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Documenting patterns of spatiotemporal change in hyper-diverse communities remains a challenge for tropical ecology yet is increasingly urgent as some long-term studies have shown major declines in bird communities in undisturbed sites. In 1982, Terborgh et al. quantified the structure and organisation of the bird community in a 97-ha. plot in southeastern Peru. We revisited the same plot in 2018 using the same methodologies as the original study to evaluate community-wide changes. Contrary to longitudinal studies of other neotropical bird communities (Tiputini, Manaus, and Panama), we found little change in community structure and organisation, with increases in 5, decreases in 2 and no change in 7 foraging guilds. This apparent stability suggests that large forest reserves such as the Manu National Park, possibly due to regional topographical influences on precipitation, still provide the conditions for establishing refugia from at least some of the effects of global change on bird communities.

Natal dispersal is a crucial life-history trait that affects both individual fitness and population structure, yet drivers of variation in dispersal probability and distance are difficult to study in wild populations. In cooperatively breeding species, individuals typically delay dispersal beyond their first breeding season and remain on the natal territory as nonbreeders, which prolongs social dynamics that can affect dispersal decisions. Using a 35-year data set covering almost 600 dispersal events in the cooperatively breeding Florida scrub-jay (Aphelocoma coerulescens), we examined the environmental and social parameters that predict dispersal probability over time and distance. In both sexes, dispersal probability increased with age, which, in turn, was negatively correlated with dispersal distance. In males, individuals occupying low-quality natal territories and living with a stepfather had an increased probability of dispersal. Older and more dominant males were more likely to inherit their natal territory. In females, which generally disperse earlier and farther than males, socially subordinate jays dispersed farther than dominant ones. Overall, jays that delayed dispersal the longest were more likely to attain breeding status near their natal territory, which was previously found to be associated with increased survival and lifetime fitness. Our results suggest that social dynamics and environmental factors on the natal territory affect delayed dispersal patterns differently for the two sexes in this cooperative breeder.

Understanding the genomic consequences of population decline is important for predicting species' vulnerability to intensifying global change. Empirical information about genomic changes in populations in the early stages of decline, especially for those still experiencing immigration, remains scarce. We used 7834 autosomal SNPs and demographic data for 288 Florida scrub jays (

Accurate maps of species ranges are essential to inform conservation, but time-consuming to produce and update. Given the pace of change of knowledge about species distributions and shifts in ranges under climate change and land use, a need exists for timely mapping approaches that enable batch processing employing widely available data. We develop a systematic approach of batch-processing range maps and derived Area of Habitat maps for terrestrial bird species with published ranges below 125,000 km2 in Central and South America. (Area of Habitat is the habitat available to a species within its range.) We combine existing range maps with the rapidly expanding crowd-sourced eBird data of presences and absences from frequently surveyed locations, plus readily accessible, high resolution satellite data on forest cover and elevation to map the Area of Habitat available to each species. Users can interrogate the maps produced to see details of the observations that contributed to the ranges. Previous estimates of Areas of Habitat were constrained within the published ranges and thus were, by definition, smaller—typically about 30%. This reflects how little habitat within suitable elevation ranges exists within the published ranges. Our results show that on average, Areas of Habitat are 12% larger than published ranges, reflecting the often-considerable extent that eBird records expand the known distributions of species. Interestingly, there are substantial differences between threatened and non-threatened species. Some 40% of Critically Endangered, 43% of Endangered, and 55% of Vulnerable species have Areas of Habitat larger than their published ranges, compared with 31% for Near Threatened and Least Concern species. The important finding for conservation is that threatened species are generally more widespread than previously estimated.

