Humans use tools. We once felt that made us special, something more than the rest of the animal kingdom. Then we discovered crows used tools. Ugh! So much for our self-proclaimed superiority.
We then tried to play down its importance by saying the angler fish using a specially shaped tongue to lure in prey didn’t count as tool use since it was a modified body part. With the same logic we dismissed many of the things we saw in nature by proclaiming real tool use didn’t rely on adapted elements from our own body but instead hinged on finding and utilizing products from our environment.
As we looked closer at nature, though, we realized that kind of tool use appeared more common than we wanted to admit.
Chimpanzees use twigs and stems to fish termites and ants out of nests, and that skill recently took a major twist when it was discovered some groups of these primates were finding ways to improve the tool so it worked better. Uh-oh.
Gorillas have been observed using sticks to gauge the depth of water as they cross streams and rivers.
Elephants strip bark from trees and shape the ligneous material to form bowls that they use to cover watering holes, thereby stopping evaporation so they can return later for another drink. And that doesn’t include their use of branches to swat away flies or their use of large stones to disable electric fences.
Otters grab rocks and use them to hammer underwater shellfish until they fall free from their rocky perches, after which the otter returns to the surface to dine on the goody.
Dolphins utilize sponges as a fishing technique, a cultural phenomenon shown to be passed from generation to generation in these brainy cetaceans. They pluck up sponges and hold them over their snout while they forage along the rough seafloor.
The Egyptian vulture uses rocks to break open ostrich eggs.
Crows use a variety of tools to reach food, some of those tools being spontaneously fashioned to fit the specific circumstances.
Woodpecker finches use cactus needles to retrieve grubs hidden deep within tree branches.
And the green heron (Butorides virescens) uses various lures to bring fish to the surface. Anything from a twig to a feather, an earthworm to a bit of crusty bread. These small, enchanting birds place their lures on the surface of the water and perch over it, stoic statues who watch carefully for a fish to take the bait. Then the bird takes the fish.
When I hunted down this green heron at the University of Texas Southwestern Medical Center rookery in the middle of April, I had hoped to see that behavior, and to capture it in photographs. Unfortunately for me, my visit came on the heals of severe thunderstorms, so the entire pond surface was covered with debris: twigs, leaves, flowers and the like. Even the heron realized the futility of placing yet one more bit of detritus on the water, so instead it stood on its perch and waited for a meal to come within striking distance.
My presence didn’t help, but neither did the presence of hundreds of other birds who use the rookery every year. I visited at the beginning of the nesting season, hence the entire area was a deluge of activity, from anhingas and Franklin’s gulls circling above the trees to at least six species of herons building nests, arguing with each other, mating, sometimes fighting, and otherwise being a loud and raucous invasion of this green heron’s attempt to grab some lunch.
When I ran across several green herons at White Rock Lake many months later, I held out hope that I’d witness their tool use for myself. I ignored the fact that it was already dusk and I’d be lucky to see the bird, let alone its fishing expedition.
No matter. A few chases, a bit of competition with ducks and egrets, another chase or two, and finally a close encounter as this green heron stood on a nearby tree branch. Much to my surprise and that of everyone around me, another remained hidden much closer than this as it considered its options to chase away the more public bird.
We were all taken by surprise when the green heron in hiding darted into the sky and an aerial pursuit took shape a stone’s throw from where we sat enjoying the evening.
Perhaps some other time I’ll have a chance to photograph the green heron’s tool-using ways.
[Please don’t badger me with regards to the fact that nothing about the green heron is actually green. As Anna said in response to the same observation: “Blue was already taken.”]