Sources of Variation in Egg Mass of Tree Swallows Tachycineta bicolor

Wiggins, David A.

doi:10.2307/3676812

Cited by 51 publications

(61 citation statements)

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“…Within clutches of tree swallows in my study, egg mass increased with laying order, which is in agreement with many previous studies of tree swallows (Zach 1982;Wiggins 1990;Ardia et al 2006;Bitton et al 2006; but see Whittingham et al 2007) and some other altricial species (Howe 1976;Ojanen 1983;Mead & Morton 1985;Hillstrom 1999;Saino et al 2004;Rosivall et al 2005;Liljesthrom et al 2012;Newbrey et al 2015). Like egg mass, yolk mass also increased with order of laying within clutches, as observed in previous studies of tree swallows (Ardia et al 2006), white-rumped swallows (Tachycineta leucorrhoa; Barrionuevo et al 2014), and red-winged blackbirds (Agelaius phoeniceus; Newbrey et al 2015), but in contrast to Chilean swallows (Tachycineta meyeni) for which size of yolk did not vary with laying order (Liljesthrom et al 2012).…”

Section: Egg and Yolk Masssupporting

confidence: 81%

“…I measured both total egg mass and egg yolk mass in relation to laying order in a population of tree swallows breeding near Prince George in north-central British Columbia (BC) to confirm the patterns of resource allocation to eggs that have previously been documented ( e.g., Zach 1982, Wiggins 1990, Ardia et al 2006, but see Whittingham et al 2007). I also tested how hatching asynchrony affects the relative performance of nestling tree swallows, specifically whether smaller, later-hatched nestlings are of inherent poor "quality" or if they may simply be unable to compensate for their initial disadvantage, in terms of competition for food or space within the nest, and whether their reduced performance relative to earlier-hatched nest mates is therefore a reflection of this persistent disadvantage.…”

Section: Introductionmentioning

confidence: 90%

“…Two related potential qualityindicating traits are egg mass and yolk mass. Both egg and yolk mass have been reported to increase with laying order (Zach 1982;Wiggins 1990;Ardia et al 2006;Bitton et al 2006;Newbrey et al 2015; but see Whittingham et al 2007), which indicates that female birds may allocate more egg components, such as albumen proteins and minerals and/or yolk lipids and carotenoids, to eggs they lay later in the laying order (Ardia et al 2006;Ferrari et al 2006; but see Newbrey et al 2015). One would expect that nestlings hatching from larger eggs laid later in the laying sequence would benefit from these extra resources and show improved performance, but experimental findings do not always support this expectation.…”

Section: What Influences Resource Allocation By Avian Parents?mentioning

confidence: 99%

“…Zach (1982) stated that tree swallows appear to use brood reduction to maximize their reproductive output, which lends support to the "broodreduction hypothesis". Based on similar studies of egg mass variation, however, Wiggins (1990) suggested that increasing egg mass as the laying sequence progressed might work to counter the size hierarchies resulting from hatching asynchrony (the "brood survival" strategy). Ardia et al (2006) found that, like total egg mass, yolk mass increases with the laying sequence in tree swallows, suggesting that hatching asynchrony is maladaptive and that females try to mitigate the detrimental effects of size hierarchies by allocating more reserves to later laid eggs.…”

Section: Introductionmentioning

confidence: 99%

“…Although the last-laid egg is generally heaviest in tree swallows, these eggs also tend to hatch last (Zach 1982, Wiggins 1990, Bitton et al 2006. First-laid eggs, in turn, tend to hatch first (Clotfelter et al 2000).…”

Section: Introductionmentioning

confidence: 99%

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Trade-offs in the early development of tree swallows (Tachycineta bicolor): offspring characteristics, offspring quality, and parental care

Unger¹

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Life-history theory predicts that because organisms have limited resources available to them, they must make decisions to prudently allocate resources in a way that maximizes fitness.Therefore, there is expected to be a trade-off between current reproductive effort and future survival and reproduction, with those individuals investing in a current breeding attempt doing so at a cost to their own survival and/or future fecundity. Altricial birds rearing young are consequently expected to be prudent in their allocation of resources between broodmaintenance and self-maintenance, and their allocation choices may be influenced by numerous offspring characteristics that potentially indicate offspring "quality" or condition.My thesis had three main goals: 1) to understand if the smallest nestling tree swallows in a nest are of inherent poor "quality", or if they are the smallest simply due to being outcompeted by their older and larger siblings; 2) to investigate whether, in an environment with parasites, it is the parents or their offspring who bear the costs associated with parasitism; and 3) to better understand the function of gape and flange colouration in nestling tree swallows. Overall, I wanted to understand how each of these nestling characteristics affect, and are affected by, parental life-history trade-offs. By pairing observational data with a cross-fostering experiment, I determined that both total egg mass and yolk mass increased with order of laying. N estlings that hatched earlier in the hatching sequence and were manipulated to be smaller within the size hierarchies in nests performed in a similar fashion as if they had retained their size advantage, but had lower immune responses, which may be because these earlier-hatched nestlings hatched from earlier-laid eggs with smaller yolks. By manipulating parasite levels in nests and then comparing nestling immune function and growth, and parental provisioning rates with control nests in a three-year study, I observed no 11 significant effects of larval blow flies parasitizing nestlings, except parasitized nestlings showed slightly lower haematocrit levels in one year. Deleterious effects of parasitism may have been compensated for by parents, as the parents of parasitized nestlings fed their young at marginally higher rates than the parents of parasite-free nestlings. By manipulating either gape redness or flange colouration (both within ultraviolet and human-visible wavelengths) of nestling tree swallows and carrying out feeding trials, I determined that parents did not preferentially feed nestlings with redder gapes. Instead, they fed nestlings with flanges that reflect in the ultraviolet more than nestlings with non-ultraviolet-reflective flanges, although only when nestlings were older. Parents also appeared to feed nestlings with blackened flanges less throughout the nestling period. Overall, my studies indicate that 1) tree swallows may allocate extra nutrients to later-laid eggs to alleviate detrimental effects of within-brood size hierarchi...

