Testing artificial fisher dens in Bridge-Seton Watershed

Project Year: 2017-2018

L. Davis

Project Lead

Davis Environmental Ltd.

Watershed/Sub-region

Coastal Region

Bridge-Seton

Project Type

Species-Based Actions

FWCP Contribution

$41,120

Action Plan Alignment

Bridge-Seton Species Action Plan

Project ID

COA-F18-W-2394

Fisher Artificial Reproductive Den Box Study

The goals of this project are to determine the extent that artificial den boxes will be used by reproductive fishers, identify the degree to which these devices will mitigate losses of natural denning habitat, provide a science-based mitigation technique to address the loss of fisher habitat, and engage stakeholders that can influence fisher habitat in the conservation efforts for this species.

Cannibalism event leads to retrofitting Fisher den boxes

Restoring or enhancing habitat is valuable, but evaluation and monitoring follow-through can be equally as important. Such is the case with the Fisher Artificial Den Box Study. Den box video monitoring has resulted in a quick and inexpensive fix that may save the lives of many Fisher kits in the future.


The entrances to the boxes have been strengthened to stop the male Fishers entering. Photo: Larry Davis.

Over the last five years, wildlife biologist, Larry Davis, and his team have installed 56 den boxes, about half of which are in the Bridge River watershed. Urban development, including reservoir creation, has resulted in the loss of large-diameter trees, which may be a limiting factor for Fisher reproduction.

The project’s main goal is to determine the extent to which these artificial den boxes will be used by female Fishers. Overall, the occupancy has been higher than anticipated, with between two and four boxes used in the last three denning seasons. In 2017, four of them had between one and three Fisher kits inside.


Female Fisher inside on the artificial den boxes. Photo: Larry Davis.

Predation of the kits can sometimes come from male Fishers, which are much larger than the females. The behaviour is to ensure that progeny from another male does not survive. Rare video footage captured a male in a persistent effort to chew his way into a box to carry out an act of cannibalism, while the female was out foraging. Two kits were killed in the event.

As a result, the biologists retrofitted every box with 2 x 4-centimetre door frames, made from solid wood, to prevent any future access from male Fishers and, in early 2018, no evidence of chewing on the frames was found. Monitoring has led to a simple fix that will help increase Fisher survival rates.

To see video of fascinating Fisher Behaviour, go to: youtu.be/CAkpibBaukU