Infection Does Not Influence the Survival of Boreal Owl Nestlings.

infection has been observed to impact the reproductive ecology and physiology of avian hosts, but its influence on nestling survival remains unclear. We investigated the effect of infection intensity, determined through triplicate PCR sample analyses, on the survival of 256 boreal owl () nestlings during an 8-yr study. Contrary to our expectations, the survival probability of boreal owl nestlings was not influenced by their infection intensity. Nestling age and infection intensity in male and female parents also did not impact nestling survival. Instead, food abundance and hatching order were the key factors influencing nestling survival. Additionally, we observed a significantly higher infection intensity in male parents compared to female parents and nestlings. We suggest a distinct division of parental roles may lead females and nestlings staying within the nest boxes (cavities) to experience lower exposure to potential vectors transmitting blood parasites than their male counterparts. Our study shows that disease may not be lethal for boreal owl chicks, exhibiting a below-average infection intensity compared to their male parents.