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Hatching Asynchrony and Hatching Success in the House Sparrow: Evidence for the Egg Viability Hypothesis
José P. Veiga and Javier Viñuela
Ornis Scandinavica (Scandinavian Journal of Ornithology)
Vol. 24, No. 3 (Jul. - Sep., 1993), pp. 237-242
Stable URL: http://www.jstor.org/stable/3676739
Page Count: 6
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We tested the "egg viability" hypothesis in the House Sparrow Passer domesticus by comparing the hatchability of clutches with different degrees of hatching asynchrony using multiple linear regression analysis. Hatching duration was directly and independently affected by clutch size, laying date and temperature. Taking these factors into account, nests with positive residuals (asynchronous nests) had a greater probability of hatching the early laid eggs successfully. This indicates that by starting incubation early and hatching asynchronously, birds may reduce embryo mortality. Asynchronous nests fledged a greater proportion of early-hatched young, but total nestling mortality did not differ between asynchronous and synchronous nests. Nestling mortality due to intrabrood competition did not constrain hatching asynchrony. The presence of highly synchronous broods seemed to indicate that in some cases hatching asynchrony was precluded by constraints acting on the laying female.
Ornis Scandinavica (Scandinavian Journal of Ornithology) © 1993 Nordic Society Oikos