Modelling the sensitivity of colonially breeding marine birds to oil spills: guillemot and kittiwake populations on the Pribilof Islands, Bering Sea.

摘要: SUMMARY (1) We develop simulation and analytic models to estimate the responses of colonially breeding marine birds environmental perturbations such as oil spills occurring within foraging area populations. (2) Short-term impacts are considered through a demographic sub-model, which simulates changes in population size age structure season, daily activities individuals estimates their energy intake mortality from direct contact with spill. The sub-model partitions adults young into age-states; transfers between states produced by immigration, breeding, emigration, growth, mortality. Survivorship is modelled function food delivery rate adults. model generates distribution at sea accordance optimization individual trip times relation projected resource levels areas surrounding colony. This then perturbed effecting reductions supply or affected an spill, recovery optimal survival various classes projected. (3) Monte Carlo sensitivity tests indicate that projections relatively robust variations input values, standard errors adult survivorship chick fledging success ranging 0.03 0.21. Other suggest system insensitive probability death following spill encounter, but substantially more sensitive responds occurrence perturbation adjusting its distribution, large availability perturbation. (4) Applications populations guillemots kittiwakes on Pribilof Islands Bering Sea guillemot greatest located shallow inshore about islands, while less severely localized over wider islands. Model explorations employing chronic low-level pollution rather than one-time St George Island could tolerate overall reduction 10% without suffering major decline success, 40% would lead total reproductive failure (5) construct three specific scenarios explore patterns models. Kittiwakes seem generally perturbations, especially those immediate vicinity colonies.