Local breeding experience and the reproductive performance of Tree Swallows (original) (raw)
Related papers
Effects of breeding density, synchrony, and experience on extrapair paternity in tree swallows
Behavioral Ecology, 1994
Effects of breeding density, synchrony, and experience on extrapair paternity in tree swallows Breeding density, synchrony, and experience are expected to influence the frequency of extrapair paternity in birds. Using DNA fingerprinting, we examined the effect of these factors on tree swallows nesting at relatively high (grids of nest-boxes) and low (solitary boxes at least 100 m from the nearest neighbor) densities and in relatively synchronous (Alberta) and asynchronous (Ontario) populations in Canada. The mean percentage of extrapair offspring per nest did not differ significantly between birds nesting in grids (43%, n = 22 families) and solitary boxes (57%, n = 12 families). Similarly, there was no significant difference in the mean percentage of extrapair offspring per nest between relatively synchronous (60%, n = 12 Alberta families) and asynchronous (41%, n = 22 Ontario families) populations. We also found no consistent pattern between extrapair paternity and breeding experience among seven males and seven females examined over two to three breeding seasons. Female tree swallows can influence the fertilization success of extrapair males by active selection and rejection of copulation partners. We suggest that this ability limits the predicted effect of various ecological factors on the frequency of extrapair paternity.
The Auk, 2004
Oћђ ќѓ ѡѕђ most fundamental discoveries in behavioral ecology has been the importance of variation in individual quality. From sexual selection (Andersson 1994) to foraging (Grant and Grant 2002) and life histories (Kruuk et al. 2002), phenotypic variation can have important eff ects on fi tness of individuals and those with which they interact. For example, in lifehistory studies, ecologists have oĞ en observed that individuals that produce more off spring also survive at a higher rate (Smith 1981, Verhulst and Tinbergen 1991). Instead of questioning the existence of fundamental trade-off s in life-history allocation, most researchers have aĴ ributed those positive correlations to nonheritable phenotypic quality variations that overwhelm underlying genetic trade-off s (Partridge and Harvey 1985). If those individual quality diff erences are AяѠѡџюѐѡ.-In many avian species, including Tree Swallows (Tachycineta bicolor), females that lay eggs earlier in the season have higher fi tness. It has been hypothesized that nonheritable variation in individual quality could explain how variation in laying date persists in the face of this apparently directional selection. Previous experimental work on Tree Swallows has suggested that natural variation in fl ight ability enables early-laying females to aĴ ain feeding rates high enough to support egg production on earlier, sparser food than later-laying females. We tested that hypothesis with standardized fl ights through a 9.75-m fl ight-performance test tunnel. One group of female swallows was tested at the height of the breeding season on 28 May regardless of their nesting phenology; another group was tested on the 11th day of incubation. Average acceleration in the tunnel was negatively correlated with clutch initiation date for the females tested on 28 May. Daily variation in ambient environmental conditions had strong eff ects on swallow fl ight performance in the tunnel, and no relationship was observed in the day-11 birds. Because natural variation in foraging performance is correlated with variation in female Tree Swallows' clutch initiation dates, fl ight ability appears to be a key element of individual quality in this species.
Journal of Animal Ecology, 2001
1We describe age-related reproductive performance and recapture rates of tree swallows (Tachycineta bicolor Vieillot) based on a 25-year study of a nestbox population in south-eastern Ontario, Canada (1975–99).2Performance improved from first-time breeders to intermediate-aged birds. Nest initiation advanced, and clutch size increased in both sexes. In females the number of hatchlings and fledglings increased, and the proportion of nests failing completely declined. Performance declined in females after ‘middle-age’, in the number of young fledged, and the proportion of young fledged relative to initial clutch and brood size. Also, the proportion of nests that failed completely increased in the oldest birds. Males showed similar patterns.3An index of performance incorporating clutch size, hatching and fledging efficiency, and two measures of total nest failure increased to, then declined after, 4 years of age in females and 3 years in males. The relationship between this index and age was best predicted by quadratic regression.4We found no support for three of four hypotheses to explain improvement in performance with age. Recapture rates declined after age 4Y in males, but remained unchanged in females until age 7Y +, while output decreased in both sexes (Residual Reproductive Value). Birds breeding repeatedly did not perform better during their first attempt compared to birds that bred only once (Selection). Birds with varied breeding experience did not differ in their performance within age-groups (Breeding Experience). We did find support for the Breeding Age hypothesis; in females with no breeding experience, there was a successive advance in laying and increase in clutch size from 2 to 4 years of age.5Improved performance may be due to skills acquired with age, such as those devoted to feeding and balancing energy demands, which are necessary to prepare and maintain individual condition prior to, and during, breeding. Senescence in performance after ‘middle-age’ may result from accumulated costs of previous breeding effort which have been identified in this species based on research elsewhere.We describe age-related reproductive performance and recapture rates of tree swallows (Tachycineta bicolor Vieillot) based on a 25-year study of a