Foraging Proficiency During the Nonbreeding Season of a Specialized Forager: Are Juvenile American Oystercatchers "Bumble-Beaks"¹Compared to Adults?

Abstract

Resumen. En muchas especies, los individuos inmaduros son menos hábiles en forrajear que los adultos, y esta diferencia puede ser particularmente crítica durante el invierno cuando la supervivencia puede estar en su nivel más bajo. Investigamos la habilidad de forrajeo de individuos adultos e inmaduros de Haematopus palliatus durante la estación no reproductiva. H. palliatus forrajea sobre presas que deben ser manipuladas con habilidades especializadas, por lo que pueden esperarse diferencias relacionadas con la edad en el comportamiento de forrajeo. Encontramos que (i) los adultos gastan más tiempo buscando que los inmaduros, (ii) una tendencia de los inmaduros a pasar más tiempo manipulando las presas que los adultos, y (iii) los inmaduros manipulan sin éxito las presas más frecuentemente que los adultos. Las tasas de alimentación y la composición de la dieta no difirieron por clases de edad. Planteamos que las aves inmaduras compensan los mayores tiempos de manipulación con los menores tiempos de búsqueda y que en última instancia la abundancia de presas en la región puede contribuir a la habilidad de las aves inmaduras a alimentarse a tasas similares a las de los adultos.Abstract. In many species, immature individuals are less proficient at foraging than are adults, and this difference may be especially critical during winter when survival can be at its minimum. We investigated the foraging proficiency of adult and immature American Oystercatchers (Haematopus palliatus) during the nonbreeding season. Oystercatchers forage on prey that must be handled with specialized skills, so age-related differences in foraging behavior may be expected. We found that adults spent more time searching than did immatures, a trend toward immatures taking longer to handle prey than did adults, and immatures more often handling prey unsuccessfully than did adults. Feeding rates and diet composition did not differ by age class. We posit that the immature birds traded off longer handling times with shorter searching times and that ultimately the abundant prey in the region may contribute to the ability of immature birds to feed at rates similar to those of adults.

Effects of Extreme Tidal Events on Semipalmated Sandpiper (Calidris pusilla) Migratory Stopover in the Bay of Fundy, Canada

“…This may have been linked to their lower mass on tagging. However, juvenile birds also tend to be less competent at foraging (Hand et al 2010;van den Hout et al 2013) and are more prone to choosing lower quality habitats (Warnock and Takekawa 1995), likely owing to inexperience and low social standing (Groves 1978). Therefore, exposure to conditions that lead to over ocean flocking could be even more energetically challenging for them, and additional work in this area is required to understand how they respond to loss of roosting habitat.…”

Foraging for high caloric anthropogenic prey is energetically costly

“…The resources or foraging patches individual animals choose to forage on may depend on the trade-off between costs and benefits of different foraging strategies [11–13]. For instance, some prey might have benefits like a high energetic value or they are beneficial for breeding success, but they might be energetically costly to forage on due to special foraging skills that need to be learned [14], a long searching or handling time [15] or a high level of predation [16] or competition [17].…”

Circulating Fat-Soluble Vitamin Concentrations and Nutrient Composition of Aquatic Prey Eaten by American Oystercatchers (Haematopus palliatus palliatus) in the Southeastern United States

“…For example, a foraging study of American oystercatchers in the Cape Romain region in the winter found most (95%) of the prey items were eastern oysters (Crassostrea virginica) and 4% were ribbed mussels (Geukensia demissa). 3 Prey species collected for this study comprised eastern oysters, ribbed mussels, blood arks (Anadara ovalis), whelks (Busycon carica), false angel wings (Petricola pholadiformis), and northern quahog clams (Mercenaria mercinaria). Samples were stored on ice until processed or frozen at À708C and thawed for processing.…”

“…2 Although numerous studies on reproductive success and population estimates have been performed, few studies have been conducted on foraging behavior and very few on dietary requirements of American oystercatchers. 1,3 The purpose of this study was to document circulating fat-soluble vitamin concentrations of American oystercatchers captured in South Carolina and Georgia, USA, as baseline data for health and habitat assessment linked with nutritional status, with application to both free-ranging and captive populations. Additionally, we report the proximate, mineral, and vitamin composition of various prey species collected from American oystercatcher foraging habitat.…”