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Human presence and landscape change can alter many aspects of ecological communities and can interact with natural factors to change host–parasite dynamics. In the study reported here, we tested whether an anthropogenic factor, urbanization, affected the abundance and size of hematophagous ectoparasites (swallow bugs: Oeciacus vicarius) found in the nests of cliff swallows (Petrochelidon pyrrhonota). We also examined how swallow bug infestations might be affected by multiple non-anthropogenic biotic and abiotic factors, including season, nest mass, nest colony size, the history of colony occupation, and the presence of other parasitic and non-parasitic arthropods in cliff swallow nests. Our sample included 73 nests collected from 18 cliff swallow colonies in Northern Colorado, USA. Results indicated that swallow bug loads were most strongly predicted by human land use and density, with urban colonies having much heavier infestations than rural colonies. Swallow bugs were more numerous in colonies that were known to have been recently occupied by cliff swallows, and in nests that contained high numbers of other parasitic arthropods, including fleas and ticks. Swallow bug population size did not vary with season, nest mass, or nest colony size, and none of our measured factors predicted swallow bug body length. Results suggest that cities may exacerbate harmful effects of avian ectoparasites by promoting large population sizes, and that these effects may be compounded by the presence of multiple parasitic species in heavily infested nests.

Aerial insectivorous birds such as swallows have been the steepest declining groups of birds in North America over the last 50 years but whether such declines are linked to contaminants has not been examined. We sampled feathers from five species of swallow at multiple locations to assess total mercury [THg] exposure for adults during the non-breeding season, and for juveniles on the breeding grounds. We assessed Hg exposure to juvenile birds in crop- and grass-dominated landscapes to determine if land-use practices influenced feather [THg]. We assayed feathers for stable isotopes (δ2H, δ13C, δ15N) as proxies for relative habitat use and diet to determine their potential influence on feather [THg]. Feather [THg] was highest in adult bank swallows (Riparia riparia) and purple martins (Progne subis) from Saskatchewan and adult cliff swallows (Petrochelidon pyrrhonota) from western regions, indicating differential exposure to Hg on the non-breeding grounds. Juvenile bank, barn (Hirundo rustica) and tree (Tachycineta bicolor) swallows had lower feather [THg] in crop-dominated landscapes than grass-dominated landscapes in Saskatchewan, potentially resulting from lower use of wetland-derived insects due to wetland drainage and intensive agriculture. Feather [THg] was related to juvenile feather stable isotopes for several species, suggesting complex interactions with diet and environmental factors. Many individuals had feather [THg] values >2 µg/g, a threshold at which deleterious effects may occur. Our findings indicate differential Hg exposure among species of swallow, regions and land-uses and highlight the need for additional research to determine dietary and finer-scale land-use impacts on individual species and populations.

Petrochelidon spilodera (Sundevall, 1850) LITERATURE. — Thonnérieux et al. (1989). STATUS. — Excluded. REMARK. — This species breeds in south Africa and winters mainly in the lower Congo basin (Borrow & Demey, 2014). Only one unsubstantiated record., Published as part of Boano, Giovanni, Belemsobgo, Urbain, Silvano, Fabrizio, Hema, Emmanuel M., Belemsobgo, Aristide, Dimobe, Kangbéni & Pavia, Marco, 2022, An annotated checklist of the birds of Burkina Faso, pp. 27-107 in Zoosystema 44 (2) on page 84, DOI: 10.5252/zoosystema2022v44a2, http://zenodo.org/record/5999691, {"references":["THONNERIEUX Y., WALSH J. F. & BORTOLI L. 1989. - L'avifaune de la ville de Ouagadougou et ses environs (Burkina Faso). Malimbus 11: 7 - 39.","BORROW N. & DEMEY R. 2014. - Field Guide of the Birds of Western Africa. II edition. Christopher Helm, London, 592 p."]}

Petrochelidon preussi (Reichenov, 1898) LITERATURE. — Dowsett (1993); Borrow & Demey (2001, 2014); Portier (2002c); Balanca et al. (2007); Sinclair & Ryan (2010); Pavia et al. (2012); Dowsett et al. (2013). FIELD DATA. — GBIF. STATUS. — Resident; Breeding., Published as part of Boano, Giovanni, Belemsobgo, Urbain, Silvano, Fabrizio, Hema, Emmanuel M., Belemsobgo, Aristide, Dimobe, Kangbéni & Pavia, Marco, 2022, An annotated checklist of the birds of Burkina Faso, pp. 27-107 in Zoosystema 44 (2) on page 83, DOI: 10.5252/zoosystema2022v44a2, http://zenodo.org/record/5999691, {"references":["DOWSETT R. J. 1993. - Afrotropical avifaunas: annotated country checklists, in DOWSETT R. J. & DOWSETT- LEMAIRE F. (eds). A Contribution to the Distribution and Taxonomy of Afrotropical and Malagasy birds Tauraco Research Report 5, Tauraco Press, Liege: 1 - 322.","BORROW N. & DEMEY R. 2001. - Birds of Western Africa. Christopher Helm, London, 832 p.","BORROW N. & DEMEY R. 2014. - Field Guide of the Birds of Western Africa. II edition. Christopher Helm, London, 592 p.","PORTIER B. 2002 c. - Liste de l'avifaune du Ranch de Gibier de Nazinga. http: // environnement. wallonie. be / projet _ nazinga / PDF / Liste _ oiseaux _ Nazinga. pdf.","BALANCA G., CORNELIS D. & WILSON R. 2007. - Les oiseaux du complexe WAP. ECOPAS. Cirad, Montpellier.","SINCLAIR I. & RYAN P. 2010. - Birds of Africa south of the Sahara. II edition. Struik Nature, Cape Town, 768 p.","PAVIA M., BOANO G., SILVANO F. & MAMADOU K. 2012. - New bird records from southwestern Burkina Faso. Malimbus 34: 57 - 81.","DOWSETT R. J., ATKINSON P. W. & CADDICK J. A. 2013. - Checklist of the birds of Burkina Faso: 1 - 12. https: // www. africanbirdclub. org / [accessed 14 October 2013]."]}

Several mortality events involving barn swallows (Hirundo rustica) and cliff swallows (Petrochelidon pyrrhonota) were reported in the Upper Midwestern states in 2017 and 2018. Barn swallow mortality followed unseasonal cold snaps, with the primary cause of death being emaciation with concurrent air sac nematodiasis. Lesions in cliff swallows were consistent with blunt force trauma from suspected car impacts. Examination of air sac nematodes from both bird species revealed morphological characters consistent with Diplotriaena obtusa. Sequence analysis of the partial 18S rRNA gene indicated the samples clustered with other species in the genus Diplotriaena. These nematodes provide a link between morphological specimens and DNA sequence data for D. obtusa.

