why are cardinals so red?

Most of the birds I see in the Minnesota backyard in the winter are variations of black and white, perhaps with a bit of chestnut, yellow-tan, or reddish accents: chickadees, nuthatches, woodpeckers, house finches, goldfinches, etc. But one bird really stands out in the winter scene, the Northern Cardinal, the male of which advertises his bright red colors all year. Forget camouflage, this bird flaunts his feathery spectacle every day; it’s the one cheery spot in the monotonous gloom of winter white, gray, and brown.


Here is Mr. Studly Cardinal in the spring, with his bright red coat of feathers.


And here he is on a bright, cold, winter day, with just bare twigs between him and a potential predator.

That red advertisement in the presence of a number of predators that would love to eat him really begs the questions:  why are cardinals so red, and why are they red all year?

Let’s start with the argument recently elaborated by Yale ornithologist Richard Prum in his delightful new book:  “The Evolution of Beauty” (2017).  Prum advances the Darwinian argument for sexual selection (as opposed to natural selection), more specifically, the role of female choice in mate selection, as the basis for why some males are so ornately decorated or colorful.


Successful male peacocks displaying to their female partners have longer, more elaborate and iridescent tails. Why?  (Photo from BirdEden.com)

The adaptationist (via natural selection) argument for why male peacocks have such long tails with intricate patterns is that this feather display proves the male is 1) stronger (able to fly away from and evade predators), 2) healthier (more energy devoted to his ornaments), and 3) more vigorous (long periods of strutting around showing off those feathers while evading predation).  Prum instead argues that it is female choice of the “most beautiful” males that has driven them to become so gaudy; that is, only the extravagantly bright and showy males will pass on their genes through successful matings.

Does this help explain why Cardinals are red?  What do you think?

I’ll add my thoughts to the discussion tomorrow.

let sleeping foxes lie

Morning coffee in hand, I ventured out to a somewhat chilly “sunroom” porch this morning and found a red fox sleeping nearby.

red fox-sleeping in snow

Morning light hasn’t made it to the backyard yet, and the thermometer on the backdoor says -10 F.

So I sat, camera in hand, and waited for the fox to wake up — for an hour and a half.  It was a long nap, perhaps needed after a long night of hunting mice, or the like.  It got boring watching the fox nap, so I opened the window for a close-up, clearer telephoto shot.

red fox-sleeping in snow

Curled up, fur fluffed up, nose tucked under tail for protection — the fox is quite comfortable at this frigid temperature.  This seems to be the typical posture of canids (dogs) sleeping in the cold.

artic fox sleeping-curious expeditions.flickr

An arctic fox sleeping in a similar position (Curious Expeditions on Flickr photostream).  Note the nice pocket of insulating snow the animal has created around it.  Arctic Fox can tolerate temperature extremes of -70 F without shivering.

wolf sleeping-Jeffrey Lepore-Science Source

A gray wolf using the same heat conservative posture while sleeping in snow (photo by Jeffrey Lepore/Science Source)

red fox-

Finally awake, now that the temperature is all the way up to O F. It must be time to get on with the day’s activities.

red fox-eating snow

First on the agenda, eat some snow — replenish some body water lost in the nightly adventure.  I could see the fox biting chunks, chewing, and licking the edges of its sleeping area.

red fox-eating snow

Licking the moisture off its muzzle

red fox-

Stretching — this is a signal that the fox will either lie down for another nap, or take off in a few minutes.

red fox-

Yawn — wow, that is a huge gape between its jaws, big enough to bite something pretty chunky. Too bad the woodchucks are hibernating.

red fox-

Looking over at me, as I tap on the window, wishing the window were open instead of closed, so I could get a better photo.

red fox-stretching

A final stretch out, and the fox is off to make its rounds of the backyard.

red fox

too cold…

It’s -13 F right now, and with a moderate wind blowing, the wind chill makes it -36 F.  That’s too cold for me, but not too cold for the hungry birds and squirrels in the backyard to come into the bird feeders for a meal.

basking gray squirrel-

Gray squirrels don’t venture out until the sun is well up on these really cold days. And before they cross snow patches to get to the feeders, they bask on the trees for a while to warm up, orienting the darker fur on their backs directly toward the sun.

basking chickadee-

Even the chickadees take a few minutes between trips to the feeder to bask a little, fluffing their feathers out to make their tiny bodies into an almost spherical shape.

basking blue jay-

The bluejay must have been too cold to move — it just sat there looking around, squinting into the sun.  I could see the wind ruffling up its feathers — brrrrrrr.

