Ecological investigations of the tundra Ecological investigations of the tundra biome in the Prudhoe Bay region, Alaska . ecologicalinvest00brow Year: 1975 171 Table 14 Comparison of grazing intensity (±SE) and the predicted time spent eating by unharassed caribou groups and reindeer. Group Caribou males Caribou, lactating females Caribou, nonlactating females and yearlings Caribou, calves (3-4 wk of age) Esophageal fistulated reindeer, nonlactating females Predicted daily Number of G -azing intensity eating intensity* observation (%%%%) (%%%%) (min) 22 + 46(40-50) 662 22 ± 57(5
Ecological investigations of the tundra Ecological investigations of the tundra biome in the Prudhoe Bay region, Alaska . ecologicalinvest00brow Year: 1975 171 Table 14 Comparison of grazing intensity (±SE) and the predicted time spent eating by unharassed caribou groups and reindeer. Group Caribou males Caribou, lactating females Caribou, nonlactating females and yearlings Caribou, calves (3-4 wk of age) Esophageal fistulated reindeer, nonlactating females Predicted daily Number of G -azing intensity eating intensity* observation (%%%%) (%%%%) (min) 22 + 46(40-50) 662 22 ± 57(53-60) 821 4 ± 49(45-53) 706 19 + Grazing intensity = (eating time/eating time + searching time) x 100. Values in parentheses are the likely range for testing this model. *Based on an observed value of for the eating intensity of females (Table 2) and the assumption that all cohorts spend approximately 66-67%%%% of the day grazing (see text). 24 346 availability was taken from previous studies on sheep (Allden and Whittaker 1970; Young and Corbett 1972) and adapted to the Prudhoe Bay site (Fig. 10b). It was assumed that (a) a mean live biomass of 45 g m^ was available to the caribou in June, and (b) the relationship be- tween percent of day spent eating and live biomass was similar for the three cohorts. Thus, three parallel lines were available for the calcula- tion of the percent of day spent eating as the live biomass altered seasonally (Fig. 10b). The simplistic expression for calculation of food intake is given as food intake = eating rate x eating time. From the above discussion, it is clear that both factors on the right side of the expression are proportional to available biomass, and the rela- tionship between daily food intake as a function of live plant biomass is shown in Fig. 11. In the present study, the mean seasonal change in biomass was estimated from the trends in Fig. 9 in five 10-day intervals commencing 20 June. At the extremes duri
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