The Paradise flycatcher Terpsiphone paradise (Linnaeus, 1758) is a rare species locally distributed in the southwestern part of Ussuriland, mainly on the Khanka-Razdolnaya Plain. In spring it arrives in late May. The breeding season is stretched from the first ten days of June to mid-August, which is determined by the necessity to lay eggs again after the first clutches are destroyed. A complete clutch contains two to five eggs (on average, 4.1 eggs per clutch). Both male and female incubate eggs. Chicks start to hatch out in the second ten-day period of July and fledge from nests at an age of 10–12 days. At the end of August, the birds leave the nesting area. A characteristic feature of Paradise flycatchers of the Ussuriland population, as well as of the species in general, is plumage-color polymorphism. Males are dimorphic in plumage coloration: the rufous morph is widespread, whereas the white morph occurs more rarely. The white-morph males account for approximately 10% of the proportion of adult males in the population. In general, the white males are more long-tailed.
The results of studies performed in the Khanka Lowland in 1978, 1980, 1986 and 1993 revealed a general negative trend in the population dynamics against the background of multiyear fluctuations in its size. At the beginning of the current century, this process acquired menacing proportions. In 2003–2007, the annual abundance of Paradise flycatchers in the monitoring area did not exceed 15
breeding pairs (i.e., the abundance of these birds decreased 8–12 times). At the same time, the breeding habitats (secondary broad-leaved forests) are in a relatively good condition. It is assumed that the main cause of the dramatic decrease in the population size is somehow related to the situation on the wintering grounds or with the migration routes.