The extent to which host group size affects the hosts’ exposure to parasites and pathogens has been explored by behavioral ecologists for almost 50 years, and we know that host and parasite taxa, mobility of host and parasite, and the extent of spatial structure within groups all affect the group-size relationship. Here we examine how the prevalence of an arthropod-borne viral pathogen changes with host group size in a host-parasite system recently invaded by an introduced species that also serves as a host for the virus. Infection by the alphavirus, Buggy Creek virus (BCRV), in swallow bugs (Cimex vicarius) increased with colony size of the cliff swallow (Petrochelidon pyrrhonota; the bugs’ principal host) in the absence of invasive house sparrows (Passer domesticus) but decreased with swallow colony size in the presence of sparrows. The sparrow-adapted lineage A of BCRV declined to near extinction in the largest cliff swallow colonies, regardless of sparrow presence. The results may reflect BCRV’s divergence into a lineage (B) that amplifies mostly in bugs and thus is transmitted more effectively in large cliff swallow colonies that maintain high numbers of the blood-feeding bugs, whereas the other lineage (A) is adapted to house sparrows and does not require large numbers of bugs and cliff swallows for effective transmission and persistence. The results show that an alternative host can modify the group-size consequences for the original host and illustrate another complexity in analyzing the costs and benefits of coloniality whenever invasive species are present. Predicting the spread of viral pathogens can be important in assessing threats to wildlife or humans, and the size of a host’s social group is regarded as a potentially important determinant of pathogen exposure. Invasive species can sometimes profoundly alter disease dynamics when they enter a host-parasite system and serve as alternative hosts, thereby either increasing or decreasing the original host’s exposure to pathogens. For an arthropod-borne virus that is vectored by a blood-feeding bug that parasitizes a colonially breeding bird, we found that virus infection in bugs increased with host (bird) group size when an invasive bird species was absent but decreased with host group size when the invasive was present. The study indicates that the presence of alternative hosts is another variable to consider in trying to predict how pathogen exposure is affected by host group size.

When an environmental cue that previously signaled a suitable habitat leads an animal to use an unsuitable site, individual fitness can decrease, ultimately leading to population declines. Such “ecological traps” may be particularly likely for birds that use human infrastructure for nesting. Here we tested whether high nest temperatures and the physical properties of barns are associated with lower breeding success for a declining population of Cliff Swallows (Petrochelidon pyrrhonota (Vieillot, 1817)). We monitored nests under barn eaves below wood and metal roofs to determine nestling survival and mass, and recorded temperature under barn eaves, to relate ambient temperature to eave temperature. We found that eave temperature increased with ambient temperatures and was higher at high temperatures and lower at cool temperatures under metal roofs than wood roofs. Nestling survival was lower during periods with higher ambient temperatures, and both survival and mass were lower under metal roofs. Our findings suggest that barn eaves, especially those with metal roofs, may be an ecological trap for Cliff Swallows, where a seemingly suitable nesting site early in the breeding season results in low breeding success. Furthermore, warming temperatures may lead to ecological traps for other bird species, particularly those nesting in man-made structures.

Host–parasite dynamics often vary over time, brought about by changes in the parasite’s virulence or the host’s ability to resist or tolerate the parasite. Although virulence evolution in microparasites is well studied, we know little about temporal change in the pathogenicity of macroparasites such as blood‐feeding insects. Using data collected over 35 yr, we report a reduction in pathogenicity of the hematophagous swallow bug (Cimex vicarius) on its Cliff Swallow (Petrochelidon pyrrhonota) host. Relative to experimentally fumigated, parasite‐free nests, the negative effects of bugs on nestling swallow body mass and survival were less in the later years of the study than in the earlier years, and the negative relationship between nestling body mass and bug abundance became weaker over time. The survival of adult birds exposed to swallow bugs increased throughout the study, while survival of birds from parasite‐free nests decreased over time. Swallow bug abundance per nest, bug body size, and bug age ratios did not change during the study. Between‐colony transmission of bugs showed less immigration into larger colonies than in earlier studies, but there was no net change in transmission. Cliff Swallows did not reduce their exposure to bugs over time by being more likely to avoid infested nest or colony sites. Parents increased the number of food deliveries to their offspring over time in the presence of parasites, but the total amount of food delivered was unchanged. The reduced cost of swallow bug ectoparasitism does not seem related to changes in parasite narrow‐sense virulence, the host’s avoidance of parasites, the presence of alternative hosts for bugs, or climate‐driven phenological mismatches. The results probably reflect the Cliff Swallow’s evolving of greater tolerance to swallow bugs, brought about by the bird’s shift from natural cliff nesting sites to artificial structures that may harbor more bugs than natural cliffs. This study shows that hosts can respond relatively rapidly to high levels of parasitism, and provides support for models that suggest the evolution of tolerance should be expected in some host–parasite systems.

Petrochelidon pyrrhonota (Vieillot, 1817) Figure 5H Material examined. Tables 1, 2. IDentificAtion. We observed this species in great flocks, foraging in the Flooded Grassland area. We observed a large number of foraging individuals in the EET and buffer zone. We identified this species by its square tail, dark blue upper, dirty white forehead and underneath, brown collar on the throat, face, and nape, and cinnamon upper tail (Ridgely and Tudor 2009)., Published as part of Vilas Boas da Frota, Angélica, Vitorino, Breno Dias, da Silva, Carolina Joana, Ikeda-Castrillon, Solange Kimie & Nunes, Josué Ribeiro da Silva, 2020, Birds of the Ramsar site Estação Ecológica de Taiamã and buffer zone, Pantanal wetlands, Brazil, pp. 401-422 in Check List 16 (2) on page 416, DOI: 10.15560/16.2.401, {"references":["Ridgely RS, Tudor G (2009) Field guide to the songbirds of South America: the passerines. University of Texas Press, Austin, 751 pp."]}

