Casting Shade

A black heron hoods its wings into a dark canopy over the shallows at Little Chem Chem, in the Tarangire ecosystem of northern Tanzania, chasing the shade it needs to fish. We had walked to the edge of the lake to watch the morning's bird activity when this one began its ritual: wings arched forward, head tucked beneath them, holding the pose for a few seconds before checking underneath for whatever had drifted into the shadow, its yellow feet the only bright color on an otherwise black bird. It is the same behavior that made this species briefly famous online, filmed appearing to play a private game of night time, day time as it opens and closes its wings, though what looks playful is entirely practical. The shade cuts the glare on the water and may draw small fish toward what looks like cover. The black heron is currently listed as Least Concern. Its dependence is narrower than that label suggests: it needs shallow, undisturbed water to hunt this way, the kind this lake still provides.