On a cold spring day in Minnesota, a Cape May warbler perched on a feeder to peck out small bits of suet, an exotic food for this insect-eating bird.

The migrating warbler was cold and hungry and desperately needed an infusion of calories to get through the day. With no insects around, it gobbled up high-energy suet as a substitute. And that's worth remarking on: The little bird was innovating, applying a novel solution to a commonplace problem. And this, by definition, is a sign of intelligence.

You may be thinking this is no big deal.

But until very recently, humans could not believe that birds were intelligent. Scientists regarded them as stimulus/response machines ruled almost entirely by instinct, with brainpower similar to that of fish and insects. This is why the phrase "birdbrain" was sometimes applied to someone who didn't seem very bright.

Because the brains of birds are small and have a different architecture from mammal brains, it was commonly believed they simply didn't have the equipment to engage in true cognition. But beginning in the 1990s, bird researchers began taking a closer look at the issue of avian intelligence. They studied birds in the laboratory and in their natural environments and began turning the conventional wisdom on its ear.

In study after study, birds showed that they're problem solvers, they're perceptive and have long and precise memories, they're planners and tool users and they learn from experience.

Signs of smarts

Humans have considered the use of tools to be a keystone sign of intelligence. Not only do crows in New Caledonia fashion twigs into spears for snagging food, they often carry them along to use on the next grub search. And consider the green heron, dropping bits of bread or sticks on the water as bait to lure fish into swimming into striking distance.

Memory is another hallmark of brainy animals, and many birds shine here, as well. The Clark's nutcracker, a cousin of crows, hides tens of thousands of pine seeds each fall to eat during the winter — and remembers where it stashed each one. Chickadees, nuthatches, crows and jays are also champions at putting food away and recalling each of their hidden stores.

Bird evolution has been a story of relentless miniaturization to reduce body weight in order to enable flight. Their brains may be small but they're jam-packed with nerve cells. New ways of testing and scanning brain activity revealed that songbirds and parrots have huge numbers of neurons in their brains, many more than, say, midsize primates. Bird smarts are now being ranked with those of dolphins, whales, great apes and elephants.

Desktop vs. smartphone

New research clearly shows that birds are intelligent beings, not little robots. Their brains are proportionately as large as many ape brains. As for the difference between bird brains and mammal brains, one researcher suggested an elegant metaphor: Mammal brains are desktop computers, while bird brains are smartphones.

Of course, not all birds are equally endowed with intelligence. Some species, among them parrots, crows, jays and ravens, are astoundingly smart, more so than, say, a robin or warbler. And within a species there can be bright lights and dim bulbs, too.

Birds live fast-paced lives, constantly bombarded with information about their complex world. They're processing floods of inputs on the fly and must make decisions rapidly, some of them matters of life or death. Merely flying from a tree perch to a birdbath involves a great deal of consideration, as a bird evaluates distances, scans for predators, factors in wind speed, watches out for competing birds and swerves to avoid obstacles. Mammals move more slowly in their world and simply don't require this kind of lightning-fast processing ability.

Biologist Franz De Waal says, "We used to think in terms of a linear ladder of intelligence, with humans on top. But nowadays we realize it is more like a bush, with lots of different branches in which each species evolves the mental powers it needs to survive."

We've tended to underestimate birds' abilities and complexities. So let's keep an open mind as new research continues to reveal more about the mental abilities of birds. In "The Genius of Birds," Jennifer Ackerman writes, birds "may be relatively small brained, but they are certainly not small minded."

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.

Field reports

Bird-watching friends provided examples of birds solving problems:

A house wren lands at the entrance to a nest box, holding a twig crosswise in its beak. The stick won't fit through the hole, no matter how many times the wren tries. So the bird works its beak along the stick, then turns it so it can push it inside.

A crow drops into a fast-food restaurant's parking lot, and hops to a discarded carryout bag. The bird methodically removes food wrappers and boxes from the bag, shaking each to scatter bits of bun, meat and French fries onto the tarmac, and then gobbles them down. The crow has taught itself that such bags hold a meal.