Conservation efforts directed at population declines for migratory animals must consider threats occurring at different stages often separated by vast distances. Furthermore, connectivity between populations and fidelity of individuals to specific habitats during the annual cycle are also important considerations. Avian aerial insectivores are experiencing steep population declines in North America, and those declines may be driven, in part, by conditions on the wintering grounds. Here, using geolocators (2 species; 4 individuals) and stable isotope (δ2H, δ13C and δ15N) measurements of feathers (3 species; 841 individuals), we identified approximate winter areas, and assessed migratory connectivity and among-year winter habitat fidelity for three aerial insectivores (Bank Swallow Riparia riparia, Barn Swallow Hirundo rustica and Cliff Swallow Petrochelidon pyrrhonota) that breed in northeastern North America. All three species of swallows are declining in this region. Our results, largely from the stable isotope analysis, suggest that these species likely winter throughout the Cerrado, La Plata Basin, and the Pampas, in South America. These most likely areas were similar among years (2013-2016) for Bank and Cliff Swallows, but varied for Barn Swallows (2014-2016). We found weak migratory connectivity for all three species, and, with one exception, weak habitat fidelity among years for individuals. For individual Barn Swallows captured in two or more years, we found high repeatability in δ13C values, suggesting some fidelity to similar habitats among years. The most likely wintering areas for these species coincide with large areas of South America experiencing high rates of land-use change.

Extreme climatic events can often lead to intense selection and serve as catalysts for rapid evolutionary change. Cold and rainy weather during a 6-day period in spring 1996 led to massive mortality of Cliff Swallows (Petrochelidon pyrrhonota) in western Nebraska and selected for birds with shorter wings and tails, larger skeletal traits, lower levels of fluctuating asymmetry, and less phenotypic variance in all traits. Here we investigate whether the same patterns of selection occurred during 2 subsequent cold and rainy weather events in this population in 2004 and 2017. Directional selection on morphological traits in 2004 was generally the same as in 1996, but in 2017 selection on tarsus length and outer tail feather length was in the opposite direction. As in 1996, selection during both events reduced phenotypic variance in most traits. The results illustrate the potential for extreme weather events to act as drivers for fluctuating directional selection on morphological traits and for period...

We use an experimental approach to evaluate the effectiveness of removing nests of a dominant competitor to create vacant nest boxes for a critically endangered parrot. We compared the number of times that Tree Martin (Petrochelidon nigricans – the dominant competitor at nest boxes) perched at or entered nest boxes intended for Orange‐bellied Parrot (Neophema chrysogaster – the subordinate nest competitor) over three time periods (before, immediately after and one week after experimental nest destruction). In the before period, rates of nest attendance by martins in treatment and control nests were not explained by treatment group. After experimental nest destruction, total attendance at boxes by martins rose to a mean of 6.1 visits over three five‐minute surveys in the treatment group, compared with 3.3 visits at control boxes. Within individual surveys, martins visited treatment boxes 4.4 times per survey one week after nest destruction, compared with only 1.6 visits in the control group. Martins in the treatment group rapidly rebuilt their nests and laid replacement clutches, and within a week, all boxes were reoccupied. Nest destruction did not increase nesting opportunities for the parrot, and increased vigilance of the dominant competitor may in fact reduce nesting opportunities in nearby boxes. Our study suggests that removing martin nests is an ineffective management action for alleviating nest competition for this parrot.

Sayornis phoebe (Eastern Phoebe) has expanded its breeding range southeasterly at water-based anthropogenic structures along forested streams in the Pee Dee region of South Carolina. Its current range is truncated in the Upper Coastal Plain, 31–35 km below the lower boundary of the Sandhills subregion (Orangeburg Scarp). The predominance in the Upper Coastal Plain of South Carolina of structures that are less suitable for nesting by Eastern Phoebes (e.g., small bridges without ledges, box culverts), in contrast to preferred structures (i.e., small bridges with ledges) available upriver in the Sandhills and eastern Piedmont of North Carolina, has not limited their colonization (∼2 km y-1 since ca. 1990). This breeding-range expansion is consistent with a correlative ecological-niche model (ENM) prediction that the Eastern Phoebe is expanding its breeding range in the Pee Dee region across a broad front toward the SC coast. This breeding-range expansion, with a slight drop in latitude and elevation, has been slower than the contemporary expansion of Petrochelidon pyrrhonota (Cliff Swallow) in the same direction in the same region. Hirundo rustica (Barn Swallow) uses water-based anthropogenic structures, but has also widely colonized land-based structures during its faster past breeding range-expansion into the Pee Dee region. Differences in the number, size, and suitability of water-based anthropogenic structures used by these 3 species suggest additional constraints that influence the colonization rate and population size of Eastern Phoebes.

Summary Many aspects of bird migration are necessarily innate. 1 However, the extent of deterministic genetic control, environmental influence, and individual decision making in the control of migration remains unclear. 2 , 3 , 4 , 5 , 6 , 7 , 8 Globally, few cases of rapid and dramatic life-history changes resulting in novel migration strategies are known. An example is latitudinal trans-hemispheric breeding colonization, whereby a subpopulation suddenly begins breeding on its non-breeding range. 9 , 10 , 11 , 12 , 13 These life-history reversals demand concomitant changes in the timing of migration, feather molt, and breeding if the population is to remain viable. 13 Cliff swallows, Petrochelidon pyrrhonota, are long-distance migrants that breed in North America and spend the non-breeding season mostly in South America. 14 However, in 2015, a small population switched hemispheres by breeding successfully in Argentina, 9 over 8,000 km from the nearest potential source, after presumably failed attempts. 15 , 16 This provided a unique chance to characterize the early mechanisms of change in migratory behavior and phenology and to assess the possibility of double breeding. We tracked cliff swallows with geolocators following their second and fourth breeding seasons in Argentina, documenting inverted seasonality, three new migratory patterns and non-breeding areas (North America, Mesoamerica, and South America), and a shift of molt phenology by approximately 6 months, all possibly arising within a single generation. These birds did not practice migratory double breeding, although some spent the boreal summer in the traditional breeding range. Our data show that fundamental phenological changes occurred very rapidly during colonization and that phenotypic plasticity can underlie profound changes in the life histories of migratory birds.

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.

