The relevance of the study is determined by the high importance of wetlands in the ecological frameworks of territories and the need for methodological approaches to identify wetlands of high conservation importance. The paper is aimed to demonstrate the indicator role of the Common crane to determine the conservation importance of wetlands on the example of the Nizhny Novgorod region. Objectives: to estimate the number of the common crane in existing and reserved protected areas; to analyze the presence of wildlife species listed in the Red Data Book of the Nizhny Novgorod region in these protected areas. The results of many years of surveys as well as data from the Red Data Book of Nizhny Novgorod region are analyzed. It is shown that within 93 protected areas of the total area 491870 ha 135598.4 ha of wetlands are protected, where 830 territorial pairs of cranes (about 60% of the regional population of the species) inhabit. Along with the common crane, these areas serve to protect almost all (91%) obligate wetland wildlife species listed in the Red Data Book of Nizhny Novgorod region, 82% of rare species associated with wetlands and 53% of species not associated with wetlands. Our calculations showed a high correlation of the number of rare wildlife species with the wetland area (correlation coefficient 0.75). The correlation of the number of rare species with the number of common crane was higher (correlation coefficient 0.82). Quantitative correlations of the number of rare wildlife species with the area of wetlands and the number of common cranes were also calculated. The obtained conclusions allow using the number of the common crane for substantiation of importance of wetlands for nature protection and establishment of protected areas.