Wolves have recolonized parts of Northeastern Washington, while other regions do not yet have established breeding packs. The return of this apex predator, may cause deer to change foraging habits. Giving-up densities (GUDs) are a common method to assess predation risk relative to patch characteristics.
The GUD is determined by setting out feeding trays with known amounts of food and an inedible substrate for a fixed time and then measuring the amount that remains. The deer must snuffle through the inedible substrate, in my case cork, to get to the food. With each bite the deer eats from the tray, the ratio of food to cork decreases. The deer must put in increasing time and effort for each additional bite he takes. The remaining amount of food at which the animal or animals decide to leave the box (give up) is an indicator of the level of apprehension or predation risk deer experience in the area.
This fall, I am preparing to test the giving up density of deer in areas with and without wolves. Stay tuned for future results!