Sex-biased demography, including sex-biased survival or migration, can impact allele frequency changes across the genome. In particular, we can expect different patterns of genetic variation on autosomes and sex chromosomes due to sex-specific differences in life histories, as well as differences in effective population size, transmission modes, and the strength and mode of selection. Here, we demonstrate the role that sex differences in life history played in shaping short-term evolutionary dynamics across the genome. We used a 25-year pedigree and genomic dataset from a long-studied population of Florida Scrub-Jays (Aphelocoma coerulescens) to directly characterize the relative roles of sex-biased demography and inheritance in shaping genome-wide allele frequency trajectories. We used gene dropping simulations to estimate individual genetic contributions to future generations and to model drift and immigration on the known pedigree. We quantified differential expected genetic contributions of males and females over time, showing the impact of sex-biased dispersal in a monogamous system. Due to female-biased dispersal, more autosomal variation is introduced by female immigrants. However, due to male-biased transmission, more Z variation is introduced by male immigrants. Finally, we partitioned the proportion of variance in allele frequency change through time due to male and female contributions. Overall, most allele frequency change is due to variance in survival and births. Males and females have similar contributions to autosomal allele frequency change, but males have higher contributions to allele frequency change on the Z chromosome. Our work shows the importance of understanding sex-specific demographic processes in accounting for genome-wide allele frequency change in wild populations.

In disturbance-prone ecosystems, fitness consequences of plant reproductive strategies are often determined by the relative timing of seed production and disturbance events, but the role of disturbances as proximate drivers of seed production has been overlooked. We use long-term data on seed production in Quercus chapmanii , Q. geminata and Q. inopina , rhizomatous oaks found in south central Florida's oak scrub, to investigate the role of fire history and its interaction with weather in shaping acorn production and its synchrony . Acorn production increased with the time since last fire, combined with additive or interactive effects of spring precipitation (+) or drought (–). Furthermore, multiple matrix regression models revealed that ramet pairs with shared fire history were more synchronous in seed production than ones that burned in different years. Long-term trends suggest that increasingly drier spring weather, in interaction with fire frequency, may drive a decline of seed production. Such declines could affect the community of acorn-reliant vertebrates in the Florida scrub, including endangered Florida scrub-jays ( Aphelocoma coerulescens ). These results illustrate that fire can function as a proximate driver of seed production in mast-seeding species, highlighting the increasingly recognized importance of interactions among reproductive strategies and disturbance regimes in structuring plant populations and communities. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

Why unrelated members form groups in animal societies remains a pertinent topic in evolutionary biology because benefits for group members often are not obvious. We studied subordinates that disperse to join unrelated social groups in the Florida scrub-jay Aphelocoma coerulescens, a cooperative breeding species mainly composed of kin-based groups. We evaluated potential adaptive benefits of dispersing to become an unrelated helper (staging) versus remaining home and dispersing only to pair and breed (direct dispersal) to understand why non-kin-based groups form. Using 35 years of demographic data, we quantified life-history aspects of staging individuals and tested associations between social and ecological factors on the natal and staging territories. We compared fitness outcomes between dispersal strategies by analysing survival, breeding recruitment and direct reproductive output. We tested for sexual asymmetry potentially driven by differences in territory acquisition patterns and female-biased dispersal for this species. Of birds that reached 1 year, 28% staged at a non-natal territory before breeding or disappearing. Staging dispersers departed at younger ages and moved greater distances than direct dispersers. When looking at proximate factors on the natal territory associated with staging, males left groups with many same-sex helpers, while females often left when their father disappeared. For both sexes, staging individuals more likely came from high-quality territories and joined groups with fewer same-sex helpers than in their natal group. While staging and direct dispersers did not differ in survival or likelihood of becoming a breeder, staging males became breeders later and had lower lifetime reproductive success than direct dispersers. In Florida scrub-jays, staging appears to be an alternative strategy for female helpers, but a best-of-a-bad-situation for males. This sexual asymmetry is consistent with males having more options than females to achieve higher reproductive success by breeding near home. Trade-offs in cost-benefits of departing the natal territory and joining unrelated groups as a helper seem to best explain alternative dispersal patterns, with optimal social queues primarily driving the benefits. This research highlights plasticity in dispersal behaviour in response to social and environmental conditions and offers a new perspective in our understanding of non-kin-based social groups.

Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity1–4. Sparse taxon sampling has previously been proposed to confound phylogenetic inference5, and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families—including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species., A dataset of the genomes of 363 species from the Bird 10,000 Genomes Project shows increased power to detect shared and lineage-specific variation, demonstrating the importance of phylogenetically diverse taxon sampling in whole-genome sequencing.

A central goal of population genetics is to understand how genetic drift, natural selection, and gene flow shape allele frequencies through time. However, the actual processes underlying these changes—variation in individual survival, reproductive success, and movement—are often difficult to quantify. Fully understanding these processes requires the population pedigree, the set of relationships among all individuals in the population through time. Here, we use extensive pedigree and genomic information from a long-studied natural population of Florida Scrub-Jays ( Aphelocoma coerulescens ) to directly characterize the relative roles of different evolutionary processes in shaping patterns of genetic variation through time. We performed gene dropping simulations to estimate individual genetic contributions to the population and model drift on the known pedigree. We found that observed allele frequency changes are generally well predicted by accounting for the different genetic contributions of founders. Our results show that the genetic contribution of recent immigrants is substantial, with some large allele frequency shifts that otherwise may have been attributed to selection actually due to gene flow. We identified a few SNPs under directional short-term selection after appropriately accounting for gene flow. Using models that account for changes in population size, we partitioned the proportion of variance in allele frequency change through time. Observed allele frequency changes are primarily due to variation in survival and reproductive success, with gene flow making a smaller contribution. This study provides one of the most complete descriptions of short-term evolutionary change in allele frequencies in a natural population to date.

Montane species worldwide are shifting upslope in response to recent temperature increases. These upslope shifts are predicted to lead to mountaintop extinctions of species that live only near mountain summits, but empirical examples of populations that have disappeared are sparse. We show that recent warming constitutes an “escalator to extinction” for birds on a remote Peruvian mountain—high-elevation species have declined in both range size and abundance, and several previously common mountaintop residents have disappeared from the local community. Our findings support projections that warming will likely drive widespread extirpations and extinctions of high-elevation taxa in the tropical Andes. Such climate change-driven mountaintop extirpations may be more likely in the tropics, where temperature seems to exert a stronger control on species’ range limits than in the temperate zone. In contrast, we show that lowland bird species at our study site are expanding in range size as they shift their upper limits upslope and may thus benefit from climate change.

In Supplementary Table 1 of this Article, 23 samples (B10K-DU-029-32, B10K-DU-029-33, B10K-DU-029-36 to B10K-DU-029-44, B10K-DU- 029-46, B10K-DU-029-47, B10K-DU-029-49 to B10K-DU-029-53, B10K-DU- 029-75 to B10K-DU-029-77, B10K-DU-029-80, and B10K-DU-030-03; styled in boldface in the revised table) were assigned to the incorrect institution. Supplementary Table 1 has been amended to reflect the correct source institution for these samples, and associated data (tissue, museum ID/source specimen ID, site, state/province, latitude, longitude, date collected and sex) have been updated accordingly. The original table is provided as Supplementary Information to this Amendment, and the original Article has been corrected online.

Early rearing conditions can have profound short- and long-term effects on survival and reproduction of vertebrates. In cooperatively breeding birds, where variable social conditions interact with other sources of environmental variation, fitness consequences of the natal environment are of particular interest. We used data from a long-term study of the Florida Scrub-Jay (Aphelocoma coerulescens) to examine how characteristics of the natal brood, territory, and social group interacted to influence future survival and reproduction. Nestling and juvenile body mass were significant positive predictors of survival from fledging through the first year of life. The area of oak scrub in the natal territory correlated positively with nestling and juvenile body mass and had two long-term consequences: it was positively related to the probability of becoming a breeder and negatively related to age at first breeding, particularly for males. Effects of natal group size were complex and partially dependent on...

