Individual study: Application of a bone-oil based repellent into a sub-soil barrier as a non-lethal means of exclusion of moles Talpa europaea within a pasture in Oxfordshire, England
R. P. D. Atkinson & D. W. MacDonald (1994) Can repellents function as a non-lethal means of controlling moles (Talpa europaea)? Journal of Applied Ecology, 31, 731-736
Non-lethal methods of controlling moles Talpa europaea have been inadequately researched. This study evaluated whether it is possible to exclude moles by the use of a bone-oil based repellent applied along a purposely ploughed small trench through the home ranges of several moles, and whether this offers a realistic alternative to the use of poisoning using strychnine which is, otherwise, the general method of mole control in the UK. The repellent used, Renardine™, had been marketed as a general repellent for problem mammals for many years and due to its reported efficacy this was selected for use in the trials.
Study site: The experiment was under taken at a mole-infested permanent pasture known as the 'Parks site'(National Grid ref: SP 517074) in Oxfordshire, southern England.
Radio-tracking: Prior to application of repellent, a number of moles were fitted with rump or tail mounted radio-tags. To establish where territories lay, moles were tracked 24 h per day for the first 29 days, and for 16- or 8-h shifts on the subsequent 47 days. Moles were tracked before and after repellent application.
Repellent application: On 1 November 1990 a small trench 2.5-5 cm wide and 50 cm deep was ploughed through the soil using an agricultural mole drainage plough. This ran in a continuous line through the home ranges of all seven moles at the site. Between 7-19 November, neat Renardine was pouring into the slit at a rate of 0.5 L/m, the slit was then infilled with peat and another 0.5 L/m of Renardine was poured over the peat. The repellent was added when radio-tracking showed that a mole was outside of the barrier and was thus potentially confined to 9-95% (dependent on where the barrier ran in relation to a territory) of its former range. This was done to see if moles excluded from a greater part of their former territory were more likely to breach the barrier.
As a form of control, the trench running through the territory of one mole was left unfilled with soil (12-19 November) and then filled with peat untreated with repellent (but with water applied as a placebo) on 20 November.
The mole population density estimated from radio-tracking was 6.7/ha. The repellent induced a change in range use with moles not crossing the barrier for an average of 26 days (4, 8, 24, 39, 40 and 40 days). Where no repellent was applied the mole breached the barrier after 4 h. There was no significant relationship between time taken to breach the barrier and the proportion of the range that had been cut off by it.
The behaviour of the moles suggests that the proportion of the range cut off by the barrier had no simple relationship with re-invasion times.
Conclusions: This experiment was designed to imitate the plausible actions of householders and greenkeepers to repel moles. The repellent treated barrier fairly effectively prevented moles from crossing into adjacent areas of former home range cut of by it. In terms of labour the barrier was a more practical method compared with inserting the repellent directly into burrows. The authors envisage that this could be a practical means for protecting market garden crops for a short, but vulnerable period. This method of application would be too labour-intensive to undertake on an agricultural scale.
The question remains as to the relative humaneness of evicting using repellent (which might be benign as it merely alters a mole’s movements, or conversely it might in some cases result in death through exclusion from a home range and forced interactions with neighbouring moles) versus poisoning with strychnine.
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