Histogram method provides a nonparametric estimate of the probability density function from which a set of data is drawn. This paper proposes a method to choose a reference density for bin width calculation for histogram estimator using line transect sampling, The method based on testing the shoulder condition of the data at hand, if the shoulder condition seems to be valid using as reference the half normal density, while if the shoulder condition does not seem to be valid, use the exponential density as a reference. Accordingly, the performances of the resultant estimator are studied under a wide range of underlying models using simulation techniques. The results demonstrate the improvements that can be obtained by applying this technique.