Jeffrey D. Brawn

University of Illinois, Urbana-Champaign | UIUC · Department of Natural Resources and Environmental Sciences

In a hybrid zone between two tropical lekking birds, yellow male plumage of one species has introgressed asymmetrically replacing white plumage of another via sexual selection. Here, we present a detailed analysis of the plumage trait to uncover its physical and genetic bases and trace its evolutionary history. We determine that the carotenoid lute...

Telomere lengths and telomere dynamics can correlate with lifespan, behaviour and individual quality. Such relationships have spurred interest in understanding variation in telomere lengths and their dynamics within and between populations. Many studies have identified how environmental processes can influence telomere dynamics, but the role of gen...

Declines in body size can be an advantageous physiological response to warming temperatures, or a result of physiological and nutritional stress. Either way, studies often assume that these climate‐induced trait changes have important implications for fitness and demography. We leveraged almost three decades of capture‐mark‐recapture data of 51 bir...

Hybrid zones are dynamic systems where natural selection, sexual selection, and other evolutionary forces can act on reshuffled combinations of distinct genomes. The movement of hybrid zones, individual traits, or both are of particular interest for understanding the interplay between selective processes. In a hybrid zone involving two lek-breeding...

The climate variability hypothesis posits that an organism's exposure to temperature variability determines the breadth of its thermal tolerance and has become an important framework for understanding variation in species' susceptibilities to climate change. For example, ectotherms from more thermally stable environments tend to have narrower therm...

Jennie Duberstein In 2023, the American Ornithological Society (AOS) ­introduced a Conservation Practitioner Award, which recognizes individuals or groups of biologists at any stage of their career for outstanding work in government agencies (from municipal, state, provincial, federal, or international levels) or nongovernmental organizations to ­f...

Lisa Sorenson Stanley Senner The American Ornithological Society (AOS) Schreiber Award honors extraordinary conservation-related scientific contributions by an individual or small team. Contributions from throughout the world and over any time period are eligible for this award, including applied research, restoration, and educational actions that...

A bstract Hybrid zones are dynamic systems where natural selection, sexual selection, and other evolutionary forces can act on reshuffled combinations of distinct genomes. The movement of hybrid zones, individual traits, or both are of particular interest for understanding the interplay between selective processes. In a hybrid zone involving two le...

West Nile virus (WNV) is prevalent in the United States but shows considerable variation in transmission intensity. The purpose of this study was to compare patterns of WNV seroprevalence in avian communities sampled in Atlanta, Georgia and Chicago, Illinois during a 12-year period (Atlanta 2010–2016; Chicago 2005–2012) to reveal regional patterns...

In response to a growing need to foster ethical behavior within scientific societies, the American Ornithological Society’s (AOS) professional ethics committee conduct a survey of members in spring 2021 to identify the primary challenges and ethical conduct concerns. The survey indicated that the AOS has a strong culture of professional ethics and...

Torpor, the temporary reduction of metabolic rate and body temperature, is a common energy-saving strategy in endotherms. Because of their small body size and energetically demanding life histories, hummingbirds have proven useful for understanding when and why endotherms use torpor. Previous studies of torpor in hummingbirds have been largely limi...

Significance We leveraged a 44-y population study of Neotropical understory birds from a protected forest reserve in central Panama to document widespread and severe declines in bird abundance. Our findings provide evidence that tropical bird populations may be undergoing systematic declines, even in relatively intact forests. The implications of t...

The cover image is based on the Letter AVONET: morphological, ecological and geographical data for all birds by Tobias et al., https://doi.org/10.1111/ele.13898. The sword‐billed hummingbird (Ensifera ensifera) is exquisitely adapted to its trophic niche as an aerial pollinator of flowerings plants (angiosperms) in the high Andes. A new global data...

Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species-level information is complete. Here we present the AVON...

Life history studies have established that trade-offs between growth and survival are common both within and among species. Identifying the factor(s) that mediate this trade-off has proven difficult, however, especially at the among-species level. In this study, we examined a series of potentially interrelated traits in a community of temperate-zon...

en Recently fledged birds often experience low survival as they undergo rapid changes in their behavior, (e.g., habitat use, mobility, and foraging rate). For species of conservation concern, information about the post-fledging period can be critical for effective management and conservation. We investigated the post-fledging ecology of endangered...

