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Incubation Mounds (incubation + mound)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Distribution, seasonal use, and predation of incubation mounds of Orange-footed Scrubfowl on Komodo Island, Indonesia

JOURNAL OF FIELD ORNITHOLOGY, Issue 2 2009
M. Jeri Imansyah
ABSTRACT Megapodes are unique in using only heat from the environment, rather than body heat, to incubate their eggs as well as the precocious independence of their chicks on hatching. Of 22 recognized species of megapodes, 9 are listed as threatened due to factors including habitat loss and fragmentation, and predation on eggs and chicks. Orange-footed Scrubfowl (Megapodius reinwardt) are conspicuous components of the Oriental/Austral avifauna that inhabit the monsoon forests of the Lesser Sunda chain of islands in Indonesia. We examined the abundance, patterns of distribution, physical characteristics, seasonal activity, and predation risk of incubation mounds of Orange-footed Scrubfowl on Komodo Island in eastern Indonesia. We surveyed 13 valleys on Komodo Island from April 2002 to January 2005 and located 113 tended and 107 untended incubation mounds. Densities of scrubfowl mounds in our study were similar to that reported by investigators during the 1970s, suggesting little change in the scrubfowl population since then. Most scrubfowl mounds were on sandy or loamy soils in open monsoon forest with little overhead shade, and placement of mounds in such areas may ensure adequate temperatures for egg incubation. Although some mounds were tended during all months, mound use peaked during the late wet season in March. During the dry season (April,November), only a few mounds were tended. Komodo dragons (Varanus komodoensis) and wild pigs (Sus scrofa) were the primary predators of scrubfowl eggs, with no indication of egg predation by humans. The valley with the largest number of untended mounds in our study also had the largest number of active Komodo dragon nests. This suggests an effect of Komodo dragons on scrubfowl numbers, but additional study is needed. SINOPSIS Los Megadopodos son únicos al usar calor del ambiente, en vez de calor corporal, para incubar sus huevos, y que sus polluelos nidífugos son independientes después de la eclosión. De las 22 especies de Megapodos reconocidas, nueve están en la lista de especies amenazadas debido a factores como pérdida y fragmentación del hábitat y depredación de huevos y polluelos. Megapodius reinwardt es un componente conspicuo de la avifauna Oriental/Austral que vive en los bosques monzones en las islas de las Sundas Menores en Indonesia. Examinamos la abundancia, patrones de distribución, características físicas, actividades temporales y riesgo de depredación en los montículos incubadores de M. reinwardt en la isla de Komodo en el este de Indonesia. Examinamos 13 valles en la isla de Komodo entre Abril 2002 y Enero 2005 y localizamos 113 montículos incubadores atendidos y 107 que no estaban siendo atendidos. Las densidades de montículos de M. reinwardt en nuestro sitio de estudio fueron similares a los reportados por investigadores en la década de los ,70, lo cual siguiere pocos cambios en la población de M. reinwardt desde entonces. La mayoría de los montículos de M. reinwardt se encontraron en suelos arenosos o margosos en bosques monzones abiertos, con poca cobertura de vegetación, y la localización de los montículos en estas áreas posiblemente aseguran temperaturas adecuadas para la incubación de los huevos. A pesar de que algunos montículos estuvieron atendidos durante todos los meses, el pico de uso de los montículos ocurrió durante el final de la temporada de lluvias en Marzo, y durante la temporada seca (Abril,Noviembre) solo algunos montículos estuvieron atendidos. Los dragones de Komodo (Varanus komodoensis) y los cerdos salvajes (Sus scrofa) fueron los principales depredadores de los huevos de M. reinwardt, y no hubo indicio de depredación por humanos. En nuestro estudio el valle con los mayores números de montículos desatendidos tenía el mayor número de nidos activos de dragones de Komodo. Este resultado sugiere la posibilidad de algún efecto de los dragones de Komodo en los números de Megapodius reinwardt, pero estudios adicionales son requeridos. [source]

Incubation temperatures and sex ratios in Australian brush-turkey (Alectura lathami) mounds

AUSTRAL ECOLOGY, Issue 4 2007
ANN GÖTH
Abstract Megapodes are exceptional among birds because they use external heat sources for incubating their eggs. In Australian brush-turkeys (Alectura lathami), this source is the heat produced by microbial decomposition in mounds of leaf litter. A recent laboratory study showed that artificial incubation of eggs at different temperatures affects the sex ratio of brush-turkey hatchlings. Here, this phenomenon is confirmed for eggs incubated in natural incubation mounds. Eggs from which females hatched were found at significantly higher incubation temperatures in the mounds (mean 33.7°C) than those from which males hatched (mean 32.9°C). Also, sex ratios of chicks from individual mounds were significantly correlated with mean incubation temperatures in those mounds. Furthermore, incubation temperatures differed significantly between incubation mounds during the same month of the year. Within some mounds, incubation temperatures differed up to 9°C between eggs, in others this difference was only up to 1°C. These latter results show that males differ in their ability to maintain stable incubation temperatures. While the effect of incubation temperatures on sex ratio is a novel discovery for any bird, it was previously suggested that incubation temperatures in megapodes also affect embryo mortality and chick survival. These combined effects of incubation temperature, and the limited ability of males to provide optimal temperatures, seem to provide answers to the question why so few birds have adopted this unusual mode of reproduction , a question asked by many behavioural ecologists and evolutionary biologists. [source]