In a survey to estimate the abundance of a rare animal species in a study region divided into N = 1000 units, an initial simple random sample of n = 100 units is selected. An adaptive cluster sampling design is used with adjacent units added to the sample whenever one or more of the animals is encountered. One of the units in the initial sample intersected a network of two units containing three of the animals, and another intersected a network of three units containing six animals. The other 98 units of the initial sample contained none of the animals. Estimate the total number of the animals in the population using draw-by-draw intersection probabilities and estimate the variance of the estimator.