The swallow bug, Oeciacus vicarius Horvath, is a hematophagous ectoparasite of the cliff swallow, Petrochelidon pyrrhonota Vieillot, and is closely related to bed bugs (Cimex spp.). Evolution of insecticide resistance has been documented for bed bugs but not studied in Oeciacus. For periods of 17 and 32 yr, two cliff swallow colonies in western Nebraska were treated during the summer breeding season using the organophosphate insecticide Dibrom. Despite continual treatments, O. vicarius has been observed frequently within these colonies. We evaluated the efficacy of Dibrom 8 on O. vicarius during the 2016 season at two treated colonies and four that had never experienced treatment. Dibrom 8 was found to be effective in 100% of trials, with immobilization within minutes and death within 72 h, for individuals from all colonies. In control treatments (water), individuals collected from treated colonies exhibited greater survival than individuals from untreated colonies, and those from active colonies (bugs fed) had greater survival than those from inactive colonies (bugs unfed). A residual effect was observed in both lab and field trials: 100% mortality occurred in the lab after exposure to filter paper substrates treated both 5 and 10 d earlier, and in the field, nests treated once early in the season had O. vicarius counts 43 d later that were

Breeding colonies of birds represent groups of individuals that associate during one breeding season, at least partially dissociate for the non‐breeding season, and may re‐associate the next year through collective settlement at another breeding site. Little is known about the extent to which colonial birds maintain group integrity when occupying different sites in different years or the benefits of long‐term associations among colonial individuals. For cliff swallows (Petrochelidon pyrrhonota) in western Nebraska, USA, we examined ecological correlates and potential benefits associated with group integrity. Using a dataset of over 25,000 individuals, we found that associations between dispersing cliff swallows were greater than would be predicted by purely random settlement among colony sites. The extent of group integrity varied widely among sites, with birds seeming to settle together more often at sites with fewer ectoparasites and at colonies similar in size and closer in physical proximity to the one they had previously occupied. Some associations of birds lasted three years in which they used a different site each year. Successful colonies had higher levels of group integrity among their settlers than did colonies that failed completely. Cliff swallows that were known to have settled with at least one conspecific from the previous year's site had a higher survival the next year than those not known to have settled with past residents. The results are consistent with cliff swallows choosing colonies based in part on parasite load and with sorting among colonies based on the birds’ preferences for colonies of certain sizes.

International audience; Carry-over effects from one stage of the annual cycle to subsequent stages can have profound effects on individual fitness. In migratory birds, much research has been devoted to examining such effects from the nonbreeding to the breeding period. We investigated potential carry-over effects influencing spring body condition, breeding phenology, and performance for 3 species of sympatric, declining Nearctic–Neotropical migratory swallows: Bank Swallow (Riparia riparia), Barn Swallow (Hirundo rustica), and Cliff Swallow (Petrochelidon pyrrhonota). To examine carry-over effects, we used structural equation modeling and several intrinsic markers, including stable isotope (δ 2H, δ 13C, and δ 15N) and corticosterone (CORTf) values from winter molted-feathers, and changes in telomere length between breeding seasons. We found support for carry-over effects for all 3 species, however, the specific relationships varied between species and sexes. Effects leading to lower breeding performance were only observed in male Bank, female Barn, and female and male Cliff Swallows. In most cases, carry-over effects were attributed to differences in stable isotope values (most commonly with δ 2H) presumably related to differences in winter habitat use, but, for Cliff Swallows, negative carry-over effects were also linked to higher CORTf values and greater rates of telomere shortening. This work provides further support for the potential role of nonbreeding conditions on population declines, and indicates how multiple intrinsic markers can be used to provide information on ecological conditions throughout the annual cycle.; Los efectos de arrastre desde una etapa del ciclo anual a las siguientes etapas pueden tener efectos profundos en laadecuación biológica individual. En las aves migratorias, se ha realizado mucha investigación para examinar estosefectos desde el período no-reproductivo al período reproductivo. Investigamos los potenciales efectos de arrastre queinfluencian la condición corporal de primavera, la fenología reproductiva y el desempeño para tres especies simpátricasde golondrinas migratorias neárticas-neotropicales en disminución —Riparia riparia, Hirundo rustica y Petrochelidonpyrrhonota. Para examinar los efectos de arrastre, usamos modelos de ecuaciones estructurales y varios marcadoresintrínsecos, incluyendo valores de isótopos estables (δ 2H, δ 13C y δ 15N) y de corticosterona (CORTf) provenientes deplumas mudadas en invierno, y cambios en el largo del telómero entre estaciones reproductivas. Encontramos apoyopara efectos de arrastre para las tres especies; sin embargo, las relaciones específicas variaron entre especies y sexos.Los efectos que llevaron a un menor desempeño reproductivo fueron solo observados en los machos de R. riparia, lashembras de H. rustica, y las hembras y los machos de P. pyrrhonota. En la mayoría de los casos, los efectos de arrastrefueron atribuidos a las diferencias en los valores de los isótopos estables (más comúnmente con δ 2H) presumiblementerelacionados con las diferencias en el uso del hábitat de invierno, pero, para P. pyrrhonota, los efectos de arrastrenegativos también estuvieron vinculados con valores más altos de CORTf y tasas más grandes de acortamiento de lostelómeros. Este trabajo brinda apoyo adicional al rol potencial de las condiciones no-reproductivas en la disminución delas poblaciones, e indica cómo los marcadores intrínsecos múltiples pueden ser usados para brindar información de lascondiciones ecológicas a través del ciclo anual.

Seven species of the feather mite genus Trouessartia Canestrini, 1899 (Astigmata: Trouessartiidae) have been recorded on swallows and martins (Passeriformes: Hirundinidae) in Manitoba (Canada). Of them, five are described as new species: Trouessartia ampulicaudata sp. n. and T. petrochelidon sp. n. from the American cliff swallow Petrochelidon pyrrhonota (Vieillot), T. bochkovi sp. n. from the tree swallow Tachycineta bicolor (Vieillot), and T. cryptocaudata sp. n. and T. progne sp. n. from the purple martin Progne subis (Linnaeus). A new species group stelgidopteryx, incorporating Trouessartia species living on hirundinids of the genera Progne, Tachycineta and Stelgidopteryx, is established. Renewed diagnoses of four Trouessartia species groups (appendiculata, crucifera, minutipes, and stelgidopteryx) restricted to hirundinids and a key to species recorded so far and potentially expected on swallows of North America are proposed. Host associations of Trouessartia species with swallows in North America are briefly discussed.

