Effect of alarm calling by male Red-winged Blackbirds on nestling begging and female provisioning behavior

• Published in: Journal of field ornithology 2011-12, Vol.82 (4), p.395-405
• Main Authors: Bernath-Plaisted, Jacy, Yasukawa, Ken
• Format: Article
• Language: English
• Subjects: Agelaius phoeniceus; alarm calls; Animal behavior; Animal nesting; Animal vocalization; Anti-predator behavior; AVIAN BEHAVIOR AND ECOLOGY; begging behavior; Bird nesting; Breeding success; Evolution; Female animals; Male animals; nest predation; Nests; Ornithology; parent-offspring communication; Playback; Predation; Predators; Progeny; provisioning; Vocalization behavior
• ISSN: 0273-8570; 1557-9263
• DOI: 10.1111/j.1557-9263.2011.00342.x

Nestling begging and parental provisioning can attract nest predators and reduce reproductive success, so parents and their offspring might be expected to respond adaptively by minimizing predator-attracting cues when predators threaten nests. Male Red-winged Blackbirds (Agefaius phoeniceus) are well known for their antipredator alarm calls that contain information about the approach of potential nest predators. We examined the begging behavior of nestlings and the provisioning behavior of females in response to antipredator alarm calls of males to test the adaptive response hypothesis. Playback experiments provided no evidence that alarm calls function to switch off vocal begging; nestlings were equally likely to beg vocally during playback and control periods. Video recordings showed that male alarm calling had no significant effect on inappropriate vocal begging (in the absence of an adult), but significantly reduced the incidence of spontaneous calling (in the absence of begging). Adult females responded to male antipredator alarm calls by delaying their provisioning visits. In addition, although having no significant effect on use of nest-arriving calls by females, male alarm calling significantly reduced their use of nest-leaving calls. We conclude that nestling and female Red-winged Blackbirds respond to male alarm calls in ways that might reduce the risk of prédation, but nestlings beg vocally when females arrive to feed them, regardless of male alarm calling, perhaps to avoid a competitive disadvantage with broodmates. El pedir comida por parte de los pichones y el proveer alimento por los padres puede atraer depredadores y reducir el éxito reproductivo, por lo que debe esperarse, de los padres y sus hijos, el ofrecer una respuesta adaptativa, minimizando las claves para atraer depredadores cuando estos amenazan los nidos. Agelaius phoeniceus es bien conocido por sus llamadas de alerta, anti-depredación la cual contiene información cuando se acerca un depredador potencial. Examinamos la conducta de pedir comida por los pichones y la conducta de proveer alimento por parte de las hembras en respuesta a las llamadas de alerta anti-depredacioón ofrecida por los machos para poner apruebas la hipótesis de respuesta adaptativa. Experimentos con grabaciones no proveyeron evidencia de que las llamadas de alarma pudieran funcionar para producir cambios en la vocalización de pedir comida por parte de los pichones; los pichones vocalizaron de igual manera dur