Tuesday, July 27, 2010


It’s not easy to get to observe the development of young birds in a nest, Most songbird nests are hidden away, hawk and eagle nests are high in trees, woodpeckers nest in holes, and ground-nesting birds tend to be precocial, the young leaving the nest soon after the eggs hatch. So when an opportunity presents itself, it’s worth taking advantage of it.

This nest of crows (American Crow, Corvus brachyrhynchos, or Northwestern Crow, Corvus caurinus) was discovered on the seventh floor of a building in the University of Washington Medical School in Seattle. The person whose office was above it alerted Netta Smith to the opportunity, and she brought a camera to work with her many days over the ensuing month to document the development of the crowlets. I was able to drop by on one occasion and watch the action when the birds were about to fledge.

Unfortunately, the eggs had already hatched when the nest was discovered. The average time until young crows leave their nest is about 32 days in the Pacific Northwest, so the eggs probably hatched on about May 1. Thus at the time of the first photo on May 5, they were about four days old. As the month progressed, the young birds looked more and more like crows.

The young developed rapidly with a constant input of food brought by the two parents, which must have had a busy time finding enough for them. Food items seemed to be mostly small and were difficult to identify, but at least some insect larvae were noted. Human garbage likely played a part, as crows in the city forage constantly in dumpsters, but they surely captured “natural” prey as well. No bird eggs or young were seen, but they play a significant part in the diet of crows.

One young disappeared from the nest and was subsequently seen on a ledge several floors below, presumably killed by a fall. This is surely more of a hazard in such a nesting place; tree branches might have stopped its fall. The other four young flourished until, one by one, they left the nest. They tussled with one another as they got larger, and when about ready to fledge, exercised their wings again and again. Netta did not see any of them actually leave the nest, but on one occasion one spent the day on a ledge across the courtyard and was fed again and again. Then they were gone.

One of the most notable things about young crows is their blue eyes. Young corvids often show signs of immaturity by having eye or bill color different from that of the adults.

Dennis Paulson

Tuesday, July 13, 2010


On July 5, I spent some time watching a Red Squirrel (Tamiasciurus hudsonicus) processing Sitka Spruce (Picea sitchensis) cones at Manning Provincial Park, British Columbia. These small squirrels (around 250 g) are frenetically active and noisy, and watching them is much like watching birds go about their activities.

Two things impressed me about this behavior, persistence and proficiency. The forest floor, in a big grove of spruces, was literally covered with cones. Obviously it was a great cone year, not always the case in any given stand of conifers, and the squirrels were taking advantage of it. This particular squirrel would take only a few seconds to locate a cone on the ground, grab it in its mouth, and carry it up to one of its favored perches on a big fallen spruce trunk.

Fortunately, this was at eye level for me, right out in the open and allowing for continued photography. I don’t know why, but he (it was an obvious male) kept coming back to the exact spot to open the cones. And he did it again and again and again. That was the persistence part. But there is every reason for them to be persistent. When food is abundant, go for it.

Proficiency was also obvious. Each cone was held only for a few minutes, while the squirrel bit off each cone scale and swallowed the seed beneath it. I couldn’t determine whether the seeds were chewed or merely swallowed, as the process was so rapid. Sitka spruce seeds are relatively small (3 mm) conifer seeds, so perhaps they could be swallowed without chewing. However, they also have a “wing” that facilitates their dispersal by wind, so that must presumably be discarded.

In any case, each cone was reduced to its central axis in just a few minutes of manipulating it, the scales falling like confetti in front of the squirrel. It was then dropped, and invariably the squirrel gave its territorial chattering call for a few seconds. then it would hop off the log and pick up another cone and start again.

This squirrel processed cone after cone as I watched. Although Tamiasciurus squirrels are well known to store many of the seeds they harvest to feed on them over the winter, I saw no indication of any caching behavior. Red Squirrels cache bushels of green spruce cones in a single protected spot throughout the summer, and these cones become important when the ground is made inaccessible by deep snow.

When cached by certain verterbrates, some seeds that are stored are lost or forgotten, and they have the potential to sprout into new plants. In some cases (gray squirrels with oaks, nutcrackers with pines), the animal may be as important in the dispersal and reproduction of the plant as the plant is in the diet of the animal. This is not the case with Red Squirrels, which, because they store cones before they open, function entirely as seed predators and not as seed dispersers.

Closer to the coast of the Pacific Northwest, including all of Puget Sound country, it is the Douglas Squirrel (T. douglasii) that typically feeds on Sitka Spruce seeds. It is just as persistent and proficient.

Dennis Paulson