Friday, March 18, 2011

Pileated Woodpecker

It is always a thrill to see this large, brilliantly red-crested woodpecker (Dryocopus pileatus). In the Edmonton area we are lucky that this distinctive woodpecker can be heard or spotted all year, especially in the forested river valley, the many ravines, and in city parks with stands of old trees. Several times a year they even come around to my feeders at home and they are regular visitors to a treed quad just in front of the building in which I have my office at the University of Alberta. 

Yesterday, this pair spent about an hour near the birdfeeders, including some suet treats, at Hawrelak Park, adjacent to the South Saskatchewan river in south Edmonton. Normally these birds are quite shy and wary. On this day they seemed not to mind being approached, perhaps because they were too interested in each other. It is early mating season for these guys. Male and female took turns flying about 70 feet up a poplar tree, throwing their heads back, and clucking while the mate listened and watched from nearby.

Males and females are easy to tell apart. The male has a vivid red crest extending from the bill to the nape and a distinctive, easily noted red moustache mark extending from the bill. Females are a bit smaller than male and with a forehead that is gray to brown and, for me the most tell-tale fieldmark, no red moustache.

The Pileated Woodpecker's choice of meal is carpenter ants. Large rectangular holes in dead wood are signs of a Pileated Woodpecker's excavations for these large ants. They also eat other insects, supplemented by seeds and fruit. Excitingly, they will also come to suet feeders.

Nests are excavated 15 to 70 feet high in a large dead tree. The unlined nest cavity may be as much as 24 inches deep. Both parents incubate three to five eggs for 15 or 16 days. The young may take a month to fledge. Last summer I had discovered a nest in a cottonwood tree and had looked forward to watching the hatchlings emerge, but then travel intervened. Perhaps this summer.

An interesting quirk about this species is that they excavate square holes. Here is an example of a female preparing a cavity in a dead cottonwood trunk. It is nearly nesting season so I will watch this one to see if this will turn into a Woodie Condo.

Saturday, March 12, 2011

Great Gray day

Wednesday, March 9, sunny , started out -18C in the morning but warmed -2C by about noon.  My aim was to comb the range and township roads (snow-covered dirt roads), looking for Great Gray Owls (and Hawk Owls, of which none were found) in the wooded areas of the Halfmoon Lake Natural Area and Opal Natural Area, roughly bounded by TWP 570 in the south, TWP 592 in the north, RR 221 in the east and RR 235 in the west. It’s prime Great Gray country. And on this day it actually was!

In Alberta, the Great Gray inhabits forests of the boreal regions and foothill regions in the central and northern parts of the province, but their total range includes the circumpolar coniferous forests of the world. The Great Gray owl is a naturally scarce species. This along with its need for declining mature forests during the nesting period has earned the classification as Sensitive in the current General Status of Alberta Wild Species report.

Since they hunt from a perch, either tree a raised dead snag or a fence post, they are often easy to spot from a distance as a large feathery blob outlined against the sky.

Although the Great Gray is the tallest owl in North America, measuring about 75cm long, most of its apparent bulk comes from its fluffy plumage and large head. Its body weight, at about 2.5 pounds, is less than that of the Great Horned Owl and the Snowy Owl.  From its perch this Great Gray listens for prey. Though their vision is good, hearing is an even more valuable tool for these forest hunters.

When their ears pick up the rustle of a vole or mouse beneath the snow, these owls don't just pounce, they plunge. With ice-pick talons tucked under their chins, Great Grays hurtle head-first into deep snow to snatch voles—diving with such power that they can shatter snow crust thick enough to hold a 180-pound person. They locate hidden prey with the help of large facial disks that funnel sound to their ears. When the plunge succeeds, the hunter wriggles out of the snow then carries the prey to a safe spot for consuming. 

The following photos are of a close encounter with Great Gray. When I spotted a pair of GGs on a range road in the Halfmoon Lake Natural Area, I stopped and got out of my vehicle with my binos. Almost immediately an owl approached and landed on a tree about 10ft above my car. I returned to the vehicle to retrieve my photo gear and proceeded to mount my lens on a tripod. When I reached into my pocket to retrieve a glove I pulled out my car keys inadvertently. They fell to the ground on the road and, in a flash of a feathery blur, GG pounced on them and lifted off with them in its talons. Oh my, I thought. Here I am on a lonely, little travelled country road, without a phone and GG has my only keys! It flew about 100ft into the forest, landed, inspected the keys, then promptly dropped them into the snow. Inedible, it must have thought. I waded through hip-deep snow, dug out my keys, and returned to my tripod. A minute later GG flew out of the forest and landed on a fence post about 50ft away, looking at me expectantly. By now I was a bit puzzled. GGs are relatively approachable, but this one is acting too oddly towards humans, I thought. It must have been fed or baited by humans before and had learned to associate people with handouts, I thought to myself. Then I noticed that it had a swath of primary wing feathers missing on its right wing. This did not affect its ability to fly (or to hunt, as I observed later), but it may be that it had been injured, nursed back to health in a wildlife hospice, then released once it could look after itself again. All the same, it looked to humans for food, as I would find out in a minute. I trained my lens on GG sitting on a post. Through my viewfinder, I saw it duck down into launch pose. Still through my viewfinder I saw it launch toward me, rapidly blurring out of focus. A split second later I felt one of its talons close on the middle finger of my right hand, my camera shutter hand. Startled, I looked up and saw GG sitting on a tree behind me. Evidently it must have seen the slight wiggle of my shutter finger and assumed that I had food in my hand. Its whack drew blood but was really quite gentle, more in the way of assertively begging for food than attacking a potential predator too close for comfort or too close to its nest.

[UPDATE: I have now found out a bit more about this owl. According to Gerald Romanchuk, among Alberta's premier birders and photographers, this owl was captured by his friend, Ray Cromie, an owl bander, a few weeks ago. Acccording to Ray, this same owl was banded by him 7 years ago, when it was aged as an after third-year bird and sexed as female. That makes this GG lady about 10 yrs old, quite remarkable, since, according to the textbooks, the average age in the wild for the GG is about 7 years. The missing wing primaries and some inner primaries, Ray and Gerald guess, is the result of an attack by a Great Horned Owl or a goshawk. As a way of helping the old lady out now and then, she has been given a mouse now and then, which explains her begging behaviour around humans. Thanks to Gerald Romanchuk for this information!]

After about 20 minutes of shadowing me from post to tree, this GG concluded I was not a sugar daddy. It flew off some distance and began to hunt. I saw it plunge into the snow about 6 or 7 times, but not with success. But I also saw the other Great Grays hunting, more often than not emerging from the snow without a catch. Of course, a vole is small, and GG's legs heavily feathered, so I may not have seen the catch even with my binoculars.

A few more of this magnificent hunter!

Oh yes, while entertaining myself with the owl (and, for a while, it with me) a moose ambled by, showing only glancing and mild interest.