It’s nearly Valentine’s Day, so here’s a bit about the love life of a little bird—the black-capped chickadee—who is such a joy to have around. Let’s start in winter, when black-capped chickadees spend their time in flocks.
Birds of a Feather
Flock formation typically starts in autumn, although it may begin earlier at higher elevations or more northerly latitudes. Anywhere from two to eighteen birds may make up a flock, with six to ten members most likely. Flocks contain adult birds who bred the previous season, “floaters” (those who didn’t get lucky or belong to more than one flock), and young chickadees born that year who’ve immigrated from other areas (to keep the gene pool diverse). Members feed together by day and roost together at night (but individually–chickadees don’t like to snuggle), but all is not calm and congenial.
Exceptionally complex social behavior occurs in winter chickadee flocks. Each member falls into a linear pecking order, with higher-ranking individuals surviving better than those ranked lower. Birds at the top of the hierarchy get the best of everything—the most nutritious food, the safest cover, the finest breeding sites. The order has a purpose: To ensure that the strongest birds can breed in ample territory that provides enough food for their young to survive and thrive.
Rank is determined by several factors:
◊ Gender: Males tend to rank higher than females, although this changes during breeding season.
◊ Age: Veterans usually overrule very young birds.
◊ Timing: Birds who join a flock late tend to tumble to the bottom of the hierarchy.
Studies have found that male-female pairs within flocks are matched in their rank status—that is, a high-ranking male is paired with a high-ranking female, a not-quite-so-popular male is paired with a not-quite-so-popular female, etc. Remind you a little of high school?
But wait—pairs within flocks? Doesn’t the pairing-off begin just before breeding season (in the spring)? You’d think so, but black-capped chickadees are way ahead of us. Researchers (yes, some people actually get paid to study cute little chickadees) have found that most flocks are initially made up of equal numbers of males and females, each of which spend more time associating with a certain member of the opposite sex than all the other members of the flock (in other words, they’re engaged!). Even the youngest flock members reportedly pair off, and it’s the female who decides which male will win her affection, as is the case in most of the animal kingdom. If a bird’s mate dies during the winter, however, mate selection is put off until springtime.
The Newlywed Game
Chickadee couples begin casually house hunting before the winter flock breaks up, even as early as mid-winter (depending on the weather). As spring approaches, their search becomes earnest and they compete—often fiercely—with others of their species for a territory. Around this time the male begins to catch food and present it to his companion.
Chickadees nest in cavities like holes in dead or dying trees (snags), rotted knotholes in living trees, or previously used woodpecker holes. When natural sites are scarce they may use a hole in the ground or an artificial nest box, as they do in my backyard. Both Mr. and Mrs. Chickadee explore their territory for nest sites and usually several are partially excavated before a decision is made (they prefer to create their own nests by digging out pieces of wood and then discarding the debris elsewhere to discourage predators who may view a pile of telltale wood chips as potential dinner). A power struggle often follows, culminating in presentations with much fanfare and bickering.
After the site is decided on (usually by the female), both members of the pair excavate the hole and bring in nest material, but, according to my reference, it is the female who builds the actual nest. Using strips of bark, moss, and other coarse material, she quietly creates a cup-shaped nest. It is then lined it with soft material such as mammal fur (she uses the “fur dispenser”—a clean suet container filled with fur donated by an especially soft cat—that I put out for them when I see signs of nest-building). At this point the dedicated male is still sweetly feeding her, but it will be during the next phase of their relationship—the egg-laying period—when she will need him the most. Laying eggs is immensely draining on a female’s energy reserves and her partner’s support is essential for her health, as well as that of their young. During this time I often hear her teeny-tiny voice calling to him in the trees, in what must be a request for assistance.
For the past six years we’ve put up our chickadee-appropropriate (clean) nest box every March and it’s been utilized every year but one (and that was due to an overzealous downey woodpecker to enlarged the entrance hole but then decided not to use it; by then the chickadee pair had found another spot). To mimic a natural nest we put about an inch of coarse wood shavings in the bottom of the box and watch the expectant mother “excavate” the box for a couple of days. Then she brings in loads of moss and finally the cat fur to make a soft, cozy nest for her babies. The entire project takes a few days to a week.
On average, chickadees lay seven eggs and incubation usually begins the day before the last egg is laid, so that all but one hatch on the same day. During incubation the mother is fed often by Dad, either directly at the nest entrance or outside on a perch, following his soft call to her.
After the young hatch, they are completely helpless and entirely dependent on their mother for warmth. Bringing home the food (mostly caterpillars) is Dad’s job for the first few days, and it’s intense, since each baby needs to eat several times an hour during the day. Later on, the female also forages for her babies. According to my reference, the mother begins providing food around day twelve, but I’ve seen both the male and female bringing food to the nestlings at day five or six; possibly this is due to the warmer temperatures in our region (as opposed to the eastern US, where spring comes later). Both parents efficiently remove poop sacs from the nest to keep it clean.
Want to help these endearing couples?
Black-capped chickadees are usually found at forest edges, and they need mature trees (preferably native)—both deciduous species in which to forage for insects and build nests, and coniferous types for cover and winter food. If you don’t have mature trees in your area, there’s no better time to plant than now! And while natural cavities are best for nesting, consider supplying a nest box for them if you don’t have snags around. Site it in a partly sunny situation (morning sunlight is optimal) and put about an inch of coarse wood shavings in the bottom. The entrance hole diameter should be 1 ⅛ inches (to keep out house sparrows), and face away from prevailing winds. One box per acre or two is plenty, since they need a large territory in which to find adequate food, although high quality habitats will support more breeding pairs. Be sure to clean the box after breeding season is over (I like to take it apart, scrub inside surfaces with hot soapy water, rinse well, and then set those surfaces in the sun for a day or two. We take ours indoors during the fall and winter and put it up again in early March to prolong its life and prevent mold growth.
Besides trees, provide clean water and, if your native plants are young, food during winter—chickadees are fond of unsalted peanuts, black-oiled sunflower seed, and suet, which is high in fat (they love my vegan peanut butter-coconut oil-sunflower seed concoction), but they also consume berries, insects, and spiders found on shrubs and trees. Spring through fall, though, nearly all of their diet and their babies’ diet is animal—such as insects, their larva, and spiders. It can take around 6,000 bits of food, on average, to successfully rear their nestlings, and native plants are best at providing it.
Reference: Smith, Susan M. 1997. Black-capped Chickadee. Stackpole Books, Mechanicsburg, PA.
To leave a comment, click on post’s title