See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/233704556 Feather pecking behaviour and associated welfare issues in laying hens Article in Avian biology research · September 2008 DOI: 10.3184/175815508X363251 CITATIONS READS 19 877 1 author: Laura M. Dixon Scotland's Rural College 12 PUBLICATIONS 204 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Investigating appetite regulation and growth in chickens View project All content following this page was uploaded by Laura M. Dixon on 05 October 2018. The user has requested enhancement of the downloaded file. AVIAN BIOLOGY RESEARCH 1 (2), 2008 73–87 Feather pecking behaviour and associated welfare issues in laying hens Laura Marie Dixona,b aDepartment of Animal and Poultry Science, University of Guelph, Ontario, Canada N1G 2W1 bPresent address: Department of Biological Sciences, University of Lincoln, Riseholme Park, Lincoln, LN2 2LG, UK E-mail address: [email protected] ABSTRACT Feather pecking, the pecking at or removal of feathers from one bird by another, is a problem in the poultry industry. Elimination of damaging feather pecking from flocks is made especially difficult by the numerous factors that appear to influence its prevalence. This review outlines the various contributors to feather pecking organised around Tinbergen’s four questions on causation, ontogeny, phylogeny and function. There is growing evidence that feather pecking (especially severe feather pecking) is related to foraging motivation and gut function. However, other factors, such as improper early experiences, strain and individual differences and perseveration of the behaviour help explain its continued occurrence, even if the birds are kept in enriched environments. To date, methods of dealing with feather pecking are inadequate and involve welfare concerns of their own and alternate solutions, such as provision of forages, are not usually successful in abolishing feather pecking behaviour. The problems of excessive pelage/plummage removal or redirected oral/foraging related behaviour are not unique to poultry and seem to occur in other species in which foraging and forage intake is important. Between species comparisons of related behaviour patterns may improve our understanding of feather pecking and help to design effective solutions. In order to solve the problem of feather pecking, the factors discussed in this review need to be accounted for or we risk applying ‘band-aid’ solutions, which may appear outwardly to be solving the problem. However, the underlying cause(s) may still be present and the animal’s welfare may still be compromised. Keywords: feather pecking, causation, ontogeny, function, phylogeny, stereotypic behaviour, poultry welfare 1. INTRODUCTION also prevent the birds from performing behaviour patterns, such as foraging and dustbathing (Dawkins, Modern day chickens (Gallus domesticus) were origin- 1977; Baxter, 1994). If captive animals are motivated to ally domesticated from the Red Jungle fowl (Gallus perform natural behaviours patterns that are not gallus) over eight thousand years ago. Initially, they possible (see for example Hughes and Duncan, 1988; were used for religious sacrifice or cockfighting until Mason et al., 2001), this may both cause stress and lead around Roman times when they began to be developed to stereotypic behaviour, defined as ‘‘repetitive beha- for food production (Wood-Gush, 1971). The modern viour induced by frustration, repeated attempts to cope poultry industry began in the early nineteenth century, andyor C.N.S. (brain) dysfunction’’, regardless of the with most producers having small flocks of dual degree of variation or repetition (cf. Mason, 2006). purpose (egg and meat) birds raised extensively with Since approximately five billion laying hens are used access to outdoors and with hens brooding their young. for production worldwide each year (estimated from As technology advanced, this changed; leading to more FAOSTAT, 2008), the welfare of a large number of intensive systems with all birds being raised indoors individuals may be compromised. Many countries are and brooded artificially, the use of dual purpose birds starting to ban the use of conventional wire or ‘battery’ decreased and selection for two different types of birds cages. For example, Switzerland has banned egg (high egg or meat production) increased (Appleby et al., production in cages for many years, whilst the EU 1992). will require all wire cages to provide perches, nest In contrast to their free ranging ancestors, modern boxes and foraging material from 2012. However, the egg layers tend to be housed in small wire cages enriching or banning of cages does not eliminate all (battery cages) which increase ease