What’s in an oink?

Did you know that the grunts made by pigs vary depending on the pig’s personality and can show important information about the welfare of this highly social species?


Animal behaviour and welfare scientists from the University of Lincoln, UK and Queens University Belfast devised an experiment to investigate the relationship between personality and the rate of grunting in pigs. They also looked into how different quality living conditions effected these vocalisations.

Findings from the study have now been released in the Royal Society journal Open Science.

The study involved 72 male and female juvenile pigs. Half were housed in spacious ‘enriched’ pens with straw bedding, while the other half were kept in more compact ‘barren’ pens with partially slatted concrete floors, which adhered to UK welfare requirements.

To get a measure of the pigs’ personalities, the researchers conducted two tests: a social isolation test and a novel object test. Each pig spent three minutes in social isolation, and five minutes in a pen with a large white bucket or an orange traffic cone they had not previously encountered. Their behaviour, including vocalisations, were observed. These tests were repeated two weeks later, allowing the researchers to determine if the pigs’ responses were repeatable – the defining characteristic of personality (also known as ‘coping style’ in animals).

They also recorded the frequency of grunts they made by counting the number of grunts produced per minute of the test, and investigated the effect different quality environments had on the sounds made.

The study indicated that pigs with more proactive personality types produced grunts at a higher rate than the more reactive animals. The study also found that male pigs (but not females) kept in the lower-quality conditions made fewer grunts compared with those housed in the enriched environment, suggesting greater susceptibility among male pigs to environmental factors.

So the more a pig oinks, the happier a pig could be!

The results add to evidence that acoustic signalling indicates personality in pigs. This may have had far reaching consequences in shaping the evolution of social behaviours, the researchers believe. The findings also suggest personality needs to be kept in mind when using vocalisation as a measure of the animals’ welfare status.

Principal investigator, Dr Lisa Collins, a specialist in animal health, behaviour and welfare epidemiology in the School of Life Sciences at the University of Lincoln, said: “The domestic pig is a highly social and vocal species which uses acoustic signals in a variety of ways; maintaining contact with other group members while foraging, parent–offspring communication, or to signal if they are distressed.

“The sounds they make convey a wide range of information such as the emotional, motivational and physiological state of the animal. For example, squeals are produced when pigs feel fear, and may be either alerting others to their situation or offering assurance. Grunts occur in all contexts, but are typical of foraging to let other members of the group know where they are.”

Mary Friel, lead author of the study and PhD student at Queen’s University Belfast, added: “The aim of this research was to investigate what factors affect vocalisations in pigs so that we can better understand what information they convey. Understanding how the vocalisations of pigs’ relate to their personality will also help animal behaviourists and welfare experts have a clearer picture of the impact those personalities have on communication, and thus its role in the evolution of social behaviour and group dynamics in social species.”

Keep your pets safe this Bonfire Night


Here we have top tips on keeping your pets calm and safe this Bonfire Night from Animal Behaviour Clinic’s Senior Technician, Lynn Hewison.

  • Walk your dog early in the day whilst it is light or early in the evening to reduce them hearing any fireworks.
  • When at home, close all doors, windows and curtains and turn the television and/or radio on to dampen any noises your pet may hear.
  • Ensure your cat is kept indoors overnight. Rabbits and guinea pigs should either be moved inside the house or into somewhere that noise can be muffled.
  • Ensure your pet has plenty of water available and food available as per your pets normal requirements. With cats, make sure the litter tray is clean and there are plenty of resources in different locations available in multi-cat households.
  • If your dog or cat goes and hides somewhere, leave them and do not try and move them somewhere else. However, if they settle in the room with you, you can offer a chew or toy to help keep them occupied.
  • If your cat or dog has a safe place they use, the use of pheromones such as Feliway (cats) or ADAPTIL (dogs) can be used to help them feel more secure in these areas.
  • If your pet is scared of fireworks or other loud noises, seek advice from your vet or through referral to the University of Lincoln Animal Behaviour Clinic here.