scholarly journals Effect of Feathers as Nest Insulation on Incubation Behavior and Reproductive Performance of Tree Swallows (Tachycineta bicolor)

The Auk ◽  
1995 ◽  
Vol 112 (4) ◽  
pp. 973-981 ◽  
Author(s):  
Michael P. Lombardo
1988 ◽  
Vol 66 (4) ◽  
pp. 827-834 ◽  
Author(s):  
Bridget J. Stutchbury ◽  
Raleigh J. Robertson

In many species of birds, clutch size decreases as the season progresses, but this is confounded by the fact that young birds not only often have smaller clutches but also breed later than older females. We examined the effect of time of season on clutch size, hatching success, and fledging success of female tree swallows (Tachycineta bicolor) in their second year (SY) and after their second year (ASY), and compared their reproductive performance while controlling for time of season. For both SY and ASY females, clutch size decreased significantly with later first egg dates, which caused number hatched and number fledged per brood to also decline as the season progressed. However, neither the proportion of eggs hatched nor the proportion of young fledged was correlated with first egg date. The within-season decline in clutch size was not due simply to replacement clutches or female age, and we argue that it is also not due to a decrease in food abundance over the breeding season. Age-related differences in reproductive success depended on the time of season. Early in the breeding season, ASY females were superior to SY females in every measure of reproductive performance; however, there were no significant differences between age-classes late in the season. ASY females were more successful than SY females in raising clutches of five or six eggs, which were most common early in the season, but there was no difference between age-classes in raising clutches of four eggs. We suggest that an age-related difference in foraging efficiency and within-season changes in the cost of competition could explain this pattern.


2008 ◽  
Vol 86 (8) ◽  
pp. 843-850 ◽  
Author(s):  
Russell D. Dawson

Decreased reproductive success among birds breeding later in the season is a common pattern in temperate environments, although the underlying mechanisms remain unresolved. The quality hypothesis suggests that high-quality individuals can begin breeding earlier in the season than poorer quality parents, and are also able to invest more in reproduction. Alternatively, the date hypothesis suggests that reduced success among late birds is due to some correlate of date, such as decreased food abundance or offspring value. To test these hypotheses, I manipulated the date that tree swallows, Tachycineta bicolor (Vieillot, 1808), raised offspring by swapping clutches among nests so that birds were raising young either earlier or later than intended, and compared reproductive performance with control nests. My results showed that fledging success was related to the date hypothesis, with later birds being less successful in raising offspring than early breeding birds. Size and mass of offspring were not explained by either hypothesis, but rather by weather conditions experienced prior to measurements being taken. My results highlight the importance of events such as periods of inclement weather that can have significant impacts on offspring quality independently of both date of breeding and parental quality.


1991 ◽  
Vol 69 (10) ◽  
pp. 2540-2547 ◽  
Author(s):  
Nathaniel T. Wheelwright ◽  
Joanna Leary ◽  
Caragh Fitzgerald

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.


The Condor ◽  
2004 ◽  
Vol 106 (2) ◽  
pp. 423-429 ◽  
Author(s):  
Jean M. Mengelkoch ◽  
Gerald J. Niemi ◽  
Ronald R. Regal

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.


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