Ground-nesting birds are particularly vulnerable to predators. The eggs are in danger from rats and foxes, and the young from cats, dogs, foxes, and hawks. Protective coloration of eggs and birds, as well as the attentiveness of the adults, gives a measure of protection. There are always hazards during migration, but Killdeer are rarely reported in the kills that occur at towers, television masts, and lighthouses. There is at least one historical account of large numbers of Killdeer having been blown off course during a severe storm.
Weather only becomes a factor if heavy spring rains wash out nests and drown very young chicks.
Killdeer returning north very early in the spring might be overtaken by a late winter storm severe enough to make it impossible for them to find food and, similarly, a few may be lost every year by not returning south soon enough. For a bird population to be healthy and stable, the same number of adult birds as there were the previous year must return in the spring ready to nest. The laying of four eggs per pair is a generous allowance to take care of the year's accidents and deaths of older birds. Reading list Bent, A.C. 1929. Life histories of North American shorebirds.