General Information: The Lincoln Index The Lincoln Index is a method used to estimate and sample the size of closed populations. This method was discovered by American ornithologist Frederick C. Lincoln in 1930. The Lincoln index is used to measure, sample and estimate the population sizes of individual animal species. It is based on the technique of capture, mark, release and recapture. The mark and recapture method involves random sampling of a population of animals, then marks all captured individuals in a recognizable but non-harmful way and does not expose them to higher levels of predation than unmarked individuals. The marked animals are then released back into the original population and allowed to mix with the general population for an appropriate period of time to allow for complete remixing of the marked individuals with the population. Once they are completely mixed back into the population, the population is then resampled. Sufficient time must pass for complete mixing of the population to occur. This process can be simplified into the equation, simple steps and symbols as follows: n1 = number of animals first marked and released. n2 = number of animals captured in the second samplem2 = number of animals marked in the second sampleN = Total populationm2/n2 = n1/NN = n1 x n2 / m2-If the number of animals recaptured in the second sample (n2 ) is less than 8, the population estimate is probably biased. - If there are losses in the population during the remixing period, then the estimate will be the population size at the time of the first sampling session. - If there are gains in p. .... middle of paper ......in size to replace pieces of straw. As the data show, in some cases the proportion of straw pieces marked in the first capture to the total population (n1/N) is not equal to the proportion of straw pieces marked in the second capture compared to the total pieces of straw during the second capture (m2). /n2). For example, 20(n1)/100(N)≠3 (m2 in the 4th trial)/10(n2). Since this is a random sampling, it is impossible to control the results, particularly the number of pieces of straw marked during the second capture. The container for the straw pieces is shaken to mix the marked straw pieces with the unmarked straw pieces. However, it is not sure whether the population is completely mixed or not. Some marked pieces of straw may get stuck in some corners with other pieces of straw even after mixing. Again, this is a random sampling process and it is inevitable that the marked straw pieces may not mix thoroughly..