During the winter, if you look closely at flocks of our feathered friends, they are not all the one type. There may be tits, finches, and buntings grouping together. To find a mate in the spring, birds must first survive the winter, which is made easier by joining forces with other birds.
There are many reasons for this, such as warmth, safety in numbers and finding food.
One of the most apparent reasons for birds flocking together during the winter is for warmth. It would be easy for a small finch to perish from the cold. But by gathering together in a group, forming a flock, the additional body heat from sometimes thousands of birds keeps everyone warm. For example, the body heat generated by large numbers of Starlings all roosting close together will raise the surrounding air temperature within the group by a few degrees. (https://www.starlingsintheuk.co.uk)
You will have heard the phrase ‘safety in numbers’. Well, it applies to birds quite literally. We know that during the breeding season, seabirds colonise in large numbers, one of the reasons being that you are safer if you are living in a large group. During the winter months, we see large numbers of mixed bird flocks. The more individuals there are, the more lookouts there will be to spot predators if you are a small finch alone, you have a greater chance of being eaten. When it is cold, fewer leaves will be on the trees and bushes, making it more difficult for birds to hide. So, predators will see you more quickly, but if there are large birds, especially in flight, it is easier to confuse your attacker.
When birds are trying to feed during the winter months, it is beneficial to the individual birds to be part of a large flock it usually means that you can feed for longer as someone always keeps a lookout. But some birds have other reasons for group living, such as Nuthatches, Treecreepers, Coal Tits, and Blue Tits, which are insectivores, meaning they eat insects. If there is a flock of these birds poking about on a tree, they are more likely to disturb any insects living there, and even if one bird misses a meal, another will benefit. (https://www.wildlifeandwords.worldpress.com)
Years ago, one study believed that two opposing forces motivated the birds (Emlen)1952. Most of the time, the birds stayed with their partners and defended their breeding sights and territory against one another. (Emlen JT.1952.Flocking behaviour in birds. The Auk 69: 160 – 170.) But they knew they needed one another for survival during the winter months. This theory is rather vague but probably explains why they tolerate others during the cold winter months when their survival is more at risk.
In conclusion, there are many benefits to flocking together in the cold winter months: warmth, protection from predators and easier access to food. Many different types of animals live together in packs or flocks for reasons the same as the flocks of birds seen in winter. If you live in a large group, you usually have a greater chance of survival due to the benefits of communal living. The main reason for the strive to survive is the same with every animal, and birds are no different. They are driven by instinctual behaviour to help pass on their genes.
Image by Ben Andrew (rspb-images.com)
Written by Carole McFadyen