The “disturbance-predation trade-off” framework explaining divergent reproductive fates of ground-nesting birds under Milu rewilding disturbance. The reintroduction of the flagship species, Père David’s deer (Milu, Elaphurus davidianus), at the Jiangsu Dafeng Milu National Nature Reserve has generated an unforeseen “ecological trap” paradox for sympatric ground-nesting waterbirds. Following habitat transformation engineered by the expanding Milu population, the ground-nesting avifauna exhibited a striking divergence in nest-site selection. Species such as the Little Tern (Sternula albifrons), Common Tern (Sterna hirundo), and Kentish Plover (Anarhynchus alexandrinus) selected bare-ground nesting sites in habitats with residual deer populations. Conversely, Saunders’s Gull (Saundersilarus saundersi) nested solitarily and exclusively in dense seepweed grounds remote from deer-occupied areas. Infrared camera monitoring revealed that while deer activity presents a conspicuous physical disturbance and trampling risk, their presence establishes a “biological shield” (predator deterrent zone) that drives predator avoidance among dominant avian species like the Oriental Magpie (Pica pica) and Grey-headed Lapwing (Vanellus cinereus). By balancing this “disturbance-predation trade-off” and amplifying collective defense, the mixed-colony nesters maintained a 68.75% combined nest survival rate. In sharp contrast, the solitary-nesting strategy of Saunders’s Gulls to avoid deer exposed them to a lethal predator community (including rats, feral dogs, and snakes), while the dense vegetation inadvertently reduced their early-warning capabilities, culminating in a catastrophic 0% reproductive success. These findings underscore that single-species recovery metrics can mask significant ecological dysfunction among sympatric taxa. Consequently, conservation frameworks must transition from single-species metrics to multi-taxa management, strategically deploying a “habitat mosaic by design” with low- to moderate-deer activity buffer zones to optimize predator deterrence while minimizing trampling risks.
Wu et al. (Wed,) studied this question.