The disturbed ground collects rainwater and puddles form. The puddles provide a comfortable wallow for the pigs. Culex quinquefasciatus, an alien mosquito, is attracted to the standing water in the puddles and wallows. The mosquitoes lay their eggs there and the population grows. Plasmodium relictum is an alien parasite found in many birds, though it has very little affect on introduced birds.
Mosquitoes become parasite carriers once they bite an infected bird.
They then spread the parasite and alien viruses to other birds in the same manner. Native honeycreepers have no resistance to the disease. They develop avian malaria or bird pox, which shortens their lives and depletes their populations.