Charles R Brown

Charles R Brown
University of Tulsa · Department of Biological Sciences

Doctor of Philosophy

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177
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Publications

Publications (177)
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The survival of insects that are dormant in winter may either increase or decrease as a consequence of elevated winter temperatures under climate change. Warming can be deleterious when metabolism of the overwintering life stages increases to the point that energy reserves are exhausted before postoverwintering reemergence. We examined experimental...
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Explaining why animal groups vary in size is a fundamental problem in behavioral ecology. One hypothesis is that life-history differences among individuals lead to sorting of phenotypes into groups of different sizes where each individual does best. This hypothesis predicts that individuals should be relatively consistent in their use of particular...
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Some birds exhibit a maxillary overhang, in which the tip of the upper beak projects beyond the lower mandible and may curve downward. The overhang is thought to help control ectoparasites on the feathers. Little is known about the extent to which the maxillary overhang varies spatially or temporally within populations of the same species. The colo...
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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 prevalenc...
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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 ov...
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The cognitive-buffer hypothesis proposes that more harsh and unpredictable environments favour animals with larger brains and resulting greater cognitive skills. Comparisons across taxa have supported the hypothesis, but it has rarely been tested within a species. We measured brain size, as inferred from head dimensions, for 1141 cliff swallow spec...
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Urbanization creates new ecological landscapes that may alter the behavior of animals occupying them. Northern cardinals (Cardinalis cardinalis) inhabit both urban and rural habitats in northeastern Oklahoma, where food availability, predator type, and plant phenology can differ. Relative to birds in rural habitats, cardinals in urban environments...
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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 func...
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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 d...
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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...
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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 lev...
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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. Parasite...
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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 c...
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Animals often confine their movements to familiar areas and preferred habitats, resulting in increased fitness through enhanced survival and reproduction. However, the link between preferential habitat use and fitness is rarely tested, especially when individual phenotype is considered. Through multi-state modeling of mark-recapture data, we assess...
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Catastrophic weather can affect individuals unequally and lead to episodic selection, but the effects of weather events are rarely documented. In August 2015, a nighttime thunderstorm led to the deaths of hundreds of purple martins (Progne subis) roosting in downtown Tulsa, Tulsa County, Oklahoma. We compared samples of birds dying to those that su...
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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 Neb...
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Animals often breed in colonies that can vary in size by several orders of magnitude. Colony-size variation is perplexing because individuals in some colony sizes have lower fitness than those in other colony sizes, yet extensive size variation persists in most populations. Natural variation in colony size has allowed us to better quantify the cost...
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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 t...
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Interspecific competition commonly selects for divergence in ecology, morphology or physiology, but direct observation of interspecific competition under natural conditions is difficult. Herbivorous white-tailed prairie dogs (Cynomys leucurus) employ an unusual strategy to reduce interspecific competition: they kill, but do not consume, herbivorous...
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The Cliff Swallow (Petrochelidon pyrrhonota) and the Barn Swallow (Hirundo rustica) occupy sympatric breeding ranges across much of North America, often nesting at colony sites that contain both species. Mixed-species nesting aggregations typically occur in box-shaped concrete culverts underneath roads or railways. Cliff Swallows’ enclosed mud nest...
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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 (...
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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 Nebr...
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When blood-feeding parasites increase seasonally, their deleterious effects may prevent some host species, especially those living in large groups where parasites are numerous, from reproducing later in the summer. Yet the role of parasites in regulating the length of a host's breeding season-and thus the host's opportunity for multiple brooding-ha...
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Episodes of food deprivation may change how nestling birds allocate energy to the growth of skeletal and feather morphological traits during development. Cliff swallows (Petrochelidon pyrrhonota) are colonial, insectivorous birds that regu­larly experience brief periods of severe weather–induced food deprivation during the nesting season which may...
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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 colon...
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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 dif...
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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 breed...
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A challenge in managing vector-borne zoonotic diseases in human and wildlife populations is predicting where epidemics or epizootics are likely to occur, and this requires knowing in part the likelihood of infected insect vectors dispersing pathogens from existing infection foci to novel areas. We measured prevalence of an arbovirus, Buggy Creek vi...
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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...
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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 co...
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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. W...
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An estimated 80 million birds are killed by colliding with vehicles on U. S. roads each year [1], and millions more die annually in Europe [2] and elsewhere. Losses to vehicles are a serious problem for which various changes in roadway design and maintenance have been proposed [3]. Yet, given the magnitude of the mortality reported for some species...
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Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption-as when certain members of the populati...
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Invasive species often display different patterns of parasite burden and virulence compared to their native counterparts. These differences may be the result of variability in host-parasite co-evolutionary relationships, the occurrence of novel host-parasite encounters, or possibly innate differences in physiological responses to infection between...
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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' fitne...
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Wild birds are rarely found with active arbovirus infections, and relatively little is known about the patterns of viremia they exhibit under field conditions or how infection varies with date, bird age, or other factors that potentially affect transmission dynamics. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an arbovirus associated with...
