Warm temperatures lead to early onset of incubation, shorter incubation periods and greater hatching asynchrony in tree swallows Tachycineta bicolor at the extremes of their range

Rates of growth and size of nestlings at fledging have important consequences for future survival and reproductive success in many passerine birds. Within broods of altricial species, these characteristics are often influenced by size hierarchies established early in the nesting period due to hatching asynchrony and within-clutch variation in egg mass, but the concurrent effect of these factors is poorly understood. We investigated the relative influence of these variables on nestling performance within broods of tree swallows, Tachycineta bicolor (Vieillot, 1808). Nestlings that hatched earlier within nests were heavier and larger than their later-hatched siblings at 4 days of age. Similarly, earlier-hatched nestlings grew their ninth primary flight feathers faster and had longer ninth primaries just prior to fledging than did later-hatched siblings. Differences in egg mass of siblings also contributed to mass and size hierarchies at 4 days of age, but did not affect any other difference in sibling performance. We conclude that within-clutch variation in performance of offspring is determined primarily by size hierarchies resulting from asynchronous hatching. Intraclutch egg-mass variation appears to have little effect on performance of siblings and may be best explained by proximate constraints on females.

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Effects of Food Abundance, Weather, and Female Condition on Reproduction in Tree Swallows (Tachycineta Bicolor)

The Auk ◽

10.1093/auk/122.4.1225 ◽

2005 ◽

Vol 122 (4) ◽

pp. 1225-1238 ◽

Cited By ~ 5

Author(s):

Jacqueline K. Nooker ◽

Peter O. Dunn ◽

Linda A. Whittingham

Keyword(s):

Body Condition ◽

Egg Laying ◽

Food Abundance ◽

Tachycineta Bicolor ◽

Laying Date ◽

Foraging Efficiency ◽

Tree Swallows ◽

Female Condition ◽

Incubation Periods ◽

Feather Clipping

AbstractFood abundance, weather, and female body condition are believed to influence the timing of breeding and reproductive performance of birds. We simultaneously studied the effects of weather and food abundance on reproduction in Tree Swallows (Tachycineta bicolor) while experimentally reducing female condition and foraging efficiency by clipping some flight feathers prior to egg laying. Control females laid larger clutches earlier in the season, had longer incubation periods, and raised heavier nestlings than experimental females. Fledging success did not differ after controlling for laying date and brood size. Greater insect abundance was associated with laying earlier in the season, heavier eggs, and shorter incubation periods. Most likely, feather-clipping affected clutch size through reduced foraging efficiency, which delayed the date of laying, rather than through loss of body condition. This outcome is consistent with the idea that Tree Swallows are “income” breeders that base their timing of reproduction on short-term rates of food intake near the time of breeding. Contrary to studies of other species, Tree Swallows do not appear to time their laying so that hatching will coincide with seasonal peaks in food supply. Rather, they appear to breed when temperature and food abundance are sufficient to allow females of a given body condition to initiate egg laying.Efectos de la Abundancia de Alimento, del Clima y de la Condición de las Hembras sobre la Reproducción en Tachycineta bicolor

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Benefits of an anti-parasite treatment are influenced by within-brood size variation in Tree Swallows (Tachycineta bicolor)

The Auk ◽

10.1093/auk/ukz078 ◽

2020 ◽

Vol 137 (2) ◽

Cited By ~ 1

Author(s):

Ilsa A Griebel ◽

Russell D Dawson

Keyword(s):

