scholarly journals Determinants of making success in female Tree Swallows (Tachycineta Bicolor)

Author(s):  
Lisha L. Berzins
Behaviour ◽  
2016 ◽  
Vol 153 (5) ◽  
pp. 525-550 ◽  
Author(s):  
Lisha L. Berzins ◽  
Russell D. Dawson

The differential allocation hypothesis posits that individuals should invest in the current reproductive attempt according to the attractiveness of their mate, but studies of allocation by males when female traits are manipulated to be more attractive are lacking. In the current study, we experimentally enhanced and reduced the plumage brightness of female tree swallows (Tachycineta bicolor) relative to controls to examine whether males adjust investment in parental care according to female attractiveness, while simultaneously performing a brood size manipulation. Contrary to our predictions, we found no evidence that males provisioned nestlings according to the plumage brightness of females. However, we found that nestling quality and fledging success were lowest when female plumage brightness was reduced and brood size was enlarged. This may be due to the plumage brightness treatment influencing agonistic interactions with other females, and may suggest that plumage brightness is a signal assessed by females.


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.


2018 ◽  
Vol 96 (6) ◽  
pp. 600-607 ◽  
Author(s):  
Lisha L. Berzins ◽  
Russell D. Dawson

That ornamental traits of females can act as signals of quality has gained empirical support, but whether and how such ornaments of females mediate social interactions with conspecifics remains less clear. Female Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) aggressively compete for and defend nest sites, and as such, nest site intrusions by conspecific females challenging ownership of a nest may prevent territory-owning females from dishonestly displaying ornamented plumage. We tested whether plumage brightness of female Tree Swallows influences nest site retention and reproductive success by experimentally enhancing or reducing their plumage brightness relative to controls prior to breeding. Females with reduced brightness were more likely to retain their nests sites and breed relative to control females and females with experimentally enhanced brightness. Females displaying enhanced brightness also tended to initiate clutches later than females with control and reduced brightness. Overall, lower nest site retention and reproductive success for females with enhanced brightness is consistent with social costs imposed on individuals dishonestly signalling high quality. Future studies in female birds should consider whether costs of losing a nest site to intruding conspecific females, especially in species where nest sites are limited, is a mechanism that maintains the honesty of signals of quality.


2020 ◽  
Vol 98 (1) ◽  
pp. 55-61
Author(s):  
Lisha L. Berzins ◽  
Russell D. Dawson

Recent empirical evidence suggests that ornamental traits displayed by female birds may reflect aspects of their quality, and function during competitive interactions and (or) social mate attraction; however, less is known about how such traits influence extra-pair paternity. In Tree Swallows (Tachycineta bicolor (Vieillot, 1808)), plumage brightness of females signals their quality and may be related to extra-pair paternity if it enables them to invade the territories of other females to seek extra-pair copulations and (or) if potential extra-pair mates perceive their plumage brightness as attractive. Therefore, to examine whether the plumage brightness displayed by females influence rates of extra-pair paternity and the number of sires per brood, we experimentally enhanced and reduced the plumage brightness of females relative to controls. Our results showed that plumage brightness treatment of the female did not influence the number of extra-pair offspring in nests or the likelihood of a brood containing extra-pair offspring. Additionally, the number of extra-pair males siring offspring within the broods of females did not differ by plumage brightness treatment. Although extra-pair paternity has been shown to be beneficial for female Tree Swallows, our results suggest that plumage brightness of females does not influence their ability to engage in extra-pair mating.


2007 ◽  
Vol 61 (11) ◽  
pp. 1725-1733 ◽  
Author(s):  
Mary K. Stapleton ◽  
Oddmund Kleven ◽  
Jan T. Lifjeld ◽  
Raleigh J. Robertson

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.


Sign in / Sign up

Export Citation Format

Share Document