Kingfisher hunting the creek in early summer

The creek moves fast here below Pincher Creek, cold and clear off the Rockies, and the light comes in at a low angle even at midday this time of year. The longest days are on. Aquatic insects are hatching from the gravel bottom in numbers they won't match again until next summer, and the creek surface is broken constantly by small rises where fish are feeding just beneath it. This is the moment a belted kingfisher has been waiting for, not in any abstract sense, but in the plain fact that it arrived here weeks ago, dug a nesting burrow into a cut bank, and has been working this stretch of water ever since.

The kingfisher is a stocky bird, larger than it looks in flight, with a heavy bill that accounts for a surprising share of its body length. The female has a rust-colored band across her belly; the male does not. Both hunt the same way. They find an elevated perch above open water, a snag, a low branch, a fencepost near the bank, and they watch. Their eyes are positioned to give them a clear view straight down into the water column. When a small fish moves into range, the kingfisher drops from the perch in a steep dive, hits the surface, and takes the fish in its bill. The whole strike from release to recovery takes less than a second. Back on the perch, the bird beats the fish against the branch to stun it, then repositions it headfirst and swallows it whole. If you are near the creek right now, the rattling call of a kingfisher carries a long way, and you may already have heard it.

What makes early summer critical for this bird is the convergence of two things happening at once. The first is the hatch. Stoneflies, mayflies, and caddisflies have been developing in the streambed gravel through the cold months, and now they are emerging as adults in large numbers. The surface film of a creek like this one is thick with them on a calm morning. The second is the fish. Brook stickleback and other small fish are feeding heavily on those emerging insects, and that feeding activity keeps them near the surface and exposed. A fish holding at the surface to feed is easier to spot from above than one holding deep in broken current. The kingfisher is not responding to the insect hatch directly; it is responding to what the hatch does to the fish. The insects concentrate the fish, and the fish concentrate the kingfisher.

The nesting burrow ties the kingfisher to this particular stretch of creek. Both parents are hunting now, carrying fish back to the burrow where the young are still being fed. A pair working a creek will defend roughly a kilometer of shoreline against other kingfishers. That territory is not arbitrary. It represents the amount of productive water the pair can work efficiently while also making the trip back to the burrow and keeping the nest supplied. A longer stretch would mean longer flights and slower delivery. The territory is sized to the biology of the nest.

The threespine stickleback, a small armored fish common in these creek systems, is a reliable prey item during this period. It is a shallow-water fish, quick, but it holds in predictable places: slack water behind boulders, the inside bends of the channel, the margins where current slows. A kingfisher that has hunted a stretch of creek for several seasons knows these spots. It works them in sequence, checking each one, moving on if nothing shows, returning later. The hunting is methodical in a way that is easy to overlook if you are only watching for the dive.

The light is long right now, and the kingfisher uses it. Hunting begins early, before the air warms and the surface glare builds, and continues into the long evening. On a clear day this close to the solstice, the bird has more usable light than at any other point in the year. Watch the snags and low branches along the bank. The kingfisher will be there, still, watching down into the water, and the creek will be moving underneath it.