Citizen science, big data, and a habitat marketplace enable dynamic habitat for migratory birds in California’s Central Valley., In an era of unprecedented and rapid global change, dynamic conservation strategies that tailor the delivery of habitat to when and where it is most needed can be critical for the persistence of species, especially those with diverse and dispersed habitat requirements. We demonstrate the effectiveness of such a strategy for migratory waterbirds. We analyzed citizen science and satellite data to develop predictive models of bird populations and the availability of wetlands, which we used to determine temporal and spatial gaps in habitat during a vital stage of the annual migration. We then filled those gaps using a reverse auction marketplace to incent qualifying landowners to create temporary wetlands on their properties. This approach is a cost-effective way of adaptively meeting habitat needs for migratory species, optimizes conservation outcomes relative to investment, and can be applied broadly to other conservation challenges.

Geographically limited dispersal can shape genetic population structure and result in a correlation between genetic and geographic distance, commonly called isolation-by-distance. Despite the prevalence of isolation-by-distance in nature, to date few studies have empirically demonstrated the processes that generate this pattern, largely because few populations have direct measures of individual dispersal and pedigree information. Intensive, long-term demographic studies and exhaustive genomic surveys in the Florida Scrub-Jay (Aphelocoma coerulescens) provide an excellent opportunity to investigate the influence of dispersal on genetic structure. Here, we used a panel of genome-wide SNPs and extensive pedigree information to explore the role of limited dispersal in shaping patterns of isolation-by-distance in both sexes, and at an exceedingly fine spatial scale (within ~10 km). Isolation-by-distance patterns were stronger in male-male and male-female comparisons than in female-female comparisons, consistent with observed differences in dispersal propensity between the sexes. Using the pedigree, we demonstrated how various genealogical relationships contribute to fine-scale isolation-by-distance. Simulations using field-observed distributions of male and female natal dispersal distances showed good agreement with the distribution of geographic distances between breeding individuals of different pedigree relationship classes. Furthermore, we built coalescent simulations parameterized by the observed dispersal curve, population density, and immigration rate, and showed how incorporating these extensions to Malécot’s theory of isolation-by-distance allows us to accurately reconstruct observed sex-specific isolation-by-distance patterns in autosomal and Z-linked SNPs. Therefore, patterns of fine-scale isolation-by-distance in the Florida Scrub-Jay can be well understood as a result of limited dispersal over contemporary timescales., Author summary Dispersal is a fundamental component of the life history of most organisms and therefore influences many biological processes. Dispersal is particularly important in creating genetic structure on the landscape. We often observe a pattern of decreased genetic relatedness between individuals as geographic distances increases, or isolation-by-distance. This pattern is particularly pronounced in organisms with extremely short dispersal distances. Despite the ubiquity of isolation-by-distance patterns in nature, there are few examples that explicitly demonstrate how limited dispersal influences spatial genetic structure. Here we investigate the processes that result in spatial genetic structure using the Florida Scrub-Jay, a bird with extremely limited dispersal behavior and extensive genome-wide data. We take advantage of the long-term monitoring of a contiguous population of Florida Scrub-Jays, which has resulted in a detailed pedigree and measurements of dispersal for hundreds of individuals. We show how limited dispersal results in close genealogical relatives living closer together geographically, which generates a strong pattern of isolation-by-distance at an extremely small spatial scale (

James A. Mills et al.-- Letter.

Habitat gap size has been negatively linked to movement probability in several species occupying fragmented landscapes. How these effects on movement behaviour in turn affect the genetic structure of fragmented populations at local scales is less well known. We tested, and confirmed, the hypothesis that genetic differentiation among adjacent populations of Florida scrub jays—an endangered bird species with poor dispersal abilities and a high degree of habitat specialization—increases with the width of habitat gaps separating them. This relationship was not an artefact of simple isolation-by-distance, as genetic distance was not correlated with the Euclidean distance between geographical centroids of the adjacent populations. Our results suggest that gap size affects movement behaviour even at remarkably local spatial scales, producing direct consequences on the genetic structure of fragmented populations. This finding shows that conserving genetic continuity for specialist species within fragmented habitat requires maintenance or restoration of preserve networks in which habitat gaps do not exceed a species-specific threshold distance.

