The Foraging Four: A Mixed Flock in Winter

According to the old saying, “birds of a feather flock together.” Sometimes. Sometimes flocks of birds are made up of different species, like the flocks of small birds that I look for – and frequently find – when I walk in the woods of Eliza Howell Park in winter.

The mixed flocks vary a little from one to another, but usually include the four species that I have come to think of as the winter woodland foursome. Clockwise from top left: Black-capped Chickadee, Downy Woodpecker, Tufted Titmouse, White-breasted Nuthatch.

         Thank you to Margaret Weber for the use of her photos in this posting.

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The Eliza Howell flocks are typically small, usually just 6 – 8, made up of 2-3 chickadees and 1-2 of each of the others. They tend to somewhat scattered, a loose flock rather than a tight one. Since the first bird I see is often a chickadee, I tend to think of the Black-capped Chickadee as the flock leader.

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I always stop walking when I see a chickadee to watch it and to check for companions. It flits from small branch to branch to log, checking openings in the bark or wood, foraging for insect eggs and whatever else is available to eat. Sometimes it drops to the ground looking for seeds.

Downy Woodpeckers are the smallest of the woodpeckers that live year-round in Southeast Michigan. They sometimes search for food higher in trees, but when moving with the mixed flock, they tend to forage quite low. Only the male has the red on the back of the head.

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The Tufted Titmouse is perhaps the most striking in appearance of this foursome. It also has a name that might seem somewhat peculiar. The “tufted” part is not surprising; it refers to the crest. “Tit” is an old Anglo-Saxon wood meaning something small. “Mouse” apparently comes from a word referring to any bird.

Of the four, Tufted Titmouse is least common in Eliza Howell. If one of the foursome is missing, it is usually the titmouse.

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White-breasted Nuthatches are sometimes referred to as the upside-down birds. They forage mostly on tree trunks and large branches, often heading down the tree.

The nuthatch is the one of the four that is most commonly heard, repeating a loud “yank.”

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The small woodland mixed flocks sometimes include another species or two (Dark-eyed Junco or Brown Creeper, perhaps), but these four are the regulars. As I stand and watch, they move through quickly, often gone minutes after I saw the first one. But I always look for them and the ‘foraging four” brighten many a gray day in winter.

Chickadees Are Not Woodpeckers, but…

I have lingered many times during my walks in Eliza Howell Park during the last eight days to watch a pair of Black-capped Chickadees as they excavate a nesting cavity in a small broken-off dead tree.

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Photo by Margaret Weber

Chickadees are cavity nesters who sometimes select an already existing cavity and sometimes dig their own. When they excavate a new hole, they often try several locations before they settle on one. (Last year they started in one location and then moved; see my post, “Chickadee Nesting Discernment,” May 4, 2018). So I was pleased and excited when it became clear that they were proceeding with this one.

Chickadees do not have the beak and head perfected for hitting wood repeatedly, as woodpeckers have. But, in the right conditions, they get the job done.

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Photo by Margaret Weber

Woodpeckers usually drill their nesting holes in dead trees, but in wood that is solid, not yet rotten. Chickadees, on the other hand, select a snag (standing dead tree) or a stump that is starting to decay. Once they get through the surface, their excavating is not so much chipping away at the wood as it is pulling the soft wood apart. In the first picture above, the bird emerged with a full beak only 3 or 4 seconds after entering the hole.

The snag they are using this year is the small slanting tree in the next picture. The hole is about 10-12 feet high. The fungi on the tree suggest that the tree has been dead for some time.

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As is usually the case in locating nests, I found the spot by watching where the bird went. The hole was about 1 ½ inches deep when I first saw it.

Two features of chickadee nest-making are worth noting.

  1. They often select a location on the snag that is somewhat protected from the weather. Here, the hole is made on the “underside” of the slanting tree (the left side as we look at this picture), where rain is less likely to enter.
  2. When woodpeckers excavate, they bring the chips to the entrance and “spit” or drop them out there. Chickadees, on the other hand, carry their excavated material 10 or more feet away from the nest before dropping, using a couple different locations. Thus, there is no base-of-the-tree clue to a predator that there is nest above.

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Photo by Margaret Weber

Chickadees dig a bowl-shaped hole about 8 inches deep before nesting. In a tree this size, that means that they will hollow out most of the inside. This drawing, from the naturalist Bernd Heinrich (The Homing Instinct, 2014), helps to show the size and explain why they are still excavating in the second week after they began.

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Both female and male excavate, but they will divide tasks in the next phases. The female will make a nest of soft material in the cavity, lay (probably) 6 eggs, and incubate them. While she is incubating, the male will feed her.

I hope to be able to observe some or much of what comes next, but for now I feel privileged to have been able to watch the first step in their nesting.

Chickadee Nesting Discernment

As someone who has a great interest in observing bird nest sites and nest construction, I sometimes wish I could communicate directly with the birds. I would especially like more information on the discernment process, the determination that a particular site is or is not suitable as a nesting spot this year.

It is not rare to see a pair of birds begin what appears to me be nest construction, only to find out in later visits that the birds have abandoned this effort.

The most recent example is Black-capped Chickadees. On April 18, 2018, I was walking near the edge of the woods in Eliza Howell Park and focused my binoculars on a dead stump.

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Chickadees are cavity nesters and they sometimes nest in an old woodpecker holes and sometimes dig out their own. When they dig their own, they usually do so in a rotten stump. So, when I saw a pair of blackcaps pecking away at the stump in April, I was excited, thinking that I might have found a chickadee nest for the first time in 5 years or so.

The next day, they were there again, so I asked Margaret Weber to see if she could get some pictures of the chickadees excavating a nesting hole. This is what she found.

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Two things are noteworthy here: the two pictures are of different beginning openings and in neither is the bird chipping away. I began to think that maybe they had been doing some exploratory drilling and were, at the time of these photos, examining what they had found.

On subsequent visits, I did not see them at the stump again and the holes were not enlarged. They have remained the same for more than a week.

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The question that I would ask if I spoke Black-capped Chickadee is this: What was unsatisfactory about this site?

While there were environmental factors (a couple Blue Jays active at the edge of the woods and a couple of humans watching), I suspect that, given the two starter holes, the reason has to do with the nature of stump wood. Perhaps it was not rotten and soft enough. After all, chickadees do not have woodpecker beaks. This is my current hypothesis.

When I next find an active self-made chickadee nest, I can compare how soft and yielding the wood is. I don’t know how long that will be, but probably before I am able to communicate directly with the birds.