We examined age-related reproductive success and the short-term consequences of dispersal by known-aged Cliff Swallows (Petrochelidon pyrrhonota) breeding in Texas from 1975–86. Clutch size increased with age in females, and males and females ≥2 yrs old fledged more young than yearlings. Sixteen percent (76/463) of birds dispersed between breeding seasons and we observed female-biased dispersal. Birds that dispersed to a different colony at age 2 produced 0.91 fewer fledglings post-dispersal compared to the previous year, and birds that dispersed at age 3 produced 0.34 more fledglings post-dispersal compared to the previous year; females experienced greater benefits than males when they dispersed at age 3 yrs. Younger dispersers incur short-term costs which might have important consequences for lifetime reproductive success for a short-lived passerine. However, potential population-level consequences from dispersal costs is likely minimal given the low rate of dispersal we observed.

Animal groups often represent nonrandom subsets of individuals, and increasing evidence indicates that individuals may sort among groups based on their personalities. The size of a group can predict its personality composition in some species due to differential suitability of a personality for groups of certain sizes, and the group itself may function more effectively if particular personality types are present. We quantified cliff swallow (Petrochelidon pyrrhonota) behavioral measures using linear and generalized linear mixed models to identify whether they: (1) varied among individuals within colonies and among colonies, (2) were related to reproductive success, and (3) predicted levels of parental care. Significant among-individual and among-colony site variation in a cliff swallow’s latency to enter its nest when presented with a novel stimulus was revealed. We also found significant among-individual variation in the number of attacks directed toward a novel stimulus at the nest and in the response to broadcast of a cliff swallow alarm call recording, but among site variation in these measures was not significant. We did not find evidence for behavioral syndromes linking the personalities measured. Differences among individuals in latency to enter the nest and the number of attacks were not significantly related to reproductive success or to the extent to which birds fed their nestlings. However, extent of nestling feeding was significantly predicted by the number of mist net captures. The limited evidence in general of systematic variation in the behavior we measured among cliff swallow colonies may reflect the different and sometimes opposing selection pressures on behavior in different social environments. Future work should perhaps examine variation in other behavioral traits, such as foraging, in cliff swallow colonies of different sizes.

Most animal groups vary extensively in size. Because individuals in certain sizes of groups often have higher apparent fitness than those in other groups, why wide group size variation persists in most populations remains unexplained. We used a 30-y mark-recapture study of colonially breeding cliff swallows (Petrochelidon pyrrhonota) to show that the survival advantages of different colony sizes fluctuated among years. Colony size was under both stabilizing and directional selection in different years, and reversals in the sign of directional selection regularly occurred. Directional selection was predicted in part by drought conditions: birds in larger colonies tended to be favored in cooler and wetter years, and birds in smaller colonies in hotter and drier years. Oscillating selection on colony size likely reflected annual differences in food availability and the consequent importance of information transfer, and/or the level of ectoparasitism, with the net benefit of sociality varying under these different conditions. Averaged across years, there was no net directional change in selection on colony size. The wide range in cliff swallow group size is probably maintained by fluctuating survival selection and represents the first case, to our knowledge, in which fitness advantages of different group sizes regularly oscillate over time in a natural vertebrate population.

Most migratory birds, particularly passerines or songbirds, migrate at night. However, diurnal migration has many benefits, including the ability to use a fly-and-forage migration strategy that allows an individual to refuel while migrating. Despite these benefits, very little research has been undertaken on diurnal migrants, including aerial foragers, who can refuel on the wing. In this study, we use the Motus Wildlife Tracking System to examine the timing of Bank Swallow (Riparia riparia), Barn Swallow (Hirundo rustica), Cliff Swallow (Petrochelidon pyrrhonota), and Tree Swallow (Tachycineta bicolor) movements during fall migration. Using these data, we confirm the “common knowledge” that these species of aerial foragers are diurnal migrants. During fall migration, 88.2% detections across all species were during the day, and the remaining detections were during civil twilight (range of sun elevation angles: –5.4° to 0°). Most of the detections during the day were consistent with migratory movement, and most detections during civil twilight were consistent with movements to and from communal roosts. Collectively, these results indicate that during fall migration, these 4 swallow species migrate during the day and, like other aerial foragers, may use a fly-and-forage migration strategy.

What maintains stasis in animal group‐size distributions is an unresolved problem in behavioral ecology. One potential driver could be rare climatic events that favor certain group sizes in ways that do not occur in normal conditions. We investigated mortality among colonially nesting cliff swallows (Petrochelidon pyrrhonota) during a rare climatic event in western Nebraska in 1996 that led to the starvation of thousands of adult birds. Colonies at the extreme end of the size distribution exhibited less size reduction (higher adult survival) than those of intermediate size. That this event resulted in disruptive selection on colony size was suggested by an underrepresentation of locally produced yearling birds that recruited into colonies of intermediate size the following year. There was no evidence that the colony‐size‐related mortality could be explained by differential sorting of birds among colonies based on body size or differing patterns of selection on morphology. The selection on colony size was likely driven by lower competition for food in the smallest colonies and better quality foraging habitat associated with the largest colonies, with these advantages enhanced in severe weather. Selection on colony size during rare climatic events can reinforce or oppose selection occurring during other times of the annual cycle. Whether such selection results in long‐term change in the colony‐size distribution may depend on the frequency and severity of these climatic events.

Petrochelidon meyeni Cabanis, 1850: 48. Now: Tachycineta leucopyga (Meyen, 1834). See Mlíkovský & Frahnert (2009). Syntype: Same specimen as the lectotype of Hirundo leucopyga Meyen, 1834 (above). Remarks. Two further two syntypes from “ Chile ” are in MHH (nos. 1454, 1455), but their other details are unknown (Mlíkovský & Frahnert 2009).

