Context and Frequency of Infanticide in Communally Breeding Guira Cuckoos

Abstract

We studied the context of brood reduction through infanticide by communally breeding Guira Cuckoos (Guira guira) in central Brazil. During seven reproductive seasons, we monitored 142 nests from egg laying until fledging. Almost all nests (97%) lost eggs through ejection, and chick deaths occurred in 72% of all nests with hatchlings. There was evidence for infanticide in 38% of the nests that exhibited some mortality. We compared egg and chick mortality in the early part of the season with the later part, when insect abundance declines, but found no significant differences. Less than one-third of all nests monitored showed asynchronous hatching of eggs, and in those that did, chick death was not in reverse hatch order. Although there are several plausible explanations for infanticide, we highlight one likely candidate, which is its interpretation as a sexually selected trait where individuals gain reproductive benefits by provoking the group's nesting failure.

Infanticide and within-clutch competition select for reproductive synchrony in a cooperative bird

“…It is possible, therefore, that selection may have favored infanticide by early-laying females, since the first-hatched victims are unlikely to be their offspring. Macedo and Melo (1999) and Macedo et al (2001Macedo et al ( , 2005 proposed several alternative adaptive hypotheses for infanticide in communally breeding cuckoos, based on data from Guira Cuckoos (Guira guira), a related species that exhibits a similar communal breeding system and similarly high levels of infanticide. One possibility is that group members commit infanticide in an attempt to destroy the entire clutch and force renesting of the group, presumably because infanticidal adults either did not reproduce in the first attempt or gained only a small share of reproduction (Macedo et al 2005).…”

Egg characteristics are unreliable in determining maternity in communal clutches of guira cuckoos Guira guira

“…Populations of the South American communally‐breeding guira cuckoo Guira guira in central Brazil reproduce during the rainy season, from mid‐August to mid‐March, with groups frequently renesting several times (Macedo 1992, Melo 1997). Reproductive guira cuckoo groups of two to 15 related and unrelated individuals use a joint nest and exhibit both cooperative as well as competitive behaviors, such as egg ejection and infanticide (Macedo 1992, 1994, Melo and Macedo 1997, Macedo et al 2001). Approximately half of all eggs laid are ejected especially at the onset of laying.…”

Isolation and characterization of dinucleotide microsatellite loci in communally breeding Guira cuckoos (Aves: Cuculidae)

“…1994) and, after chicks hatch, some adults provide more parental care than others (Macedo 1994; Pacheco 2002). High rates of egg ejection and infanticide are other components of the evident reproductive conflict within groups (Macedo et al . 2001; Pacheco 2002).…”

“…Their mating system is polygynandrous with no complete monopoly of reproduction by one individual of either sex (Quinn et al 1994) and, after chicks hatch, some adults provide more parental care than others (Macedo 1994;Pacheco 2002). High rates of egg ejection and infanticide are other components of the evident reproductive conflict within groups (Macedo et al 2001;Pacheco 2002).…”