Brood Size ◽

Herd Immunity ◽

Relative Size ◽

Size Variation ◽

Underlying Mechanism ◽

Tachycineta Bicolor ◽

Hatching Asynchrony ◽

Control Group ◽

Tree Swallows ◽

Size Hierarchy

Abstract In all animals, susceptibility to parasites can differ among individuals. Young, nest-bound birds are exposed to a diversity of nest-dwelling ectoparasites that typically feed on their blood. Within broods, hatching asynchrony creates size hierarchies that result in morphological and physiological variation among nest mates, and susceptibility to parasites also may vary predictably with this size hierarchy. Our objective was to use a broad-spectrum, anti-parasite drug, ivermectin (IVM), to treat individual nestling Tree Swallows (Tachycineta bicolor) and assess how nestling susceptibility to parasites varied both within and among broods. Broods were either assigned to an IVM group, where half of the nestlings in a brood received IVM injections and half received control injections of pure sesame oil, or to a control group, where all nestlings received oil injections. We found that the IVM treatment reduced parasite loads for broods as a whole, thereby benefiting all nestlings in IVM broods and suggesting our treatment resulted in herd immunity. Specifically, nestlings from IVM broods had higher hemoglobin concentrations, regardless of whether they received injections with IVM or oil, and greater fledging success, than nestlings from control broods. On the contrary, IVM treatment did not strongly affect nestling morphology, with only marginal effects on the growth rate of ninth primary feathers, and the effects of the treatment on 2 other morphological traits depending on temporal factors. Variation in size within broods, however, influenced the chance of an individual fledging, which increased with relative size within a brood, but only under lower parasite loads (i.e. IVM broods). By experimentally manipulating nestling susceptibility to parasites, we have demonstrated variation in nestling response to an anti-parasite treatment both within and among broods, and future studies should investigate the underlying mechanism for why certain nestlings along the brood size hierarchy are more susceptible to parasites.

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Laying order, hatching asynchrony and nestling body mass in Tree Swallows Tachycineta bicolor

Journal of Avian Biology ◽

10.1034/j.1600-048x.2000.310308.x ◽

2000 ◽

Vol 31 (3) ◽

pp. 329-334 ◽

Cited By ~ 32

Author(s):

Ethan D. Clotfelter ◽

Linda A. Whittingham ◽

Peter O. Dunn

Keyword(s):

Body Mass ◽

Tachycineta Bicolor ◽

Hatching Asynchrony ◽

Tree Swallows ◽

Laying Order

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Individual, Temporal, and Seasonal Variation in Sperm Concentration in Tree Swallows

The Condor ◽

10.1093/condor/104.4.803 ◽

2002 ◽

Vol 104 (4) ◽

pp. 803-810

Author(s):

Michael P. Lombardo ◽

Armetris N. Forman ◽

Matthew R. Czarnowski ◽

Patrick A. Thorpe

Keyword(s):

