scholarly journals Plumage characteristics in tree swallows Tachycineta bicolor: Honest signals of condition, reproductive investment and mating strategies.

2008 ◽  
Author(s):  
Pierre-Paul Bitton
Keyword(s):  
Reproductive Investment ◽  
Mating Strategies ◽  
Tachycineta Bicolor ◽  
Tree Swallows ◽  
Honest Signals

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.

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 Diet of the Nestling Tree Swallow

The Condor ◽  
2004 ◽  
Vol 106 (2) ◽  
pp. 423-429 ◽  
Author(s):  
Jean M. Mengelkoch ◽  
Gerald J. Niemi ◽  
Ronald R. Regal
Keyword(s):  
Open Water ◽  
Time Of Day ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Larval Stages ◽  
Terrestrial Origin ◽  
The Mean ◽  
Foraging Radius

Abstract Dietary samples from nestling Tree Swallows (Tachycineta bicolor) in northwestern Minnesota were compared to invertebrate availability as measured by aerial tow nets. The majority of the biomass in the nestlings' diet was adult insects with larval stages of aquatic origin, while absolute numbers of insects of both aquatic and terrestrial origin were similar. Orders of invertebrates in the diet and available were similar in number but not in biomass. Diet showed little variation by time of day, date of sampling or the age of the nestling. The mean number of odonates in the nestling Tree Swallows' diet increased exponentially as the percentage of open water and open water + cattail marsh increased within a 400-m foraging radius. Dieta de los Pichones de Tachycineta bicolor Resumen. Se compararon muestras dietarias de pichones de la golondrina Tachycineta bicolor tomadas en el noroeste de Minnesota con la disponibilidad de invertebrados medida con redes aéreas. La mayor parte de la biomasa en la dieta de los pichones correspondió a insectos adultos con estadíos larvales de origen acuá tico, mientras que los números absolutos de insectos de origen acuático y no acuático fueron similares. Los órdenes de invertebrados presentes en la dieta y disponibles en el ambiente fueron similares en números pero no en biomasa. La dieta mostró poca variación entre horas del día, fechas de muestreo o edad de los pichones. El número promedio de odonatos en la dieta de los pichones de T. bicolor aumentó exponencialmente a medida que se incrementó el porcentaje de agua abierta y de agua abierta + pantanos de espadañas dentro de un radio de forrajeo de 400 m.

BIOACCUMULATION AND TROPHIC TRANSFER OF POLYCHLORINATED BIPHENYLS BY AQUATIC AND TERRESTRIAL INSECTS TO TREE SWALLOWS (TACHYCINETA BICOLOR)

2006 ◽  
Vol 25 (4) ◽  
pp. 1017 ◽  
Author(s):  
Jonathan D. Maul ◽  
Jason B. Belden ◽  
Becky A. Schwab ◽  
Matt R. Whiles ◽  
Brian Spears ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Trophic Transfer ◽  
Tachycineta Bicolor ◽  
Tree Swallows ◽  
Terrestrial Insects
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