer dug the holes to nibble on young dune grass shoots.  Others think they were dug by coyotes or wolf.  Does anyone know for sure?

Another surprise was this cliff with around 30 Cliff Swallow nesting holes. A section of the dune fell away leaving a sheer vertical dune face.  It is amazing that the Cliff Swallows moved right in considering that this dune formation did not exist last year.

The Cliff Swallow's back, wings, and crown are a deep blue; the belly is lighter in color. They also have a chestnut-colored face, dark throat, and pale gray nape. Three field marks are especially useful in distinguishing the Cliff Swallow including a white forehead, buff rump, and short, squared-off tail. The Cliff Swallow also has two white streaks down its back.

I didn't actually get to see one of the birds, so here is a picture from the Internet.

Cliff Swallows originally inhabited open canyons and river valleys with rocky cliffs for nesting. Many still nest in these habitats, but others have adapted to nesting on man-made structures, especially under bridges and freeways. Cliff Swallows can be seen in farmland, wetlands, prairies, residential areas, road cuts and over open water. They require a source of mud for their nests, and they apparently have specific nesting requirements that are as yet unknown, as their distribution is patchy, and there are many areas that appear to be suitable habitat that host no Cliff Swallows.

Cliff Swallows forage high in the air, soaring in circles, but they are less agile in flight than other Washington swallows. This is one of the most social land-birds of North America, generally nesting in large colonies (of up to 3,500 nests!) During nesting season Cliff Swallows gather at mud puddles to collect mud that they carry to their nests in their bills. While at these puddles, both males and females flutter their wings up high, which appears to prevent attempts at forced copulation. Extra-pair copulations are common, as is brood parasitism. Females will lay eggs in other females' nests and will also carry eggs in their beaks from their own nests to the nests of others.

Cliff Swallows feed almost entirely on flying insects.

Cliff Swallows have tidy, well-constructed nests, formed from balls of mud that they collect in their beaks. These nests are built on vertical walls, natural or man-made, frequently with some sort of sheltering overhang. Barns, bridges, and large buildings are regularly used. Birds of both sexes begin by dabbing a circle of mud onto a wall and then adding mud-balls from the bottom of the rim up and out, eventually forming a jug-shaped nest. Unlike Barn Swallows, they do not add sticks or straw to the mud structure, but they do line the nest with grass and feathers. Both members of the pair incubate the four to five eggs for 14 to 16 days. Both feed the young, which leave the nest 21 to 23 days after hatching. The parents continue to feed the young for three to five days after they leave the nest. The young of a colony assemble in large crèches, and Cliff Swallow parents use a sophisticated vocal communication system to locate their own chicks within the crèche.

Cliff Swallows migrate to and from southern South America in large flocks, over a considerable period of time. Most return in early April, appearing at natural nesting sites earlier than they appear at man-made sites. The famous swallows of Capistrano are Cliff Swallows, and, contrary to legend, they return to Capistrano in late February, considerably earlier than the fabled March 19. The date of fall departure varies from year to year, although fall migration typically begins by early August, soon after the young become independent.

This is the habitat range for the Cliff Swallow.

Here are a couple of more shots taken once I arrived at the Lake Superior shoreline.  Both these pictures were taken at the "Ghost Forest."

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