Spend seasonal estimation diet of American mink on the river B. Irgiz between 2000 and 2011. The basis of nutrition predator: spring – amphibians (24.5% BIO), crayfish (43.1% BIO), mammals (21.3% BIO); summer – fish (29.3% BIO), amphibians (22.6% BIO), mammals (13.3% BIO); autumn – amphibians (43.3% BIO), fish (15.5% BIO), mammals (11.8% BIO); winter – fish (30.8% BIO); mammals (30.1% BIO). The regularities of changes in the composition of the diet in the conditions of anthropogenic load. The highest trophic niche fixed summer (BA = =0.76), the lowest – in the winter (BA = 0.12).