New Danish study is out of range

The one totally predictable thing about ranging behaviour is that most birds come out in the evening.

Every producer knows this and every research project has confirmed it…up to now. Because a large scale Danish study into ranging behaviour has just come to the opposite conclusion. After four years studying 37 flocks of layers scientists from the Danish Institute of Agricultural Sciences have declared that ranging decreases during the day.

In a report in the journal British Poultry Science even the research team admit that their result was “unexpected”. They then reveal why they produced this bizarre outcome. The researchers worked strict office hours and did all their observations between 9am and 3.30pm. So they made no recordings at all when most birds were out.

Given this kind of basic flaw there will not be a producer in Europe who will not regard the results from this study as dubious. Particularly the main finding that in over 637 visits to farms only nine per cent of birds were, on average, seen on the range. This compares with 40 per cent and over in other studies.

The researchers also seemed to disregard the fact that as it is the custom to keep birds in during wintry weather in Denmark their ranging habits would clearly be affected.

Other findings included the fact that the use of range area declined with increasing age. This was again contrary to the expectation that as birds become increasingly familiar with their surroundings they would range more. The report suggests that older birds, having lost feathers, may spend more time inside feeding or that they might simply be suffering from a reduction in activity levels associated with ageing.

The Danes did at least establish that the number of hens on range declined with higher wind speeds and rainfall levels. As far as temperature was concerned numbers increased up to 17 ºC when they began declining. “There appeared to be a tendency for the percentage of hens outside to decrease with flock size,” says the report although the findings were not significant, unlike other studies which have appeared to show two cut off points, one when flocks exceed 500 and the second when flock size goes over 4000.

The project also included an experiment to test whether artificial range cover encouraged birds to go out. Some flocks were offered access to range with a camouflage netting ‘tent’ for every fifty birds placed at regular intervals down the range. The nets did have a very small effect on the numbers of birds ranging and their wider distribution away from the house.