of egg collection, welfare problems and hens in alternative husbandry decrease the incidence of certain diseases and allow for systems also experience several of these (Appleby and large numbers of birds to be fed economically and Hughes, 1991; Baxter, 1994; Duncan 2001; Appleby housed (CARC, 2003). However, these cage systems et al., 2004). doi: 10.3184/175815508X363251 74 Laura Marie Dixon A welfare problem that often occurs more frequently 2. WHAT AFFECTS THE FEATHER PECKING BEHAVIOUR in alternative husbandry systems is the stereotypic OF DOMESTIC FOWL? behaviour of feather pecking (Blokhuis, 1986, 1989), the pecking at and possible removal of feathers from Over 40 years ago, Tinbergen wrote an influential one bird by another (Hoffmeyer, 1969). Feather paper describing methods that could be used to inves- pecking can be divided into two distinct types, gentle tigate behaviour patterns by dividing the study of feather pecking and severe feather pecking. Gentle behaviour into four questions relating to causation, feather pecking involves the feathers being gently ontogeny, phylogeny and function (Tinbergen, 1963). pecked at or nibbled and can be sub-divided into These levels of explanation are still thought to be useful pecks to various feather targets that are thought to be today (e.g. Olsson and Keeling, 2005) and thus will be driven by exploration and repeated pecks to a single used to organise this review of factors affecting feather location on a feather (Newberry et al., 2007). By pecking behaviour. contrast, severe feather pecking involves the vigorous pecking at and possible removal of feathers (McAdie 2.1 Causation and Keeling, 2002). It is unclear if gentle and severe feather pecking stem from different motivational Causation refers to what produces the behaviour systems (Kjaer and Vestergaard, 1999). However, it is pattern, taking into account both internal and external severe feather pecking that constitutes the greater stimuli and the mechanisms by which these produce welfare concern (e.g. Blokhuis and Wiepkema, 1998), the behaviour (Tinbergen, 1963). The two main moti- and thus will be the main focus of this review. vational hypotheses behind feather pecking involve Since feather pecking has been associated with redirected dustbathing motivation or redirected fora- barren and stressful environments, its occurrence ging motivation due to lack of appropriate litter may be an indicator of reduced welfare (Green substrates. The term ‘motivational’ refers to what et al., 2000; Huber-Eicher and Sebo, 2001). causes an animal to perform a particular behaviour However, the primary welfare concern is that it can pattern and the amount of effort put into performing lead to cannibalism, which can be divided into two that behaviour (Toates, 1986; Mason et al., 2001). types: (1) cloacal cannibalism in which the vent area Dustbathing and foraging behaviour patterns would of the bird is pecked and which may lead to the normally (i.e. in free living birds) be directed to pecking out of abdominal organs; and (2) tissue substrates but instead may get redirected or transferred pecking in denuded areas where the exposed skin to an alternative stimulus (feathers of other birds) when is pecked, leading to haemorrhage (Savory, 1995). the animal’s response is inhibited or frustrated With both kinds of cannibalism, the damage can be (Dawkins, 1990). In this paper frustrated will refer to severe enough that the bird has to be euthanised. instances where the behaviour pattern is not possible or Hughes and Duncan (1972) did not find a correlation is being thwarted in some way (i.e. the bird is housed between cloacal cannibalism and feather pecking but with no substrate or can see but not access a substrate). severe feather pecking leading to blood on the Redirected will refer to instances where the behaviour feathers stimulates increased pecking of that area pattern is being directed to an inappropriate stimulus, and potentially leads to other types of cannibalism such as dustbathing or foraging behaviour being trans- (Allen and Perry, 1975; Cloutier et al., 2000). ferred to the feathers of other birds. This transference Feathers that have been damaged, but that are not can continue even if the original motivated behaviour bloody, also attract increased pecking (McAdie and is no longer frustrated (for example, the bird has access Keeling, 2000). to a substrate) due to habit formation or perseveration This review will describe the known factors that of the behaviour (see below). contribute to feather pecking behaviour organised Vestergaard (1994) proposed that feather pecking is around Tinbergen’s four questions on causation, onto- redirected dustbathing due to lack of appropriate