Wednesday, November 12, 2008

Corvids Part V - The Gray Jay

The Gray Jay, Perisoreus canadensis, occupies permanent all-purpose territories in climatically hostile territories made possible by its unusual food storage behavior. Copious, sticky saliva from enlarged salivary glands is used to fasten food items in trees, food that is used extensively by pairs throughout the winter and other times of the year.

Gray Jays often carry food with their feet in flight, which is unusual for songbirds. This bird is truly omnivorous, eating everything from live beetles to dead deer. Gray jays consume berries and a variety of insects, notably grasshoppers, caterpillars, bees, and wasps. During winter, they eat lichens, as well as carrion and even the occasional small, live rodent.

At only ten inches long, this is one of the smallest jays in the world, with light gray underparts, medium-gray upper parts, and a partial black cap on the back of an otherwise white head. On the Pacific coast of Washington and Oregon these birds have more extensive black on the head and noticeably darker backs with conspicuous white streaks. Individuals from the southern Rockies have black caps that don’t reach as far as the eye and a white forhead, giving that race a noticeably more white-headed appearance. The rather fluffy bird looks a lot like an over-grown chickadee with its dark crown and short bill. Until August, juvenile birds are a dark, sooty gray all over, though slightly darker on the head.

Most Gray Jays inhabit forests with black, white and Engleman spruce or jack or lodgepole pines. While they inhabit forests where temperatures are cold enough to successfully store caches of perishable food, they do not live in the seemingly idea Sierra Nevadas where no spruce or these two pines occur. Apparently it is the tree bark of the trees they prefer; pliable scales arranged in a shingle-like configuration that allows Gray Jays to wedge food items easily up into dry, concealed storage locations. Storage may also be assisted by the antibacterial properties of the bark and foliage of boreal tree species. There are exceptions in subspecies along the coasts of Washington and northern California and in the White Mountains of New Hampshire where the absence specific trees is matched by the absence of cold temperatures that necessitate storing food.

These jays live in pairs, each defending an area of about 50-250 acres against its neighbors. Often a pair is accompanied by a third bird, usually the dominant young from the pair’s own previous nesting, but sometimes it is an unrelated immigrant expelled from another territory. The pair or trio (rarely quartet) moves through the forest in a loose group, scanning the surroundings for food and keeping a sharp eye out for predators.

They do not migrate, but may move down-slop during winter. What they eat is similar to other jays, however they cannot open cones and do not rely on boreal seed crops. While some food is eaten directly, many individual items or pieces are coated with sticky saliva and ‘pasted’ in thousands of individual hiding places up in the trees, often in bark crevices...generally above snow-level. These food stores make it possible for Gray Jays to avoid the hazards of migration and to have an annual adult survival rate that is much greater than for most other comparably small birds; nearly eighty percent. Surprisingly, most Gray Jay deaths occur not in the harsh and apparently foodless boreal winter, but in the summer; probably due to migratory raptors.

Gray Jays readily capitalize on novel food sources. They have learned that humans can be an excellent source of food: not only stealing the bait in traps or food left out at camp sights, they will come to an outstretched hand to take bread, raisins or cheese. This tameness can also lead to the pilferage of food not offered, and is responsible for it earning several nicknames: meat-bird, camp robber, venison-hawk, moose-bird and, most notable of all, ‘whiskeyjack’ a corruption of the Native American name, variously written as wiskedjak, whiskachon, wisakadjak; a mischievous prankster.

While Gray Jays are widespread in boreal and sub alpine habitats only lightly occupied by humans, we may have a significant impact on these birds through climate warming; which plays havoc with food storage; perhaps the most singularly important factor in late winter nesting. And these birds do nest in late winter, but oddly only nest once.

The reason might be that, while nesting at a seemingly hostile time of year, their cached food supplies insures success in spite of the seeming lack of food sources. Because of their stored food supples, Gray Jays are able to successfully raise young and have nesting over and done with before most birds even return from migration. This gives them a jump on storing food for the next winter. All in all, because of their cached food supplies, they are able to produce more young more often than if they re-nested or nested only once later in the season. Climate change is affecting this success.

