Filling the hungry gap - late-winter supplementary feeding of farmland birds
From January 2013, a new Environmental Stewardship option will encourage farmers to provide seed for farmland birds in order to increase their late-winter survival and subsequent breeding season numbers. The option follows several years of research by the Game & Wildlife Conservation Trust (GWCT), RSPB and British Trust for Ornithology (BTO) into the benefits of providing seed food in what has become widely known as the 'hungry gap'. This article sets out some lessons learned from our experience of the technique at the GWCT Allerton Project's research and demonstration farm at Loddington, Leicestershire.
'Wild Bird Seed Mixtures' is an existing Stewardship option that provides a valuable source of seed food in winter, with a combination of crop species satisfying a wide range of birds, Our work at Loddington has explored ways of managing these crops to optimise seed yields and food availability for birds. Even so, the popularity of these crops with birds means that the food supply becomes depleted by January. Figure 1 provides an illustration of how bird numbers initially respond to declining sources of natural food by moving into the seed crops, and how the food supply becomes exhausted as a result. We have found that the use by birds of supplementary sources of seed food, mainly grain provided in feed hoppers, increases in this late-winter period, with bird numbers being significantly higher in February and early March than at the same feed sites in January.
We have also been able to compare bird numbers at the farm-scale between a series of years in which we provided late-winter food and a series of years in which we did not. In the January to March period (but less so in the early winter), there are more than twice as many birds on the farm when food is provided than when it is not. The fact that bird numbers are higher when food is provided is not terribly surprising, but it does emphasise the importance of seed food in this later-winter period. What is more important is any relationship between late-winter feeding and the numbers of birds present the following breeding season. At Loddington, we have found that, for those species using the feeders, late-winter numbers are correlated with numbers present in May and June, with breeding bird numbers being 30% higher in years when late-winter seed food was provided.
So, having established the case for late-winter provision of seed food for farmland birds, how canthis food best be provided, and what species are likely to benefit?