With upcoming global wind-energy build-out estimated in millions of units, cumulative environmental impacts must be considered and understood to promote responsible expansion of this renewable energy source. In June 2009, 30 wildlife scientists convened in Racine, Wisconsin, USA to identify key research priorities concerning wind energy's potential impacts on migratory wildlife (birds and bats). This working group suggested 4 areas where improved science is most needed to evaluate the impacts of wind-energy development on migrating animals more accurately than can be accomplished today: 1) standardized protocols and definitions; 2) new methods and models for assessing and forecasting risk; 3) documenting lethal and sub-lethal effects at existing wind facilities; and 4) improved facility-site access, data access, and data management for researchers. Focused research based on these priorities will both quantify potential risks associated with wind-energy development and help derive science-based, peer-reviewed, best-management practices for existing and future wind projects. © 2011 The Wildlife Society.

Biodiversity conservation in an era of global change and scarce funding benefits from approaches that simultaneously solve multiple problems. Here, we discuss conservation management of the island scrub-jay (Aphelocoma insularis), the only island-endemic passerine species in the continental United States, which is currently restricted to 250-square-kilometer Santa Cruz Island, California. Although the species is not listed as threatened by state or federal agencies, its viability is nonetheless threatened on multiple fronts. We discuss management actions that could reduce extinction risk, including vaccination, captive propagation, biosecurity measures, and establishing a second free-living population on a neighboring island. Establishing a second population on Santa Rosa Island may have the added benefit of accelerating the restoration and enhancing the resilience of that island's currently highly degraded ecosystem. The proactive management framework for island scrub-jays presented here illustrates how ...

The Imperial Woodpecker (Campephilus imperialis) of Mexico—the largest woodpecker in the world—probably became extinct in the late 20th century, without known documentation of the species in life. We describe a recently discovered 16-mm color film of an Imperial Woodpecker taken in 1956 by William L. Rhein. The film documents climbing strides, launches, flights, and foraging of one female Imperial Woodpecker. For perches and foraging the woodpecker used dead or recently dead Durango Pines (Pinus durangensis). Trunks of perch and foraging trees were of the largest diameters available in this tree species. After allowing for possible inaccuracies in the frame speed of the film, we found that the Imperial Woodpecker had slow climbing strides and a fast wingflap rate compared with other woodpeckers. Following landmarks documented during the 1956 expedition, we identified and surveyed the film site in 2010. The site was in coniferous forest in lightly undulating terrain at 2,700–2,900 m elevation. In...

Variation in ecological and demographic characteristics may alter the value of extrapair paternity (EPP) for socially monogamous species, thereby leading to variation in mating strategies among conspecific populations. Environmental factors influencing the need for parental care, and demographic factors influencing relatedness of social pairs or availability of unrelated extrapair partners, are both predicted to influence the direct and indirect benefits of EPP in cooperatively breeding birds. We examined genetic mating strategies in 3 long-term study populations of cooperatively breeding Florida scrub-jays (FSJs; Aphelocoma coerulescens) in which the value of EPP—or opportunities for it—was likely to vary: a fragmented site with a high frequency of inbreeding (potentially elevating the value of EPP as a means of increasing offspring heterozygosity); a suburban population with high rates of brood reduction (potentially elevating the value of shared parental investment); and a wildland site with a high frequency of unrelated breeders and opposite-sex auxiliaries (potentially elevating the opportunity for shared within-group parentage). Despite these differences, genetic monogamy dominated at all sites: 100% of the offspring sampled from the suburban site (144 offspring) and fragmented site (258 offspring), and 99.5% of offspring from the wildland site (367 of 369 offspring) were produced monogamously. Rare exceptions in our study populations demonstrate that, even in the FSJ, genetic monogamy is a plastic trait. The near ubiquity of genetic monogamy across 3 ecologically different study sites, however, suggests that this tendency toward monogamy is impervious to the population-level environmental and social variation that we documented. Key words: Aphelocoma coerulescens, extrapair paternity, Florida scrub-jay, genetic monogamy. [Behav Ecol]

