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Egg size and asymmetric sibling rivalry in red-winged blackbirds

  • Behavioral ecology - Original Paper
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Abstract

How big to make an egg is a life history decision that in birds is made coincident with a series of other similar decisions (how many eggs to have, whether to fortify them with maternally derived hormones or immune system boosters, whether to hatch the eggs synchronously or asynchronously). Though within-population variation in egg size in birds has been well studied, its adaptive significance, if any, is unclear. Here we examine within-population variation in egg size in relation to asymmetric sibling rivalry in a 17-year study of red-winged blackbirds (Agelaius phoeniceus), an altricial songbird. Egg mass showed a twofold range of variation, with roughly 80% of the variation occurring across clutches. By commencing incubation before the clutch is complete, mothers create advantaged core and disadvantaged marginal elements within their brood. Previous work on this system has shown that sibling competition is asymmetric, and that core offspring enjoy priority access to food, and as a consequence show higher growth and lower mortality than marginal offspring. Here we examine the effect of initial egg size on nestling growth and survival in relation to these competitive asymmetries. Egg mass was strongly linked to hatchling mass, and remained significantly related to the mass of both core and marginal nestlings; the effect of egg size was stronger for core offspring early in the nestling period, but the disparity between core and marginal nestlings narrowed as they approached fledging age, and slower growing marginals fell victim to brood reduction. The effect of egg mass on survival differed dramatically between core and marginal nestlings. Egg mass was significantly related to the survival of marginal but not core nestlings: below average egg mass was associated primarily with very early mortality. Asymmetric sibling competition is clearly a strong determinant of the consequences of egg size variation.

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References

  • Amundsen T (1995) Egg size and early nestling growth in the snow petrel. Condor 91:345-35

    Google Scholar 

  • Amundsen T, Slagsvold T (1991) Hatching asynchrony: facilitating adaptive or maladaptive brood reduction? Acta XX Congress International Ornithology, New Zealand 1990, pp 1707–1719

  • Amundsen TT, Slagsvold T (1996) Lack’s brood reduction hypothesis and avian hatching asynchrony: what’s next? Oikos 76:613–620

    Article  Google Scholar 

  • Amundsen T, Slagsvold T (1998) Hatching asynchrony in great tits: a bet-hedging strategy? Ecology 79:295–304

    Article  Google Scholar 

  • Beletsky L (1996) The red-winged blackbird: the biology of a strongly polygynous songbird. Academic Press, New York

    Google Scholar 

  • Bortolotti GR, Negro JJ, Surai PF, Prieto P (2003) Carotenoids in eggs and plasma of red-legged partridges: effects of diet and reproductive output. Physiol Biochem Zool 76:367–374

    Article  CAS  PubMed  Google Scholar 

  • Christians JK (2002) Avian egg size: variation within species and inflexibility within individuals. Biol Rev 77:1–26

    Google Scholar 

  • Clark AB, Wilson DS (1981) Avian breeding adaptations: hatching asynchrony, brood reduction and nest failure. Q Rev Biol 56:253–277

    Article  Google Scholar 

  • Clogg CC, Petkova E, Haritou A (1995) Statistical methods for comparing regression coefficients between models. Am J Soc 100:1261–1293

    Article  Google Scholar 

  • Fiala KL (1981) Sex ratio constancy in the red-winged blackbird. Evolution 35:898–910

    Article  Google Scholar 

  • Forbes S (2009) Portfolio theory and how parent birds manage investment risk. Oikos 118:1561–1569

    Article  Google Scholar 

  • Forbes S (2010) Family structure and variation in reproductive success in blackbirds. Behav Ecol Sociobiol 64:475–483

    Article  Google Scholar 

  • Forbes S, Glassey B (2000) Asymmetric sibling rivalry and nestling growth in red-winged blackbirds. Behav Ecol Sociobiol 48:413–417

    Article  Google Scholar 

  • Forbes S, Thornton S, Glassey B, Forbes M, Buckley N (1997) Why parent birds play favourites. Nature 390:351–352

    Article  CAS  Google Scholar 

  • Forbes S, Glassey B, Thornton S, Earle L (2001) The secondary adjustment of clutch size in red-winged blackbirds (Agelaius phoeniceus). Behav Ecol Sociobiol 50:37–44

    Article  Google Scholar 

  • Forbes S, Grosshans R, Glassey B (2002) Multiple incentives for parental optimism and brood reduction in blackbirds. Ecology 83:2529–2541

    Article  Google Scholar 

  • Glassey B, Forbes S (2002) Begging and asymmetric nestling competition. In: Wright J, Leonard ML (eds) Evolution of nestling begging: competition, cooperation and communication. Kluwer, Dordrecht, pp 269–281

