168 
Table 11 
Botanical composition of rumen samples obtained by field rumenotomy on four 
caribou at Prudhoe Bay (July 1972). 
Vegetation Plant Number of samples Mean occurrence 
class species containing the species species class 
Salix arctica 2 23 
S. lanata 1 3.0 
S. reticulata 3 0.5 
S. rotundifolia 1 0.3 
S. pulchra 4 les) 
Miscellaneous * 2-3 16.7 
Shrubs 4 34.3 
Cyperaceae 4 16.6 
Carex aquatilis 3 3e2 
Eriophorum spp. 4 8.9 
Dupontia fisheri 3 5.9 
Equisetum spp. 3 11 
Gramineae 3 2.8 
Grass-like 38.5 
Compositeae (flower heads) j 0.3 
Polygonium viviparum 2 0.6 
Valeriana capitata 1 tr 
Saxifraga spp. 1 tr 
Ste/laria spp. 1 tr 
Miscellaneous’ 2-3 8.9 
Herbs 9.8 
Cetraria spp. 2 1.4 
Dactylina arctica 1 0.3 
Sphaerophorus globosus 1 0.3 
Thamnolia vermicularis 2 1.0 
Lichen 3.0 
Dead plant parts 14.4 14.4 
Totals 100.0 100.0 
“Partially digested plant parts; could not be identified into species. 
variation may be high within the Dryas heath/ 
snowbed community, depending on the relative 
contribution of the snowbed species to the 
communities. Also, variations in the amount of 
willows in the Dupontia wet meadow/brook 
bank community could result in variations in 
live biomass of between 30 and 90 g m?. 
Food intake of reindeer and caribou 
In principle, an estimate of daily food intake 
by adult caribou could be made by: (a) deter- 
mining the rate of eating (RI, g DM consumed 
per min eating time) of a tractable animal; and 
(b) relating RI to observations on the amount of 
time caribou spend eating. Thus, food intake (g 
d') = RI (g min'') x average daily eating time 
(min d'). 
(a) Estimation of eating rates. A quantita- 
tive estimate of food ingestion was made by 
assuming that all ingested food could be collect- 
ed from an esophageal fistula during a grazing 
period of fixed, or known, duration. A summary 
of rates of esophageal egesta collection rates for 
experiments in 1972 is shown in Table 13. A 
considerable variation in rate of intake was 
noted within vegetation types (coefficient of 
variation = 34-75%), and the variance (1.52 
g min’') was high relative to the mean rate of 
