Avian Incubation

White, Fred N.; Kinney, James L.

doi:10.1126/science.186.4159.107

Cited by 212 publications

(151 citation statements)

References 15 publications

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“…data), females have a more developed brood patch than males (Skutch, 1957;White & Kinney, 1974;Deeming, 2002). Aside from the effective transfer of heat to eggs, the brood patch also appears to be important for assessing egg temperature using an array of thermo-receptors located on the bare skin (White & Kinney, 1974;Haftorn & Reinertsen, 1982Zerba & Morton, 1983). Consequently, females are likely to have superior information about the thermal status and requirements of the clutch than males.…”

Section: Discussionmentioning

confidence: 99%

Contrasting effects of reduced incubation cost on clutch attendance by male and female European starlings

Magrath¹,

Overveld²,

Komdeur³

2005

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SummaryIn biparental birds, the relative contribution of the sexes to parental care can be viewed as a co-operative equilibrium that reflects the relative costs and benefits to each parent. If there are asymmetries in these costs or benefits, then any changes to the cost of care could result in a corresponding adjustment to their relative contribution. Incubation is a parental activity, shared in many species, which is costly both in terms of energy expenditure and time. In this study we manipulated the cost of incubation for pairs of European starlings (Sturnus vulgaris) by experimentally warming selected clutches to examine how this affected attendance by each parent. We found that total nest attendance did not differ between heated and control nests, although there was some evidence among heated nests that attendance declined with increasing effectiveness of the heater. Furthermore, relative male contribution was greater at heated than control nests resulting from the net effect of females tending to reduce, and males increase, attendance. We suggest that this shift in relative attendance may have been observed because females have a more developed brood patch and are more sensitive and responsive to clutch temperature than males. Consequently, females tended to reduce attendance at heated nests while males, with less reliable information on the clutch's thermal status, increased attendance to compensate for the reduction by the female. We also found that females at heated nests were lighter than at control nests, possibly because they were able to shed the additional fat reserves, a characteristic of incubating birds, earlier than females at control nests. We suggest that adjustment of clutch temperature in biparental species provides a valuable approach to investigating factors, including functional differences, asymmetries in brood value, and parental negotiation rules, that shape the roles of the sexes in incubation.3)

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Section: Discussionmentioning

confidence: 99%

Contrasting effects of reduced incubation cost on clutch attendance by male and female European starlings

Magrath¹,

Overveld²,

Komdeur³

2005

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“…Zebra finch eggs in these experimental treatments were exposed to periodic cooling patterns similar to those experienced by eggs of uniparentally incubating passerines in nature (White and Kinney 1974), which resulted in embryos smaller after 12 d of incubation than embryos incubated at a constant temperature. For their size, these embryos also had less remaining yolk and higher mass-specific metabolic rates than embryos from control eggs.…”

Section: Discussionmentioning

confidence: 99%

“…For developing bird embryos, maintenance of egg temperature (T e ) by the incubating adult has long been thought to be essential for proper development (White and Kinney 1974;Webb 1987). In a few species, it is known that prolonged cold exposure on the scale of hours to days reduces metabolic rate and rate of development (Tazawa et al 1989), reduces hatching success * Corresponding author; e-mail: cro@iastate.edu.…”

Section: Introductionmentioning

confidence: 99%

Periodic Cooling of Bird Eggs Reduces Embryonic Growth Efficiency

Olson

Vleck

2006

Physiological and Biochemical Zoology

170

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For many bird embryos, periodic cooling occurs when the incubating adult leaves the nest to forage, but the effects of periodic cooling on embryo growth, yolk use, and metabolism are poorly known. To address this question, we conducted incubation experiments on eggs of zebra finches (Taeniopygia guttata) that were frequently cooled and then rewarmed or were allowed to develop at a constant temperature. After 12 d of incubation, embryo mass and yolk reserves were less in eggs that experienced periodic cooling than in controls incubated constantly at 37.5C. Embryos that regularly cooled to 20C had higher mass-specific metabolic rates than embryos incubated constantly at 37.5C. Periodic cooling delayed development and increased metabolic costs, reducing the efficiency with which egg nutrients were converted into embryo tissue. Avian embryos can tolerate periodic cooling, possibly by adjusting their physiology to variable thermal conditions, but at a cost to growth efficiency as well as rate of development. This reduction in embryo growth efficiency adds a new dimension to the fitness consequences of variation in adult nest attentiveness. Disciplines Ornithology | Other Ecology and Evolutionary Biology | Terrestrial and Aquatic Ecology | Zoology CommentsThis article is from Physiological and Biochemical Zoology 79 (2006) ABSTRACTFor many bird embryos, periodic cooling occurs when the incubating adult leaves the nest to forage, but the effects of periodic cooling on embryo growth, yolk use, and metabolism are poorly known. To address this question, we conducted incubation experiments on eggs of zebra finches (Taeniopygia guttata) that were frequently cooled and then rewarmed or were allowed to develop at a constant temperature. After 12 d of incubation, embryo mass and yolk reserves were less in eggs that experienced periodic cooling than in controls incubated constantly at 37.5ЊC. Embryos that regularly cooled to 20ЊC had higher mass-specific metabolic rates than embryos incubated constantly at 37.5ЊC. Periodic cooling delayed development and increased metabolic costs, reducing the efficiency with which egg nutrients were converted into embryo tissue. Avian embryos can tolerate periodic cooling, possibly by adjusting their physiology to variable thermal conditions, but at a cost to growth efficiency as well as rate of development. This reduction in embryo growth efficiency adds a new dimension to the fitness consequences of variation in adult nest attentiveness.

