Interspecific offspring killing in owls

Abstract

In Baranya County (Southern Hungary), tawny owls (Strix aluco) and barn owls (Tyto alba) sequentially use the same nest boxes in a significant number of cases. A total of 460 broods were observed between 1996 and 2003 and, in 12 cases, whole broods of dead tawny owl chicks were registered that had apparently been killed. On investigating the reproductive life characteristics, population sizes, and frequency of killing in these two species, it was concluded that: (1) with growing barn owl population, the number of sequential broods increases but changes in tawny owl population size have no effect on the frequency of sequential broods; (2) the number of killings depends on the number of sequential broods; and (3) with growing barn owl population, the number of killings also grows and this change is unaffected by the size of the tawny owl population. However, no killing occurs as long as 50-60% of the nest boxes are unoccupied. There is no killing either until the percentage of nest boxes occupied by barn owls reaches 40%, although a threshold value like this cannot be shown for the tawny owl. In the cases when a barn owl breeding follows the tawny owl's, the percentage of killing is significantly higher compared to that when barn owls do not breed in the same box. These results indicate that barn owls kill the offspring of tawny owls. By these means, they obtain a breeding place earlier than without killing the chicks of the other species, and this results in higher reproductive success.

Interspecific Infanticide and Infant‐Directed Aggression by Spider Monkeys (Ateles hybridus) in a Fragmented Forest in Colombia

“…Cases of infanticide between these two wren species were almost certainly based on food resource competition, since nestlings were killed only during a pronounced food shortage. Barn owls ( Tyto alba ) have been reported to increase their reproductive success by killing the broods of tawny owls ( Strix aluco ) in times of breeding place shortage (Mátics et al, 2008 ). The underlying causes of interspecific infanticide are still poorly understood, as the key adaptive hypothesis proposed to explain conspecific infanticide [e.g., the “sexual selection” hypothesis: Hrdy, 1979 ; van Schaik, 2000 ] cannot be applied to cases of interspecific infant killing.…”

Effects of the risk of competition and predation on large secondary cavity breeders

“…Barn Owls can disrupt nests of the smaller species by destroying clutches, killing the young (Mátics et al 2008), or even killing the adults (Génot and Nieuwehuyse 2002;Roulin 2002;Charter et al 2007a). …”

Nesting success and productivity of the Common Barn-owl Tyto alba: results from a nest box installation and long-term breeding monitoring program in Southern Hungary

“…Although the earlier studies demonstrated that the application of nest boxes increased the clutch size and breeding success compared to natural nesting sites (Marti et al 1979, Johnson 1994, the advantages of nest boxes were questioned by a Hungarian study, which showed that the survival of owls differed between the artificial nest box and the 'natural' environment of a church tower (Klein et al 2007). Moreover, in the case of the artificial nest box application, more species could occupy the same nest boxes which realise competitive situation or predation (Charter et al 2010a) such as the interspecific offspring killing which was reported in the interaction between Tawny Owl (Strix aluco) and Common Barn-owl (Mátics et al 2008).…”