Basking to gain what little radiant heat the sun provides at this time of year can be effective in warming up, but wind currents that penetrate fur and feathers carry that precious heat away.  What can a small animal do to cope with this intense winter cold?  Activity helps, as muscles generate heat, but that comes at a cost to be repaid by eating more.  Shivering helps, and when animals are not active, muscles engage in isometric tremors that generate heat, which is also expensive, but not as much as flying or running across the snow and climbing trees.   The only animals that seem unperturbed by this weather are the feisty little red squirrels.

red squirrel-

Red Squirrels must generate a lot of heat dashing around, because they spend almost no time basking and a lot of time digging into the snow looking for buried treasures (food) and running up and down trees to stash whatever they find away.

Mug shots — take 2

Birds and mammals seem to sense when you’re staring at them, willing them to stare back so you can get a great portrait with the glowing eyes looking right out of the frame.  It’s hard to achieve though, and mammals in particular resist eye contact, as that often is interpreted as a threat to them.  This is where telephoto magnification is essential, but even when I am quite a distance away, mammals just as often turn away as I raise the lens to focus.  Obviously their eyesight is a lot better than mine.

Common Loon-

A Common Loon emerged from a dive right in front of me providing a unique close-up of the detail in its feathers.

female Pileated Woodpecker

This female Pileated Woodpecker was so busy drilling into the tree, she didn’t notice (?) me walking closer to get my best shot.

european forest buffalo (wisent)-

A European forest buffalo (wisent) intent on eating and with no interest whatsoever in raising its head to make eye contact. I can see that they have long golden eyelashes though…


Young Javelina crossing the road in front of our car near Portal, Arizona. Hairy beasts with long snouts, beady eyes, and stubby legs, not at all related to pigs (which evolved in Eurasia), but convergent in looks and habits.

mule deer-

Mule deer look like White-tailed deer (a different species) but have enormous ears, darker (blackish) tails, and darker gray fur. Usually found only in western North America plains, deserts, mountains, grasslands, etc.  Deer don’t see as well in the daytime as some more diurnal animals, and they often stare motionless for a few moments before bounding away or turning their back on the camera.

white-tailed buck-antler growth

Antler growth begins in the spring in White-tailed bucks. This looks like the start of what will grow into a large rack, and I wonder if this guy is the same animal as the one in the next photo.  I kept waiting for this guy to turn around and face me, but no…all I got was a side view.

white-tailed buck-antlers-

I’m behind a glass door and across two backyards from big buck, but he raises his head to look toward me when I tap on the window.

mexican wolf-at the Sonora desert museum, Tucson

A Mexican Wolf just barely raised its glance toward observers as it strolled through its pen in the Sonora desert museum in Tucson.  This is a subspecies of the Gray Wolf, but is on the verge of extinction in its native habitats in the southwestern U.S. and northwestern most Mexico due to loss of open hunting areas and predator removal.  Their fur coat has accents of black and white on the back and their under hair is yellower than that of the Gray Wolf.

mountain lion-

Big cats overheat quickly in the desert sun, as this one did pacing in its pen at the Sonora desert museum. Back in its cooler cave, panting, the puma/cougar/mountain lion finally raised its head and looked in my direction. Pumas are usually found in the mountains, but will venture into grasslands and even more arid desert habitat if there is sufficient game.

Mug shots – take 1

It’s great when you can get really close to the wildlife, i.e., right in their “faces”, to grab a “mug shot”.  I didn’t get many this year, but there were a few opportunities, assisted either by my extremely long (600 mm) telephoto lens or my trusty macro, to get up close and personal with the local wildlife on our travels and in my backyard.

hoverfly-on coneflower

Hoverfly gleaning pollen and/or nectar from New England Asters.

american-painted-lady-on sedum

American-painted-lady-on fall-blooming Sedum; they came through by the dozens to congregate on late-blooming flowers


Honeybees foraged on New England Aster; I saw more of them this year than in the last 5 years combined.


A tiny carpenter bee feasting on pollen from newly opened anthers on a coneflower.


We found a Bullfrog calling in a desert oasis in Arizona. Kind of ugly, but beautiful eyes…that might be a mosquito on his upper lip trying to get a meal.