Sperm Concentration ◽

Egg Laying ◽

Tachycineta Bicolor ◽

Tree Swallows ◽

Sperm Production ◽

Period 2 ◽

Incubation Periods ◽

Nestling Period ◽

Sperm Depletion ◽

Fertility Insurance

Abstract We determined sperm concentrations in Tree Swallows (Tachycineta bicolor) by manually expressing semen samples from males during prelaying, egg-laying, incubation, and nestling periods. Sperm concentrations varied by orders of magnitude (0–109 sperm mL−1) among males. Sperm concentrations were highest during the incubation period and lowest during the prelaying period. None of the samples collected during the prelaying, egg-laying, and incubation periods were devoid of sperm. In contrast, 45% of samples collected during the nestling period lacked sperm. Sperm concentrations (1) did not vary over the course of the morning during prelaying, egg-laying, and incubation periods but significantly increased during the nestling period; (2) did not vary with the date that samples were collected during prelaying, egg laying, and incubation but significantly decreased with date during the nestling period; and (3) did not vary with the number of fertile females at the study site during any part of the breeding season. We hypothesize that the variations in sperm concentration arose from a combination of factors including intrinsic differences among males, daily patterns of sperm depletion associated with copulation, and an end-of-season decline in sperm production. If males vary in sperm availability then female Tree Swallows may benefit from pursuing extra-pair copulations as fertility insurance. Variación Individual, Temporal y Estacional en la Concentración de Esperma en Tachycineta bicolor Resumen. Determinamos la concentración de esperma en Tachycineta bicolor tomando manualmente muestras de semen de machos durante los periodos de pre-puesta, puesta de huevos, incubación y con pichones. La concentración de esperma varió en órdenes de magnitud (0–109 esperma por mL) entre machos. Las concentraciones de esperma fueron mayores durante el periodo de incubación y menores durante el periodo de pre-puesta. Todas las muestras colectadas durante los periodos de pre-puesta, puesta e incubación contuvieron esperma. En contraste, el 45% de las muestras colectadas durante el período con pichones no contuvieron esperma. Las concentraciones de esperma (1) no variaron durante el curso de la mañana en los periodos de pre-puesta, puesta e incubación, pero aumentaron significativamente durante el periodo con pichones; (2) no variaron con la fecha en la que las muestras fueron colectadas durante los periodos de pre-puesta, puesta e incubación, pero disminuyeron significativamente con la fecha durante el periodo con pichones; y (3) no variaron durante toda la estación reproductiva con el número de hembras fértiles en el sitio de estudio. Hipotetizamos que esta variación en la concentración de esperma se originó de una combinación de factores incluyendo diferencias intrínsecas entre machos, patrones diarios de vaciamiento de esperma asociados con la cópula, y una disminución al final de la estación en la producción de esperma. Si los machos varían en la disponibilidad de esperma, entonces las hembras de T. bicolor se beneficiarían de obtener copulaciones extra-pareja para asegurar la fertilidad.

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Begging calls and parental feeding decisions in tree swallows ( Tachycineta bicolor )

Behavioral Ecology and Sociobiology ◽

10.1007/s002650000290 ◽

2001 ◽

Vol 49 (2-3) ◽

pp. 170-175 ◽

Cited By ~ 75

Author(s):

M. L. Leonard ◽

Andrew G. Horn

Keyword(s):

Tachycineta Bicolor ◽

Tree Swallows ◽

Parental Feeding

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The costs of reproduction in tree swallows (Tachycineta bicolor)

Canadian Journal of Zoology ◽

10.1139/z91-358 ◽

1991 ◽

Vol 69 (10) ◽

pp. 2540-2547 ◽

Cited By ~ 42

Author(s):

Nathaniel T. Wheelwright ◽

Joanna Leary ◽

Caragh Fitzgerald

Keyword(s):

Life History ◽

Clutch Size ◽

Brood Size ◽

Life History Theory ◽

Tachycineta Bicolor ◽

Laying Date ◽

Tree Swallows ◽

Costs Of Reproduction ◽

Return Rates ◽

Trade Offs

We investigated the effect of brood size on nestling growth and survival, parental survival, and future fecundity in tree swallows (Tachycineta bicolor) over a 4-year period (1987–1990) in an effort to understand whether reproductive trade-offs limit clutch size in birds. In addition to examining naturally varying brood sizes in a population on Kent Island, New Brunswick, Canada, we experimentally modified brood sizes, increasing or decreasing the reproductive burdens of females by two offspring. Unlike previous studies, broods of the same females were enlarged or reduced in up to 3 successive years in a search for evidence of cumulative costs of reproduction that might go undetected by a single brood manipulation. Neither observation nor experiment supported the existence of a trade-off between offspring quality and quantity, in contrast with the predictions of life-history theory. Nestling wing length, mass, and tarsus length were unrelated to brood size. Although differences between means were in the direction predicted, few differences were statistically significant, despite large sample sizes. Nestlings from small broods were no more likely to return as breeding adults than nestlings from large broods, but return rates of both groups were very low. Parental return rates were also independent of brood size, and there was no evidence of a negative effect of brood size on future fecundity (laying date, clutch size). Reproductive success, nestling size, and survival did not differ between treatments for females whose broods were manipulated in successive years. Within the range of brood sizes observed in this study, the life-history costs of feeding one or two additional nestlings in tree swallows appear to be slight and cannot explain observed clutch sizes. Costs not measured in this study, such as the production of eggs or postfledging parental care, may be more important in limiting clutch size in birds.

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