So far, the researchers assumed that a well camouflaged nest guarantees the survival of the boys. But obviously the activity of the parents during the rearing plays an important role.
As part of the study, the working group followed ten species of birds during the brood. Depending on how much a species cared for their offspring, squirrel or jay came on the scene with varying frequency to attack the boy. That it was indeed the parental care that attracted the enemies resulted from long-term observations from oviposition to the time the boys left the nest.
While the eggs hatch, most parents sit motionless in the nest most of the time. Therefore, the eggs are relatively safe from enemies at this time. Only when the adult birds are constantly foraging for food and keep the nest clean, the danger of hostile attacks increases. Bird species in which the parents are particularly concerned about the offspring were therefore more at risk.
Image: Thomas Martin