You'll be amazed just how many niches your backyard has. In the picture at the right, see that cluster of pale dots showing up against the fence? That's a glowing cloud of frenziedly zigzagging gnats slowly drifting across a backyard lawn. In this case, an open area is a niche for whatever mysterious thing the gnats are doing.

Of course, you can't just let the matter rest there. Really, what were those gnats doing? It must have been important to them, because they spent a lot of energy and time doing it. With the Internet, there's no reason to let a good question like that go unanswered. In the search window of a browser, the question was written out: "Why do gnats form clouds?" Several pages almost instantly turned up answering that question.

Drawing of gnat in Robert Hooke's 1667 Micrographia; public domain image courtesy of National Library of Wales

The page said that gathering in swarms makes it easier for male and female gnats to find each other and mate. Of course! What else could cause any creature to perform such exhausting aerobatics? Moreover, the page said, the swarming clouds often form against features in the landscape that help the gnats show up better to one another -- like the shaded fence behind the cloud in the picture. It all made sense. One gets a nice-feeling buzz from figuring out stuff like that.

Well, the lesson is this: What to us may seem like a backyard sterilized with incessant lawn mowing and prodigious dosages of insecticides and weed killer -- such as the unfortunate one in the picture -- still may provide nurturing natural niches for rainbows of natural plants and animals. Consider the classic ecological study by R.H. MacArthur, done in 1958, entitled Population Ecology of Some Warblers of Northeastern Coniferous Forests

NICHES IN A TREE...

Photo © Greg Scott

In our backyards some of the "ugliest" places may be the most ecologically beautiful. At the right you see the remains of a dead tree that is a center of species diversity. Chimney Swifts nest in the hollow trunk. Notice the metal sheath at its base to keep animals such as house cats from climbing the tree to get to the nest. The tree's decaying wood is tunneled through by untold numbers of wood-eating insects, which attract woodpeckers. That dead tree is a beautiful, thriving CITY of living things and it's great that it's being protected!

It's an ecological principle that no two species can for long occupy the same niche at the same time and the same place -- because one species will drive the other away. With this in mind, MacArthur wondered what was going on when he saw that in a single spruce tree, five different species of closely related birds, all wood-warblers, were nesting and foraging for food.

MacArthur did what any good naturalist does when a question like this arises -- he watched his critters. Here's what he found:

• Each species nested at a different level above the ground
• Though all five bird species ate insects, on the average they found their insects in different parts of the tree
• There were differences in feeding strategies among the warblers: If two different warblers found themselves on the same branch, one might be probing among spruce needles, while the other could be searching for insects on the branch's bark

Therefore, a single tree -- even a backyard tree -- is like a whole city where, if you know where to look, a rainbow of plants and animals can be found occupying their own unique niches. Since typical backyards often support more than single trees, the actual number of niches there may turn out to be mind boggling!

But, to discover these niches and the wonderful plants and animals occupying them, you must simply always keep your eyes open, and be prepared to see anything...