The previous post talked about ways to determine what a bird thinks about their environment using preference or motivation tests. The general rule of thumb is that chickens, or even animals in general, move towards things they like and move away from things they don't like. The nature of this movement, like when they move away or when they come back, tells us something about how they feel.
So not only can we ask them what they think about their environment, we can also ask how they feel about us! There are two main types of behaviour tests that look at how animals feel about people: the human approach test and the stationary human test. These are also known as tests to assess the human-animal-relationship.
Human Approach Test
Also called the "Avoidance Distance Test" or the "Withdrawal Test," the Human Approach Test involves approaching an animal or a group of animals and measuring their response. The underpinning theory behind this test is that, by default, most animals see people as a threat or at least something unknown. The reaction of the animal to an approaching human can demonstrate their level of comfort with humans.
It also is relatively easy to modify depending on the type of environment the animal is in. For example, there are slightly different versions that can be used in cage barns versus free run barns. The aisles are often wider in free run barns, allowing the observer more space with which to approach the birds. Typically, they would begin to approach a specific bird and then measure the distance when the bird starts to withdraw both of their feet. In a cage barn, the observer chooses a bird with their head out of the cage and starts to approach the cage step by step. They would measure the distance to the cage when the bird withdraws their head into the cage. In an experimental setting, the distance to the cage may be drawn on the floor for ease of measurement.
The key measure used in both of these examples is the minimum distance between the person and the animal being approached before they try and get away. The shorter this distance, the more the animal is willing to take risks in order to investigate the human.
An additional test that may be added onto the Human Approach Test is called the Touch Test, which can only be done in free run barns (see Forkman and Keeling, 2009; pp. 87-102). The observer approaches a group of birds and, after squatting down, counts the number of birds within an arms length. Then they attempt to reach out and touch any three hens within reach.
Stationary Human Test
Also called the "Approaching Humans" test, it is the opposite of the test described above. In a controlled experiment, a human observer stands (or sits) still inside an arena and they measure the time it takes for an individual animal to approach. There is usually a grid overlaid on the floor so the animal's location can be precisely tracked using video equipment.
There are also modifications that can be made to this test to make it more feasible to do on farm, regardless of whether the birds are in a cage or a free run barn. If in a cage barn, the observer may stand in front of a cage and count the number birds sticking their heads out of the cage in front of them after a set amount of time. In a free run barn, the observer may instead measure the number of birds within a defined area after a set amount of time.
An On-Farm Experiment: Temperament Test
I wanted to conduct a behaviour test that would help me to understand the general temperament of the birds in both cage and free run barns. I ended up creating a test that mixed the above two tests and focused on group behaviour instead of individual behaviour. It is a work in progress and I will likely tweak it next year to encompass more of the countable metrics described above (e.g. number of birds with their heads out in a cage barn), but it's a start!
Objective: To determine whether a flock finds the presence of a human observer aversive based on how they react within a five-minute observation period.
Birds that are unafraid of people will interact within five minutes (peck hand if in a cage or peck boot if in an aviary). If the bird does not interact, they may express three potential behaviour states: approach the observer, stand still in neutral posture, or avoid the observer. Birds that remain afraid will continue to avoid (Avoid > Avoid). Birds that become afraid during the course of five minutes will start avoiding after initially being calm (Stand > Avoid).
Method: An observer chooses three locations at random within the barn. Once in position, the observer takes an initial photo and makes an observation about bird behaviour and positioning. After 5 minutes OR after bird interacts with hand (in cage barn) or boot (in free run barn), the observer takes a second photo and observes bird behaviour. Photographs are used to document general positioning relative to observer (i.e. hand placement or boot position) but behaviour observations are made in situ.
There are three main behaviour categories:
Avoid = Birds with their backs to the observer, may be actively trying to escape, running away (not in view of camera in free run barns)
Stand = Birds standing still, facing observer or neutral stance. May have returned to normal behaviour. Still some distance away (> 1 bird length in free run barns). Calm demeanor.
Approach = Birds facing observer and approaching hand or boot, may be interacting or not but seemingly curious, not afraid. Within 1 bird length.
Results: In general, birds housed in aviaries were more likely to interact or at least approach the observer within the observation period. Brown birds in aviaries were generally calmer than white birds in aviaries. Pullets in cages were the most fearful of humans, which may be due to their environment or their age.
Hens in conventional cages, before: After:
Hens in enriched cage, before: After:
Pullets in an aviary, before: After:
Hens in an aviary, before: After:
Conclusion: This behaviour test was feasible in a barn environment and generated some interesting data. Repeating this test with more flocks at different ages and in different housing environments may reveal patterns around how different variables influence the temperament of a flock. This test may also be useful to determine whether different management strategies (e.g. the use of radios, pekstones or other enrichments) influence the temperament of a flock.
Further Reading
B. Forkman and L. Keeling (eds) Assessment of Animal Welfare Measures for Layers and Broilers. Welfare Quality Reports No. 9, Cardiff University, 2009.
Birte L. Nielsen. Asking Animals: An Introduction to Animal Behaviour Testing. CABI, 2020.