Age‐related change in breeding performance in early life is associated with an increase in competence in the migratory barn swallow Hirundo rustica

Abstract

Summary 1.We investigated age-related changes in two reproductive traits (laying date and annual fecundity) in barn swallows Hirundo rustica L. using a mixed model approach to distinguish among between-and within-individual changes in breeding performance with age. 2. We tested predictions of age-related improvements of competence (i.e. constraint hypothesis) and age-related progressive disappearance of poor-quality breeders (i.e. selection hypothesis) to explain age-related increase in breeding performance in early life. 3. Reproductive success increased in early life, reaching a plateau at middle age (e.g. at 3 years of age) and decreasing at older age ( > 4 years). Age-related changes in breeding success were due mainly to an effect of female age. 4. Age of both female and male affected timing of reproduction. Final linear mixed effect models (LME) for laying date included main and quadratic terms for female and male age, suggesting a deterioration in reproductive performance at older age for both males and females. 5. We found evidence supporting the constraints hypothesis that increases in competence within individuals, with ageing being the most probable cause of the observed increase in breeding performance with age in early life. Two mechanisms were implicated: (1) advance in male arrival date with age provided middle-aged males with better access to mates. Yearling males arrived later to the breeding grounds and therefore had limited access to high-quality mates. (2) Breeding pairs maintaining bonds for 2 consecutive years (experienced pairs) had higher fecundity than newly formed inexperienced breeding pairs. 6. There was no support for the selection hypothesis because breeding performance was not correlated with life span. 7. We found a within-individual deterioration in breeding and migratory performance (arrival date) in the oldest age-classes consistent with senescence in these reproductive and migratory traits.

Great tits growing old: selective disappearance and the partitioning of senescence to stages within the breeding cycle

“…Selective disappearance was found to mask performance declines at the population level for offspring birth weight, but not calving date in red deer ( Nussey et al 2006). Similarly, age-specific laying date and clutch size improved with ALR in mute swans (McCleery et al 2008), but not in barn swallows Hirundo rustica (Balbontin et al 2007). Our own results for reproductive traits underlying recruitment show that, for any given age, female great tits of longer reproductive lifespan do not lay more eggs, hatch more chicks or raise more fledglings than females Table 2.…”

Reproductive improvement and senescence in a long-lived bird

“…In some of the studies listed in the previous paragraph and in some additional studies accounting for unobserved heterogeneity, reproductive senescence was previously found for red deer Cervus elaphus (24,34), barn swallows (27), black-legged kittiwakes (22), mute swans (42), wood thrushes (33), great tits Parus major (45), and reindeer (35). Note that none of these studies of reproductive improvement and senescence decompose change at the population level into average individual change and compositional change.…”

“…There are only a few comprehensive analyses that appropriately account for unobserved heterogeneity. For reproductive improvement in early life these studies are: reindeer Rangifer tarandus (25,35), barn swallows Hirundo rustica (27), common gulls Larus canus (22), mute swans Cygnus olor (42), wood thrushes Hylocichla mustelina (33), the laying date in oystercatchers Haematopus ostralegu (5), and the breeding probability in black-legged kittiwake Rissa tridactyla (46). We found only two studies that do not show any improvement in certain reproductive performance measures when accounting for compositional change, although there was an apparent improvement when not accounting for the bias.…”

“…Only a few studies, however, have tried to correct for compositional change within the population (5, 22, 24, 25, 27, 33-35, 42, 45, 46). Different authors have speculated about the importance of selective disappearance and individual changes, but they have not been able to quantify the contributions (15,18,25,27,28,31,33,35,42,45,(47)(48)(49)(50). Such quantification can be carried out using the approach that we are proposing here.…”

Better the devil you know: common terns stay with a previous partner although pair bond duration does not affect breeding output

“…Contrary to our findings, there is evidence that, in some species, breeding performance improves with the duration of pair bond. This has been reported in northern fulmars (Fulmarus glacialis [38]), short-tailed shearwaters (Puffinus tenuirostris [39]), barnacle geese (Branta leucopsis [40], Cassin's auklets (Ptchoramphus aleuticus [41]), barn swallows (Hirundo rustica [21]) and little penguins [32].…”