The birds of the Danube Delta


Following an almost two-decade (1951-1970) research of the Danube Delta territory, 274 bird species were identified of 176 were brooding (sedentary and migratory) and 98 non-brooding ones (winter, passage, erratic, and accidental birds).
The species of brooding birds occurring in the Danube Delta were classified into 12 main biotopes, the classification criterion being represented by the nesting place where they show the greatest relative density.
The species of non-brooding deltaic birds were classified into the biotopes they visit while resting on the Danube Delta’s territory and they are connected to by the way these biotopes are providing their food. The ornithological biotopes of the Danube Delta belong to three well-individualized habitats, namely the aquatic, the amphibian and the terrestrial ones.
The number of biotopes increases from the aquatic to the terrestrial environment, while their dimensions follow an inverse proportionality, as they are smaller in the terrestrial and larger in the amphibian and aquatic environments.
As to their dynamics, the brooding birds include: 44 sedentary species and 132 migratory ones. The great number of migratory species is explained by the optimal conditions of nesting and especially of feeding the deltaic biotopes are providing in the warm season of the year. This phenomenon is also supported by the presence – in different deltaic biotopes as against the common ones – of some species, which in the rest of their area cover other life environments.
The non-brooding species include: 35 winter species visit the Danube Delta only in winter; 46 passage species which cross the delta’s territory only in spring and in autumn; 6 erratic ones which irregularly show up in different biotopes and 11 accidental species.
According to their geographical origin, the delta birds contain the following types: arctic species (27); Siberian (32); European (108); Mediterranean (29); Mongolian (33); Chinese (2)