“…Most of them are socially monogamous; to date, only one case of polygyny has been recorded (Mitrus and Soć ko, 2005). The earliest males arrive in the Białowiez · a Forest in late April to early May , older males arrive significantly earlier (Mitrus, 2007b).The red-breasted flycatchers breed solitarily in natural tree cavities (Mitrus and Soć ko, 2004) in deciduous or mixed stands, in low densities of up to 2.0 pairs/10 ha (Wesołowski et al, 2002(Wesołowski et al, , 2006(Wesołowski et al, , 2010.…”