Fig 2. Stable isotope values vs date of sample collection.

Sample collection date may be up to 14 days after samples were removed from the bear because hair traps were checked every 1–2 weeks. The longest guard hair available were selected from each sample. Some of these hairs were sectioned in thirds by length to analyze seasonal diet, the average of the 3 sectioned values is presented here. Grizzly bears detected in drainages with spawning salmon are shown in red symbols (n = 54). Green symbols indicate bears were detected in drainages without spawning salmon (n = 40). Filled symbols indicate the hair was likely from an entire season of growth, lighter fill means the period of growth is less certain though still likely from an entire season of growth and, unfilled symbols indicate the hair were likely grown the year of sampling and hence represent a partial year’s growth. Salmon began to be available to bears in mid-July but were not widespread until mid-August.