Estimating the size of street-dwelling populations by means of mark-resighting counts: theoretical considerations and empirical results

Fattorini Lorenzo, Università degli Studi di Siena
Ghellini Giulio, Università degli Studi di Siena

Mark-resighting methods constitute technologically advanced approaches to abundance estimation which may be adopted as alternative to capture-recapture methods. In mark-resighting experiments a sample of animals is captured and marked and resightings are performed during subsequent occasions. The main advantage of mark-resighting methods is that resightings are generally cheaper to acquire than physically capturing and handling the animals. Recently, in cetacean population surveys, the marking procedure has been easily performed avoiding the capture of the animals to be marked. Marked animals are simply those readily recognizable owing to some characteristics. The purpose of this paper is to propose the use of mark-resighting procedures to estimate the abundance of street-dwelling populations, when the marked individual are persons identified in the initial part of the survey in such a way as to be easily recognized in the subsequent occasions. A simulation study is performed in order to determine the performance of the method.