A Chuckwalla was sunning itself at the Sonora desert museum in Tucson. Dark pigmented scales on its underside help it soak up heat from rocks. Chuckwallas love to hide in rock crevices and resist being pulled out from their hiding place by puffing up their body with air, expanding into any empty space in the crevice.

snapping turtle-

Snapping Turtles have large jaws and long necks, but this one was protecting itself by withdrawing into its carapace.  My what beady little eyes you have, Mr. Turtle.

Great Blue Heron-

Eye to eye with a Great Blue Heron

molting mallard ducks-

Male Mallard Duck before molting a new set of showy feathers

Black-capped Chickadee-

Chickadee with an attitude…

sparring in the snow

The deer herd wandered through the backyard for the first time in quite a while.  A few does, three bucks, and assorted youngsters of the year.  Two of the bucks got into a couple of short shoving matches, primarily instigated by “big buck” (he of enormous girth photographed in mid-November).   The rut might be mostly concluded, but there seems to be enough residual hormone circulating to ensure the male dominance hierarchy is still on-going in the herd.

White-tailed deer bucks

“Big buck” on the approach to his younger, smaller herd member…

White-tailed deer bucks

One minute they are ambling through the woods picking up the stray leaves and twigs to eat…and the next minute they are butting heads.  Buck on the left is getting shoved backward by “big buck”.

White-tailed deer bucks

Ouch, “big buck’s” antler tine looks like it’s poking into the smaller buck’s right eye.

White-tailed deer bucks

Staring contest — who’s the boss? You can tell “big buck” is asserting his dominance just by the difference in the posture of the two.

One minute they are ambling through the woods picking up the stray leaves and twigs to eat...and the next minute they are butting heads. 

Back to amicable feeding, side by side…

One minute they are ambling through the woods picking up the stray leaves and twigs to eat...and the next minute they are butting heads. 

and then suddenly, “big buck” turns to face off with his buddy again…(the difference in the size of the two bucks is more noticeable in this shot, and their antlers seem to be different colors)

White-tailed deer bucks

once again locking horns (antlers)…

White-tailed deer bucks

and once again, the smaller of the two bucks gets a tine in the eye

Now we see the advantage of that larger, more complex rack on older bucks, with tines that can reach into the sensitive facial areas of their competitors.  Of course, the added stature and muscle mass helps those big bucks push their smaller competition around as well.  Thanks for the show, boys.

running on water

Watching ducks and swans take off from the mostly unfrozen lakes the other day, I was impressed with how important those big, webbed feet are in keeping the birds’ bodies up near the surface of the water.  For example, a light-bodied, male Hooded Merganser “ran” on the water less than 50 feet before it was air-borne.

male hooded merganser running on water

The merganser’s feet barely touched the water surface as its rapid wingbeats lifted it into the air.

These small diving ducks weigh only 1-2 lb, so getting air-borne from the water surface is less of an impressive achievement.  However, Trumpeter Swans, the heaviest bird in North America, weigh 20-30 lb, and lifting those big bodies into the air requires the combined effort of both feet and wings.

trumpeter swans running on water

Initially, it looks like a lot of splashing without much lift taking place.

trumpeter swan running on water

Their bodies are so close to the water on take-off, they can’t utilize their powerful wing down-stroke for lift, so the large surface area of the feet really is essential in pushing the bird up.

trumpeter swan running on water

Even as the bird begins to lift above the water surface, it still can’t use the down-stroke for lift;  the feet continue to propel the bird upward.

And those are some really big feet aiding the launching effort.  Swans rarely show off those big appendages that are so useful in water take-offs, as well as digging up the bottom sediment while they forage.

trumpeter swan landing-

Coming in for landing with webbed feet fully extended to brace for impact…

The birds with probably the longest required take-off pathway from water are the loons.  With relatively short wings and legs placed far to the rear, loons need two to three times the distance for take-off that ducks do, and as they take-off, they too appear to be skipping along the water surface — or even hydroplaning.

loon running on water-northof49photography.com

A Common Loon (or Northern Diver) in mid-take-off (photo by northof49photography.com)

The true masters of “running on water”, however, have to be the Western Grebes, whose courtship dance is a synchronized ballet of movement across the water, all performed without a single wingbeat, paddling with just their feet in completely upright posture.  A clip from David Attenborough’s Life of Birds shows this incredible feat the best.

odd couples

When they’re not competing for food or space (nest holes, etc.), different species of birds sometimes pair up in odd couples, seemingly coexisting without much ado.  It’s as if they either don’t recognize their differences or don’t care about them.  Hmm…wonder if there is a lesson there for us?

