Cows Have Best Friends

A herd of cows can look like a crowd of identical animals drifting slowly across a field. Watch for a while, though, and patterns begin to appear. Some cows spend a great deal of time together. Some lick each other’s necks and heads. Some seem to be at the centre of everything, while others keep mostly to themselves. Scientists who study cattle behaviour have been measuring these patterns, and they point to something many farmers already suspected: cows have favourite companions.

One of the clearest signs is grooming. A study published in Frontiers in Veterinary Science in 2020 defines allogrooming as a cow repeatedly using her tongue to lick another cow’s body, and it is a common sight in any herd. The authors write that bonds between individual cows and their preferential relationships are mainly established, maintained and reinforced through this grooming. In other words, a lick on the neck is not just housekeeping. It is part of how a friendship is built and kept.

That study followed the grooming within a group of dairy cows as a social network, recording who groomed whom. It found considerable differences between individuals. Some cows were very active and central in the network, giving and receiving plenty of grooming, while others hardly interacted at all. The researchers also found a significant reciprocity effect: cows tended to groom the individuals that had previously groomed them. A kindness, it seems, is often returned.

These relationships can last a long time. The same paper refers to earlier findings that calves raised together for at least the first six months of their lives formed preferential relationships that lasted for several years. And the authors stress why this matters: for cattle, the social environment is a very important part of their welfare, so understanding who grooms whom can help farmers design management that fits the animals’ social needs.

Company seems to matter even for very young animals. In a study published in PLOS ONE in 2014, researchers compared dairy calves housed on their own with calves housed in pairs, and gave them two tests. In a learning task that asked calves to reverse a colour choice they had already learned, the pair-housed calves did better. In a test with an unfamiliar object, the pair-housed calves gradually got used to it over repeated visits, while the calves kept alone did not show the same change.

So the next time you pass a field and see two cows standing close together, grazing side by side or quietly grooming one another, you may be looking at more than a coincidence. Cows notice who is around them, build relationships through grooming, and often return the favour. There is a good chance that at least one of them has a clear preference about who stands next to her, and that she would very much like it to stay that way.