nestbox population in south-eastern Ontario, Canada (1975–99).Performance improved from first-time breeders to intermediate-aged birds. Nest initiation advanced, and clutch size increased in both sexes. In females the number of hatchlings and fledglings increased, and the proportion of nests failing completely declined. Performance declined in females after ‘middle-age’, in the number of young fledged, and the proportion of young fledged relative to initial clutch and brood size. Also, the proportion of nests that failed completely increased in the oldest birds. Males showed similar patterns.An index of performance incorporating clutch size, hatching and fledging efficiency, and two measures of total nest failure increased to, then declined after, 4 years of age in females and 3 years in males. The relationship between this index and age was best predicted by quadratic regression.We found no support for three of four hypotheses to explain improvement in performance with age. Recapture rates declined after age 4Y in males, but remained unchanged in females until age 7Y +, while output decreased in both sexes (Residual Reproductive Value). Birds breeding repeatedly did not perform better during their first attempt compared to birds that bred only once (Selection). Birds with varied breeding experience did not differ in their performance within age-groups (Breeding Experience). We did find support for the Breeding Age hypothesis; in females with no breeding experience, there was a successive advance in laying and increase in clutch size from 2 to 4 years of age.Improved performance may be due to skills acquired with age, such as those devoted to feeding and balancing energy demands, which are necessary to prepare and maintain individual condition prior to, and during, breeding. Senescence in performance after ‘middle-age’ may result from accumulated costs of previous breeding effort which have been identified in this species based on research elsewhere.
Phenotypic plasticity in response to breeding density in tree swallows: An adaptive maternal effect?
Hormones and Behavior
Territorial animals breeding in high-density environments are more likely to engage in aggressive competition with conspecifics for resources necessary for reproduction. In many avian species, increased competition among breeding females results in increased testosterone concentrations in egg yolks. Generally, elevated yolk testosterone increases nestling growth, competitive behaviors, and bold behavioral traits. However, few studies provide an environmental context with which to examine the potential adaptive benefits of these phenotypic changes. In this study, tree swallow (Tachycineta bicolor) breeding density was altered to modify levels of social competition and yolk testosterone. We measured nestling growth, competitive ability, and breathing rate in response to a stressor using a partial cross-foster design. Females breeding at high-density experienced more aggressive, competitive interactions and their eggs had higher testosterone concentrations. Nestlings that hatched in hi...
Animal Behaviour, 2007
In socially monogamous passerines, extrapair paternity can increase the variance in male reproductive success. If gaining extrapair fertilizations is linked to specific secondary sexual ornaments, the opportunity for sexual selection is enhanced. Therefore, to understand the evolution of male phenotypic characteristics, it is important to identify traits that predict male extrapair mating success. Tree swallows show among the highest rates of extrapair paternity known to occur in birds, yet it is unclear whether male extrapair mating success is associated with phenotypic traits that honestly advertise individual quality. We compared morphological characteristics and plumage coloration of male tree swallows that sired extrapair offspring with those that sired only within-pair offspring in the same breeding population to identify the characteristics that predict extrapair fertilization success. Males who produced extrapair offspring had brighter plumage, and were more likely to be returning breeders, than males that did not have extrapair young. In paired comparisons, however, there was no difference between extrapair males and the male they cuckolded. These results suggest that female tree swallows may prefer brighter or older individuals as extrapair mates, but also, that older males may invest more energy in pursuing extrapair copulations. Furthermore, since females had extrapair offspring in their nest regardless of their social mate's morphometric or plumage attributes, we suggest that extrapair mating may be a reproductive strategy allowing females to increase the genetic diversity, while maintaining genetic quality, of their offspring.
The high frequency of extra-pair paternity in tree swallows is not an artifact of nestboxes
Behavioral Ecology and Sociobiology, 1996
A common criticism of nestbox studies is one of creating artificial nesting conditions and breeding behavior different from what would be seen under natural conditions. We assessed the frequency of extrapair paternity (percentage of broods with at least one extra-pair young) in 25 families of tree swallows (Tachycineta bicolor) nesting in natural cavities and compared it to that in a nestbox population. We found that 84% of females nesting in natural cavities obtained fertilizations from extra-pair males. These extra-pair males fathered 69 % of all nestlings. Studies of tree swallows breeding in nestboxes have shown that 50-87 % of broods contained extra-pair young, with extra-pair males fathering 38 -53 % of all the young. In broods with extra-pair paternity, natural cavities contained a significantly greater proportion of extra-pair young than did nestboxes. Despite differences in nesting habitat and female age structure, the frequency of extrapair paternity did not differ significantly between the natural-cavity and nestbox populations. Therefore, the presence of extra-pair paternity in tree swallows is not an artifact of nestboxes or of artificial nesting conditions.