Northern Pintail-American Wigeon

A couple of Northern Pintail and American Wigeon males swam around together in a shallow lake near Brownsville, Texas last January.  Ducks often form rafts of mixed species when they flock up on their wintering grounds.

lazuli bunting-black-headed grosbeak

A Lazuli Bunting and a Black-headed Grosbeak are perfectly happy to share the bird feeder.  These distinctly different looking species (both brightly colored males) are both members of the Cardinal family and they overlap in both their breeding ranges and their wintering areas.

But where there is competition for food or nesting areas, aggressive threats or attacks often ensue, even between individuals of the same species.  Close proximity is not tolerated, and everyone gets hyperactive and flighty.  It’s not a lot different than what happens in human societies living in crowded conditions.

Red-winged blackbirds

Red-winged blackbirds engage in all-out battles with each other over monopoly of a food source.

harris hawk- crested caracara interaction

The postures exhibited in this interaction between an adult Harris hawk and a juvenile Crested Caracara tell the story: the hawk owns this meat, and open-beak threats make the caracara back off in submission.

Will it be competition or coexistence between two species or two individuals — odd couple or fierce combatants?

gray squirrel for breakfast

I complain that I have too many gray squirrels in the backyard, clever ones that manage to defeat all the squirrel barriers on bird feeders.  It’s my own fault for supplying too much bird seed, but there is an unexpected benefit to attracting squirrels — attracting their much more photogenic predators.

red fox with gray squirrel kill-

I missed the actual fox-squirrel encounter, however, the fox was making sure the squirrel was dead by biting it in the neck several times.

red fox with gray squirrel kill-

checking for life from another angle…

red fox with gray squirrel kill-

bite it again, just to make sure…

red fox with gray squirrel kill-

So, eat it now, or save for later?

Save for later, was apparently the decision, as the fox picked the squirrel up in its jaws and trotted off behind bushes and the neighbor’s house to have some privacy.

Foxes and probably the Great Horned Owls in the backyard have been doing a fine job of keeping the local rabbit population in check.  In fact, I rarely see a rabbit munching on my flowers any more.  As is usually the case, when one population of prey decreases, there is increased pressure on other prey species, in this case, the gray squirrels that annually produce a new crop of naive youngsters that like to hang out near the bird feeders.  And therein lies the balance of nature…

Note: these are not the best photos of a photogenic fox; they were shot on a very gray day, early in the morning, through dirty windows, with a much too slow shutter speed — but the action was exciting!

big bruiser in the backyard

This guy is big! The biggest one I think I have seen near my backyard, anyway. He calmly strolled onto the neighbor’s lawn about 20 feet from their house, and plopped himself down on the lawn for a morning rest.

buck with big antlers-

The photo doesn’t do justice to his size and girth, but it’s obvious he has a pretty massive neck.

Not only are there multiple tines in his rack, but some are quite broad, meaning this guy took in a good measure of protein and minerals (e.g., calcium) in his summer diet while those antlers were developing.  Maybe he discovered a nice vegetable plot with peas and beans, or a stash of acorns.

buck with big antlers-

You would need to develop those neck muscles just to hold up the weight of those antlers.

Males need a high protein (as much as 16% protein in younger animals), mineral-rich diet not just to grow antlers but to develop the protein and fat stores that will carry them through the energy-intensive rut season and the remainder of the winter.   How much leafy green stuff would they have to chow down each day to take in that much protein?

That’s a trick question, because the protein they absorb doesn’t come directly from their food, but from the microbial fermentation products, and from digesting the microbes themselves, that deer and other ruminant herbivores raise in their complex, four-compartment stomachs.  So, the better they feed their microbial friends, the more nutrients the microbes pass onto their deer hosts.

buck with big antlers-

He looks like a champion contender, doesn’t he, ready to take on the competition?

Males might lose as much as 30% of their body mass during the rut, depending on the level of competition and number of competitors they face, so gaining as much mass as possible during the summer is integral to their success and their survival.

I know I’m doing my part to sustain these guys, judging from the number of perennials in my garden that get munched down to their roots every summer.