Steroid Hormone Levels Are Related to Choice of Colony Size in Cliff Swallows

Brown, Charles R.; Brown, Mary Bomberger; Raouf, Samrrah A.; Smith, Linda C.; Wingfield, John C.

doi:10.1890/05-0246

Cited by 20 publications

(23 citation statements)

References 50 publications

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“…The same constraints may have applied to birds from nonfumigated sites that sought very large colonies (for whatever reason) the next year: these birds tended to switch to one of the fumigated sites and not to other nonfumigated colonies. The relatively few birds dispersing from fumigated colonies tended to choose ones much smaller, on average, perhaps in part because those individuals were not suited to large colonies (Brown, Brown, Raouf, Smith, & Wingfield, 2005). …”

Section: Discussionmentioning

confidence: 99%

“…This could be modulated in part by stress hormones, if these birds had been in the ‘wrong’ colony size (i.e. one too large) the first year (Brown et al, 2005). …”

Section: Discussionmentioning

confidence: 99%

“…In this study, we explored fidelity to particular colony sites in colonially nesting cliff swallows, Petrochelidon pyrrhonota , integrating results on philopatry with what is already known about colony choice in this species (Brown & Brown, 2000; Brown, Brown, & Danchin, 2000; Brown, Brown, Raouf, Smith, & Wingfield, 2005). Using long-term mark–recapture data, we examined how site fidelity varies with individual characteristics, such as sex and age, and with colony level characteristics, such as size and frequency of site occupancy.…”

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confidence: 99%

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Why come back home? Breeding-site fidelity varies with group size and parasite load in a colonial bird

2017

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Fidelity to a past breeding site is widespread among animals and may confer both costs and benefits. Colonial species occur at specific sites that can accommodate multiple breeders, and the choice of whether to return to last year's site or disperse elsewhere can affect colony site use, the colony size distribution and individual fitness. For the colonial cliff swallow, Petrochelidon pyrrhonota, which occupies colonies of widely different sizes, we used a 30-year field study in western Nebraska to investigate how the extent of infestation by ectoparasites and colony size affected breeders' colony site fidelity between years. We compared philopatry at colonies where parasitic swallow bugs, Oeciacus vicarius, had been removed by fumigation with that at nonfumigated sites exposed to natural levels of ectoparasites. About 25% of birds at nonfumigated colonies returned to their previous year's site, whereas about 69% of birds at fumigated colonies did so. Site fidelity was greatest at nonfumigated sites that changed the least in size between years. Birds were less likely to return to a nonfumigated site as the colony there became increasingly larger. Individuals philopatric to both nonfumigated and fumigated sites resided in colonies more similar in size between years than did dispersing birds. Most cliff swallows settled within 6 km of their previous year's site, indicating that many nonphilopatric birds still may have had some familiarity with the local landscape surrounding the site to which they moved. Removal of ectoparasites at a site allows large colonies to persist there perennially, probably contributing to higher philopatry because such large colonies are rare and would have been difficult to find had the residents dispersed. Cliff swallows are likely to be sensitive to both colony size and general familiarity with a given site or landscape region, and probably integrate these with other cues to select breeding colonies.

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Section: Discussionmentioning

confidence: 99%

“…This could be modulated in part by stress hormones, if these birds had been in the ‘wrong’ colony size (i.e. one too large) the first year (Brown et al, 2005). …”

Section: Discussionmentioning

confidence: 99%

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Why come back home? Breeding-site fidelity varies with group size and parasite load in a colonial bird

2017

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“…The next step is to determine if individuals' histories of colony choice are related to specific phenotypic traits (Brown and Brown 2000a, Brown et al 2005, Roche et al 2011) under different ecological scenarios. Analyses are underway to study individual choice of colony size for our population.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal unpredictability of colony size in Cliff Swallows across 30 years