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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 wh...
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The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alp...
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Invasive species can disrupt natural disease dynamics by altering pathogen transmission among native hosts and vectors. The relatively recent occupancy of cliff swallow (Petrochelidon pyrrhonota) nesting colonies in western Nebraska by introduced European house sparrows (Passer domesticus) has led to yearly increases in the prevalence of an endemic...
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The encephalitic arthropod-borne viruses (arboviruses) can cause a variety of serious human and wildlife diseases, including eastern equine encephalomyelitis, western equine encephalomyelitis, St. Louis encephalitis, Japanese encephalitis, and West Nile neuroinvasive disease. Understanding how these pathogens are dispersed through the environment i...
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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 s...
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Determining the effect of an invasive species on enzootic pathogen dynamics is critical for understanding both human epidemics and wildlife epizootics. Theoretical models suggest that when a naive species enters an established host-parasite system, the new host may either reduce ('dilute') or increase ('spillback') pathogen transmission to native h...
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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, unus...
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Nestling birds are rarely sampled in the field for most arboviruses, yet they may be important in arbovirus amplification cycles. We sampled both nestling and adult house sparrows (Passer domesticus) in western Nebraska for West Nile virus (WNV) or WNV-specific antibodies throughout the summer of 2008 and describe pathology in naturally infected ne...
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Alphaviruses (Togaviridae) have rarely been found to persist for long in the adult insects that serve as their vectors. The ectoparasitic swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius Horvath), the vector for Buggy Creek virus (BCRV; Togaviridae, Alphavirus), lives year-round in the mud nests of its host, the cliff swallow (Petrochelidon pyr...
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Buggy Creek virus (BCRV; family Togaviridae, genus Alphavirus) is an arbovirus transmitted by the ectoparasitic swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) to cliff swallows (Petrochelidon pyrrhonota) and house sparrows (Passer domesticus). BCRV occurs in two lineages (A and B) that are sympatric in bird nesting colonies in the central Gr...
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Alphaviruses (Togaviridae) infect wild birds, but clinical illness and death attributable to virus in naturally infected birds is rarely reported, particularly for small passerine species or nestlings. Buggy Creek virus is a unique alphavirus in the Western equine encephalomyelitis virus (WEEV) complex that is vectored by the cimicid swallow bug (O...
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Most arthropod-borne viruses (arboviruses) show distinct serological subtypes or evolutionary lineages, with the evolution of different strains often assumed to reflect differences in ecological selection pressures. Buggy Creek virus (BCRV) is an unusual RNA virus (Togaviridae, Alphavirus) that is associated primarily with a cimicid swallow bug (Oe...
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A largely unanswered question in the study of arboviruses is the extent to which virus can overwinter in adult vectors during the cold winter months and resume the transmission cycle in summer. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an unusual arbovirus that is vectored primarily by the swallow bug (Hemiptera: Cimicidae: Oeciacus vica...
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We sampled 100 Cliff Swallows (Petrochelidon pyrrhonota), just after arrival in Nebraska breeding areas, to ascertain if migrating birds re-introduce Buggy Creek virus (BCRV; Togaviridae) to north-temperate localities in spring. Most birds sampled were previously banded and were known to have used parasite-free nesting colonies in past summers and/...
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Alphaviruses (Togaviridae) rarely have been found to be vertically transmitted from female arthropods to their progeny. We report two isolations of Buggy Creek virus (BCRV), an ecologically unusual alphavirus related to western equine encephalomyelitis virus, from field-collected eggs of cimicid swallow bugs (Oeciacus vicarius Horvath), the princip...
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Arboviruses have seldom been found overwintering in adult vectors at northern latitudes in North America. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an ecologically unusual arbovirus vectored principally by the cimicid swallow bug (Oeciacus vicarius Horvath). The ectoparasitic bugs reside year-round in the mud nests of their host, the cli...
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Un determinante potencial del tamaño de las colonias de aves es la disponibilidad local de alimento en el área de nidificación. La golondrina Petrochelidon pyrrhonota es una especie insectívora que nidifica en el sur oeste de Nebraska (USA) en colonias que fluctuan entre 2 y más de 3000 nidos. Estas golondrinas se alimentan de una gran variedad de...
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Utilizamos análisis de captura y recaptura para describir la supervivencia de juveniles y adultos entre 1993 y 2001 en una población de Philetairus socius, una especie de ave paserina colonial con cría cooperativa del sur de África. Examinamos la variación temporal en la supervivencia, y la importancia de la longitud del período de apareamiento y d...
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Explaining why breeding colonies vary in size has been a persistent problem in the study of animal spatial distribution. One hypothesis is that colony size reflects local food availability, which may be affected by the number of conspecifics feeding in a given area. We investigated whether colony size in Cliff Swallows (Petrochelidon pyrrhonota) wa...
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Researchers commonly collect blood samples from wild birds, and most workers assume that blood sampling has no adverse effect on the birds’ survival. Few studies, however, have done controlled comparisons among bled and non-bled individuals and estimated survival using modern statistical methodology. We used a data set on Cliff Swallows (Petrocheli...
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Deriving from a workshop held in 2005, this book brings together much of the work being done on chickadees and titmice in North America. Seventeen chapters by leading North American parid biologists address the neurobiology and endocrinology of spatial behavior and food caching, photoperiodism, timing of reproduction, phylogeography, hybridization,...
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During a 25-year study of Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, we observed Lithobates catesbeianus prey on, or attempt to prey on, Cliff Swallows. As we were mist-netting Cliff Swallows at a 10-nest colony on 7 July 1998, a L. catesbeianus attempted to eat a Cliff Swallow that was caught in the net.
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Buggy Creek virus (BCRV) is an unusual arbovirus within the western equine encephalitis complex of alphaviruses. Associated with cimicid swallow bugs (Oeciacus vicarius) as its vector and the cliff swallow (Petrochelidon pyrrhonota) and house sparrow (Passer domesticus) as its amplifying hosts, this virus is found primarily in the western Great Pla...
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One probable cost of dispersing to a new breeding habitat is unfamiliarity with local conditions such as the whereabouts of food or the habits of local predators, and consequently immigrants may have lower probabilities of survival than more experienced residents. Within a breeding season, estimated daily survival probabilities of cliff swallows (P...
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Addressing evolutionary questions in the wild remains a challenge. It is best done by monitoring organisms from birth to death, which is very difficult in part because individuals may or may not be resighted or recaptured. Although the issue of uncertain detection has long been acknowledged in ecology and conservation biology, in evolutionary studi...