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.