Does ranging behaviour go against the grain for modern chickens?

Public perception is that it is ‘natural’ and hence desirable for hens and chickens to range outdoors. In the UK, sales of free-range eggs have steadily risen to around 40% of consumption, of which 80% are produced under the RSPCA’s Freedom Food label based on welfare assurance. Free-range chicken at around 2.5 million birds per year accounts for about 4% of the UK market, where recent television campaigns by celebrity chefs have tended to further increase consumer demand for free-range chicken and eggs. However in most commercial flocks relatively few chickens use the outdoor range area. A survey of 25 free-range laying hen flocks by Whay et al, (2007) found that the estimated use of range in calm, dull weather was 15 to 80% with a median of 30% and fewer birds were seen outside in the larger flocks (flock sizes ranged from 3,000 to 16,000 hens). Mußlick et al, (2004) reported as few as 4% of birds outside in large flocks of 16,000. Similarly low use of range was found by Bubier and Bradshaw (1998) for large flocks and higher stocking rates (e.g. mean 5.1 % for flocks of 2,450 housed at 9.1 hens/m2), however they recorded over 42% outside in smaller flocks of 490 hens housed at 5.4 hens/m2. Conventional genotypes of broilers do not range far (Weeks et al, 1994). Dawkins et al (2003) observed 40 flocks of 20,000 broilers finding very few ranging in winter, and even in summer, the maximum number seen outside during daylight hours at any one time was less than 15% of the total flock. Both researchers and free-range egg producers are currently investigating ways of making the range more attractive to hens by using a variety of additions to the basic grass pasture such as trees, branches, dustbaths, small roofed areas, perches and sandpits. The tropical jungle environment of chickens’ ancestors would have included trees, shrubs and small clearings with considerable opportunities to forage for berries and various insects. Importantly too, wild Jungle fowl live in small (about 6 adults) multi-age groups and lay eggs in clutches. Under such conditions birds may spend 60% of the day foraging (Dawkins, 1989). The modern laying hen is in a completely different environment. Socially she lives in very large same-age, same-sex groups. Although 500 birds is a recommended flock size (e.g. Soil Association organic standards) several thousand are more common. The maximum number of flock-mates that can be recognised by each hen is not known, but is thought to be slightly less than one hundred individuals (Nicol et al., 1999). In larger flocks there appears to be no stable pecking order or group cohesion. Thus the whole flock is unlikely to be motivated to follow a few birds out onto range as invariably happens with backyard flocks. Rather, particularly when (potential) predators appear, the birds outside are more likely to return to the safety of numbers. The thermoneutral zone of hens is about 20o to 35o C, although they can tolerate lower temperatures with more feed (Marsden et al, 1987). The European climate is, therefore, uncomfortably cold for hens much of the time. Coupled with wind, rain and mud is it surprising that hens ‘vote with their feet’ and stay mainly indoors? Indeed it appears that only unsatisfactory conditions in house such a plastic floor type (Whay et al, 2007) or a deficient diet (Elwinger et al, 2008) is likely to persuade hens to venture outside to any extent. I propose a more equable compromise that could better provide for hens’ needs and welfare is a greater space allowance with large verandas or winter gardens that afford protection from predators and precipitation, whilst allowing birds to experience fresh air and natural light. These existing semi-range systems provide many of the benefits and few of the disadvantages of complete free range. Birds access such areas via popholes from the main house considerably more freely than they use similar access to range (personal observations) indicating such environments are preferred. They could be further enriched to enhance foraging. It is also possible that enriched free-range environments could be developed that would provide hens with greater protective cover and improved hygiene compared with prevalent relatively bare paddocks. References Bubier, N.E. and Bradshaw, R.H. (1998) Movement of flocks of laying hens in and out of the hen house in four free range systems. British Poultry Science 39: S5–S18 Dawkins, M.S. (1989) Time budgets in red junglefowl as a baseline for the assessment of welfare in domestic fowl. Applied Animal Behaviour Science 24: 77-80 Dawkins, M.S, Paul A. Cook, P.A., Whittingham, M.J., Mansell, K.A. and Amy E. Harper, A.E. (2003) What makes free-range broiler chickens range? In situ measurement of habitat preference. Animal Behaviour 66: 151-160 Elwinger, K., Tufvesson, M., Lagerkvist, G. and Tauson, R. (2008) Feeding layers of different genotypes in organic feed environments. British Poultry Science 49: 654-665 Marsden, A., Morris, T.R. and Cromarty, A.S (1987) Effects of constant environmental temperatures on the performance of laying pullets. British Poultry Science 28: 361-380 Mußlick, M., Reichardt, W., Gayer, P. and Hochberg, H. (2004) Auslaufnutzung. In: U. Bergfeld, K. Damme, M. Golze & W. Reichardt (Eds), Alternative Legehennenhaltung. Evaluierung Alternativer Haltungsformen für Legehennen. Schriftenreihe der Sächsischen Landesanstalt für Landwirtschaft Heft 8. Sächsische Landesanstalt für Landwirtschaft, Dresden, pp. 123-138 Nicol, C.J., Gregory, N.G., Knowles, T.G., Parkman, I.D. and Wilkins, L.J. (1999) Differential effects of increased stocking density, mediated by increased flock size, on feather pecking and aggression in laying hens. Applied Animal Behaviour Science 65: 137-152 Whay, H.R., Main, D.C.J., Green, L.E., Heaven, G., Howell, H., Morgan, M., Pearson, A. and Webster, A.J.F. (2007). Assessment of the behaviour and welfare of laying hens on free-range units. Veterinary Record 161: 119-128