Верификация нового гуманного метода оценки обилия мелких млекопитающих с помощью биомаркеров

Abstract

Potential problems of the previously developed reconnaissance bottle-based method for estimating abundance of small mammals were studied. Our first aim was to determine which of the two intervals between bottles on a transect (five or ten meters) is prone to higher measurement errors because of individuals who visit more than one bottle per day. The second aim was to compare selectivity of bottles and snap traps depending on the species and sex-age structure of a community. Spot alternate marking with oat-grain bait containing rhodamine B or tetracycline was used. Plastic bottles with baits were placed on transects with an interval of five or ten meters. A day later animals were caught by snap traps baited by a standard bread bait and the biomarkers were searched. Individuals with both rhodamine and tetracycline marks were considered to have visited more than one bottle per day. There was no statistically significant difference between the two ways of placing bottles based on the proportion of individuals with a double mark (5.3% on the ten meters line and 6.2% on the five meters line). Completeness of marking was higher when the interval was five meters (max = 77%) than when it was ten meters (max = 46%), which might raise the accuracy of the abundance estimation. Selectivity of both bottles and snap traps depending on the species, sex or age of a rodent did not differ. The received results confirm that recalculation of the abundance index acquired using the bottle-based method into relative population numbers is legitimate. Rhodamine B was proven to be a more efficient biomarker than tetracycline.