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Section: Egg and Yolk Masssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 90%

Section: What Influences Resource Allocation By Avian Parents?mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Trade-offs in the early development of tree swallows (Tachycineta bicolor): offspring characteristics, offspring quality, and parental care

Unger¹

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Reproductive ecology of tree swallows (Tachycineta bicolor) with high levels of polychlorinated biphenyl contamination

McCarty

Secord

1999

Enviro Toxic and Chemistry

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Abstract-Tree swallows (Tachycineta bicolor) breeding along the Hudson River forage extensively on PCB-contaminated insects that emerge from the river. We studied the reproductive ecology and behavior of tree swallows breeding at several sites along the Hudson River. Related work has shown that PCB levels in both eggs and chicks were among the highest ever reported in this species, with concentrations comparable to those found in aquatic organisms in the Hudson River. In 1994, reproductive success at PCB-contaminated sites was significantly impaired relative to other sites in New York. Reduced reproductive success was largely due to high levels of nest abandonment during incubation and reduced hatchability of eggs. In 1995, reproductive output was normal, but higher than expected rates of abandonment and supernormal clutches persisted. Growth and development of nestlings was not significantly impaired. Given the levels of contamination in this population, the success of most Hudson River tree swallows reinforces the importance of understanding interspecific differences in the effects of contaminants.

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Egg Mercury Concentration and Egg Size Varies with Position in the Laying Sequence in two Songbird Species

Hartman,

Ackerman,

Cooney

et al. 2024

Enviro Toxic and Chemistry

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In birds, mercury embryotoxicity can occur through the transfer of mercury from the female to her eggs. Maternal transfer of mercury can vary by egg position in the laying sequence, with first‐laid eggs often exhibiting greater mercury concentrations than subsequently laid eggs. We studied egg mercury concentration, mercury burden (total amount of mercury in the egg), and egg morphometrics by egg position in the laying sequence for two songbirds: tree swallows (Tachycineta bicolor) and house wrens (Troglodytes aedon). Egg mercury concentration in the second egg laid was 14% lower for tree swallows and 6% lower for house wrens in comparison with the first egg laid. These results indicate that in both species, after an initial relatively high transfer of mercury into the first egg laid, a smaller amount of mercury was transferred to the second egg laid. This lower mercury concentration persisted among all subsequently laid eggs (eggs three to eight) in tree swallows (all were 14%–16% lower than egg 1), but mercury concentrations in subsequently laid house wren eggs (eggs three to seven) returned to levels observed in the first egg laid (all were 1% lower to 3% greater than egg 1). Egg size increased with position in the laying sequence in both species; the predicted volume of egg 7 was 5% and 6% greater than that of egg 1 in tree swallows and house wrens, respectively. This change was caused by a significant increase in egg width, but not egg length, with position in the laying sequence. The percentage of decline in mercury concentration with position in the laying sequence was considerably lower in tree swallows and house wrens compared with other bird taxonomic groups, suggesting that there are key differences in the maternal transfer of mercury into songbird eggs compared with other birds. Finally, we performed simulations to evaluate how within‐clutch variation in egg mercury concentrations affected estimates of mean mercury concentrations in each clutch and the overall sampled population, which has direct implications for sampling designs. Environ Toxicol Chem 2024;00:1–11. Published 2024. This article is a U.S. Government work and is in the public domain in the USA.

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Sources of Variation in Egg Mass of Tree Swallows Tachycineta bicolor

Cited by 51 publications

References 0 publications

Trade-offs in the early development of tree swallows (Tachycineta bicolor): offspring characteristics, offspring quality, and parental care

Trade-offs in the early development of tree swallows (Tachycineta bicolor): offspring characteristics, offspring quality, and parental care

Reproductive ecology of tree swallows (Tachycineta bicolor) with high levels of polychlorinated biphenyl contamination

Egg Mercury Concentration and Egg Size Varies with Position in the Laying Sequence in two Songbird Species

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