What are possible causes of all 3 eastern bluebird nestlings being found dead in their nest box?

Possible causes for all three eastern bluebird nestlings being found dead in their nest box include predation, where a predator may have accessed the nest; environmental factors such as extreme temperatures or lack of food; or disease, which could have spread rapidly among the nestlings. Additionally, human-related disturbances, such as disturbances during nesting or toxic exposure, could also contribute to their mortality. It’s essential to investigate the nest environment and surrounding area for clues to determine the specific cause.