Petrochelidon meyeni Cabanis, 1850: 48. Now: Tachycineta leucopyga (Meyen, 1834). See Ml��kovsk�� & Frahnert (2009). Syntype: Same specimen as the lectotype of Hirundo leucopyga Meyen, 1834 (above). Remarks. Two further two syntypes from ��� Chile ��� are in MHH (nos. 1454, 1455), but their other details are unknown (Ml��kovsk�� & Frahnert 2009)., Published as part of Ml��kovsk��, Ji���� & Frahnert, Sylke, 2017, Type specimens and type localities of birds (Aves) collected during F. J. F. Meyen's circumnavigation in 1830 ��� 1832, pp. 1-22 in Zootaxa 4250 (1) on page 11, DOI: 10.11646/zootaxa.4250.1.1, http://zenodo.org/record/439779, {"references":["Cabanis, J. (1850) Museum Heineanum. Vol. 1. Die Singvogel. Ferdinand Heine, Halberstadt, viii + 234 pp.","Mlikovsky, J. & Frahnert, S. (2009) Nomenclatural notes on Neotropical swallows of the genus Tachycineta Cabanis (Aves: Hirundinidae). Zootaxa, 2209, 65 - 68."]}

In this study we examined patterns of habitat occupancy by canyon wrens (Catherpes mexicanus), an insectivorous, cliff-obligate bird species, in Northern Colorado. Canyon wren territories are generally large and widely spaced, and it is currently unclear if their densities are limited by the availability of cliff habitats that have particular biotic and/or abiotic attributes. We used playback of conspecific song to survey 138 cliff sites and found 23 occupied territories, confirming the species occurs in low densities. Using a model-fitting approach, we assessed the importance of seven factors hypothesized to be important to canyon wren territory settlement and found occupied territories had cliffs that were more likely to be overhung, rather than vertical. Habitat occupancy of canyon wrens was also associated with the presence of cliff swallows (Petrochelidon pyrrhonota) and their nests, with canyon wrens observed nesting and foraging within cliff swallow nests throughout the year. As no abiotic...

The swallow bug (Oeciacus vicarius) is the only known vector for Buggy Creek virus (BCRV), an alphavirus that circulates in cliff swallows (Petrochelidon pyrrhonota) and house sparrows (Passer domesticus) in North America. We discovered ants (Crematogaster lineolata and Formica spp.) preying on swallow bugs at cliff swallow colonies in western Nebraska, U.S.A. Ants reduced the numbers of visible bugs on active swallow nests by 74-90%, relative to nests in the same colony without ants. Ant predation on bugs had no effect on the reproductive success of cliff swallows inhabiting the nests where ants foraged. Ants represent an effective and presumably benign way of controlling swallow bugs at nests in some colonies. They may constitute an alternative to insecticide use at sites where ecologists wish to remove the effects of swallow bugs on cliff swallows or house sparrows. By reducing bug numbers, ant presence may also lessen BCRV transmission at the spatial foci (bird colony sites) where epizootics occur. The effect of ants on swallow bugs should be accounted for in studying variation among sites in vector abundance.

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 (≥1-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.

The cliff swallow (Petrochelidon pyrrhonota) and the cave swallow (Petrochelidon fulva) both construct nests entirely out of mud and aggregate in large colonies (tens to thousands of nests) suggesting they can be considered as geomorphic agents. This study analyzes 16 swallow colonies to address the following three research questions: (1) What is the total sediment present at each colony? (2) What is the annual rate of sediment transport by swallows for nesting purposes? and (3) Is there a significant difference in mud-nest mass between the cave swallow’s cup-shaped and the cliff swallow’s gourd-shaped mud-nest? The total sediment present across all sites was estimated at 2125 kg, ranging from 11.5 kg in the smallest colony to 953.6 kg in the largest colony. In one summer, cliff and cave swallows transported an estimated 560 kg of sediment across all sites, with the greatest colony constructing 233 nests weighing an estimated 193.4 kg. Statistical analysis determined there to be a significant difference i...

Cave swallows (Petrochelidon fulva) have undergone a dramatic range expansion in the southwestern United States. In south Texas, this has coincided with a concurrent decline in culvert-nesting barn swallows (Hirundo rustica), leading some authors to suggest that colonizing cave swallows negatively impact barn swallows. Here we compare the reproduction of syntopic nesting barn and cave swallows in culverts and under bridges at the northeastern edge of the expanding cave swallow distribution. Cave swallows in northeastern Texas had reproductive success comparable to natural populations further south. Syntopic nesting barn swallows had much-reduced reproductive success when compared with results of studies in this area prior to colonization by cave swallows. Though cave swallows had higher fledging success, this trend was only significant for culvert-nesting birds. Barn swallows nesting under bridges did better than their counterparts in culverts, possibly because of structural differences and their...

A challenge of life-history theory is to explain why animal body size does not continue to increase, given various advantages of larger size. In birds, body size of nestlings and the number of nestlings produced (brood size) have occasionally been shown to be constrained by higher predation on larger nestlings and those from larger broods. Parasites also are known to have strong effects on life-history traits in birds, but whether parasitism can be a driver for stabilizing selection on nestling body size or brood size is unknown. We studied patterns of first-year survival in cliff swallows (Petrochelidon pyrrhonota) in western Nebraska in relation to brood size and nestling body mass in nests under natural conditions and in those in which hematophagous ectoparasites had been removed by fumigation. Birds from parasitized nests showed highest first-year survival at the most common, intermediate brood-size and nestling-mass categories, but cliff swallows from nonparasitized nests had highest survival at the heaviest nestling masses and no relationship with brood size. A survival analysis suggested stabilizing selection on brood size and nestling mass in the presence (but not in the absence) of parasites. Parasites apparently favour intermediate offspring size and number in cliff swallows and produce the observed distributions of these traits, although the mechanisms are unclear. Our results emphasize the importance of parasites in life-history evolution.

Global climate change is altering the breeding phenology of many organisms, and one reported consequence of warmer average temperatures is earlier breeding times in migratory songbirds of north temperate latitudes. Less studied are the potential interactions between earlier breeding and social behavior in colonial species. We investigated how breeding time, as measured by colony initiation dates across the entire summer, in Cliff Swallows (Petrochelidon pyrrhonota) of southwestern Nebraska, USA, changed over a 30-year period and could be predicted by climatic variables, year, and colony size. Mean colony initiation date became earlier over the study, with variation best predicted by the extent of drought severity on the breeding grounds: colonies initiated earlier in warmer and drier years. Colony initiation dates were more asynchronous across the population in cooler and wetter years. There was no effect of climatic conditions during the nonbreeding season. Larger colonies started earlier in the year than smaller ones, probably because of the cost of ectoparasitism and the benefit of social foraging, both of which varied with colony size, date, and climatic conditions. The inverse relationship between breeding time and colony size was more pronounced in years with more severe drought. This study is one of the few to show that breeding phenology of a long-distance migrant bird is sensitive primarily to drought severity on the breeding grounds and that climate change can influence social behavior. If climate change exacerbates drought in the future, Cliff Swallow breeding time will likely become more strongly linked to group size.

