Factors That Can Negatively Impact Bluebird Survival
Weather: snow, rain, wind, cold, heat drought, water, winter kill all can have a negative effect. Colder than normal weather in over wintering grounds can suppress reproduction in the spring.
Predators: snakes, raccoons, feral and domestic cats, owls, hawks, crows, squirrels, weasels, black bears, opossums, chipmunks, mice
Big 3 > house sparrows, tree swallows, house wrens
Problem species > starlings, chickadees, titmice, nuthatch, woodpeckers, cowbirds, flycatchers
Pests: ants, paper wasps, mud wasps, carpenter bees, mites, lice, blowflies, parasites
Human: lack of proper management, no (or improper) predator guard, boxes do not meet design standards, wrong location, lack of monitoring, too many nest boxes, uneducated about bluebirds, vandalism,
Other: disease, cars, flying into buildings, migration, chemicals, insecticides, nest entanglements (string/horse hair)
Fact: Approximately 70% of young & 50% of parent bluebirds die each year.
Bluebirds thrive on active management. Proper management may be the key to their survival.
Read these articles for greater detail on Competitors, Predators & Problems.
Nest Competitors and Other Problem Species by Allen Jackson
House Wrens: Native Species but Major Problem for Bluebirds by Allen Jackson
Competitors, Predators & Problems