Search

Over the past decade, the field of molecular genetics has revolutionized our understanding of avian mating systems, by demonstrating that social bonds might not accurately reflect parentage because of unknown levels of cryptic mating (e.g., extra-pair copulations). Use of molecular genetics tools for paternity analysis requires genetic material from putative parents and nestlings. Unfortunately, high nest predation rates often preclude detailed genetic studies of tropical taxa. Here, we describe a nondestructive method that increases the efficiency of obtaining genetic material from offspring for a group of tropical passerines (Pipridae). The method entails replacing eggs with plaster replicas, incubating eggs artificially, and returning hatchlings to their original nests for further development. This method greatly improved our ability to sample offspring, as we collected genetic material from 100% of manipulated nests, compared to 52% of unmanipulated nests. Key words: ex situ incubation, manakin, nest predation, Pipridae, plaster eggs. Durante la ultima decada, el campo de la genetica molecular ha revolucionado el entendimiento de los sistemas de apareamiento de las aves, demostrando que los lazos sociales observados pueden no reflejar paternidad con precision, debido a niveles desconocidos de apareamiento criptico (e.g., copulaciones extra-pareja). El uso de herramientas de genetica molecular para el analisis de paternidad requiere material genetico de padres putativos y polluelos. Desafortunadamente, la alta tasa de depredacion de nidos en especies tropicales usualmente impide la realizacion de estudios geneticos detallados. Aqui se describe un metodo no destructivo que incrementa la eficacia para obtener material genetico de polluelos de un grupo de aves paseriformes tropicales (Pipridae). El metodo consiste en reemplazar huevos con replicas de yeso, incubar los huevos artificialmente y devolver los polluelos a los nidos originales para su posterior desarrollo. Este metodo incremental significativamente nuestra habilidad de muestrear polluelos, pudiendo colectar material genetico del 100% de los nidos manipulados, comparado con una colecta de material genetico de solo el 52% de los nidos no manipulados.

Lekking is classified as a form of male-dominance polygyny in which males lack control of resources essential for the acquisition of females. Of particular interest to behavioral ecologists has been the mechanistic basis of male spatial aggregation and the maintenance of site fidelity over time. The 'hotspot' hypothesis has been proposed as both an ultimate and proximate mechanism by which males aggregate in locations where females are likely to be encountered. The hypothesis has been extended to include areas of the environment that act to constrain females' use of space. Here, we test a prediction of this hypothesis for three species of manakins (Pipridae): that leks are located in places where fruit, the main food for these frugivorous birds, is plentiful. We compared four lek sites with four non-lek control sites of Golden-headed (Pipra erythrocephala), Wire-tailed (P. filicauda), and White-crowned (P. pipra) manakins in an Amazonian forest in Ecuador. Our results show that lek sites had higher fruit biomass than control sites. Moreover, lek sites had more plants bearing ripe fruit as well as a higher fruit biomass per plant than control sites. Thus, our results support the environmental hotspot hypothesis as an explanation for current lek site occupancy and suggest that fruit availability may also explain the placement of traditional manakin lekking sites. We also discuss a potential direct benefit for subordinate male manakins derived from the notion of central-place foraging and public information-sharing. Received 7 June 2004, accepted 2 July 2005. Key words: hotspot hypothesis, lek placement, male aggregation, manakins, Pipridae. Resumen.--El apareamiento en asambleas de cortejo esta clasificado como un tipo de poliginia basada en la dominancia de los machos, en la que estos carecen de control sobre recursos esenciales para la adquisicion de hembras. Los mecanismos que subyacen a la agregacion espacial de los machos y al mantenimiento de la fidelidad a los sitios han sido de particular interes para los ecologos del comportamiento. La hipotesis de los 'puntos calientes' (lugares en los que se concentran recursos) ha sido propuesta como un mecanismo tanto filtimo como proximo para explicar por que los machos se agregan en lugares donde es altamente probable que se encuentren hembras. Esta hipotesis ha sido extendida para incluir a las areas del ambiente que actuan limitando el uso del espacio por parte de las hembras. En este estudio ponemos a prueba una prediccion de esta hipotesis para tres especies de saltarines (Pipridae): las asambleas de cortejo deben estar ubicadas en lugares donde los frutos, la principal fuente de alimento de estas aves frugivoras, son abundantes. Comparamos cuatro sitios con asambleas de cortejo con cuatro sitios control sin estas para Pipra erythrocephala, P. filicauda y P. pipra en un bosque amazonico en Ecuador. Nuestros resultados indicaron que los lugares en que estaban ubicadas las asambleas de cortejo presentaron una mayor biomasa de frutos que los sitios control. Ademas, los sitios de cortejo presentaron mas plantas con frutos maduros y una mayor biomasa de frutos por planta que los sitios control. Pot lo tanto, nuestros resultados apoyan la hipotesis de los 'puntos calientes' de concentracion de recursos como una explicacion para la ocupacion actual de los sitios por las asambleas de cortejo, y sugieren que la disponibilidad de frutos podria igualmente explicar las ubicaciones tradicionales de estas asambleas en los saltarines. Tambien discutimos un beneficio directo potencial para los machos subordinados derivado de los conceptos de forrajeo alrededor de un lugar central y de compartir informacion publica.

Determination of a bird’s age or cohort is critical for studies on avian demography, occurrence patterns, behavior, and conservation management. Age designations have largely been developed in north-temperate regions and utilize calendar-based or seasonally based codes; however, in tropical regions and in the southern hemisphere, these coding systems have limited utility at best. To address these issues, we had previously devised the “WRP system,” based on the nomenclature of Humphrey and Parkes (H–P) and Howell et al., which defines molts in an evolutionary context applicable to birds globally. Here we refine and build upon core concepts and definitions of the WRP coding system, resolving key limitations that were identified during its first decade of use. The WRP system employs a three-letter alpha code in which each letter describes a different aspect of H–P terminology: the molt cycle (which informs a bird’s age) and molt and plumage status within the cycle (each of which can also inform age). Here we recommend the continued use of most of the original (“core”) WRP coding while augmenting the system with an optional adjunctcode entry for comprehensiveness, clarity, and flexibility, and we clarify a few additional codes to cover less common molting and plumage strategies. For most users, from 7 to 13 core and 1 adjunct WRP code will be sufficient to describe all plumages and provide molt status and ages for demographic studies or other purposes. The revised WRP system is flexible enough to be adapted to the specific goals of programs while also providing core codes that can facilitate the comparison of avian age, molt, and plumage status on a global basis. We anticipate that our revised and standardized version of the WRP system will be easily adopted and could eventually replace calendar-based and seasonally based coding. [ABSTRACT FROM AUTHOR]