Many organisms of temperate latitudes exhibit declines in reproductive success as the breeding season advances. Experiments can delay the onset of reproduction for early breeders to investigate the consequences of late nesting, but it is rarely possible to observe a distinct second round of nesting in species that normally nest only once. The colonial cliff swallow (Petrochelidon pyrrhonota) is a migratory songbird that has a relatively short breeding season in the western Great Plains, USA, with birds rarely nesting late in the summer. Previous work suggested that ectoparasitism is a primary reason why reproductive success in this species declines over the summer. At colony sites where nests were fumigated to remove ectoparasitic swallow bugs (Oeciacus vicarius), cliff swallows frequently undertook a distinct round of late nesting after previously fledging young that year. Mark-recapture revealed that late-nesting pairs at these colonies produced fewer offspring that survived to the next breeding season, and that survival of late-nesting adults was lower during the next year, relative to pairs nesting earlier in the season. These reproductive costs applied in the absence of ectoparasites and likely reflect other environmental costs of late nesting such as seasonal declines in food availability or a delayed start of fall migration. Despite the costs, the estimated fitness for perennial early-and-late nesters in the absence of ectoparasites was equivalent to that of birds that nested only early in the season. The collective disadvantages of late nesting likely constrain most cliff swallows to raising a single brood in the middle latitudes of North America.

Variation in group size is characteristic of most social species. The extent to which individuals sort among group sizes based on age may yield insight into why groups vary in size and the age-specific costs and benefits of different social environments. We investigated the age composition of Cliff Swallow (Petrochelidon pyrrhonota) colonies of different sizes over 18 years at a long-term study site in western Nebraska, USA. Using years elapsed since banding as a relative measure of age for over 194,000 birds, we found that the proportion of age-class-1 swallows (birds banded as nestlings or juveniles or adults in the year of banding) of both sexes increased in larger colonies and at colony sites becoming active later in the summer. Age composition was unrelated to how often a particular colony site was used. The effect of colony size most likely reflected the fact that older birds return to the same colony site in successive years even when the colony size there decreases, and that yearlings and immigrants benefit more from larger colonies than do older, more experienced individuals. The date effect probably resulted in part from later spring arrival by younger and/or immigrant swallows. At fumigated sites where ectoparasitic swallow bugs (Oeciacus vicarius) had been removed, age composition did not vary with either colony size or colony initiation date. The patterns reported here appear to be driven partially by the presence of ectoparasites and suggest that the hematophagous bugs influence variation in Cliff Swallow group composition. Our results are consistent with the hypothesis that variation in colony size reflects, in part, age-based sorting of individuals among groups.

Although the ability to recognize related offspring is essential in the evolution of social behavior, the cues that birds use to identify their own offspring are not fully understood. The Cliff Swallow (Petrochelidon pyrrhonota) is a highly social species that nests in large colonies and exhibits a high incidence of both conspecific brood parasitism and extrapair fertilization, behaviors that can potentially lead to parents investing energy and resources in unrelated offspring, which reduces the parents' genetic fitness. Because parents continue to feed offspring after they leave the nest, parents also risk investing in unrelated offspring by misidentifying their own young after mobile, postfledging juveniles form creches. Cliff Swallows possess a unique system of variable juvenile facial patterns, ranging from almost entirely black to almost entirely white. Interestingly, although these patterns are highly variable and distinctive in juveniles, they disappear upon maturation. We used image analy...

Since first confirmation of nesting in 1987, there has been a steady southward expansion of breeding Tachycineta bicolor (Tree Swallow) in Alabama. Using 220 breeding season occurrence records, we performed a breakpoint analysis to quantify the breeding expansion rate of Tree Swallows in the state. Between 1988 and 2013, our models indicated Tree Swallows expanded ∼130 km south at a mean rate of 5.2 km/year. Possible drivers of this southward expansion include increased artificial nest box availability, aerial insect declines in more northern historic ranges, changing climate, and altered land-management practices. Our findings indicate Tree Swallows are following a similar southward breeding expansion pattern to that exhibited by Hirundo rustica (Barn Swallow) and Petrochelidon pyrrhonota (Cliff Swallow) in recent decades.

Enhanced vigilance against predation is often an advantage of living in groups, but most studies have not examined individual-specific variation in the propensity to be vigilant among the animals within a group. We studied vigilance at the nest in colonially nesting Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska in 2011 and 2012, and asked whether differences among individuals were consistent over time, whether vigilance varied among different colonies, and whether there were positive or negative fitness consequences of different levels of vigilance. We found significant among-individual variation in extent of vigilance and some variation among different colony sites. Vigilance also varied with date and nesting stage, but other phenotypic characteristics of a bird had no effect on vigilance. Differences among individuals in vigilance were not strongly related to their reproductive success that season, but more vigilant individuals were more likely to attempt intrusions into th...

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 whethe...

Petrochelidon pyrrhonota (Cliff Swallow) initially expanded its breeding range to the Great Pee Dee River corridor of the Carolinas in the early 1980s. In 2012, I documented approximately 1700 active nests of the Cliff Swallow at 20 colony sites in the Lower Piedmont of North Carolina and Coastal Plain of South Carolina along this river corridor. Cliff Swallows nested primarily at bridges and other water-based sites but also bred at several land-based sites, including the first colony documented at a highway overpass in the Carolinas. Compared to colony sizes in the early 1980s and mid-1990s at 3 major sites in North Carolina, numbers in 2012 were approximately 1500% and 400% higher, respectively. Before this study, Cliff Swallows nesting along the Great Pee Dee River was documented only as far as Cheraw, at the Fall Line. This study demonstrates that breeding now occurs 145 km farther south along this corridor at 6 sites, including 2 sites in the tidewater region of South Carolina. Several bridges along this corridor with favorable structural characteristics for breeding are still unoccupied. The breeding range expansion front of interior populations along and near the Great Pee Dee River has moved slowly (≈3.25 km/yr), in an apparently stepwise manner. However, the gap between expanding interior and coastal populations is confounding the pattern of range expansion in the Lower Coastal Plain of South Carolina.

