In flocks, songbirds in tune with needs

Shelly Merritt of Alpharetta writes to ask if the flock of 14 or so cardinals she’s regularly seeing in her yard this winter is out of the ordinary. “They go to the feeders together and seem to spend most of their time together,” she said. “Is this something that I just have not noticed before, or is this unusual?”

Actually, the question is typical of those we get this time of year. Other folks write to ask why robins, bluebirds, blue jays and other birds gather in flocks of 10 to 50 individuals or more during winter. Some think it strange that the birds would form groups so compatible —- especially since individual songbirds are very combative in spring when they vie for mates and territory.

Flocking, though, is quite common among our resident birds in winter. Hormone levels are at low ebbs, and the birds are much less aggressive than during breeding season.

And obviously, flocking has important benefits —- or the birds wouldn’t do it.

One major advantage is more security in numbers, especially during winter. This time of year, trees, shrubs and other plants are devoid of leaves or have shriveled to lifeless brown masses. The woods mostly are barren, and birds have few hiding places, which makes them easier targets for predators.

But a mass of birds flying, swooping and swirling in unison, like schooling fish, can confuse predators such as hawks, making it more difficult for the predator to single out and snatch one of the smaller birds. Also, more alert eyes while a flock is resting or foraging for food can reduce its vulnerability to a surprise attack. There is no guarantee, of course, that birds in a flock are completely immune from predators, but being a flock member greatly increases the chances of survival.

Another big benefit to flocking is an enhanced ability to spot and communicate food sources. Robins, for instance, primarily eat berries in winter. Such food may be abundant, but finding it can be difficult for an individual bird. Again, with more eyes searching for food, a flock of birds has a better chance of finding nourishment than a lone bird.

While flocks of larger songbirds, such as robins and cardinals, are generally made up of birds only of the same feather, smaller birds —- Carolina chickadees, tufted titmice, kinglets, nuthatches, downy woodpeckers, pine warblers —- often mix together in roving bands to forage and protect themselves.

Walking in the woods during winter, you may think they are devoid of any birds. Then, suddenly, a flock of these mixed species will land nearby, making the woods seem alive all around you. The flock’s high-pitched tweets, especially those of the chickadees, call attention to predators or new food sources —- and keep flock members in touch as they roam through the woods.

In another month or so, though, the days will be longer and warmer. Hormones will kick in. The birds that seem so agreeable now will be feistier. The flocks will disband. Individuals will seek mates and territories and be ready to do battle with any other bird that crosses them.

Cardinal flocks common

Perhaps because of their bright-red colors that stand out against drab winter backgrounds, cardinal flocks seem to get special attention this time of year.

Small flocks of cardinals are common all over Georgia in winter. In some cases, flocks have been reported with as many as 100 birds.

Cardinal flocks usually are made up of approximately equal numbers of males and females —- perhaps a reflection that cardinals form one of the strongest pair bonds among all songbirds. The flocks usually contain a mix of older adults and young that hatched out in the spring. Most likely, the smaller flocks are family groups that have stayed together after the young are full grown and able to care for themselves. During feeding, males dominate females and adults dominate juveniles.

As with most songbird flocks, cardinals began flocking in late summer when nesting season ended. Except for a sharp, distinctive “chip,” the flocks mostly are quiet now.

That is about to end, however. In early February, the flocks will start breaking up. Males will start announcing the approach of spring with their loud, cheery whistles —- one of the earliest of Georgia’s songbirds to start singing to attract mates and defend territory. Females will respond with their soft, bubbly calls. By February’s end, cardinal mating season will be under way.

In the sky

Look for the moon, which was last quarter last night, to rise about midnight and set around midday this week, said David Dundee, astronomer with the Tellus Northwest Georgia Science Museum. Mercury is very low in the west just after sunset. Venus shines brightly in the west just after sunset and sets in the west about three hours later. Saturn rises out of the east about 10 p.m. Mars and Jupiter are not easily observed right now.

seabrk@comcast.net