Effect of Landscape Elements on the Symmetry and Variance of the Spatial Distribution of Individual Birds within Foraging Flocks of Geese

Abstract

Behavioural instability is a newly coined term used for measuring asymmetry of bilateral behavioural traits as indicators of genetic or environmental stress. However, this concept might also be useful for other types of data than bilateral traits. In this study, behavioural instability indices of expected behaviour were evaluated as an indicator for environmental stress through the application of aerial photos of foraging flocks of geese. It was presumed that geese would increase anti-predator behaviour through the dilution effect when foraging near the following landscape elements: wind turbines, hedgerows, and roads. On this presumption, it was hypothesized that behavioural instability of spatial distribution in flocks of geese could be used as indicators of environmental stress. Asymmetry in spatial distribution was measured for difference in flock density across various distances to disturbing landscape elements through the following indices; behavioural instability of symmetry and behavioural instability of variance. The behavioural instability indices showed clear tendencies for changes in flock density and variance of flock density for geese foraging near wind turbines, hedgerows, and roads indicating increasing environmental stress levels. Thus, behavioural instability has proven to be a useful tool for monitoring environmental stress that does not need bilateral traits to estimate instability but can be applied for indices of expected behaviour.

Use of Ethograms to analyse Shoaling Behaviour of Mackerel (Scomber scombrus) in an Aquarium

“…If more time had been available and a conitunous focal sampling had been chosen, the movement units might have been more prominent compared to the instantaneous method. The continuous focal sampling have been used in studies on wild geese and captive polar bears with focus on behavioural instability as a novel approach (Bech-Hansen et al, 2019;Linder et al, 2020). Behavioural instability as a stress indicator could be a useful application in future studies on shoal behaviour using the movement category in a more specified ethogram.…”

Using Behavioral Instability to Investigate Behavioral Reaction Norms in Captive Animals: Theoretical Implications and Future Perspectives

“…Behavioral instability was introduced as a method of studying the symmetry of behavior, by observing bilateral behavioral traits, for example, how many times an individual looks to the left, versus the right or up and down. Bech-Hansen et al [20] introduced two variables to this concept, BSYM and BVAR. BSYM is the behavioral instability of symmetry, meaning the deviation from a symmetric distribution for the studied behavior; BVAR is the variance of residuals for the studied behavior, where a higher variance indicates a smaller capacity for anticipating a behavior when stressors are present [19].…”

Assessment of Abnormal Behaviour and the Effect of Enrichment on Captive Chimpanzees in Aalborg Zoo

“…As welfare and stress are often considered opposites, stress is usually a factor that is minimized or avoided to increase the welfare of the captive animals (Veissier & Boissy 2007). A stressor to the animals could be environmental stress, which can be measured by the use of the concept of behavioural instability (Bech-Hansen et al, 2019;Pertoldi et al, 2016). To assess the welfare of captive chimpanzees, their behaviours are often compared to the behaviours observed in wild chimpanzees, because the behaviour displayed by wild chimpanzees is regarded as optimal (Yamanashi & Hayashi, 2011).…”