Cardinals make it easy on us: There's no confusing those red-on-red males with any other bird in the back yard: If it's an all-over bright red with a crest on its head, it's a cardinal. Kids are delighted to be able to recognize them and their distinctive song, and most adults put cardinals high on their list of favorite birds.
In deep winter, it's not unusual to gaze out at your feeders or birdbath and see 10 or more cardinals sharing the same space, a spectacular sight against the snow. Such groups are made up of pairs of cardinals gathering in the morning or late afternoon for some seed or a much-needed drink of water. Although we call this a flock, cardinals aren't social birds like goldfinches and cedar waxwings, which spend their days with others of their kind.
A flock of cardinals is a temporary aggregation, made possible because the red birds' strong territorial instincts are lessened in the wintertime. Outside of breeding season, a pair doesn't feel the need to jealously guard its home territory. As cardinals move around during feeding times, their activity attracts others to join them. Since they eat the same foods and seek the same kinds of shelter, it's not surprising that cardinals find themselves rubbing shoulders with fellow cardinals.
In fact, researchers have found that flock size rises as the temperature falls. A group searching for food is invariably more successful than just one or two birds, so pairs join up and wheel around to forage together over a wide area during the day. This strategy is useful in a season that requires more energy to survive. It's also safer to spend time with a flock, because that means more eyes on alert for predators.
Here's another way cardinals make it easy on us -- they don't change their looks with the seasons. Goldfinches almost disappear in winter, looking like another species entirely after molting into their drab olive-buff non-breeding-season feathers. Unlike many other songbirds, cardinals look the same throughout the year.
After the rigors of breeding season, cardinals replace worn feathers through an early fall molt, males emerging with a new coat for the next few seasons. Females maintain their lovely brown-gold wash with red accents year-round, too. Cardinal color comes from the pigments in berries and other foods in their diet.
Standing out does have its cost, however. That brilliant red advertises that a male is healthy and adept at finding sources of food, but it also makes him highly visible to predators. I looked out a window on a January morning (ironically, as I wrote this column) to see a sharp-shinned hawk -- a bird-eating raptor -- fling itself into a neighbor's shrubbery. House sparrows shot out to the left and a male cardinal flew to the right. The hawk caught the cardinal in a flash and flew off to enjoy its meal.
They're so familiar we may take them for granted, but northern cardinals are a fairly recent immigrant to Minnesota. The "northern" in their name distinguishes them from a South American bird, but our red bird had traditionally been a bird of the South -- and a ground feeder. As pioneering young cardinals moved northward, they found they could flourish in areas kept clear of snow during the winter, such as railroad lines. So young birds followed the railroads to the north, arriving in our area to stay in the 1930s.
Cardinals are out there, enlivening our winter days with their sweet "what-cheer, what-cheer, birdie, birdie, birdie" songs. Soon they'll regain their territorial instinct and we'll see only the pair that owns each of our back yards.
Val Cunningham, a St. Paul nature writer, bird surveyor and field trip leader, can be reached at email@example.com.
TIPS FOR ATTRACTING CARDINALS
Some people who feed birds are frustrated by their apparent inability to attract cardinals. Since these birds often feed at dawn and at dusk, they may be passing unnoticed in the shadows. Once cardinals put your feeders on their foraging route, nothing can keep them away. Try these tips to catch their eyes:
• Offer sunflower seeds, their favorite food, in platform or tray feeders.
• Maintain a birdbath in all seasons, since cardinals are thirsty birds.
• Provide shelter in the form of evergreens and dense deciduous shrubbery.
• Keep cats indoors, since ground feeders are highly vulnerable to these predators.