Mass Variation in Breeding Wood Thrushes

Johnson, R. Kent; Roth, Roland R.; Paul, John

doi:10.2307/1368386

Cited by 10 publications

(3 citation statements)

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“…Like many other male songbirds, male Florida Scrub‐Jays did not gain mass early in the breeding cycle (review in Moreno 1989b, but see Johnson et al 1990). Because male body mass did not increase significantly during gonadal recrudescence, we assume that mass loss later in the breeding cycle was unrelated to gonadal regression.…”

Section: Discussionmentioning

confidence: 99%

Body mass variation in breeding Florida Scrub-Jays

Brand

Bowman

2012

Journal of Field Ornithology

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Many birds lose mass when feeding dependent young and multiple hypotheses have been proposed to explain this loss. The reproductive-stress hypothesis suggests that mass loss results from an energy deficit. The flight-efficiency hypothesis suggests that breeders lose mass in advance of feeding young to save energy during flight. The reserve-mobilization hypothesis suggests that female breeders accumulate energy reserves during egg production and incubation and mobilize those reserves to meet their own energy needs after eggs hatch. Finally, birds may lose mass due to gonadal regression. From 1999 to 2001, we attracted Florida Scrub-Jays (Aphelocoma coerulescens), sedentary cooperative breeders, to a portable electronic balance. Our objective was to determine which hypotheses might best explain mass variation during breeding. Both male and female Florida Scrub-Jays lost mass during the period of nestling care (males, 3.2%; females, 6.5%), but not when feeding fledglings, despite this being the period of peak effort. Such results are consistent with both the flight-efficiency and reserve-mobilization (females only) hypotheses. We also found a significant negative influence of brood size on mass change in males, providing support for the reproductive-stress hypothesis, and we conclude that, for males, both the flight-efficiency and reproductive-stress hypotheses apply. For female scrub-jays, our results were consistent with the flight-efficiency and energy-reserve mobilization hypotheses, both of which view mass loss as beneficial. RESUMEN. Variación en la masa corporal en individuos reproductivos de Aphelocoma coerulescensMuchas aves pierden masa corporal cuando alimentan a sus pichones y se han propuesto varias hipótesis para explicar dicha pérdida. La hipótesis de "estrés reproductivo" sugiere que la pérdida de masa es el resultado de un déficit energético. La hipótesis de "eficiencia de vuelo" sugiere que en los reproductores la pérdida en masa es en antelación a la alimentación de los pichones, en aras de ahorrar energía para el vuelo. La hipótesis de "movilización de reserva" sugiere que las hembras reproductoras acumulan reservas de energía durante la producción de huevos e incubación y luego movilizan dichas reservas para cumplir con la demanda energética luego del eclosionamiento. Finalmente, las aves pueden perder masa corporal debido a la regresión de la gónada. De 1999 al 2001, atrajimos a una balanza electrónica a individuos del Azulejón (Aphelocoma coerulescens), que son reproductores sedentarios cooperativos. Nuestro objetivo fue determinar que hipótesis pudiera explicar la variación en masa durante el periodo reproductivo. Ambos, hembras y machos, perdieron masa durante el periodo de atención a los pichones (machos, 3.2%; hembras, 6.5%), pero no durante el periodo de alimentar a los volantones, siendo este el periodo de mayor esfuerzo. Estos resultados son consistentes con ambas hipótesis, la de eficiencia de vuelo y la de movilización de reservas (solo en las hembras). Además encontramos una influenc...

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Section: Discussionmentioning

confidence: 99%

Body mass variation in breeding Florida Scrub-Jays

Brand

Bowman

2012

Journal of Field Ornithology

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“…It has generally been interpreted as a consequence of the energetic demands of breeding, the reproductive stress hypothesis (Ricklefs 1974, Harris 1979, Monaghan et al . 1989, Moreno 1989, Wendeln and Becker 1996) and has been used as an index of reproductive costs (Askenmo 1977, Bryant 1979, Nur 1984, Johnson et al 1990). However, an alternative hypothesis explains the loss of body mass as an intrinsic process, known as programmed anorexia (Mrosovsky and Sherry 1980), a means of ensuring a lower cost of foraging through decreased flight cost (Freed 1981, Norberg 1981).…”

