A New Method for Calculating the Population Density of Terrestrial Animals Using Camera Traps with Assessment of Roe Deer (Capreolus pygargus Pallas, 1771) (Cervidae, Mammalia) Population Density in the Khingan Nature Reserve as an Example

Abstract

A new method for calculating the population density of terrestrial animals, which are not amenable to individual identification, using photos or video images obtained by automatic cameras is proposed for discussion. The method is based on the continuous registration of animals on sites formed by the detection zones of camera traps with subsequent extrapolation of the results to the entire study area. A much simpler mathematical apparatus is a significant difference between our proposed method and other methods of accounting by camera traps, which allows it to be applied by a wide range of users. Both the positional measures and the scattering measures necessary for subsequent statistical analysis are calculated quite easily. Also, one of our method’s advantages is no need to know the animal movement speed, the most difficult parameter to calculate, especially in the snowless period of the year. An example of using the bootstrap method is given for the case when the input data distribution parameters do not correspond to the normal one. Using the de Moivre–Laplace theorem, the probability that the animals resting on their beds would get into the detection zone of the camera trap matrices is estimated, which is necessary for the correct use of the proposed method. Solutions are proposed for cases when this probability is low. The problems of our proposed method and their possible solutions are described. An example of calculating the density of roe deer in the open oak forest of the Khingan Nature Reserve is given on the basis of our data obtained from four camera traps.