Predation patterns on artificial nests of ground nesting pheasants in the montane forest, Southwest China

Nest predation is a major cause leading to reproductive failure of many avian species. Identifying nest predators is crucial for understanding the ecological context of nest predation and habitat management. The mountains of Southwest China harbors numerous species in the Phasianidae family, many of them endemic or threatened, however, little is known on the nest predation pressure on these ground breeders. We placed 32 artificial nests (each containing two chicken eggs) in broadleaf montane forests with different vegetation structure, and monitored predators with infrared-triggered cameras. The artificial nests were resembling nests of Golden Pheasant Chrysolophus pictus, a representative of the threatened species inhabiting montane broadleaf forest. We analyzed how environmental factors impact survival of artificial nests using Cox proportional hazards regression. With a failure rate of 62.5%, we recorded 40 predations where eggs were preyed or moved away, 19 predation attempts where animals spotted and contacted with, but failed to prey on or move away the eggs, and 109 pass-by events. Corvids, especially Large-billed Crow Corvus macrorhynchos was the primary culprit, committing all but one predations on artificial nests. Other potential predators included Pere David's Rock Squirrel Sciurotamias davidianus, Eurasian Jay Garrulus glandarius, Red-billed Blue Magpie Ltrocissa erythrorhyncha, Chinese Porcupine Hystrix hodgsoni and muridaes. We found that understory cover and vertical openness were the determining factors on survival of artificial nests. Presence of understory cover and low vertical openness significantly increased survival time of artificial nests. We didn't detect significant effects from horizontal openness and distance to nearest patrol trail. Further studies with real nests are however required to examine these conclusions, and to explore reproduction strategies of ground nesting pheasants coping with threats from avian predators.