    Google Scholar 

  • Hall M, Blount J, Forbes S, Royle N (2010) Does oxidative stress mediate the trade-off between growth and self-maintenance in structured families? Funct Ecol 24:365–373

    Article  Google Scholar 

  • Holcomb LD, Twiest G (1970) Growth rates and sex ratios of red-winged blackbird nestlings. Wilson Bull 82:294–303

    Google Scholar 

  • Hurlbert SH (1984) Pseudoreplication and the design of ecological field experiments. Ecol Monogr 54:187–211

    Article  Google Scholar 

  • Krist M, Remes V, Uvirova L, Nadvornik P, Bures S (2004) Egg size and offspring performance in the collared flycatcher (Ficedula albicollis): a within-clutch approach. Oecologia 140:52–60

    Article  PubMed  Google Scholar 

  • Lipar JL, Ketterson ED, Nolan V Jr (1999) Intraclutch variation in testosterone content of red-winged blackbird eggs. Auk 116:231–235

    Google Scholar 

  • Maddox JD, Weatherhead PJ (2008) Egg size variation in birds with asynchronous hatching: is bigger really better? Am Nat 171:358–365

    Article  PubMed  Google Scholar 

  • Mock DW, Forbes LS (1995) The evolution of parental optimism. Trends Ecol Evol 10:130–134

    Article  Google Scholar 

  • Mock DW, Parker GA (1997) The evolution of sibling rivalry. Oxford University Press, Oxford

  • Monaghan P, Nager RG (1997) Why don’t birds lay more eggs? Trends Ecol Evol 12:270–274

    Article  Google Scholar 

  • Reed WL, Turner AM, Sotherland PR (1999) Consequences of egg-size variation in the red-winged blackbird. Auk 116:549–552

    Google Scholar 

  • Risch TS, Rohwer FC (2000) Effects of parental quality and egg size on growth and survival of herring gull chicks. Can J Zool 78:967-97

    Google Scholar 

  • Roff DA (2002) Life history evolution. Sinauer, Sunderland

    Google Scholar 

  • Royle NJ, Surai PF, Hartley IR (2001) Maternally derived androgens and antioxidants in bird eggs: complementary but opposing effects? Behav Ecol 12:381–385

    Article  Google Scholar 

  • Schwabl H (1996) Maternal testosterone in the avian egg enhances postnatal growth. Comp Biochem Physiol A 114:271–276

    Article  CAS  Google Scholar 

  • Slagsvold T, Wiebe KL (2007) Hatching asynchrony and early nestling mortality: the feeding constraint hypothesis. Anim Behav 73:691–700

    Article  Google Scholar 

  • Slagsvold T, Sandvik J, Rofstad G, Lorentsen O, Husby M (1984) On the adaptive value of intraclutch egg-size variation in birds. Auk 101:685–697

    Google Scholar 

  • Weatherhead PJ, Dufour LW (2005) Limits to sexual size dimorphism in red-winged blackbirds: the cost of getting big? Biol J Linn Soc 85:353–361

    Article  Google Scholar 

  • Weatherhead PJ, Muma KE, Maddox JD, Knox JM, Dufour KW (2007) Morphology versus molecules: sexing red-winged blackbird nestlings. J Field Ornithol 78:428–435

    Article  Google Scholar 

  • Williams TD (1994) Intraspecific variation in egg size and egg composition in birds: effects on offspring fitness. Biol Rev 69:35–59

    Article  CAS  PubMed  Google Scholar 

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Acknowledgments

This work complies with the current laws of Canada. This work would not have been possible without the assistance of a very large number of enthusiastic field assistants. Space does not allow us to acknowledge them all but we would like to thank in particular the following members of the Swamp Crew: Kristin Tuchscherer, Kristjana and Jessie Lee Cameron, Dobryan Tracz, Nagu Atmuri, Dean Swedlo, Saumya Jayakumar, Aaron Trachtenberg, Leanne Grieves, James Rogers, Jodi Griffith, Suzanne Thornton, Richard Grosshans and Barb Glassey. Two anonymous reviewers provided helpful comments on the manuscript. This work was funded by the Natural Sciences and Engineering Research Council of Canada.

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  1. Department of Biology, University of Winnipeg, 515 Portage Avenue, Winnipeg, MB, R3B 2E9, Canada

    Scott Forbes & Mark Wiebe

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  1. Scott Forbes
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  2. Mark Wiebe
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Correspondence to Scott Forbes.

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Communicated by Chris Whelan.

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Forbes, S., Wiebe, M. Egg size and asymmetric sibling rivalry in red-winged blackbirds. Oecologia 163, 361–372 (2010). https://doi.org/10.1007/s00442-010-1629-x

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