Behavior: Mockingbird Wing-flashing

It is nice to see that the berries in the yard, planted for the birds, are just beginning to ripen. These include cherry, viburnum, blueberries and coral honeysuckle. I eagerly watched a Northern Mockingbird help itself to several honeysuckle berries (below). What interested me was that it ‘flashed’ its wings before picking a berry.

Moving along the hedgerow it entered on the far side of the honeysuckle before working its way towards the berries. As it approached the berry it paused for a few seconds, and then proceeded to open its wings in a series of staggered jerks, maybe 4 or 5, before the wings finished just above horizontal, revealing the large white wing patch on each wing (below). This is known as ‘wing-flashing’. It then cautiously picked a berry and ate it. This process was repeated less than a minute later.

I have seen this behavior in mockingbirds when they are on the ground foraging but never when it was in a shrub. This brings up an intriguing question, why is the mockingbird flashing its wings?

The white wing patches are mostly hidden when the wing is folded (see top photo), but they become very prominent when the wing is lifted. No one knows for sure why they do this. Is it used for sexual display? Is it a signal of wariness, or to ward off potential danger? Or used in territorial disputes? Is it related to foraging? Does the white color reflect light, to make it easier to see prey, or is the white flash intended to flush insects for the mockingbird to catch?

While studies have shown that birds foraging on the ground seem to have greater success hunting using this ‘wing-flash’ technique, its primary function is still unclear. The bird I witnessed in the vine tangle was certainly not worried about flushing a berry! Personally, I like the theory that by flashing its wings in this instance, it is showing that it feels uncomfortable and nervous. It does not want to be noticed and wants to keep others away from its find.

How important is the white color in the wing? All mockingbird species ‘wing-flash,’ yet most have no white in the wing. This is also true of thrashers. This behavior is similar to the wing-flickering that I noticed in Gray Catbirds and blogged about on June 9. All these birds belong to the same family, Mimidae, the Mimids, and even though the catbird has no white in the wings, this motion must be a characteristic behavior associated with this family.