Flashing wings as a hunting technique

Northern mockingbird IMG_2475©Maria de Bruyn resLast year, during a nature walk, I witnessed young Northern mockingbirds (Mimus polyglottos) displaying odd behavior as they strutted around on the ground. They would walk and hop a bit and then suddenly spread their wings wide and wider still, then close them and continue pecking on the ground.

Some research on the Internet revealed that they were engaged in a phenomenon known as wing flashing. There are various theories about why mockingbirds flash their wings -– to startle insects, ward off predators, attract a mate. So far, there is no scientific consensus on why they do this.

Northern mockingbird IMG_8889©Maria de BruynresNorthern mockingbird IMG_8904©Maria de Bruynres

Having seen both adult and juvenile birds performing this behavior again this year, however, I’ve become convinced it is part of their hunting technique. Those who promote this idea have suggested that the sudden appearance of the bird’s white wing-bars startles insects, but others argue that insects are not alarmed by the color white.

Northern mockingbird IMG_2816©Maria de Bruyn res

Northern mockingbird IMG_2604©Maria de Bruyn res

My own theory is that when the mockingbirds flash their wings, it creates air currents and disturbs the grasses, thereby uncovering and rustling up bugs. This year I clearly saw the birds catching and consuming insects just after a completed wing flash.

snowy egret IMG_3610© Maria de Bruyn

Later in the summer, I witnessed a similar kind of wing flashing used as a hunting technique by an entirely different species, the snowy egret (Egretta thula). These elegant white birds have long black legs ending in feet that look like they are covered with yellow rubber gloves. They stalk the shallows of waterways such as marshes and ponds looking for prey. The bird I saw was fishing in tidal pools along the Atlantic Ocean shore.

snowy egret IMG_3286© Maria de Bruyn

snowy egret IMG_3270© Maria de Bruyn

It is thought that the egrets use their large feet to stir up the sand underwater so that they can more easily see potential food as they forage. Part of the time, they will simply stand like statues, waiting for a fish to swim nearby so that they can suddenly plunge their long beaks into the water to get their meal.

snowy egret IMG_3313©Maria de BruynThis worked at least part of the time for this particular bird, as s/he got a few fish down. It required a lot of patience, however.

snowy egret IMG_3423© Maria de Bruyn res

At a certain point, the bird decided on a more active approach. S/he flew to another tidal pool and then began running to and fro in the water, flapping his/her wings open and closed.

snowy egret IMG_3575© Maria de Bruynsnowy egret IMG_3574© Maria de Bruyn

Occasionally, this was complemented by a leap into the air and plunge into the water – obviously behavior calculated to startle and scare up the fish lurking below the water’s surface.

snowy egret IMG_3606© Maria de Bruynsnowy egret IMG_3617© Maria de Bruyn

snowy egret IMG_3623© Maria de BruynThe tactic worked.

It was fascinating for me to see two such different bird species using their wings in a similar fashion as a hunting method. One of the things I love about wildlife watching -– you can always see and learn something new!

snowy egret IMG_3659© Maria de Bruyn