Nesting Biology of the Scaly-Sided Merganser (Mergus squamatus, Mergini, Anatidae) in Primorye, Russia

Abstract

The nesting biology of the scaly-sided merganser (Mergus squamatus) was investigated over 17 years (2001–2017) in both artificial and natural nest sites in Primorye. Artificial nest sites were provided along fifteen rivers. A total of 205 nests were recorded: 190 nests in artificial sites and 15 in natural cavities. The occupation rate of nest boxes (27.8%) was significantly higher than that of nest tubes (20.2%). The clutch size averaged 11.08 ± 0.05 (N = 145) eggs. Inter- and intraspecific nest parasitism was described, and the effect of parasitism on nest success was evaluated. Clutch onset (average in terms, i.e., median clutch) during the study period was revealed to be more advanced compared with the initial years. Apparent nest success (70.4 ± 4.0%) was independent of the cavity type, with no significant difference noted between artificial and natural sites. The artificial nest program is an effective way to increase the productivity of this endangered bird species. A total of 1334 ducklings reliably hatched in artificial nest sites during 2002–2017.