Hares were electronically tagged as part of a study which revealed a growing threat to their declining numbers, it has been disclosed.
The movements of two dozen hares in South Armagh were monitored by radio transmitters day and night for a year as researchers examined eating, sleeping and hiding habits.
Seven later died - some killed by foxes - but farm machinery is causing a far greater death toll, especially at the height of the breeding season when silage cutters mow down the long grass where leverets are born.
Unless more is done to protect their natural habitat, the Irish hare population is in danger of going the same way as the corncrake, it has been claimed. Hundreds of thousands of hares could be found across the countryside at the turn of the 20th century, but the numbers last year were an estimated 27,400.
A Queen's University research team, led by Dr Neil Reid, Quercus Centre Manager at the School of Biological Sciences, found that hares required an intricate patchwork of good-quality grassland for feeding, as well as tall uneven vegetation, such as rushes, for hiding and sleeping.
Dr Reid said: "Hares may mistake the tall grass of silage fields as a good spot for lying-up and giving birth. Silage is harvested during the peak period when leverets are born in late spring and early summer and the machinery used may trap and kill young hares, driving local population declines year after year. Basically hares have fallen foul of an ecological trap."
As part of the research, 24 hares in South Armagh had small collars with radio-transmitters fitted around their necks, allowing Dr Reid and his team to track their every move.
The new Northern Ireland Countryside Management Scheme implemented by the Department of Agriculture and Rural Development includes a specific measure to target the hare.
Farmers who sign up receive hectarage payments for postponing cutting their silage until after July 1 and for maintaining rushy field margins.
But there is a clear need for a change in mowing strategy, according to Dr Reid. "Fields are frequently mowed from the edge to the centre for convenience but it surely can't be that difficult to do it the other way around? Adopting 'hare-friendly' mowing regimes, similar to those adopted to minimise the impact of harvesting on ground-nesting birds, may help mitigate the effects. Unfortunately, leverets tend not to run so it may not work, but it's worth testing."