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“…Even maximum ambient temperatures in midelevation tropics (e.g., 25°C) are quite cold relative to bird embryonic development (16). As a result, periodic absences (i.e., inattentiveness of eggs) by incubating parents during the daytime (parents incubate all night) cause relatively cold egg temperatures (14)(15)(16). Absences are commonly longer among tropical birds, causing egg temperatures to commonly drop as low as 18°C and average colder temperatures than north temperate relatives (16).…”

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confidence: 99%

“…Embryos of many ectotherm species experience lower growth efficiency and require more energy in colder environments that thereby yield longer embryonic periods and smaller and lower-quality hatchlings (5-10). Bird embryos are ectothermic, especially during early incubation, and embryos develop best at quite high (i.e., 35.5-39.5°C) temperatures associated with the high body temperatures of birds (11)(12)(13)(14)(15). Even maximum ambient temperatures in midelevation tropics (e.g., 25°C) are quite cold relative to bird embryonic development (16).…”

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confidence: 99%

Egg size variation among tropical and temperate songbirds: An embryonic temperature hypothesis

Martin

2008

Proc. Natl. Acad. Sci. U.S.A.

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Species with ''slow'' life history strategies (long life, low fecundity) are thought to produce high-quality offspring by investing in larger, but fewer, young. Larger eggs are indeed associated with fewer eggs across taxa and can yield higher-quality offspring. Tropical passerines appear to follow theory because they commonly exhibit slow life history strategies and produce larger, but fewer, eggs compared with northern species. Yet, I show here that relative egg mass (corrected for adult mass) varies extensively in the tropics and subtropics for the same clutch size, and this variation is unexplained. I propose a hypothesis to explain egg size variation both within the tropics and between latitudes: Relative egg mass increases in species with cooler egg temperatures and longer embryonic periods to offset associated increases in energetic requirements of embryos. Egg temperatures of birds are determined by parental incubation behavior and are often cooler among tropical passerines because of reduced parental attentiveness of eggs. Here, I show that cooler egg temperatures and longer embryonic periods explained the enigmatic variation in egg mass within and among regions, based on field studies in tropical Venezuela (36 species), subtropical Argentina (16 species), and north temperate Arizona (20 species). Alternative explanations are not supported. Thus, large egg sizes may reflect compensation for increased energetic requirements of cool egg temperatures and long embryonic periods that result from reduced parental attentiveness in tropical birds.clutch size ͉ incubation ͉ life history ͉ passerines U nderstanding why species differ in the number and size of offspring is a central question of life history theory because these traits exert a major influence on fitness (1, 2). Indeed, egg and yolk mass can strongly affect offspring fitness across taxa (2, 3). Larger eggs and higher-quality offspring are thought to be favored for competitive environments and associated ''slow'' life history strategies (i.e., long life, slow development, low fecundity) (1-3) that often typify tropical species (4). These larger young are expected to come at the expense of fewer young, and this tradeoff has been widely observed among taxa other than birds (1-3). In birds, a tradeoff between egg size and number is often weak or nonexistent (2), such that egg size variation is puzzling. Tropical and subtropical passerines, however, appear to follow theory because they commonly exhibit slow life histories and produce larger eggs associated with smaller clutch sizes compared with north temperate species (4). Yet, this apparent affirmation of theory may be an illusion because relative egg mass (corrected for body mass) varies extensively in the tropics whereas clutch size does not (Fig. 1), and this egg size variation is unexplained. I propose a hypothesis for egg size variation within and among latitudes for birds and other organisms with ectothermic embryos: egg mass is relatively larger in species with greater energetic requirements of ...

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Avian Incubation

Cited by 212 publications

References 15 publications

Contrasting effects of reduced incubation cost on clutch attendance by male and female European starlings

Contrasting effects of reduced incubation cost on clutch attendance by male and female European starlings

Periodic Cooling of Bird Eggs Reduces Embryonic Growth Efficiency

Egg size variation among tropical and temperate songbirds: An embryonic temperature hypothesis

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