The demands of incubation and avian clutch size

Thomson, David; Monaghan, Pat; FURNESS, ROBERT W.

doi:10.1017/s0006323198005180

Cited by 147 publications

(64 citation statements)

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“…These responses to an enhanced energy supply are more easily understood if incubation is an inherently costly stage in the annual cycle of birds. Recent evidence indeed suggests, in contrast to earlier assumptions (Walsberg & King 1978), that the costs associated with incubation are not negligible, at least among uniparental incubators (Tatner & Bryant 1993;Williams 1991;Thomson et al 1998).…”

Section: Discussionmentioning

confidence: 82%

Heating nest–boxes reveals an energetic contraint on incubation behaviour in great tits, Parus major

Bryan

Bryant

1999

Proc. R. Soc. Lond. B

106

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According to the`energetic-bottleneck' hypothesis, incubation in birds is constrained by the availability of energy. Hence, uniparental incubators are predicted to respond to a change in energy supply by adjusting, positively or negatively, the time spent warming the clutch. Energetic constraints on incubation in the great tit (Parus major) were demonstrated by heating nests, so that the night-time thermostatic component of daily energy expenditure in females was reduced by comparison with a control group. Birds in heated nests increased the time allocated to incubation during the day by 55 minutes, consistent with the predictions of the energetic-bottleneck hypothesis. Daily energy expenditure of all birds was inversely related to night-time ambient temperature, and did not di¡er between warmed and control birds on mild nights. When temperatures were low, however, escalation of daily costs was less for birds in heated nests. It is suggested that the balance of the energy budget may e¡ect a proximate control on the constancy of incubation, with likely implications for reproductive success.

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Section: Discussionmentioning

confidence: 82%

Heating nest–boxes reveals an energetic contraint on incubation behaviour in great tits, Parus major

Bryan

Bryant

1999

Proc. R. Soc. Lond. B

106

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“…In fact, there were no signi¢cant di¡erences between these groups and the trends actually went in the opposite direction (¢gure 2). On the other hand, incubation itself can be relatively demanding, particularly when, as in this study, birds are incubating at temperatures outside the thermoneutral zone (Williams 1996;Thomson et al 1998). Experimental changes in incubation costs alone can have ¢tness consequences (Heaney & Monaghan 1996;Monaghan & Nager 1997;Bryan & Bryant 1999).…”

Section: Discussionmentioning

confidence: 93%

Experimental evidence that age-specific reproductive success is independent of environmental effects

Daunt

Wanless²,

Harris³

et al. 1999

Proc. R. Soc. Lond. B

107

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An age-speci¢c improvement in reproductive performance has been reported in many iteroparous breeders. However, whether this is a consequence of intrinsic di¡erences in competence amongst age classes or extrinsic di¡erences in the environment they experience is unclear since the timing of breeding within a season generally also di¡ers with age. To disentangle these e¡ects, we experimentally manipulated the timing of breeding in shags, Phalacrocorax aristotelis. Old and young individuals thus reared their chicks at the same time both early and late in the breeding season. When breeding in the same environmental conditions, old pairs performed consistently better than young pairs. These data clearly demonstrate that the age-related di¡erences in reproductive performance are not a result of environmental e¡ects, but rather a consequence of intrinsic di¡erences in brood rearing capacity.

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“…A male-biased tertiary sex ratio is 16 common in birds, most likely because adult females in general suffer higher mortality as a result of 17 higher metabolic demands and greater risk of predation during incubation (e.g., Trivers, 1996; 18 Thomson et al, 1998;Donald, 2007 and females dominate males and may mate with more than one male each year (Crome, 1975). Moa, 28…”

Section: Sex Ratios 37mentioning

confidence: 99%

Highly skewed sex ratios and biased fossil deposition of moa: ancient DNA provides new insight on New Zealand's extinct megafauna

Allentoft

Bunce

Scofield

et al. 2010

Quaternary Science Reviews

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the other three moa taxa combined at BHV. A subsample of 227 individuals had sufficient nuclear 28 DNA preservation to warrant the use of molecular sexing techniques, and the analyses uncovered a 29 remarkable excess of females in both deposits with an overall male to female ratio of 1 : 5.1. Among 30 juveniles of E. curtus, the only species which was represented by a substantial fraction of juveniles, 31 the sex ratio was not skewed (10 ♂, 10 ♀), suggesting that the observed imbalance arose as a result of 32 differential mortality during maturation. Surprisingly, sex ratios proved significantly different 33 between sites with a 1 : 2.2 ratio at BHV (n = 90) and an entire 1 : 14.2 at PV (n = 137). Given the 34 mobility of large ratites, and the proximity of the two fossil assemblages in space and time, these 35 differences in taxonomic and gender composition indicate that moa biology and the local environment 36 have affected the fossil representation dramatically and several possible explanations are offered. 37Apart from adding to our understanding of moa biology, these discoveries reinforce the need for 38 caution when basing interpretation of the fossil record on material from a single site. 39 40

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The demands of incubation and avian clutch size

Cited by 147 publications

References 0 publications

Heating nest–boxes reveals an energetic contraint on incubation behaviour in great tits, Parus major

Heating nest–boxes reveals an energetic contraint on incubation behaviour in great tits, Parus major

Experimental evidence that age-specific reproductive success is independent of environmental effects

Highly skewed sex ratios and biased fossil deposition of moa: ancient DNA provides new insight on New Zealand's extinct megafauna

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