New deer repellent improves survival during possum control

Date 20 September 2019

Trials of a new deer repellent treatment for 1080 possum control cereal baits have returned promising results for deer survival.

Close to 40 percent of deer exposed to repellent baits survived during a recent aerial 1080 possum control operation in the Northern South Island, while all (100 percent) of possums in the same area died.

To eradicate bovine TB and support New Zealand’s agricultural exports, OSPRI has to keep possum populations low with aerial 1080 operations over areas of mountainous terrain which also support wild deer herds.

To reduce the by-kill of wild deer without affecting the effectiveness of 1080 control of possums, OSPRI is researching new deer repellents for use in aerial 1080 possum control operations. See the Deer Repellent Trial factsheet here.

Wild deer are a well-adapted and fast-breeding introduced browser disliked by some conservationists for the damage they cause to native forest species. But leaving a breeding population alive after possum control is important to deer hunters.

In December 2018, OSPRI engaged research partner Manaaki Whenua Landcare Research to trial a new formulation of deer repellent in toxic cereal baits. The trial was undertaken as part of planned TBfree possum control operations in the Awatere and Clarence valleys of Marlborough during August 2019.

In the Awatere area where toxic baits were used without deer repellent, all 11 of the radio-collared deer monitored throughout the operation were killed. Where deer repellent bait was used in the Clarence Valley, 11 out of 30 (36%) of the monitored deer survived, which will lead to more rapid population recovery.

OSPRI will continue to work with manufacturers on the development of repellent formulations and undertake further trials as part of upcoming TBfree possum control operations.

Collared Deer

Where deer repellent bait was used in the Clarence Valley possum control operation, 11 out of 30 of the monitored deer survived