Replacement Broods in a Cavity Nesting Bird Species under High Predation Pressure in Primeval Forest

Abstract. Predation is one of the most important factors influencing breeding success. Many bird species suffer from high losses because of predators. I studied breeding success and replacement broods in the Red-breasted Flycatcher Ficedula parva. The Red-breasted Flycatcher is a small bird breeding in natural holes in dense deciduous and mixed forests of Europe. Data were collected during twelve breeding seasons in a primeval forest, in the Bialowieża National Park, Northeast Poland, the best preserved and protected area of the Białowieża Forest with a rich community of birds and mammals including predators. Almost half of the broods of the Red-breasted Flycatcher were lost and most of them because of predation. In cases where the brood was lost in the period of egg laying or incubation, females tended to lay a replacement clutch. First and replacement nest-sites differed insignificantly in characteristics, but new clutches were always laid in a new site. Out of 68 broods, in which a loss was found, replacement broods were recorded in 47.1% cases. Replacement clutches were much smaller and pairs raised significantly fewer fledglings. The proportions of successful and lost broods were similar in the first and replacement attempts (56.1%, and 46.7%, respectively). Red-breasted Flycatchers choose shallow nest-sites that allow the females to observe their surroundings. This allows the female to escape from the nest when a predator approaches, increasing the possibility of a repeat clutch and the attainment of breeding success in the same season.