Last but not the least: effects of laying sequence on egg color variation and embryonic development of Russet Sparrow (Passer cinnamomeus)

Abstract

Background: Laying sequence has important effects on eggshell color and embryonic development in birds. Some birds can allocate resources unevenly among the eggs within a clutch, prioritizing those at the beginning of the laying sequence, in order to maximize reproductive success. The changes in egg color according to laying sequence may be an adaptation to pressure from predators or brood parasites. Methods: In this study, effects of laying sequence on egg color and embryonic heart rate in Russet Sparrows (Passer cinnamomeus) were investigated using artificial nest boxes. The eggs were divided into three groups: first to be laid, intermediate in the laying sequence, and last to be laid. We maintained the eggs in an incubator and measured embryonic heart rates. Results: Avian visual modeling showed that the background color brightness of the last eggs laid was significantly higher (whiter) than those of the other eggs. All eggs were about the same size and hatched around 13 days, indicating that laying sequence significantly affected embryonic development speed; the last eggs to be laid developed significantly faster than did the first in the clutch. Conclusions: Our study quantified the effect of laying sequence on egg color variation and proved that laying sequence has an important effect on embryonic heart rate in Russet Sparrows.

Adaptive responses of the embryos of birds and reptiles to spatial and temporal variations in nest temperatures

“…R. Soc. B 286: 20192078 in some avian species, but the underlying driving forces for this phenomenon have yet to be elucidated [50,51].…”

Variation in Bird Eggs—Does Female Factor, Season, and Laying Order Impact the Egg Size, Pigmentation, and Eggshell Thickness of the Eggs of Capercaillie?

“…However, this depends on whether Cuckoos are absent or not [ 24 ]. While variation in Weaver eggshells has been described in the context of female identity, in the Russet sparrow ( Passer cinnamomeus ) it was proven that laying order has an important effect on eggshell pigmentation—their last laid eggs were significantly lighter [ 25 , 26 ]. Wendeln’s [ 27 ] research indicated that pigmentation may reflect female health and condition in Blue tits ( Cyanistes caeruleus ).…”

Nest site availability and niche differentiation between two cavity‐nesting birds in time and space

“…Despite similar nesting requirements, russet sparrows and green‐backed tits have different patterns of habitat occupation. Within the populations studied, all observable russet sparrows were found to be living and breeding in human settlements (Huo, Su, Niu, Yang, & Liang, ; Yang et al, ), while green‐backed tits were living from human settlements to forest areas, but their nests were rarely found in human settlements (Yang, Liang, & Møller, ). Competition for nesting sites of these two species should be under strong selection pressure because: (a) the nest site is an essential resource for avian reproduction that determines how many offspring or genes birds can transmit to the next generation; (b) green‐backed tit and russet sparrow are both secondary cavity‐nesting birds that cannot make, but can only occupy, existing cavities for breeding; (c) cavities are much more limited as a resource than other nest sites such as bushes or trees; and (d) unlike flexible resources such as food, competition for cavities is a typical example of interference competition in that cavities cannot be used by different pairs of birds at a time within most stages of the breeding cycle that last more than one month (i.e., stages including nest building, egg laying, egg incubation, and chick feeding).…”

“…Despite similar nesting requirements, russet sparrows and green-backed tits have different patterns of habitat occupation. Within the populations studied, all observable russet sparrows were found to be living and breeding in human settlements (Huo, Su, Niu, Yang, & Liang, 2018;Yang et al, 2012), while greenbacked tits were living from human settlements to forest areas, but their nests were rarely found in human settlements (Yang, Liang, & Møller, 2019). Competition for nesting sites of these two species should be under strong selection pressure because: (a) the nest site is an essential resource for avian reproduction that determines how many offspring or genes birds can transmit to the next generation;…”