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confidence: 99%

Changes in body condition in breeding kittiwakes Rissa tridactyla

Moe¹,

Langseth²,

Fyhn³

et al. 2002

Journal of Avian Biology

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We investigated the seasonal pattern of changes in body condition of breeding black‐legged kittiwakes Rissa tridactyla in Svalbard (79°N) to evaluate whether changes in body condition were a consequence of the energetic demands of breeding (the reproductive stress hypothesis) or of voluntary anorexia to attain lower flight costs during chick rearing (the programmed anorexia hypothesis). Adult body condition was recorded from early egg laying to fledging and was examined in relation to date (relative to hatching), sex, parental time‐budget, brood size and reproductive success. To distinguish between the two hypotheses we evaluate whether the reduction in body condition occurred during or ahead of the energetically most demanding part of the chick‐rearing period. We combine our results on changes in body condition and time‐budget with published information on field metabolic rate (FMR) and chick energy requirements from studies in the same colony.  Our calculations of adult energy requirements and energy intakes indicate that the first part of the chick‐rearing period was energetically the most demanding period, because adult energy requirement per hour spent off the nest was highest in this period, and adults were time constrained because of the need for 24‐h brooding of the chicks.  During the incubation period female body condition increased slightly, but significantly, while male body condition was stable. During the first part of the chick‐rearing period, female and male body condition decreased by 14.8% and 8.4%, respectively. During the second part of the chick‐rearing period, both male and female body condition remained stable. The reductions in body condition occurred during the phase which was suggested to be the energetically most demanding part of the chick‐rearing period, thus supporting the reproductive stress hypothesis. Parental body condition during the incubation period was positively related to the probability of successfully fledging young, providing additional support for the reproductive stress hypothesis.

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“…The first study of Wood Thrush (Hylocichla mustelina) at the University of Delaware woodlot looked at the species' reproductive success (Longcore and Jones 1969). Since 1973 a banded population of Wood Thrushes has been studied by Roland R. Roth and his students (e.g., Johnson et al 1990, Roth and Johnson 1993, Weinberg and Roth 1998. W. Gregory Shriver and his students are continuing the Wood Thrush studies.…”

Section: Delaware Division Of Natural Resources and Environmentalmentioning

confidence: 99%

Contributions to the History of North American Ornithology

Nettleship¹,

join(²,

Jackson³

1997

Colonial Waterbirds

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The Massachusetts Audubon Society (MAS) was established in 1896, becoming the first state Audubon society and a model for scores of state and local Audubon societies established in the first half of the twentieth century. Initially focused on eliminating use of feathers of wild birds in the millinery trade, its vision rapidly expanded to encompass a broad spectrum of educational and conservation initiatives. MAS printed educational leaflets, bird calendars, and beginning in 1917, a Bulletin of the Massachusetts Audubon Society that was issued nine times a year. A junior membership category, together with classes, programs, and summer camps, emphasized educational objectives that have been the hallmark of MAS since its inception. The first president of MAS, William Brewster, was a leader in conservation matters nationally, especially in the formation of the American Ornithologists' Union. He thus was able to link MAS with national concerns including passage of national and international bird protection legislation. Brewster typified the strong leadership that MAS had in its formative years. Another early president, Edward Howe Forbush, was the first state ornithologist for Massachusetts. Habitat preservation became a major concern of MAS; with acquisition in 1916 of Moose Hill, in Sharon, MAS began a sanctuary system that developed into a statewide network of bird sanctuaries and centers for local education programs. MAS played an important role locally and nationally in the development of sport "birding," an effort that continues to generate support for conservation nationally. Unlike many local and state Audubon societies, which became branches of the National Audubon Society, the Massachusetts Audubon Society has remained independent throughout its existence.On a January afternoon in 1896, Harriet L. Hemenway of Clarendon Street, Boston, went to have high tea with her cousin Minna B. Hall.

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Mass Variation in Breeding Wood Thrushes

Cited by 10 publications

References 20 publications

Body mass variation in breeding Florida Scrub-Jays

Body mass variation in breeding Florida Scrub-Jays

Changes in body condition in breeding kittiwakes Rissa tridactyla

Contributions to the History of North American Ornithology

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