28 May 2015

Who ate the grain?

A new study by the Game & Wildlife Conservation Trust has revealed that more than 67 per cent of the food provided through hoppers for game and farmland birds was consumed by pest species, particularly rats, pigeons and corvidsIt is now widely recognised that game and other struggling farmland birds have a better chance of survival when over-winter supplementary grain is provided to sustain them over the leanest times of the year. But until now there has been no systematic research on how much of this costly, but life-saving food is wasted on rats and other undesirable pests.

For the first time, a new study, carried out by researchers from the Game & Wildlife Conservation Trust (GWCT) and published in the Journal of Wildlife Management(1), has identified how much food is consumed by desirable and non-desirable species as well as finding clever ways of reducing this problem. 

Shockingly, the study revealed that more than 67 per cent of the food provided was consumed by pest species, particularly rats, pigeons and corvids – all of which are rapidly increasing in number in the UK.

This two-year study, carried out by Dr Carlos Sanchez-Garcia and supervised by Dr Francis Buner from the GWCT, involved putting camera traps on nearly 260 game feeders containing wheat grain on three lowland farms in Southern England in Oxford and Hampshire during the winters of 2012 and 2013. Over this period more than 160,000 photographs showing the various visitors to the feeders were taken and analysed as part of the study.

Carlos Sanchez-Garcia explains the significance of this study: “Our previous research has shown how much gamebirds and declining farmland bird species benefit from this important activity and how it improves their breeding performance later in the year. However, over-winter feeding is both time-consuming and costly, and without mitigation measures being applied to control unwelcome visitors, more than half of the food may be consumed by non-target species.”

One estate within the study provided more than 26 tons of wheat for their birds through 215 feeders from September through to the end of spring (May) the following year. Without rat control this estate could have lost many thousands of pounds worth of grain to unwanted pests.

Over the two year period 47 individual species were recorded visiting the feeders (33 birds and 14 mammals), with just 10 species accounting for 90 per cent of the wildlife appearing in the photographs. Top of the list were pheasant, woodpigeon, rat, mice, dunnock, grey partridge, blackbird, yellowhammer, rook and red-legged partridge. In addition, 15 species of songbirds – including six UK species of conservation concern including, yellowhammer, house sparrow, linnet, song thrush and starling were recorded using the feeders.

Game feeders are typically placed along or within tall vegetation such as hedgerows, but these locations are also favoured by brown rats and grey squirrels or by species associated with hedgerow and woodland cover such as corvids and pigeons.

As part of the study, the researchers wanted to identify whether location made a difference to the amount of food consumed by non-target species, whilst not deterring game and songbirds. In the trial, feeders along hedgerow cover were attractive to all species except corvids who preferred more open fields. Interestingly when the feeders were moved and only available in open fields the gamebirds and songbirds used these feeders but not the rats. Additionally when the feeders were located in the hedgerow and periodically moved 25 metres from the original location the gamebirds and songbirds located them at the new locations within 1-3 days, whereas the rodents needed 2-4 days to locate the feeders.

Carlos Sanchez-Garcia says: “As this study identifies, over-winter feeding can be a costly and time-consuming exercise when pest control is not carried out at the feeders. This large scale study identifies that current feeding practices used by farmers and gamekeepers need to be revised to ensure that mainly target species and not pests are the beneficiaries of this important food source.

“Our previous studies stress the need to continue feeding in late winter and we would recommend that feeders are placed along hedgerows when efficient control of rats is maintained and to place feeders in open fields when no efficient rat control is carried out. A regular change of the feeder location (every 7-10 days) is also recommended to reduce the impact of rodents and other unwelcome visitors.”

Summing up the research, Carlos adds: “Over-winter supplementary feeding is now an important option within Government Agri-environment Schemes, particularly as research on the GWCT’s Allerton Project showed that this one simple management tool can increase breeding pairs of species such as dunnock, chaffinch and yellowhammer by as much as 30 per cent. Putting in place techniques that ensure that our declining farmland birds benefit the most from this practice is therefore a vital factor in the continuing effort to reverse the declines of some of our most vulnerable bird species.”

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Photocaption: A new study by the Game & Wildlife Conservation Trust has revealed that more than 67 per cent of the food provided through hoppers for game and farmland birds was consumed by pest species, particularly rats, pigeons and corvids.

Notes to editors:

1. The study, ‘Supplementary winter food for gamebirds through feeders: Which species actually benefit? is published in the Journal of Wildlife Management and is co-authored by Dr Carlos Sanchez-Garcia, Dr Francis Buner and Dr Nicholas Aebischer. This study was co-funded by the GWCT and Fundacion Caja Madrid, (Spain).

2. The Game & Wildlife Conservation Trust (GWCT) – providing research-led conservation for a thriving countryside.  The GWCT  is an independent wildlife conservation charity which has carried out scientific research into Britain’s game and wildlife since the 1930s. We advise farmers and landowners on improving wildlife habitats and we lobby for agricultural and conservation policies based on science. We employ 22 post-doctoral scientists and 50 other research staff with expertise in areas such as birds, insects, mammals, farming, fish and statistics.  We undertake our own research as well as projects funded by contract and grant-aid from Government and private bodies.   The Trust is also responsible for a number of Government Biodiversity Action Plan species and is lead partner for grey partridge and joint lead partner for brown hare and black grouse. For Information, contact: Morag Walker – Head of Media, Telephone – direct-dial: 01425-651000. Mobile – 07736-124097    www.gwct.org.uk