Eggshell spotting does not predict male incubation but marks thinner areas of a shorebird's shells

Bulla, Martin; Šálek, Miroslav; Gosler, Andrew

doi:10.1525/auk.2012.11090

Cited by 24 publications

(3 citation statements)

References 62 publications

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“…Apart from their protective role (camouflage) in the eggshells of birds building open nests, such as blackbird and song thrush, the “signaling function hypothesis” and “structural function hypothesis” suggest other functions for pigment spots. The first hypothesis refers to the quality of female and involvement of male in egg care 37 , while the second indicates that pigment spots intensify areas of reduced calcium saturation on eggshell, improving its durability 38 , 39 . Our results may contribute to expanding the knowledge about the structural function.…”

Section: Discussionmentioning

confidence: 99%

“…Protonmotoric pigment spots on the surface may have a similar function. Researchers have been investigating the function of eggshell pigment spots in recent years [37][38][39] . Apart from their protective role (camouflage) in the eggshells of birds building open nests, such as blackbird and song thrush, the "signaling function hypothesis" and "structural function hypothesis" suggest other functions for pigment spots.…”

Section: Discussionmentioning

confidence: 99%

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Analysis of ultrastructure and microstructure of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshell by scanning electron microscopy and X-ray computed microtomography

Damaziak

Marzec

2022

Sci Rep

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The unique structure of the egg allows for efficient reproduction on land. Although the functions of the egg are ensured by the concomitant cooperation of all its structures, the eggshell also plays a significant role. Apart from maintaining an aqueous environment within the egg along with controlled gas exchange, the color and pigmentation pattern of eggshell contributes to identification and protection. As a result of all these functions, the structure, shape, and pigmentation of eggshell greatly vary across the class of birds, and understanding these three variability-determining factors may aid in better interpretation of evolutionary mechanisms. In this study, we analyzed for the first time the structure, mineral composition, and characteristics of the pigmentation of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshells. The shell of blackbird eggs is much thicker compared to the shell of song thrush eggs which is due to a much thicker crystalline and palisade layers. In both species, strongly elongated mammillary knobs are observed, which create a large space between the mineralized shell and the egg membranes. The blackbird egg shell has a higher water vapor conductivity which is due to the larger diameter of the circle and the surface area of individual pores. The primary compound entering the mineral composition of the shell in both species is CaCO3 however, the thrush egg shells contained more Mg in all layers except the crystalline layer, and S in the crystalline and palisade layers. The two species clearly differ in the size and distribution of pigment spots on the eggshell. We suppose that the differences in shell structure and pigmentation presented in this study may in the future provide a basis for explaining the reasons for the much lower reproductive efficiency of song thrush compared to blackbird.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Analysis of ultrastructure and microstructure of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshell by scanning electron microscopy and X-ray computed microtomography

Damaziak

Marzec

2022

Sci Rep

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“…As for the second assumption, a relationship between parental investment and eggshell coloration has been found through correlational [30,31] and experimental studies [9,13,14,32,33]. However, other studies failed to find such a relationship [18,[34][35][36][37][38]. These mixed results make necessary further experimental studies to explore such association, measuring parental investment during the incubation period.…”

Section: Introductionmentioning

confidence: 99%

Cosmetic coloration of cross-fostered eggs affects paternal investment in the hoopoe (Upupa epops)

et al. 2021

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The signalling hypothesis suggests that avian eggshell coloration is a sexually selected female signal advertising her quality to its male partner, thereby stimulating his provisioning rate. This hypothesis has been tested for structural eggshell pigments, but not for cosmetic colorations, such as that produced by the uropygial secretion on eggshells. During the breeding season, female hoopoes ( Upupa epops ) host in their uropygial glands symbiotic bacteria. Females actively smear the eggshells with their secretion, protecting embryos from pathogenic trans-shell infections and changing eggshell coloration. Because the colour of the secretions is related to their antimicrobial potential, cosmetic eggshell coloration may act as a cue or even as a post-mating sexually selected signal if it affects male provisioning rates. To experimentally test this hypothesis, we cross-fostered already-smeared clutches between hoopoe nests, and quantified male feeding behaviour to females before and after the experiment. This approach allows disentanglement of the effects of female quality and of egg coloration on male investment. In accordance with the hypothesis, males adjusted their provisioning rate to the eggshell cosmetic coloration. This is, to our knowledge, the first experimental demonstration that egg colour stained with uropygial secretion could act as a post-mating sexual signal of female quality to males.

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Biliverdin- and protoporphyrin-based eggshell pigmentation in relation to antioxidant supplementation, female characteristics and egg traits in the canary (Serinus canaria)

Hargitai

Boross

Nyíri

et al. 2016

Behav Ecol Sociobiol

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Eggshell spotting does not predict male incubation but marks thinner areas of a shorebird's shells

Cited by 24 publications

References 62 publications

Analysis of ultrastructure and microstructure of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshell by scanning electron microscopy and X-ray computed microtomography

Analysis of ultrastructure and microstructure of blackbird (Turdus merula) and song thrush (Turdus philomelos) eggshell by scanning electron microscopy and X-ray computed microtomography

Cosmetic coloration of cross-fostered eggs affects paternal investment in the hoopoe (Upupa epops)

Biliverdin- and protoporphyrin-based eggshell pigmentation in relation to antioxidant supplementation, female characteristics and egg traits in the canary (Serinus canaria)

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