The Wonder of Flock Formations

Brent Geese © Terry Whittaker/2020VISION

Birds of a feather flock together, but have you ever wondered why that is? Our friends from Bird Aware Solent share some secrets of our coastal birds' avian gatherings.

The fading of summer need not be a melancholic time of year, in fact we’re now starting to welcome lots of visitors that will add a splash of brightness to our shores. This season is the last phase of a migration journey that sees thousands of ducks, geese, and wading birds travel to the Solent. Many of these birds will have travelled from lands as distant as Iceland and even Siberia.

We often think of migratory flocks as intimate gatherings, and this is sometimes the case – geese and cranes, for example, fly in family groups. But these flocks can just as easily form because individual birds happen to be travelling in the same direction. Strangers set off, instinctively following the same route, and then converge with others following that path. A flock of ducks might simply have formed a random gathering for a few hours.

Whether strangers or acquaintances, all birds stand to benefit from the advantages of flocking. Keeping together means more eyes to spot approaching shelter, land, or predators – even birds without an immediate need for the first two will flock together in the name of safety. To maintain the cohesion of their group, however temporary it may be, members of the flock call out to each other as they fly.

Two Dark-bellied Brent geese captured mid-flight

© IanCameron-Reid 

The most famous flock formations are made by swans, geese, and waders, which often assume a ‘v’ or boomerang shape. This shape has a secret purpose: it saves energy, which on a long journey could be vital to an individual completing its migration. Let’s consider the example of the dark-bellied brent goose, which is a significant winter species in the Solent; one tenth of the world’s population visits here each year!

In a ‘v’ formation, every bird except the leader gets a lift from the upwash, or upward-moving air, generated by the bird in front. By positioning themselves carefully, and flapping their wings at the right time, they can spend more time gliding and use less energy. They even take turns being the leader so that everyone gets a rest. But being further back can be tricky too, as the entire formation must be aligned for them to benefit.

Dunlin in flight

Dunlin flock in flight © Deryn Hawkins

The Solent is an incredibly important place for coastal birds, especially in the winter months. Its mudflats and saltmarshes offer rich feeding grounds; ideal for combatting cold weather and preparing for a long migration home. These birds can lose precious feeding time if startled, so try to admire them from a distance when you can.

These fantastic bird facts come courtesy of Bird Aware Solent, a partnership initiative that brings together the Wildlife Trust and other local organisations to protect our coastal birds. They share their amazing knowledge of our feathered friends in person, through their dedicated rangers, and online through their educational resources. Check them out to learn more about how you can help.