Abstract
Simple SummaryForest grouses are among the most endangered ground-nesting birds in Central Europe. Their rapid population decline was associated with habitat loss and increasing predation risk leading to low breeding success. The aim of this study was to describe black grouse nest predators and potential predation risk in a study area with a small, extant population of black grouse (Ore Mts.) and in a study area with an already extinct grouse population (Jeseníky Mts.) in the Czech Republic. In order to determine the predation intensity to black grouse nests, 50 artificial nests (28 in Ore Mts., 22 in Jeseníky Mts.) were monitored using camera traps. The results showed that 56% of nests were predated. Within the time needed for successful incubation of the eggs (25 days), the nest survival probability was on average 45.5%. The proportion of depredated nests did not differ between habitat types (i.e., open forest interior, clearing, forest edge). The stone marten was the main potential nest predator in both study areas (39% in total), followed by common raven (25%) and red fox (22%). In conclusion, our study revealed the high predation pressure on black grouse nests which corresponds with increasing population trends of mesopredators and wild boars in Central Europe.We evaluated the spatiotemporal patterns of predation risk on black grouse nests using artificial nests that were monitored by camera traps in mountain areas with a small extant (Ore Mts.) and already extinct (Jeseníky Mts.) black grouse population. The overall predation rate of artificial nests was 56% and we found significant differences in survival rate courses over time between both study areas (68% Ore Mts. vs. 41%, Jeseníky Mts.). Within the time required for successful egg incubation (25 days), nest survival probability was 0.32 in the Ore Mts. and 0.59 in Jeseníky Mts. The stone marten (Martes foina) was the primary nest predator in both study areas (39% in total), followed by common raven (Corvus corax, 25%) and red fox (Vulpes vulpes, 22%). The proportion of depredated nests did not differ between habitat types (i.e., open forest interior, clearing, forest edge), but we recorded the effect of interaction of study area and habitat. In Ore Mts., the main nest predator was common raven with seven records (37%). The Eurasian jay (Garrulus glandarius) was responsible for most predation attempts in Jeseníky Mts. (five records, i.e., 83%), while in the Ore Mts., most predation attempts were done by red fox (six records, i.e., 38%).
Highlights
Ground-nesting bird species populations have dramatically decreased during recent decades in Europe [1,2,3] with most dramatic declines reported for larger species such as waders and bustards inhabiting agricultural landscape [2,4,5,6] or forest grouses (Tetraonidae) [7,8,9,10,11,12]
We recorded 28 of 50 artificial nests depredated in both study areas during a 30-day period which corresponds to relatively high predation rate (56%)
19 of 28 (68%; 95% Confidence intervals (CI): 48–84%) artificial nests were depredated in the Ore Mts. and 9 out of 22 (41%; 95% CI: 21–64%) artificial nests were depredated in the Jeseníky Mts
Summary
Ground-nesting bird species populations have dramatically decreased during recent decades in Europe [1,2,3] with most dramatic declines reported for larger species such as waders and bustards inhabiting agricultural landscape [2,4,5,6] or forest grouses (Tetraonidae) [7,8,9,10,11,12]. The long-term population decline and range contraction of black grouse (Lyrurus tetrix) has been recorded in the majority of its distribution area, including the British Isles, continental Europe, and Fennoscandia [7,8,12,13,14,15,16]. The predation of adult birds, nests, and chicks is among the most important reasons of black grouse population decline [8,16,18]. The reasons for adult bird mortality are relatively well-researched, as predation has been found to be the proximate cause of mortality in adult black grouse [8,19]
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