Avian species across diverse lineages collect and incorporate mammalian hair into their nests (Tóth 2008). This widespread behavior can be adaptive, as hair, fur or wool insulates nests and so enhances nestling survival and recruitment in colder climates (Hilton et al. 2004, Mainwaring et al. 2014, Järvinen and Brommer 2020, Deeming et al. 2020; re...

Synopsis Many animal species have evolved extreme behaviors requiring them to engage in repeated high-impact collisions. These behaviors include mating displays like headbutting in sheep and drumming in woodpeckers. To our knowledge, these taxa do not experience any notable acute head trauma, even though the deceleration forces would cause traumati...

Rainfall regime, the amount and timing of annual precipitation, can influence the breeding phenology, individual fitness, and population dynamics of tropical birds. In Neotropical regions with rainfall seasonality (i.e. wet and dry seasons), the warm phase of the El Niño Southern Oscillation (ENSO) can exacerbate seasonal drought and negatively imp...

Significance Parent–offspring conflict has explained a variety of ecological phenomena across animal taxa, but its role in mediating when songbirds fledge remains controversial. Our analysis of nesting and postfledging survival rates within 18 songbird species found that offspring commonly leave safer nesting environments for riskier postfledging o...

The Tufted Titmouse Baeolophus bicolor is well known for its stereotyped “peter-peter-peter” song, but anecdotal reports of its song’s diversity also exist. We identified an atypical song in East-Central Illinois, USA, that has persisted for several years in the same vicinity. We used a spectrogram-based comparison metric to assess song similarity...

Characterizing heat tolerance is critical for predicting an organism's vulnerability to climate warming. Recent studies of ectotherms report that impacts of climate warming are expected to be greater in the tropics, where ectotherms tend to have lower heat tolerances and experience air temperatures closer to their heat tolerance limits than their t...

Biotic selective pressures dominate explanations for the evolutionary ecology of tropical endotherms. Yet, abiotic factors, principally precipitation regimes, shape biogeographical and phenological patterns in tropical regions. Despite its importance, we lack a framework for understanding when, why, and how rain affects endotherms. Here, we review...

en Ecological disturbance is an important factor that influences the abundance and distribution of species. Treefalls are a prominent source of disturbance in tropical forests, but robust characterization of community change after treefalls requires baseline data that are often not available. We capitalized on 25 yr of avian mark–recapture data fro...

Haemosporidian parasites are widespread in birds and are commonly used to evaluate ecological, evolutionary, and behavioral consequences of pathogen infection. While haemosporidian parasites may be important agents of selection, information on the incidence and outcomes of infection in many wild birds remains incomplete and warrants further inquiry...

Phenotypic flexibility can be an important determinant of fitness in variable environments. The climatic variability hypothesis (CVH) predicts that phenotypic flexibility in thermoregulatory traits will be greater in temperate species than tropical species as a means of coping with increased temperature seasonality at higher latitudes. However, sup...

Most species are distributed such that their density and occupancy is greatest in one habitat, although they are found in other habitats. For example, a species with a high affinity for forests (its primary habitat) may also use urban areas and shrublands (its alternative habitat), although occupancy of these habitats would be lower. While habitat...

Arthropod-borne viruses are among the most genetically constrained RNA viruses, yet they have a remarkable propensity to adapt and emerge. We studied wild birds and mosquitoes naturally infected with West Nile virus (WNV) in a 'hot spot' of virus transmission in Chicago, IL, USA. We generated full coding WNV genome sequences from spatiotemporally m...

Logistical and technological limitations have constrained the characterization of behavioural development in songbirds, particularly during the post-fledging period. Recently, advances in radio-telemetry technology- A utomated radio-telemetry systems (ARTS) capable of recording continuous, high-resolution spatial-temporal data on radio-tagged birds...

Biodiversity at tropical latitudes is notably great and increasingly threatened by habitat loss and the direct or indirect effects of climate change. Estimates vary but there is reasonably strong evidence that current rates of species extinction and local extirpations are historically high and increasing. Habitat loss and fragmentation owing to agr...

