Saturday, April 23, 2011

Rough-legged Hawk (Buteo Lagopus)

Today, out on the range west of Bittern Lake, the Rough-legged Hawks outnumbered the Red-tails. I must have seen a dozen as they hunted on the range while moving north to their breeding grounds. The Rough-Legged Hawk (Buteo Lagupus) is a circumpolar Buteo -- the Hawk of the North. It nests in the far north, generally above the tree line of Alaska and Canada, including the lower high arctic islands. In these regions lemmings are the main food item.

We see them here throughout Alberta during migration, from mid-October through November, and again from mid-March to May. Some will overwinter in the province if the winter is mild and the snow cover not too deep; most will move the lower US during the winter.

This is a big hawk, about 48-60 cm tall. The name "Rough-legged" Hawk refers to the feathers on its legs that go down to its toes. The Rough-legged Hawk, the Ferruginous Hawk, and the Golden Eagle are the only American hawks to have legs feathered all the way to the toes. The rear view in the photo below shows is leg jammies.


Commonly with pale, streaked chest and broad dark belly, but it also has an all dark form, but still with pale wing feathers and white at base of tail.

Its nest is a large bowl of sticks, sometimes including cariboo bones, typically on a cliff ledge. It is lined with grasses, sedges, small twigs, and greenery.

Monday, April 18, 2011

Merlin (Falco columbarius)

The Merlin is a small falcon -- similar in size to a blue jay -- of the prairies, boreal forests, and subarctic areas of North America. Males average 24-27 cm long, with a wingspan of 53-58 cm. As in most raptors the females are somewhat larger, with measurements of 28-30 cm and 61-68 cm, respectively. Merlins are unusual among raptors in that the sex of adults can be told apart by plumage. Males are slate blue-gray above, with bold black tail bands; females are brown with buff-coloured tail bands. Both have a whitish throat and a buff breast moderately to heavily streaked with brown. In general the plumage of juveniles is similar to that of adult females. I would call this an adult female. She was waiting for her mate while I was photographing. When he arrived they both fluttered off with their "keek, keek, keek" spring mating calls.

Its scientific name is Falco columbarius - a reference to its original North American name of "pigeon hawk," as columbarius means "pertaining to a dove or pigeon" in Latin. “Pigeon hawk” alluded to the Merlin’s pigeon-like flight, though it does in fact prey on pigeons. I’ve seen a Merlin take down a Rock pigeon a good number of times on the campus of the University of Alberta. The Old French esmerillon is the root of both "Merlin" and the modern French name for the species, "Faucon √©merillon.

In the photo above you see what appears to be a streak of blood on its undertail. Likely mess left after a recent kill. The bulk of their diet consists small songbirds. When hunting, the Merlin typically flies over open forest or grassland at high speed (up to 70 km/h), flushing out birds and snatching birds who react too slowly. Merlins are extremely agile, able to make remarkably rapid changes of direction to keep up with their quarry. Alternatively, Merlins may hunt by watching for activity from a perch, and then launching into rapid flight from there. Merlins also feed on insects, especially in migration when they often grab dragonflies or butterflies out of the air and eat them while in flight.

The Merlin is rapidly colonizing urban areas on the prairies. It is the most abundant hawk in the city precincts of Edmonton. I have seen it hunting in my backyard, even colliding with my living room window. At the moment, they are noisily courting and establishing nesting territories.

Saturday, April 16, 2011

Spring arrivals

Here is a set of spring arrivals from the last few weeks. I'll add a few more comments as I have time.

Monday, April 11, 2011

Barred Owl (Strix varia)

The Barred Owl (Strix varia) is common, though sparse, in much of Alberta’s forested regions. I have heard and seen them regularly in Edmonton’s ravines that are rich in the riparian habitat, with mature conifers, water and open spaces, that they like. During the day these nocturnal hunters tend to roost and doze rather high up and under cover of thick foliage, so spotting them is a challenge and getting good unobstructed photographs even more so. The Barred Owl is a highly vocal owl, giving a loud and resounding "hoo, hoo, too-HOO; hoo, hoo, too-HOO, ooo" which is often mnemonically phrased by ornithologists as "Who, cooks, for-you? Who, cooks, for-you, all?" – the last syllable descends and fades noticeably. Because the song has eight hoots, ending in a descending oo-aw, one of its nicknames is Eight Hooter. They will call in the daytime as well as at night. Now, during the mating and early nesting season, I most often hear them especially near dawn and dusk, then I try to follow my ear to their perch.

They get their name from the white horizontal barring on the chest and vertical barring on the belly. They are round-headed with a whitish/brown facial disk with dark brown trim. The eyes are blackish-brown, and the beak is bright yellow and almost covered by feathers. They have a long tail. There is no difference in plumage between males and the larger females.

It hunts mainly from a perch, feeding on small mammals, birds, amphibians, reptiles, and insects. It prefers to nest in a natural tree hollow, but it will also use an abandoned stick nest of another species. I have read that they prey on birds on the wing, but I wonder about that, given their lumbering flight. Being nocturnal hunters it is more likely that they take birds once they have settled into their nighttime roosts.

Barred Owls have been known to live up to 23 years in captivity and 10 years in the wild. The Great Horned Owl is the most serious predatory threat to the Barred Owl. Although they often live in the same areas, the Barred Owl will avoid parts of its territory that is occupied by a Great Horned Owl.

Wonder why its second Latin name is varia? In Latin, varia is a form of the word “various,” meaning diverse. Barred Owls have also been known as Northern Barred Owl, Swamp Owl, Striped Owl, Hoot Owl (a widely used popular name), Eight Hooter (because it calls in a series of eight hoots), Round-Headed Owl, Laughing Owl, Crazy Owl, Black-Eyed Owl, Le Chat-huant du Nord (French for “The Hooting Cat of the North”) and Wood Owl, among others.