The extent to which fluctuating selection can maintain evolutionary stasis in most populations remains an unresolved question in evolutionary biology. Climate has been hypothesized to drive reversals in the direction of selection among different time periods and may also be responsible for intense episodic selection caused by rare weather events. We measured viability selection associated with morphological traits in cliff swallows (Petrochelidon pyrrhonota) in western Nebraska, U.S.A., over a 14-year period following a rare climatic event. We used mark-recapture to estimate the annual apparent survival of over 26,000 individuals whose wing, tail, tarsus, and bill had been measured. The fitness functions associated with tarsus length and bill dimensions fluctuated depending on annual climate conditions on the birds’ breeding grounds. The oscillating yearly patterns may have slowed and occasionally reversed directional change in trait trajectories, although there was a trend over time for for all traits except tarsus to increase in size. The net positive directional selection on some traits, despite periodic climate-associated fluctuations, suggests that cliff swallow morphology in the population is likely to keep changing and supports recent work contending that selection in general does not fluctuate enough to be an effective driver of stasis.

Wild birds play a key role in the amplification and transmission of many of the arthropod-borne viruses (arboviruses). Determining the extent to which birds are affected by these viruses is critical in predicting the pathogens' spread or maintenance in vertebrate host populations. Little is known about how arboviruses affect amplifying hosts' fitness, especially in cases where these viruses infect nestling birds. Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the Swallow Bug (Oeciacus vicarius) to Cliff Swallows (Petrochelidon pyrrhonota) and House Sparrows (Passer domesticus) that have recently occupied Cliff Swallow nesting colonies. We examined fitness, as measured by fledging success, of House Sparrows occupying Cliff Swallow nesting colonies in western Nebraska. Most nestlings naturally infected by BCRV at 4–6 days of age died, and even older nestlings, when infected, showed fledging success of

We report details of a serendipitous encounter in July 2010 with a gopher snake (Pituophis catenifer) hunting in the mud nests of Cliff Swallows (Petrochelidon pyrrhonota). The swallow nests occurred beneath a deeply overhung sandstone cliff ledge in a box canyon of Ferron Creek in the shale deserts near Ferren, Emery County, Utah. The inaccessibility of the nests and the movement of the snake to and through them attest to both the extraordinary climbing ability of the gopher snake and the nest site selection and nest construction ability of the swallows.

The variation in breeding-colony size seen in populations of most colonial birds may reflect heritable choices made by individuals who are phenotypically specialized for particular social environments. Although a few studies have reported evidence for genetically based choice of group sizes in birds, we know relatively little about the extent to which animals potentially rely on experience versus innate preferences in deciding with how many conspecifics to settle at different times of their lives. We conducted a cross-fostering experiment in 1997-1998 on cliff swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, USA, in which some individuals were reared in colonies different in size from those in which they were born. Breeding-colony sizes chosen by this cohort of birds were monitored by mark-recapture throughout their lives. A multistate mark-recapture analysis revealed that birds in their first breeding year chose colony sizes similar to those of their birth, regardless of their rearing environment, confirming a previous analysis. Beyond the first breeding year, however, cliff swallows' colony choice was less dependent on where they were born. Birds born in small colonies and reared in large colonies showed evidence of a delayed rearing effect, with these birds overwhelmingly choosing large colonies in later years. Heritabilities suggested strong genetic effects on first-year colony choice but not in later years. Cliff swallows' genetically based colony-size preferences their first year could be a way to ensure matching of their phenotype to an appropriate social environment as yearlings. In later years, familiarity with particular colony sites and available information on site quality may override innate group-size preferences when birds choose colonies.

We analyzed the mitochondrial cytochrome b gene of three vagrant Cave Swallow (Petrochelidon fulva) specimens from Illinois, New York, and New Jersey and compared them to published sequences from across the breeding range of the species. All three specimens were assigned to the southwestern United States/Mexico subspecies (P. f. pallida group) on the basis of plumage coloration. Molecular results reveal that all three birds possess unique and novel mitochondrial haplotypes that are closely related to haplotypes from known P. f. pallida individuals. None of the three haplotypes from the vagrant individuals is within the monophyletic clade of haplotypes that corresponds to the Caribbean subspecies (P. f. fulva).

Unusual climatic events often lead to intense natural selection on organisms. Whether episodic selection events result in permanent microevolutionary changes or are reversed by opposing selection pressures at a later time is rarely known, because most studies do not last long enough to witness rare events and document their aftermath. In 1996, unusually cold and wet weather in southwestern Nebraska led to the deaths of thousands of Cliff Swallows (Petrochelidon pyrrhonota) over a 6-day period. Survivors were skeletally larger, with shorter wings and tails, and had less asymmetry in wing length than those that died. We determined trajectories of morphological traits in the decade following this event by measuring yearling birds each year from 1997 to 2006. Wing and middle tail-feather lengths continued to decrease, bill length and width continued to increase, tarsus length was unchanged, and levels of asymmetry in wing length increased. Cumulative directional change in wing, tail, and bill length...

Many of the arthropod-borne viruses (arboviruses) show extensive genetic variability and are widely distributed over large geographic areas. Understanding how virus genetic structure varies in space may yield insight into how these pathogens are adapted to and dispersed by different hosts or vectors, the relative importance of mutation, drift, or selection in generating genetic variability, and where and when epidemics or epizootics are most likely to occur. However, because most arboviruses tend to be sampled opportunistically and often cannot be isolated in large numbers at a given locale, surprisingly little is known about their spatial genetic structure on the local scale at which host/vector/virus interactions typically occur. Here, we examine fine-scale spatial structure of two sympatric lineages of Buggy Creek virus (BCRV, Togaviridae), an alphavirus transmitted by the ectoparasitic swallow bug (Oeciacus vicarius) to colonially nesting cliff swallows (Petrochelidon pyrrhonota) and invasive house sparrows (Passer domesticus) in North America. Data from 377 BCRV isolates at cliff swallow colony sites in western Nebraska showed that both virus lineages were geographically structured. Most haplotypes were detected at a single colony or were shared among nearby colonies, and pair-wise genetic distance increased significantly with geographic distance between colony sites. Genetic structure of both lineages is consistent with isolation by distance. Sites with the most genetically distinct BCRV isolates were occupied by large numbers of house sparrows, suggesting that concentrations of invasive sparrows may represent foci for evolutionary change in BCRV. Our results show that bird-associated arboviruses can show genetic substructure over short geographic distances.