NATIONAL PARK SERVICE Wolf Ecology and Prey Relationships on Isle Royale

Formulas used to calculate stratum variance and confidence intervals for aerial moose censuses (from Wolfe and Jordan, unpubl. data).

Individual stratum variance (s_i²) was calculated in the following manner:

where:

m_ij = number of moose in jth plot of the ith stratum.
a^ij = area (mile²) of the jth plot of the ith stratum.
m_i = mean density (moose/mile²) of the ith stratum.
n_i = number of plots sampled in the ith stratum.
P_i = proportion of total area of the jth stratum sample.

Standard error of the mean density for the island:

respectively, of the individual strata.

95% confidence interval for population estimate of the island (X):