Common Birds Astound Scientists

Look at some denizens of your
garden or town and be amazed

— Often the most astonishing facts of biology are right around us and we don’t even realize it —

Black capped chickadee (Wikimedia Commons)

The Brain Science of Tiny Birds With Amazing Memories (Duke University, 24 March 2023). These small garden birds are so common we barely notice them. But they might be performing feats of memory that humans could not equal. One black-capped chickadee can cache thousands of seeds a day, and remember where each one is stored. “Black-capped chickadees have an incredible ability to remember where they’ve cached food in their environments,” writes Sophie Cox. “They are also small, fast, and able to fly.” The Duke University scientists were amazed at their memories, so they put them to the test.

They have to remember not just the location of cached food but also other features of each hiding place, and they often have only moments to memorize all that information before moving on. According to Aronov, individual birds are known to cache up to 5,000 food items per day! But how do they do it?

Chickadees, like humans, rely on the brain’s hippocampus to form episodic memories, and the hippocampus is considerably bigger in food-caching birds than in birds of similar size that aren’t known to cache food.

A hippocampus alone, though, cannot remember things, any more than memory card in a camera will store photos without a photographer. Aronov’s team set up a testing arena “optimized for chickadee ergonomics,” with lots of places to hide seeds under flaps. The scientists built it so that they could watch from underneath where the birds put seeds. Then they outfitted the test birds with helmets for testing which neurons were firing.

A single moment of caching, Aronov says, is enough to create a new, lasting, and site-specific pattern. The implications of that are amazing. Chickadees can store thousands of moments across thousands of locations and then retrieve those memories at will whenever they need extra food.

Even after gathering the data, the scientists still don’t understand how the little birds’ memories work. Can the bird visualize the sight of each cache? Last words: “Scientists aren’t sure.”

Hummingbirds use torpor in varying ways to survive cold temps (Washington University in St. Louis, 15 March 2023). Hummingbird season has arrived in the southern states. These much-loved miniature gems of ornithology show off many examples of engineering prowess, such as their tongues that function as nectar traps (see Illustra film).

The team of scientists at Washington University studied some of the 168 species of hummingbirds in Colombia. Hummingbirds can go into a state of reduced metabolism called torpor, “somewhere between a power nap and hibernation” as described by a researcher. What they found is that in cold, the little birds can precisely adjust the amount of torpor needed to survive.

“Earlier research had suggested that torpor was a way of completely shutting metabolism down to minimal levels,” Baldwin said. “Our findings join a growing body of evidence to suggest that when animals enter torpor, they have diverse options to calibrate aspects of torpor to their environment.”

For example, the researchers found that hummingbirds can enter into deep or shallow torpor; they can remain in torpor for just a few hours or the entire night; and they can begin coming back from torpor hours or just minutes before sunrise. When they exit torpor, some hummingbirds warm up gradually, while others return quickly to normal body temperatures.

Scientists Find Crows Are Capable of Recursion — A Cognitive Ability Thought to Be Unique to Humans and Other Primates (Beauty of Planet Earth, 4 April 2023). Crows are not the most beautiful of birds, nor are their songs the loveliest (except to other crows), but they deserve medals in other categories. What is recursion, as studied in crows by scientists?

OK, so what’s recursion? It’s the capacity to recognize paired elements in larger sequences – something that has been claimed as one of the key features of human symbolic competence. Consider this example: “The rat the cat chased ran.” Although the phrase is a bit confusing, adult humans easily get that it was the rat that ran and the cat that chased. Recursion is exactly this: pairing the elements “rat” to “ran” and “cat” to “chased”.

Tests by scientists at the University of Tübingen showed that crows are able to do recursion better than monkeys can. But birds and monkeys have no common ancestor, so how did that happen?

As usual, when scientists describe details in the living world, they have less to say about evolution. The only exception in these 3 articles was a passing reference about hummingbirds: “Even though we don’t know which came first — an increase in readiness to use torpor or the ability to persist at high elevations — we think that hummingbirds’ readiness to use torpor is likely tied to their evolutionary conquest of mountain habitats,” said chief Darwin storyteller JW Baldwin.

We should appreciate birds and observe them more. They are varied and fascinating. Sometimes they can be a nuisance. I have tried twice this season to re-seed my lawns, but no matter what I try, the birds find the seeds. I have covered the seeds with topping soil. I hung flashy reflective ornaments that spin in the breeze. I put up a fake owl. I turned on the sprinklers more often. I even put bird netting over a portion of the yard. It worked pretty well, but the little sparrows could find any tiny hole and get inside. Often I would find ten to twenty birds pecking away at the yard, finding every seed at all hours of the day and night. They must have good eyes and senses of smell to pick out such tiny seeds and gulp them down in a series of rapid pecks. No matter what I tried, they always outwitted me. It’s been irritating but I have to admire their skills! They’re cute, too.