Effective habitat management requires understanding habitat needs across a species' life history stages. In songbirds, management of breeding habitat is generally focused on the pre-nesting and nesting stages, while habitat use during the critical post-fledging stage remains understudied and is seldom a target for management. In 2014 and 2015, we d...

Culex flavivirus (CxFV) is an insect-specific flavivirus infecting Culex mosquitoes, which are important vectors of West Nile virus (WNV). CxFV and WNV cocirculate in nature and coinfect Culex mosquitoes, including in a WNV "hotspot" in suburban Chicago. We previously identified a positive association between CxFV and WNV in mosquito pools collecte...

Phenotypic traits developed in one life-history stage can carryover and affect survival in subsequent stages. For songbirds, carryover effects from the pre- to post-fledging period may be crucial for survival but are poorly understood. We assessed whether juvenile body condition and wing development at fledging influenced survival during the post-f...

Biodiversity in tropical regions is particularly high and may be highly sensitive to climate change. Unfortunately, a lack of long-term data hampers understanding of how tropical species, especially animals, may react to projected environmental changes. The amount and timing of rainfall is key to the function of tropical ecosystems and, although sp...

Multiple vector-borne pathogens often circulate in the same vector and host communities, and seasonal infection dynamics influence the potential for pathogen interactions. Here, we explore the seasonal infection patterns of avian malaria (Haemosporida) parasites (genera: Plasmodium and Parahaemoproteus) and West Nile virus (WNV) in birds and mosqui...

The prevalence of vector-borne parasites varies greatly across host species, and this heterogeneity has been used to relate infectious disease susceptibility to host species traits. However, a few empirical studies have directly associated vector-borne parasite prevalence with exposure to vectors across hosts. Here, we use DNA sequencing of blood m...

Examining physiological traits across large spatial scales can shed light on the environmental factors driving physiological variation. For endotherms, flexibility in aerobic metabolism is especially important for coping with thermally challenging environments and recent research has shown that aerobic metabolic scope [the difference between maximu...

Local abiotic conditions (microclimates) vary spatially and selection of favorable microclimates within a habitat can influence an animal’s energy budgets, behavior, and ultimately, fitness. Insectivorous birds that inhabit the understory of tropical forests may be especially sensitive to environmental variation and may select habitat based on micr...

Social cues are often used by birds when selecting breeding habitats, however, little is known about the timing and influence of social cues within or across seasons. The ontogeny of social information within newly available habitat is essentially unknown and potentially relevant to habitat management, as the primary approach of many conservation i...

Antibody duration, following a humoral immune response to West Nile virus (WNV) infection, is poorly understood in free-ranging avian hosts. Quantifying antibody decay rate is important for interpreting serologic results and for understanding the potential for birds to serorevert and become susceptible again. We sampled free-ranging birds in Chicag...

Multiple mosquito-borne parasites cocirculate in nature and potentially interact. To understand the community of parasites cocirculating with West Nile virus (WNV), we screened the bloodmeal content of Culex pipiens L. mosquitoes for three common types of hemoparasites. Blood-fed Cx. pipiens were collected from a WNV-epidemic area in suburban Chica...

Animals can decrease their individual risk of predation by forming groups. The encounter-dilution hypothesis extends the potential benefits of gregariousness to biting insects and vector-borne disease by predicting that the per capita number of insect bites should decrease within larger host groups. Although vector-borne diseases are common and can...

Various ecological and physiological mechanisms might influence the probability that two or more pathogens may simultaneously or sequentially infect a host individual. Concurrent infections can have important consequences for host condition and fitness, including elevated mortality risks. In addition, interactions between coinfecting pathogens may...

Nesting success and avian communities were compared between tilled and no-till soybean fields in Illinois. No-till had greater densities of birds than tilled fields, and the overall community in no-till was of greater conservation value due to more grassland birds using no-till compared with tilled fields. Nesting density was greater in no-till (4....

Author Summary The distance and direction of adult mosquitoes movement on the landscape are important processes in the spread of mosquito-borne diseases, and are critical to understand to the development of effective intervention programs. Here we present a novel approach to study adult mosquito dispersal by using stable isotope enrichment of natur...

