Seasonal Decline in Brood Sizes of Sympatric Waterfowl (Anas and Aythya, Anatidae) and a Proposed Evolutionary Explanation

Toft, Catherine A.; Trauger, David L.; Murdy, H.W.

doi:10.2307/4343

Cited by 33 publications

(20 citation statements)

References 35 publications

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“…Toft et al . (1984) suggested that females investing less in reproduction, for example by nesting late and laying small clutches, should live longer and have more breeding attempts in their lifetime than females nesting early and laying large clutches.…”

Section: Discussionmentioning

confidence: 99%

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Reproductive performance of Common Goldeneye Bucephala clangula females in relation to age and lifespan

Milonoff¹,

Pöysä²,

Runko³

2002

Ibis

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We studied the effects of female age and length of lifespan on reproductive performance in the Common Goldeneye Bucephala clangula, a precocial species with self‐feeding chicks. Dependent variables studied were the occurrence of failed nesting attempts and non‐breeding years, clutch size, nesting and hatching success, female condition and recovery rate of offspring. To avoid misinterpretations resulting from age‐dependent quality changes in the cohorts, individuals with different lifespans were separated in the analyses. There was no evidence that females of different lifespan differed in reproductive strategy. The data revealed no significant differences in nest losses, occurrence of non‐breeding years, timing of nesting or clutch size, but the physiological condition of short‐lived females was poorer than that of longer living females. This accords with the prediction that poor‐quality females invest proportionally more in reproduction than high‐quality females and consequently die earlier. The most productive individuals were those that lived longest. The only indication of senescence was the low recovery rate of offspring produced by old females. The last breeding attempt did not differ in any observable respect from the penultimate attempt, implying that the last investment in reproduction was no heavier than the previous one.

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Section: Discussionmentioning

confidence: 99%

“…As a consequence, short‐lived individuals should, on average, have higher annual reproductive output than longer‐lived individuals. Toft et al . (1984) suggested that individuals could achieve the highest possible fitness by using different reproductive strategies.…”

mentioning

confidence: 99%

Reproductive performance of Common Goldeneye Bucephala clangula females in relation to age and lifespan

Milonoff¹,

Pöysä²,

Runko³

2002

Ibis

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“…If this is true and there is an equilibrium between birds with different laying dates, one would expect that late birds, with a low reproductive output, have a higher survival rate than early breeders with a high reproduction (Toft, Trauger & Murdy 1984). If this is true and there is an equilibrium between birds with different laying dates, one would expect that late birds, with a low reproductive output, have a higher survival rate than early breeders with a high reproduction (Toft, Trauger & Murdy 1984).…”

Section: Discussionmentioning

confidence: 99%

Laying Date in the Coot: Effects of Age and Mate Choice

Perdeck¹,

Cavé²

1992

The Journal of Animal Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. Laying date in coots advanced with the age of both the male and the female. 2. Individual females had different but rather constant laying dates. After controlling for these differences, the effect of female age on laying date remained, but that of male age disappeared. This implies that both early and late females advanced their laying date when becoming older. It also implies that male age has no direct effect on laying date, but that older males are better able to compete for earlylaying females. 3. Selective loss of late-breeding females from a cohort is a potential additional cause for a correlation between age and laying date. However, female survival rate was independent of laying date, thus refuting the selection hypothesis. 4. The data supported neither increased reproductive effort with age (residual reproductive value hypothesis), nor differential delay of reproduction between early and late females (delayed reproduction hypothesis) as additional explanations for the advancement of laying date with age. This advancement in the individual female is therefore considered to be due to increasing quality (maturation hypothesis). 5. The repeatability of laying date in females was 0-32, but the heritability, estimated with daughter-mother regression, was only 0-02. This indicates that the variation in laying date between individuals is predominantly environmental.

