The use of DiazaCon to limit fertility by reducing serum cholesterol in female grey squirrels, Sciurus carolinensis


  • Presented at 8th European Vertebrate Pest Management Conference in Berlin, September 26–30th 2011.

  • This article ‘The use of DiazaCon to limit fertility in grey squirrels Sciurus carolinensis (Gmelin)’ was written by Brenda Mayle, Mark Ferryman and Andrew Peace of the Forest Research Department. It is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

Correspondence to: Brenda A Mayle, Forest Research, Centre for Human and Ecological Sciences, Farnham, Surrey GU10 4LH, UK. E-mail:;


BACKGROUND: The grey squirrel, Sciurus carolinensis Gmelin, is an invasive alien species introduced into Great Britain in the late nineteenth century and into Northern Italy during the early twentieth century. Grey squirrels have displaced the native European red squirrel, Sciurus vulgaris L., throughout much of Great Britain and have a significant impact on trees and woodlands through bark-stripping activity. In Britain, eradication is no longer an option at a regional scale, but fertility control offers a non-lethal approach to reducing negative impacts. The cholesterol mimic DiazaCon has been successfully used to inhibit reproduction in some species. These studies aimed to evaluate whether DiazaCon is effective in inhibiting reproduction in grey squirrels.

RESULTS: DiazaCon reduced serum cholesterol levels in female grey squirrels at a range of doses. The period of effect increased with increasing dose. Reproduction rate was not significantly different between treatment and control groups owing to a lack of breeding in controls.

CONCLUSIONS: DiazaCon has potential to reduce serum cholesterol levels enough and for a sufficient period to reduce fertility in female grey squirrels. Information on baseline physiology and blood chemistry of grey squirrels is required to inform interpretation of the level of significance of the effect. © Crown copyright 2012. Reproduced with permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.