Journal of Animal Ecology, 2000
1. One way that animals may select breeding sites is by assessing the reproductive success of conspeci®cs in one season and settling the next year in those habitat patches where success collectively had been greatest. This sort of habitat assessment may promote the formation of colonies at high quality sites. 2. We examined whether cli swallows, Petrochelidon pyrrhonota, in southwestern Nebraska used conspeci®c breeding performance to choose colony sites. 3. Reproductive success at colony sites varied spatially within seasons and between seasons, and was autocorrelated at a site from one year to the next, but not over longer time intervals. Cli swallows thus met the conditions for potential use of information on conspeci®c breeding performance. 4. Among sites re-used in consecutive years, those with highest collective success in one season showed the greatest rates in colony growth the next season, including the greatest in¯ux of immigrants. 5. The probability of colony-site re-use in successive years increased with collective reproductive success and average breeder body mass (a measure of individual condition) the previous season. 6. Cli swallows probably use conspeci®c breeding performance in selecting colonies. This mechanism is one component of habitat selection that also includes attraction to conspeci®cs and assessment of an individual's own success.
Experimental mate replacement does not increase extra-pair paternity in tree swallows
Proceedings of the Royal Society B: Biological Sciences, 1998
Before the onset of female fertility, we removed 12 early-settling male tree swallows (Tachycineta bicolor) from their nest-boxes and mates, and allowed replacement males which had been £oaters to settle with the original female residents. We predicted that females which had their original mate choice altered (experimentals) would be more likely to obtain extra-pair fertilizations than females which remained paired with their original, early-settling mates (controls). The proportion of females obtaining extra-pair fertilizations, however, did not di¡er between controls and experimentals, indicating that mating tactics of female tree swallows were una¡ected by mate replacement. However, di¡erences between early-settling and replacement males did exist. Replacement males had shorter wing chords than early-settling males, suggesting that they were younger. Moreover, a signi¢cantly greater proportion of replacement males than early-settling males were unringed and thus new to the study site. Our results suggest that if females are choosing males for good genes, then early-settling males are not superior in genetic quality to the smaller replacement males which had originally been £oaters.
Survival of extrapair and within-pair young in tree swallows
Behavioral Ecology, 2001
In monogamous species, it is generally accepted that males seek extrapair matings to increase their reproductive success without additional parental investment; however, the benefits of extrapair matings to females are much less clear. One possibility is that females obtain genes for enhanced offspring viability from the extrapair sires. If this is the case, then the increased viability of extrapair young may be evident throughout the period of embryonic development as well as later in life. Tree swallows (Tachycineta bicolor) have one of the highest known levels of extrapair mating in birds, and females have substantial control over the paternity of their offspring. We used molecular techniques to determine the parentage of nestlings and unhatched embryos to examine the possibility that female tree swallows gain viability benefits for their extrapair offspring. Although both extrapair paternity and mortality of embryos and nestlings were high (89% and 54% of broods respectively), we found no difference in the viability of within-pair and extrapair young prior to fledging. In addition, extrapair young were not more likely to be male. There was no bias in the sex of young at fledging, but unhatched embryos were more likely to be male. Our results do not support the idea that female tree swallows engage in extrapair mating to increase offspring viability, at least early in life.
2008
In altricial birds, parental care after fledging should be terminated as soon as the benefits from deserting the young outweigh those from continuing parental care. In seasonal environments, multiple breeders may trade off fitness benefits of the time invested in the care of fledglings of one brood against the benefits of an advanced start of the subsequent clutch. Using radiotelemetry of 494 fledglings in 114 families (of 88 pairs) of the double-brooded barn swallow, Hirundo rustica, we found that, irrespective of the offspring quality, the duration of postfledging parental care was shorter for first broods than for single and second broods. A shorter duration of postfledging care was associated with a steeper decline in feeding rates after fledging. Postfledging parental care also depended on the pair's breeding season length and on the phenotypic quality of the female parent. We suggest that pairs that start other reproductive bouts in the same season and pairs with high chances of survival to subsequent years reduce parental effort in the current brood to maximize lifetime reproductive output. The results support the hypothesis that multibrooded birds adjust the duration of postfledging care in relation to future reproductive attempts because of an intraseasonal trade-off in the allocation of time between successive broods.