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“…Another view is that the decrease in clutch size is not adaptive and is merely an artifact of some physiological process such as decreased hormonal activity (Soikkeli 1967), although Farner and Follett (1979) point out that even physiological responses such as photorefractoriness may be adaptive. Toft et al (1984) examined the seasonal decline in brood size of a number of duck species and, as here, rejected various proximate causes that had been proposed to explain the decreasing clutch size. They suggested that the ultimate explanation for the seasonal decline in brood size was an increased proportion of duckling mortality occurring at fledging in late hatched broods compared with earlier hatched broods in which a greater proportion of mortality occurred earlier in the nesting cycle.…”

Section: Clutch Sizementioning

confidence: 99%

Nesting of northern pintails in Alberta: laying date, clutch size, and renesting

Duncan¹

1987

Can. J. Zool.

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DUNCAN, D. C. 1987. Nesting of northern pintails in Alberta: laying date, clutch size, and renesting. Can. J . Zool. 65: 234-246. Nesting of northern pintails was studied in southern Alberta where breeding densities are high. Adults nested earlier and laid larger clutches than did yearlings in the wild. Captive pintails nested earlier, laid larger clutches, and appeared to renest more readily than did wild birds. Food may limit each of these parameters in the wild. The reproductive output of female pintails nesting in high densities in southern Alberta appears to be lower than that of birds breeding at Delta, Manitoba, because of reduced clutch size and lower renesting rate. Clutch size was strongly correlated with laying date but the laying of larger clutches by adults in the wild (and by captive birds relative to wild birds) was not simply a consequence of earlier nesting. A number of proximate causes suggested to explain the seasonal decline in clutch size (hen age, renesting, declining food resources, and decreased body reserves) were rejected. Whatever the mechanism through which laying date influences clutch size, the ultimate reason for this phenomenon may be a seasonally declining survival rate of young which has selected for reduced reproductive effort later in the breeding season. Captive pintails fed a 14% or 29% protein diet after laying their first clutches did not differ in frequency of renesting, clutch size, or renest interval. DUNCAN, D. C. 1987. Nesting of northern pintails in Alberta: laying date, clutch size, and renesting. Can. J. Zool. 65 : 234-246. La nidification des canards pilets a fait l'objet d'une Ctude dans le sud de ]'Alberta oh la densite des canards reproducteurs est ClevCe. En nature, les adultes construisaient leur nid plus t8t et pondaient plus d'oeufs que les canards de 1 an. Les canards en captivitk nichaient Cgalement plus t8t, pondaient plus d'oeufs et semblaient plus enclins 2 nicher de nouveau que les canards pilets en nature. I1 est possible qu'on nature la nourriture constitue un facteur limitant pour chacun de ces parametres. La production d'oisillons par les femelles qui nichent en grands nombres dans le sud de ]'Alberta semble plus faible que celle des oiseaux qui se reproduisent a Delta, Manitoba, car le nombre d'oeufs pondus est moins ClevC et les nidifications rCpCties sont plus rares. Le nombre d'oeufs produits est fortement reliC a la date de ponte, mais la ponte d'un plus grand nombre d'oeufs par les adultes en nature (et par les oiseaux en captivitk comparativement aux oiseaux en nature) ne dipend pas uniquement de la date plus hiitive de la nidification. Un certain nombre d'hypothkses sur les causes immkdiates de la diminution du nombre d'oeufs pondus au cours de la saison (iige des femelles, nidifications rCpCtCes, declin des ressources alimentaires, diminution des reserves CnergCtiques) ont dQ etre rejeties. Quel que soit le mkcanisme responsable de I'influence de la date de ponte sur le nombre d'oeufs pondus, il est possible que la raison ultime du phCnom...

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Seasonal Decline in Brood Sizes of Sympatric Waterfowl (Anas and Aythya, Anatidae) and a Proposed Evolutionary Explanation

Cited by 33 publications

References 35 publications

Reproductive performance of Common Goldeneye Bucephala clangula females in relation to age and lifespan

Reproductive performance of Common Goldeneye Bucephala clangula females in relation to age and lifespan

Laying Date in the Coot: Effects of Age and Mate Choice

Nesting of northern pintails in Alberta: laying date, clutch size, and renesting

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