Survival of a bright red beacon

A male cardinal is the most common, North American “animal” of size that is virtually all red, a color used by few wildlife species hereabouts. We have a few small red beetles and salamanders plus several birds, like tanagers, that mix bright red with other others, but what else is almost all-red?

Cardinals don't seem to need camouflage.

Ornithologists say male cardinals have probably evolved their bright, distinctive color to attract female cardinals. However, how do they survive so well in the wild with such a rare, flashy outfit that, even among the fully leaved trees of summer, seems to stand out like a sore thumb?

Hawks see red. Why, then, don’t they decimate the population of male cardinals, which seem to do little to hide themselves, especially in winter when the deciduous trees have no leaves for cover.

The answer probably lies in our own perception of color vs. a bird’s perception.
“Birds see very differently from the way that we do,” says Chris Elphick, assistant professor of ecology and evolutionary biology at the University of Connecticut.

“They see into the ultraviolet ranges and have different types of receptor cells in their eyes, so a bird that seems the brightest to us is not necessarily the brightest to another bird — such as a hawk.

“How a hawk sees a cardinal — or anything else — is thus hard for us to conceive,” he adds.

An evolutionary biologist named John Endler found that how a color looks can depend on surrounding colors because of the wavelengths of light that are absorbed by the environment. Thus, in the forest full of green, red light tends to be absorbed, so red objects would not stand out the way they would against, for instance, a snowy background. “This phenomenon helps explain why scarlet tanagers — or any number of warblers — can be so hard to pick out even when there are not leaves obscuring them,” Professor Elphick observes.

He adds: “It’s important to remember that evolution always involves a balance between benefits and costs. Being conspicuous has potential costs — e.g., increased predation risk — but if those risks are balanced by greater benefits — e.g., more/better reproductive opportunities — then maybe that’s OK, evolutionarily speaking.

“Also, hawks are rare relative to cardinals, so even though a cardinal may be vulnerable when it encounters a hawk, there may be enough cardinals that do not have such encounters that the selection pressure to be less conspicuous is not as great as it might seem. And, of course, just because a cardinal is seen by a hawk doesn’t mean it will get caught.”

Laura Erickson, science editor at the Cornell Lab of Ornithology, reports that hawks can definitely see red. “But they can see a whole spectrum of colors, and much of their favored prey is more muted in color, so there is no good reason for hawks to focus on cardinals.

“Cardinals, like Scarlet Tanagers, spend much of their time hidden in foliage, and it’s very difficult for even accipiters [bird hawks] to grasp prey from the branches that cardinals favor.

“Goldfinch or Prothonotary Warbler yellow, Blue Jay blue, and oriole orange are almost certainly at least as vivid to a hawk’s eyes.

“The brilliant colors of many birds, especially when found on males only, tend to be territorial and sex signals. Of course, birds do tend to be safer when not noticeable to anything, so many of the most brilliant birds do molt out of those bright colors during the non-breeding season. New feathers on male Northern Cardinals are edged with brown, and the tips wear away to reveal the brightest red at the end of winter/early spring. But Baltimore Orioles and Blue Jays stay in their bright feathers year round.”

Laura adds, no doubt with a smile, “You know what color is even rarer than red in the bird world? Pink. Apparently, birds shun Mary Kay cosmetics, too.” 

The hungry hawks

The striking Rich Josephs photograph of this of a Red-tailed Hawk consuming a crow is a dramatic example of why hawks and other raptors were once hated and hunted. Hawks, owls and eagles feed on a variety of birds and smaller mammals. For hawks and owls, at least, mammals and birds are their primary source of food.

Catching squirrels, rabbits, mice, and birds in the wild is often not easy, and requires skill, stealth and timing. More often than not, the raptor is unsuccessful and the prey escapes.

When farmers took over much of the landscape in the 18^th and 19^th Centuries, they eliminated some raptor prey, but also introduced others. What’s more, some of the new fare were easy pickings.

Chickens were so popular with some hawk species that any hawk that attacked domesticated fowl was called a “chicken hawk.” However, the Red-tailed Hawk was probably what farmers saw most, and was the most feared “chicken hawk.”

In a way, this is unusual. Red-tails are not true “bird hawks.” Many Accipiters like the Sharp-shinned and Cooper’s Hawks feed primarily on birds and are designed to catch them on the wing – they are smaller, sleeker and have long tails that allow them to maneuver quickly. By comparison, the bigger Red-tailed Hawk is not as agile. It can catch an occasional crow or waterfowl, but it’s unlikely a Red-tail could nail the chickadee or titmouse that a Sharpie can catch.
When the European farmers arrived, they provided virtually flightless fowl to the native raptors. Domesticated chickens were slow, fat and tasty. It was Red-tail heaven – until the farmers got good guns. Hawks were treated as vermin, bounties were paid for their bodies, and countless numbers of them were killed.

Even in modern-day Ridgefield, “chicken hawks” are at work. Last fall, we got a call from Wendy Llewellyn who had recently returned to maintaining full-sized, egg-laying chickens at her home. One day, “they were making strange noises,” she said. She looked outside and “there was what I assume was a hawk, trying to take off with one of them,” Wendy said. “I ran out and the hawk dropped the chicken.”

A week earlier, her cat had been limping. “When I brought her to the vet, he said she looked like she had been in a fight and was covered with lacerations,” Wendy said, wondering whether it was a tom cat – or the hungry hawk.

Small mammals are the main fare of the Red-tail, our most common hawk, and if the opportunity arises, the Red-tail may attack small dogs and cats.

“Large raptors, such as Red-tailed Hawks and Great Horned Owls, can indeed kill a small pet,” says Hawks Aloft, a raptor conservation organization. “We have received dozens of inquiries about six-pound dogs, ten-pound dogs, etc., all the way up to a 60-pound dog. There is no specific cut-off weight at which your pet’s safety is guaranteed. If the size of your dog or cat is similar to or not much larger than naturally occurring raptor prey, there is a risk.”

Early one morning a couple years ago, I was walking our nine-pound Chihuahua, Charley, down the road when suddenly I saw a Red-tail flying straight at us, only about eight feet off the ground. I am sure he was eying Charley, who was about 10 feet ahead of me on a leash. However, as soon as the hawk noticed me, he veered upward and headed off into the woods.

We never leave Charley alone in the yard. He and any other small dog or cat could be lunch for not only large raptors, but coyotes, the recently reintroduced Fishers (large, mammal-eating weasels), perhaps foxes, and maybe even cougars (reliably sighted in Ridgefield last year).

So keep Fido and Kitty indoors or under surveillance.