Predation in Organic and Free-Range Egg Production

Abstract

On organic and free-range poultry farms, a free-range is provided for animal welfare reasons. However, farmers report sightings of birds of prey and sometimes foxes or other predators within the free-range areas. In addition to seeing actual attacks, they also find chicken carcasses in the free-range, the deaths of which they attribute to predators. In addition, and in contrast to indoor poultry farmers, organic/free-range farmers report hundreds of chickens missing, per flock, when comparing the slaughterhouse arrival numbers with farm mortality records. The farmers assume these missing animals are hens that vanished from the free-range area and that predation is the major cause for their disappearance. If so, predation may impact farm yields. This study investigated whether birds of prey kill chickens on organic/free-range egg production farms and the impact, in terms of numbers of chickens and yield losses. This study was to provide qualitative and quantitative information in support of chicken mortality caused by birds of prey. Data were collected through field observations on organic/free-range farms (n = 11) and an online survey among organic/free-range farmers. Seventy-nine field observations on 11 farms resulted in 141 sightings of birds of prey, mostly common buzzards (Buteo buteo) and northern goshawks (Accipiter gentilis). Forty-four dead hens were found, 36 of them were very likely killed by either birds of prey or foxes. Sixteen attacks on hens by goshawk or buzzard were seen. There were no reasons to assume the attacked hens were in a poor condition prior to the attack. From responses to the online survey (n = 27 farms experiencing predation), it was estimated that on average 3.7% of hens of organic/free-range flocks were killed by predators, while total mortality was 12.2%. After calculating missed yield per killed hen, it was roughly estimated that per flock, predation caused yield losses of EUR 5700 on an average organic farm (size 12,700 hens) and EUR 6700 on an average free-range farm (size 25,000 hens).