A case of infanticide in the Spot-billed Duck in circumstances of high breeding density

Abstract

The first observations of infanticide by a precocial avian species, Spot-billed Duck ( Anas poecilorhyncha ), were recorded on a small pond at Yatsu tidal flat, central Japan, from May to June 2000, where six families of conspecific and one Gadwall A. strepera family, respectively, occupied territories. A female Spot-billed Duck with 11 ducklings attacked ducklings of all the other families killing eight conspecifics and three of the Gadwall. High breeding density (15.0 families/ha) may have increased the aggression of the female.

First videotaped infanticide in the common pochard Aythya ferina

“…The infanticidal behaviour was similar to that reported by Shimada et al (2002) for a female spot-billed duck Anas poecilorhyncha (J.R. Forster, 1781). When the killer female was about 4 m from the victim duckling, she quickly approached it while the mother of the victim escaped leaving her young alone (see Electronic supplement).…”

“…There are two cases when one Infanticide in Common Pochard 1017 duckling pecked a victim, so ducklings seem to be very interested in what their mother (perpetrator) is doing. The mother of the victim kept at a distance of about 10 m from the perpetrator's family, and did not protect her own young, like females of the gadwall, Anas strepera (L., 1758) and the spot-billed duck, Anas poecilorhyncha (Shimada et al 2002).…”

“…The resource competition hypothesis states that infanticide may provide the perpetrator or its offspring with increased access to resources such as food, nesting sites, or space (Ebensperger 1998). In agreement with Shimada et al (2002) it can be proposed that the latter hypothesis can be applied to the adaptive explanation of the occurrence of infanticide in the common pochard. It is not known, however, whether the space or food were limited factors for the two observed families.…”

“…Moreover, infanticide by females is observed largely in facultatively polygynous systems of altricial birds where a female kills young or destroys eggs of a rival female to obtain greater paternal investments from a polygynous male (sexual selection hypothesis) (Veiga 1990;Hansson et al 1997). There are, however, only sporadic reports of infanticide by precocial birds (e.g., ducks and shorebirds: Owen & Black 1990;Fujioka 1992;Shimada et al 2002). Here, we provide a documented record of infanticide induced by female common pochard Aythya ferina (L., 1758) in natural conditions.…”

Non-parental infanticide in a dense population of the Black-billed Magpie (Pica pica)

“…This is because infanticide in general is rare and difficult to observe, as indicated by the fact that only 17 direct observations of infanticide have been reported in 25 years of studies of 98 broods (on average) of barn swallows per year (Møller 2004), or that only three direct observations have been noted in 10 years of studies on 60-80 broods of the house sparrow per year (Veiga 2004). Therefore, it is important to publish direct observations of infanticide, especially in species from which it has not yet been reported (examples of papers describing single infanticide events by females: Prokop et al 2009;Shimada et al 2002). Despite the scarcity of direct observations, some evidence suggests that the likelihood of infanticide in birds increases in high-density situations (e.g.…”