As fly-fishing anglers, most of us approach a river with a certain intensity, especially when we find a good hatch of flies and rising trout. Under those conditions, it is very easy to become engrossed by the fishing and not be aware of all of the other life around us. 

In essence, the river environment consists of two completely different ecosystems: the water body itself and the habitat surrounding it. And as anglers, we all know that the river proper supports the fish that inhabit it—in our case, the various species of trout, along with aquatic insects and other organisms. 

Yet there are other creatures that live around and depend upon a river for food and shelter. Those creatures can vary, depending on whether a river is a tailwater or freestone environment. Since tailwaters provide a good volume of water throughout a fishing season, it’s more likely that the birds and animals dependent on those systems will have a more sustained food supply than those living around freestone waters.

Once the flow for the East Branch of the Delaware River was increased from 19 cubic feet per second (CFS) to 70 CFS in the summer of 1977, I saw some dramatic changes in the species that began to show up around that river. I clearly recall fishing one pool during several evenings in late May and early June. At that time, there would be very good hatches of pale evening duns, beginning right around 6 p.m. And right about that time, a flock of swallows would show up, sit on the power line that crossed over that pool, and wait for the hatch to begin. Once the duns appeared, the swallows would leave their perch, skim over the surface and pick off the hapless mayflies. 

It was fun to watch these colorful little birds go about their feeding. Sadly, ever since the flow in the upper East Branch was increased from 70 CFS to 140 CFS during the summer, I no longer see these swallows waiting on the power line for their evening meal. I don’t know what the reason is, other than the fact that it seems the hatches are not as prolific as they once were. And that could be because the water is just too cold for some species of mayflies.

Years ago, while staying at Peaceful Valley, I always fished until dark. Almost every evening when the spinner falls began, the bats would begin to prowl the surface, picking off the dead and dying flies. One evening, casting to a rising trout, my back cast stopped in midair. For a minute, I thought it was a tree limb, except my line fell to the ground. When I went to investigate, I found a small bat flopping around. The little fellow had mistakenly taken my fly as a living insect. Rather than handle the bat, I snipped the tippet about a foot above, and the little thing flew off. 

Once again, since the release has been increased, I no longer see bats working the evening spinner falls. 

Swallows and bats are only two of the many forms of wildlife that depend on a river for part of their food supply. During good fly hatches, it was not uncommon to see goldfinches and eastern kingbirds dart from the stream-side vegetation and capture mayflies in mid-flight.

One afternoon, I saw eight eagles soaring above our campground on the upper East Branch. Populations of those birds have increased dramatically since DDT was banned. And they, like the swallows and bats, depend on rivers for part of their food supply. While not as abundant as eagles, there are always a few ospreys around, looking for a quick meal provided by a careless trout. In May, it was all too common to see several mother mergansers, with a brood of up to 14 babies, swimming upstream, close to shore, looking for small trout to eat. Who knows how many little trout these birds consume? Every once in a while, a kingfisher would flash by, ever vigilant for a trout a little too close to the surface. Sometimes, when fishing the home pool, I’d be startled to hear a very sharp crack behind me, only to see that a beaver was announcing its unhappiness with my presence in its river.

These are only some of the creatures that depend on rivers for food and shelter. Upon occasion there are otters, always a few deer, and once in a while a black bear. And then in spring, there are always a few geese nesting near a river, feeding on the lush grass in the meadows and pooping profusely when flying overhead. I’ve been bombed with falling fecal matter more than once!

So the rivers that we fish are not only trout streams that provide a challenge, but also important habitats for a variety of upland animals and birds. Mostly we don’t pay attention to them because we are fishing, but they are ever-present and make up a significant part of the near-river ecosystem. Next time out, take break, look around, and see what other creatures are sharing a river with you!