Ziploc Bags for Preventing Bears from Smelling Food

Abstract

Wilderness activities occasionally result in bear-encounters. To deter bears from detecting food scents, the American Bear Association recommends double-bagging food carried into the wilderness. Our objective was to determine if food sealed in double-bagged Ziploc bags would decrease the ability of bears to detect food scents as compared to food in unsealed Ziploc bags. This was a prospective randomized single-blinded study performed on bears at Northwest Trek Wildlife Park, WA. Two black bears (Ursus americanus) and 2 brown bears (Ursus arctos) were presented with open buckets in front of their enclosures: one concealing food wrapped in 2 layers of Ziploc bags and another with empty Ziploc bags. The time the bears spent at each bucket was recorded for 30 seconds. In the first phase, Ziplocs were open; in the second, Ziplocs were sealed. The average time the bears spent at the open Ziplocs with food and open Ziplocs without during the first phase of the experiment was 9.573 and 6.613 seconds, respectively (N = 75). The average time spent at the closed Ziplocs with food and closed Ziplocs without in the second phase of the experiment was 6.25 and 6.8875 seconds, respectively (N = 80). The standard deviation for all average times was 1.5 seconds. An independent samples 2-tailed t-Test demonstrated a statistically significant difference (P = 0.032) when comparing the time the bears spent at the open Ziplocs with food to the closed Ziplocs with food. There was no statistically significant difference between the controls from both phases of the experiment (P = 0.854). The bears spent a statistically significant greater time at the open Ziplocs with food compared to the closed Ziplocs with food. These data suggest that sealing food in 2 layers of Ziploc bag may decrease the ability of bears to detect the scent of food from within. We advise following the ABA recommendations.