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Providing evidence to improve practice

Individual study: Contrafreeloading in grizzly bears: implications for captive foraging enrichment

Published source details

McGowan R.T.S., Robbins C.T., Alldredge J.R. & Newberry R.C. (2010) Contrafreeloading in grizzly bears: implications for captive foraging enrichment. Zoo Biology, 29, 484-502


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Carnivores: Present food frozen in ice Management of Captive Animals

A small replicated study in 2010 of grizzly bears Ursus arctos horribilis in a research facility in the USA, found that when food was presented simultaneously in ice-blocks and unfrozen, the bears spent less time manipulating and investigating frozen food compared to the unfrozen food. When apples and salmon were presented in ice blocks, bears spent less time manipulating (apples: 27 seconds; salmon: 76 seconds) and investigating (apple: 4 seconds; salmon: 2 seconds) compared to the same items that were freely available (manipulate: 1122 seconds (apple), 874 seconds (salmon); investigate: 8 seconds (apples), 15 seconds (salmon)). Four bears were routinely fed at 07:00 h daily and given a snack at 15:00 h on their regular schedule. During the experimental condition, bears were presented with five foraging choices simultaneously: apples, apples in ice, salmon, salmon in ice and plain ice. Behaviour was recorded using continuous focal sampling for six one-hour observation periods per bear.

Carnivores: Present food inside objects (e.g. Boomer balls) Management of Captive Animals

A replicated study in 2010 of grizzly bears Ursus arctos horribilis in a research facility in the USA, found that when presented with apples in boxes, they spent more time manipulating the object compared to an empty cardboard box but a similar time manipulating freely available apples. The bears spent more time manipulating a cardboard box filled with apples (524 seconds) and free apples (1060 seconds) compared to an empty cardboard box (105 seconds). Six bears were fed simultaneously over three days, consisting of three one hour trials. Each bear was presented with free apples, apples in cardboard box and a cardboard box. Behaviour was recorded using continuous focal sampling for one hour observation periods.