The century-long debate over the meaning and utility of the subspecies concept has produced spirited print but only superficial consensus. I suggest that genuine consensus about subspecies is an impossible goal, because trinomial epithets will inevitably be applied to a heterogeneous mix of evolutionary phenomena, thereby precluding genuine standardization of the concept. Populations that have intermediate levels of phenotypic differentiation and geographic isolation from one another often fall into a region I refer to as the "zone of art," where even skilled experts can disagree about the validity of any one subspecific treatment. The trinomial system cannot accurately represent the kind of information now available about genetic and character variation across space. Instead, ever more accurate tools are being perfected for quantitative, standardized descriptions of variation. These analyses—not subspecies classifications—will keep providing new scientific insights into geographic variation. Eve...

Studies comparing dispersal in fragmented versus unfragmented landscapes show that habitat fragmentation alters the dispersal behavior of many species. We used two complementary approaches to explore Florida Scrub-Jay (Aphelocoma coerulescens) dispersal in relation to landscape fragmentation. First, we compared dispersal distances of color-marked individuals in intensively monitored continuous and fragmented landscapes. Second, we estimated effective dispersal relative to the degree of fragmentation (as inferred from two landscape indexes: proportion of study site covered with Florida Scrub-Jay habitat and mean distance to nearest habitat patch within each study site) by comparing genetic isolation-by-distance regressions among 13 study sites having a range of landscape structures. Among color-banded individuals, dispersal distances were greater in fragmented versus continuous landscapes, a result consistent with other studies. Nevertheless, genetic analyses revealed that effective dispersal decreases as the proportion of habitat in the landscape decreases. These results suggest that although individual Florida Scrub-Jays may disperse farther as fragmentation increases, those that do so are less successful as breeders than those that disperse short distances. Our study highlights the importance of combining observational data with genetic inferences when evaluating the complex biological and life-history implications of dispersal.

1. Using data on breeding birds from a 35-year study of Florida scrub-jays Aphelocoma coerulescens (Bosc 1795), we show that survival probabilities are structured by age, birth cohort, and maternal family, but not by sex. Using both accelerated failure time (AFT) and Cox proportional hazard models, the data are best described by models incorporating variation among birth cohorts and greater mortality hazard with increasing age. AFT models using Weibull distributions with the shape parameter > 1 were always the best-fitting models. 2. Shared frailty models allowing for family structure greatly reduce model deviance. The best-fitting models included a term for frailty shared by maternal families. 3. To ask how long a data set must be to reach qualitatively the same conclusions, we repeated the analyses for all possible truncated data sets of 2 years in length or greater. Length of the data set affects the parameter estimates, but not the qualitative conclusions. In all but three of 337 truncated data sets the best-fitting models pointed to same conclusions as the full data set. Shared frailty models appear to be quite robust. 4. The data are not adequate for testing hypotheses as to whether variation in frailty is heritable. 5. Substantial structured heterogeneity for survival exists in this population. Such structured heterogeneity has been shown to have substantial effects in reducing demographic stochasticity.

James A. Mills et al., The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers., C.T. was funded by the French Agence Nationale de la Recherche (grant ANR-12-ADAP-0006).

We examined the demographic consequences of road mortality in the cooperatively breeding Flor- ida Scrub-Jay ( Aphelocoma coerulescens ), a threatened species restricted to the oak scrub of peninsular Flor- ida. Between May 1986 and July 1995 we monitored the survival and reproductive success of a color-banded population of jays along a two-lane highway at Archbold Biological Station. Annual mortality of breeding adults was 0.38 on road territories, significantly higher than the rate of 0.23 for breeders on nonroad territo- ries. High mortality on road territories appeared to be a direct result of automobile traffic per se and not a consequence of road-induced changes in habitat characteristics. Mortality was especially high for immigrants without previous experience living along the road: in their first two years as breeders on road territories, na- ive immigrants experienced annual mortality of 0.50 and 0.45. From year 3 onward, however, annual mor- tality dropped to 0.29, not significantly different from the rate for birds on nonroad territories. This experi- ence-dependent decline in road mortality could be caused either by surviving jays learning to avoid automobiles or by selective mortality operating through time (demographic heterogeneity). Proximity to the road had no effect on nesting success beyond its indirect effects on breeder experience and group size. Because the mortality of 30- to 90-day-old fledglings was significantly higher on road territories than on nonroad ter- ritories, however, breeder mortality greatly exceeded production of yearlings on road territories. Roadside ter- ritories therefore are sinks that can maintain populations of Florida Scrub-Jays only via immigration. Be- cause Florida Scrub-Jays do not avoid roadside habitats and may even be attracted to them, road mortality presents a difficult challenge for the management and conservation of this threatened and declining species. Vida y Muerte en la Carretera: Consecuencias Demograficas de Mortalidad Asociada a la Carretera en la Urraca Azuleja de florida