Aviation safety is an important concern in wildlife management as bird strikes risk human lives and result in costly damage. Habitat management can decrease bird abundances locally at airports. We tested soil manipulation as a technique to reduce local bird presence by establishing experimental plots with either intact topsoil or "stripped" subsoil...

Hosts are commonly infected with a suite of parasites, and interactions among these parasites can affect the size, structure, and behavior of host–parasite communities. As an important step to understanding the significance of co-circulating parasites, we describe prevalence of co-circulating hemoparasites in two important avian amplification hosts...

The occurrence of extrapair paternity (EPP) in socially monogamous species varies greatly among species and across latitudes. Recent work suggests that birds residing in less seasonal, tropical environments will have lower levels of EPP than seasonal tropical and temperate species. Less seasonal tropical birds are predicted to have the lowest rates...

Researchers often attach radio transmitters and other devices to free-living birds without a clear understanding of the possible consequences for their study organisms or their data. Although transmitters may affect parental investment (nest defense and offspring provisioning), this possibility has received little attention. We tested this hypothes...

Bird-facilitated introduction of ticks and associated pathogens is postulated to promote invasion of tick-borne zoonotic diseases into urban areas. Results of a longitudinal study conducted in suburban Chicago, Illinois, USA, during 2005–2010 show that 1.6% of 6,180 wild birds captured in mist nets harbored ticks. Tick species in order of abundance...

Grassland birds are known to use conspecific cues during the breeding season but use of public information among grassland heterospecifics has not been investigated. While studying conspecific behavior in Grasshopper Sparrows (Ammodramus savannarum) in Central Illinois in 2011, we observed significantly higher densities of Eastern Meadowlarks (Stur...

Many species of tropical birds have prolonged incubation periods compared to other tropical species and to most species in temperate latitudes. One hypothesis for prolonged incubation is that these tropical species reduce nest attendance to minimize the risk of predation. The resulting decrease in average egg temperature would reduce embryo growth...

United States military bases provide habitat for a diverse suite of wildlife species despite intense anthropogenic disturbance inherent in training activities. Little research has examined how military activity affects wildlife reproduction. We compared parental investment, reproductive success, offspring and adult quality, and stress hormone conce...

Suboscine passerine birds are one of the most prominent components of Neotropical avifaunas, yet they remain relatively poorly studied in comparison with their sister-clade, the oscine passerines. This situation appears to be changing rapidly as more ornithologists realize that suboscine birds offer ideal study systems for investigating a variety o...

This file includes additional methodological descriptions regarding mosquito collection, laboratory diagnostics, and avian host surveys. (DOC)

This file contains host species force of infection values which represent the number of infectious Cx. pipiens mosquitoes resulting from feeding on each host species. (DOC)

This file contains the diagnostic plots (residuals and Q-Q plot) for the statistical models. (DOC)

This file is a table of Cx. pipiens host selection ratios for each host species at 11 field sites in southwest suburban Chicago, Illinois. (DOC)

The influence of host diversity on multi-host pathogen transmission and persistence can be confounded by the large number of species and biological interactions that can characterize many transmission systems. For vector-borne pathogens, the composition of host communities has been hypothesized to affect transmission; however, the specific characte...

Culex flavivirus (CxFV) is an insect-specific flavivirus globally distributed in mosquitoes of the genus Culex. CxFV was positively associated with West Nile virus (WNV) infection in a case-control study of 268 mosquito pools from an endemic focus of WNV transmission in Chicago, United States. Specifically, WNV-positive Culex mosquito pools were fo...

The factors that affect survival until reproduction are essential to understanding the organization of life histories within and among species. Theory predicts, for example, that survival until reproduction influences the optimum level of reproductive investment by parents, which might partly explain prolonged parental care in species with high fir...

Survival of offspring is a key fitness component and, for birds, the threat of predation on nests is especially influential. Data on rates of nest success from tropical regions are comparatively few, conservation-relevant, and essential for assessing the validity of models comparing the life histories and behavior or birds across latitudinal gradie...

We investigated how variation in the timing and amount of annual precipitation influenced annual variation in the fecundity of the Spotted Antbird (Hylophylax naevioides) in central Panama from 1998 to 2001. The onset of nesting varied significantly by year and corresponded with a notably strong episode of El Niño–Southern Oscillation that generate...