Detrended fluctuation analysis of behavioural responses to mild acute stressors in domestic hens

KMD Rutherford*, MJ Haskell, C Glasbey, RB Jones, AB Lawrence

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Fractal analysis provides a novel measure of behavioural complexity and has previously revealed subtle alterations in behaviour under biologically costly conditions, such as parasitism or disease. The analysis is based upon the temporal pattern of behaviour that, although rarely considered in behavioural studies, may provide information in addition to standard measures of duration and frequency. Such information could be useful in assessing the welfare of confined animals.

Using ISA Brown pullets, we wished to test the hypothesis that fractal analysis reveals novel behavioural alterations during stress. The behaviour of undisturbed birds in their home pen was compared to the behaviour of the same birds: (1) in a novel arena, (2) in their home pen following blood withdrawal and (3) in their home pen following 5 min of mechanical restraint plus blood withdrawal. Detrended fluctuation analysis (DFA), which calculates fractal complexity measures for time series data, was applied to sequences of vigilance behaviour and walking. These two behavioural parameters where chosen because they are relatively simple to measure and might be expected to alter under stress.

When compared to home pen behaviour, complexity in vigilance behaviour increased in the novel arena (P <0.001) and following restraint and blood sampling (P <0.05) but was unaltered following blood withdrawal only (P = 0.36). Total time spent vigilant was increased in the novel arena (P = 0.001) but not following restraint (P = 0.45) or blood withdrawal (P = 0.11). The complexity of walking patterns and the total time spent walking were similar in all situations.

In conclusion, DFA provides a novel measure of temporal behavioural complexity in chickens. In contrast to studies of chronic situations in other animals, acute stress caused an increase in behavioural complexity in the present experiment. This increased complexity occurred independently of changes in the duration of behaviour suggesting that DFA can reveal more subtle changes in behavioural organisation during stress. If such behavioural alteration represents a non-specific stress response this methodology could allow objective comparisons of different stressors to be made. (C) 2003 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)125-139
Number of pages15
JournalApplied Animal Behaviour Science
Issue number2
Publication statusPublished - 5 Sep 2003


  • chickens
  • stress
  • fractals
  • behavioural complexity
  • detrended fluctuation analysis
  • FEAR
  • LONG


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