Transgenerational effects of maternal immune challenge in tree swallows (Tachycineta bicolor)

2002 ◽  
Vol 80 (5) ◽  
pp. 918-925 ◽  
Author(s):  
G A Lozano ◽  
R C Ydenberg
Keyword(s):  
Egg Laying ◽  
Tachycineta Bicolor ◽  
Cell Mediated Immunity ◽  
Immune Challenge ◽  
Ecological Context ◽  
Allocation Of Resources ◽  
Tree Swallows ◽  
Immune Development ◽  
Nestling Growth ◽  
Better Than

The fact that avian eggs contain antibody of maternal origin is well documented, but only recently has this phenomenon been considered in an ecological context. We used tree swallows (Tachycineta bicolor) to examine the possibility of transgenerational immunity and its effect on nestling growth and immune development. We measured cell-mediated immunity with a delayed-hypersensitivity assay and antibody-mediated immunity with a hemagglutination test with sheep red blood cells (SRBCs). We tested for differences in immunocompetence and growth between nestlings from females who had been exposed to a novel antigen prior to egg laying and nestlings from unexposed females. To determine whether the effect, if any, resulted from something transferred to the eggs prior to egg laying or from subsequent changes in parental behaviour, nestlings were exchanged so that at each nest half the nestlings were from females who had been injected with SRBCs and half were from females who had not been exposed to SRBCs. Finally, brood sizes were independently manipulated to either 4 or 6 nestlings. We failed to detect maternal antibodies in any nestlings, and whether a female was exposed to SRBCs or not had no effect on the growth or cell-mediated immunity of her brood. However, nestlings in smaller broods grew better than nestlings in larger broods, though we did not find the expected differences in cell-mediated immunity. Furthermore, within each nest, nestlings whose mothers had been exposed to SRBCs grew better than nestlings whose mothers had not been exposed. These results are contrary to the idea of a simple trade-off in the allocation of resources between parasite protection and reproduction; however, they support the idea that exposure of females to parasites prior to egg laying leads to better nestling growth, and are congruous with the possibility of mithridatic parental care.

scholarly journals The stress of parenthood? Increased glucocorticoids in birds with experimentally enlarged broods

2011 ◽  
Vol 7 (6) ◽  
pp. 944-946 ◽  
Author(s):  
Frances Bonier ◽  
Ignacio T. Moore ◽  
Raleigh J. Robertson
Keyword(s):  
Positive Relationship ◽  
Reproductive Effort ◽  
Reproductive Investment ◽  
Tachycineta Bicolor ◽  
Relative Fitness ◽  
Allocation Of Resources ◽  
Tree Swallows ◽  
Parental Behaviour ◽  
Poor Condition ◽  
Before And After

Variation in baseline glucocorticoid (cort) levels can be attributed, at least in part, to differences in energetic demands confronting individuals. Elevated baseline cort levels are routinely interpreted as indicating individuals in poor condition, with low relative fitness. However, when greater reproductive effort increases energetic demands, individuals with high cort might paradoxically be those with the highest fitness. Here, we experimentally test the hypothesis that increased reproductive demand causes increases in baseline cort (the Cort-Adaptation hypothesis). We measured maternal baseline cort before and after experimentally enlarging and reducing brood sizes in tree swallows ( Tachycineta bicolor ). Females with experimentally enlarged broods had greater increases in baseline cort and fledged more offspring than females with reduced broods. Additionally, females with greater increases in baseline cort had higher offspring-provisioning rates than females with lower changes in cort. These findings demonstrate that increased reproductive demand can cause increased baseline cort. As yet, we do not know if these increases in cort cause increased allocation of resources towards reproduction, but the positive relationship between parental behaviour and cort suggests that increased cort does not always interfere with reproductive investment, and might instead facilitate it.

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

The Auk ◽  
2005 ◽  
Vol 122 (4) ◽  
pp. 1225-1238 ◽  
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

Tree Swallow (Tachycineta bicolor) nest success and nestling growth near oil sands mining operations in northeastern Alberta, Canada

2019 ◽  
Vol 97 (6) ◽  
pp. 547-557 ◽  
Author(s):  
Christine M. Godwin ◽  
Robert M.R. Barclay ◽  
Judit E.G. Smits
Keyword(s):  
Reproductive Success ◽  
Oil Sands ◽  
Industrial Development ◽  
Nest Success ◽  
Tachycineta Bicolor ◽  
Tree Swallows ◽  
Reference Sites ◽  
Mining Operations ◽  
Contaminant Exposure ◽  
Nestling Growth

Industrial development and contaminant exposure may affect reproductive success and food quality for birds. Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) nesting near oil sands development in northern Alberta (Canada) potentially experience elevated environmental stressors that could influence reproduction. We measured reproductive and growth endpoints in Tree Swallows, predicting reduced reproductive success and nestling growth near oil sands operations compared with reference sites. We also identified the invertebrate prey in the stomach contents of nestlings to understand variability in the diet and its potential effect on growth and survival of nestlings. From 2012 to 2015, clutch initiation varied among years but was not influenced by proximity to oil sands operations. Hatching and fledging success decreased in response to increased precipitation, regardless of location. Measurements of nestling growth reflected the variation associated with nestling sex and possibly asynchronous hatching. The composition of the nestling diet was significantly different; birds near oil sands development consumed Odonata, whereas birds at reference sites consumed Ephemeroptera. Nestlings from all sites consumed relatively high quantities of terrestrial insects. Our results demonstrate that factors such as weather conditions, diet, hatching order, and nestling sex are important when interpreting the potential effects of oil sands development on nest success and nestling growth.

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

The Condor ◽  
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.

The costs of reproduction in tree swallows (Tachycineta bicolor)

1991 ◽  
Vol 69 (10) ◽  
pp. 2540-2547 ◽  
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.

scholarly journals Growth of Nestling Thick-billed Murres (Uria lomvia) in Relation toParental Experience and Hatching Date

The Auk ◽  
2002 ◽  
Vol 119 (3) ◽  
pp. 827-832 ◽  
Author(s):  
J. Mark Hipfner ◽  
Anthony J. Gaston
Keyword(s):  
Extended Period ◽  
Egg Laying ◽  
Avian Species ◽  
Parental Age ◽  
Hatching Date ◽  
Direct Effects ◽  
Breeding Performance ◽  
Uria Lomvia ◽  
Nestling Growth ◽  
Parental Experience

Abstract In many avian species, reproductive success increases with parental age and experience, and declines seasonally. However, it is difficult to evaluate how parental attributes affect reproduction independently of date effects, because young, inexperienced pairs generally lay later than older, experienced pairs. We examined how parental experience and timing affected nestling growth in the Thick-billed Murre (Uria lomvia), an Arctic seabird that lays a single-egg clutch, by taking advantage of a natural contrast made possible by marked within-group synchrony. That is a common feature at murre colonies, and enabled us to monitor the breeding performance of experienced pairs over an extended period that overlapped with breeding by inexperienced pairs late in the season. Whereas growth of offspring raised by experienced parents was unaffected by their hatching date, offspring raised by inexperienced parents grew more slowly than those raised concurrently by experienced parents. Therefore, parental experience influenced nestling growth rates whereas timing did not, a result that accords with previous studies on this species. Absence of direct effects of timing of egg-laying on breeding success of Thick-billed Murres stands in sharp contrast to many other avian species, and seems surprising for an Arctic-nesting species often assumed to be strictly time-constrained in its breeding.

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