When young Gray Jays fledge, they huddle together for warmth at the start and eventually begin foreging through the forest as part of the family group. However, at about 55 days, about June, the dominant juvenile will expel younger siblings from the territory. The dominant young bird, occasionally two, will accompany parents for the following fall and winter; benifiting from their experience and protection. While some are able to hook up with pairs that were uncessfully at breeding that year, some eighty percent of the banished birds die. So why doesn’t this banishment happen later in the year?

One reason may be that young birds are most likely not very good at caching food for their first winter. Though they start this behavior quite young, they require their parents help to survive that first year; and it is likely most adult birds would not be able to subsidize more than one, or possibly two, extra birds.

Another interesting fact is that Gray Jays while these birds begin nesting again in February or March, they will not tolerate that dominant juvenile’s assistance. Many birds, particularly tropic species and notably including jays, help feed nestlings and participate in defending them from predators. Such help has been shown to improve the production of surviving young and since the helpers are usually non breeders with the same genes, the helper-bird increases their own genes in the next generation…just as if they had bred themselves.

Keeping a nest inconspicuous is one way to avoid predators, so it might be advantageous to disallow help from the previous year’s youngsters. However, while the breeding pair will not tolerate help feeding nestlings, it will allow help once the young have left the nest and can fly a bit. This makes sense as, once they can fly nestlings are more easily able to avoid predators. This is supported by the fact that, while in the nest, even the parents help keep the nest inconspicuous by bringing maximum amounts of food at each visit and later make more frequent feedings with smaller food loads.

Calls are generally soft, husky or whistled notes in a short series; "cha-cha-cha-cah." or a clear whistled "whee-oo." Listen here.





Sources include:

Pictures from Wikipedia

7 comments:

Kitt said...

I love camp robbers. They're quite common around all the ski areas I've visited, what with all the abundant handouts from lodge diners. But even when I've been snowshoeing on a quite trail, they show up as soon as I stop for a granola bar or to eat my sandwich.

Beverly said...

Yeah, I likes 'em too. Like big ol' chickadees...but louder! LOL

Gallicissa said...

What a comprehensive post!
I learnt a lot, thanks.

Larry Jordan said...

Hi Beverly, That must be one of the most enlightening bird posts I have ever read. The next trip I take to Lassen Park here in Northern California, I will see if I can get a Gray Jay to eat out of my hand! Wonderful post and great photos and video too.

Beverly said...

Thanks Larry! I enjoy the research, but hearing or seeing is apparently not enough for me to really learn something. I do better if I write it down…so this has been a lot of fun for me, and I learn a lot too!

Velma said...

These are my favorite birds! They used to come to my home every so often. There were about 6 or 7, then last year there were 3 that stayed all year. They fly to my door and want food. One had a very sore foot, that ended up healing after losing all claws but two. We call it Stubby. It is one of the parents of 4 young last year. They all seem to be staying year around again. They come daily to my door, looking in to say they are ready to eat! They land on my hand, and are a great joy. I counted 10 the other morning. I heard about the STAYERS, and LEAVERS, but do you suppose since they have lots of food they are all staying? Velma in Olympia

Beverly said...

Hi Velma,

Thanks for stopping by and leaving a comment!

Yes, I just love these little Jays, too. They just seem so perky; friendly and inquisitive.

I have a couple of Blue jays who come regularly, but they are far too shy to land on my hand. I have read over and over that, feeding birds is always a good idea; especially in the wintertime. Still, bird-feeders apparently amount only to about a quarter of a bird’s food supply, so feeding them is not considered detrimental to their comings and goings during migration. If you can find a distribution map of these cool birds, you’ll see they consider your area ‘home’, regardless of feeders.

That you have them living and breeding in your yard is neat! What a joy, huh?

There is a White-winged Dove hanging around my place for the past several months. Several weeks ago, I noticed it had feathers on its feet; as if it walked through something sticky and then settled down over its feet. Sadly, at least one foot has turned all black and claw-like; it won’t put weight on it, either. I’m afraid I’ll be calling him Stubby, too. I just hope the other foot is okay!