Landlords should be alert for evidence of predation, dropped owl feathers, plucked martin feathers, chewed-off martin wings, etc. Since martins feed solely on flying insects, they are extremely vulnerable to weather conditions that affect insect availability. If poor weather persists for more than 2 or 3 days, martins begin to die of starvation. Heat waves and droughts can also be a problem. When air temperatures go above 100 F. for many days, nestlings can perish from overheating.
Prolonged drought can also adversely affect insect numbers.
Some weather conditions may contribute to a population explosion of external parasites normally found in martin nests, including fleas, nest mites, and blowfly larvae. Never use pesticides in nests or boxes. It is also a good practice to furnish crushed egg shells or crushed oyster shells, bought at local feed store. Migration Older martins arrive at the established colony sites first. West of the Rocky Mountains, Purple Martins have different nesting habits.