Brown

Roche

2013

Ecological Monographs

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Abstract. Most colonially breeding animals occupy colonies that range in size from a few pairs to thousands of individuals, but the causes of colony size variation are largely unknown. Three general hypotheses are: (1) that variation in colony size is maintained by fluctuating selection via spatial and temporal changes in fitness associated with different colony sizes; (2) that colony formation reflects heterogeneity in habitat, with some sites having resources to support more individuals than others; and (3) that individuals assess the presence or annual reproductive success of current colony residents at each site and aggregate preferentially at high-quality sites. These hypotheses make predictions about how consistent colony size should be across sites and among years. We examined temporal and spatial variability of colony size for .200 Cliff Swallow (Petrochelidon pyrrhonota) colony sites in western Nebraska across a 30-year period. A colony's substrate type, annual population size in the study area, and whether the nesting season was relatively warm or cool, influenced average annual colony size. While some Cliff Swallow colony sites hosted perennially large colonies and others perennially small ones, between-year variability in colony size at most sites was high. Annual colony size distributions were relatively stable over 30 years and provided no evidence for long-term directional changes in colony size. The only ecological characteristic that was strongly associated with Cliff Swallow colony size at a site was the type of nesting substrate, with bridges tending to have larger colonies and being more frequently occupied than other substrates. Some sites showed annual changes in colony size consistent with the birds' basing their choice of colony on the presence or success of conspecifics, but many sites did not conform to a pattern expected if coloniality is a by-product of traditional aggregation. Colony size in Cliff Swallows was temporally and spatially unpredictable when viewed across the 30 years of this study. Each of the three hypotheses to explain size variation may have applied at certain sites, but the pattern of colony size variability leant the most support to the hypothesis that fluctuating selection on group size maintains colonies of widely different sizes.

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“…For example, ectoparasite load, risk of starvation, predation, and foraging efficiency vary among 123 colonies, often in relation to colony size, and all could influence individual performance at a site Brown and Brown 1996, 1999. Whereas previous work has mostly focused on determining how individuals sort among groups based on age, hormonal ability to handle stress, or parasite resistance (Brown and Brown 1996;Brown et al 2005, this study suggests that individuals might also sort based on life-history strategy.…”

Section: Trade-offs and Sorting Among Coloniesmentioning

confidence: 99%

Parent–offspring resemblance in colony-specific adult survival of cliff swallows

2015

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Survival is a key component of fitness. Species that occupy discrete breeding colonies with different characteristics are often exposed to varying costs and benefits associated with group size or environmental conditions, and survival is an integrative net measure of these effects. We investigated the extent to which survival probability of adult (C1-year old) cliff swallows (Petrochelidon pyrrhonota) occupying different colonies resembled that of their parental cohort and thus whether the natal colony had long-term effects on individuals. Individuals were cross-fostered between colonies soon after hatching and their presence as breeders monitored at colonies in the western Nebraska study area for the subsequent decade. Colony-specific adult survival probabilities of offspring born and reared in the same colony, and those cross-fostered away from their natal colony soon after birth, were positively and significantly related to subsequent adult survival of the parental cohort from the natal colony. This result held when controlling for the effect of natal colony size and the age composition of the parental cohort. In contrast, colony-specific adult survival of offspring cross-fostered to a site was unrelated to that of their foster parent cohort or to the cohort of non-fostered offspring with whom they were reared. Adult survival at a colony varied inversely with fecundity, as measured by mean brood size, providing evidence for a survival-fecundity trade-off in this species. The results suggest some heritable variation in adult survival, likely maintained by negative correlations between fitness components. The study provides additional evidence that colonies represent non-random collections of individuals.

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Steroid Hormone Levels Are Related to Choice of Colony Size in Cliff Swallows

Cited by 20 publications

References 50 publications

Why come back home? Breeding-site fidelity varies with group size and parasite load in a colonial bird

Why come back home? Breeding-site fidelity varies with group size and parasite load in a colonial bird

Spatial and temporal unpredictability of colony size in Cliff Swallows across 30 years

Parent–offspring resemblance in colony-specific adult survival of cliff swallows

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