3.1 Nest survival
Of the artificial nests, 44% (N =39) were depredated in 2017 and 39% (N = 35) in 2018. The two year average nest predation rate at Evo was 24% and at Maaninka 61%. Wildlife cameras revealed that most common nest predator species were Eurasian magpie (Pica pica, 33% of the depredated nests), raccoon dog (Nyctereutes procyonoides , 16%), hooded crow (Corvus corone cornix , 16%; Figure 2) and Eurasian jay (Garrulus glandarius , 11%). To a lesser extent, nests were destroyed by pine martens (Martes martes, 7%) and common ravens (Corvus corax, 7%), while one nest per species were predated by the American mink (Neovison vison ), western marsh harrier (Circus aeruginosus ), common crane (Crus crus ), European badger (Meles meles ) and domestic dog (Canis lupus familiaris ). Two nest predators remained unknown due to camera failure. An average depredation time for the artificial nests was 2.9 days. Only four nests (2 in 2017 and 2 in 2018) were depredated in less than five hours after establishment (minimum 1.5 hours), suggesting that the predators did not follow researchers to the nests.
Daily nest survival was significantly higher in forest compared to shoreline (Table 1). Nest survival also tended to have slight, but significant negative relationship with field percentage around the water bodies. As expected, shoreline nest daily survival was significantly higher around ponds than around lakes (Table 2). Again, nest survival tended to have slight, but significant negative relationship with field percentage around the water bodies.