Nest loss and chick mortality in capercaillie (Tetrao urogallus) and hazel grouse (Bonasa bonasa) in West Carpathians
2002
Saniga, M. (Slovenska Akademia Vied, Stare Hory (Slovak Republic). Ustav Ekologie Lesa)
Nest and chick losses in capercaillie and hazel grouse were studied in the mountains of Central Slovakia between 1983 and 2001. Fourty-nine (65 %) out of 75 capercaillie clutches were destroyed. The main mammalian egg predators were Martes foina, Martes martes, Mustela sp., Vulpes vulpes (altogether 22 %), Sus scrofa (9 %), and Ursus arctos (3 %). The predation pressure on capercaillie and hazel grouse nests decreased significantly during the incubation period (74 % of nest losses during the first half of May, 54 % in the second half of May). Nest losses in both capercaillie and hazel grouse followed the fluctuation in small rodents, with lowest losses during peak year (57 %) and highest losses during crash year (82 %) and prepeak year (80 %). Average number of capercaillie chicks accompanying a hen in June significantly decreased during the study period (5.0 in 1983, 2.6 in 2001). In contrast, in hazel grouse, no significant decrease in number of chicks per hen in June was recorded during the study period.
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