Threatened Florida scrub–jays ( Aphelocoma coerulescens breed communally, are restricted to xeric sandy scrub habitat, generally disperse fewer than three territory diameters. Closely related Western scrub–jays ( A. californica ) do not breed communally, have a broader habitat range, disperse greater distances, and are not threatened. We compared the genetic structure of 445 individuals in 11 populations in Florida with 157 individuals in eight populations of Western scrub–jays. At ten microsatellite loci, Florida had 24 out of 47 total alleles, while Western scrub–jays had 44. The Florida populations were more differentiated ( G ST = 0.048) than were a set of five California populations ( G ST = 0.015). A randomization extension of a Mantel test showed a stronger correlation between geographic and Cavalli–Sforza genetic distances among Western than Florida populations. Neighbour–joining trees clustered Florida populations from the same sandy ridge systems, suggesting that habitat continuity is more important than geographic proximity in allowing gene flow and preventing differentiation. For Western populations, isolation by distance appears to be the major determinant of genetic structure. Our results suggest that contrasting genetic structures may arise between closely related species, as a result of differences in ecology and social system. Conserving extant genetic variation in Florida jays will require maintaining viable populations in each of the major sandy ridge systems.

Extensive behavioural and pedigree data on a colour-marked population of Florida scrub-jays (Aphelocoma coerulescens) suggested that this cooperatively breeding species is monogamous, with extremely rare exceptions in which males have two mates. We used multi-locus DNA fingerprinting to test these observations by determining genetic parentage. Despite restricted dispersal and high relatedness between behavioural parents and non-breeding members of the group, DNA fingerprints provided sufficient variability to determine parentage unambiguously in almost all cases. We found no evidence of extra-pair fertilisation of females or egg dumping, and confirmed a suspected case of polygyny in which a mother and daughter laid and incubated in the same nest. Our results confirm that detailed behavioural data allow accurate assignment of genetic parentage in this species. In Florida scrub-jays, large territory size may limit opportunities for cuckoldry, and persistent intense competition for limited breeding space may lead to low variance in the quality of established male breeders. These factors would reduce both the opportunity for, and benefits of engaging in extra-pair fertilisations. Delayed dispersal and cooperative breeding in this species have not evolved as avenues for direct reproduction by unpaired individuals.

Although predation and starvation are considered the prime causes of post-fledging mortality, uncertainty exists about the importance and timing of these two factors. Reproductive success in Florida Scrub-Jays (Aphelocoma coerulescens) is positively correlated with amount of oak scrub in a territory. Using ptilochronology, we assessed whether scrub-jay fledglings in different territories differed in nutritional condition, because differential nutritional condition could be responsible directly (starvation) or indirectly (depredation) for territory-specific mortality. We measured three indices of feather growth in young jays: feather total length was significantly positively related to proportion of a territory covered by open oak scrub, whereas the relationship between amount of oak scrub and feather mass or daily feather growth rate approached significance. These results suggest that nutritional condition plays a role in survival of young Florida Scrub-Jays and that relatively subtle differences in territory composition may contribute to variation in overall reproductive success.

We describe massive autumn migrations of dragonflies (Odonata) which occurred at Chicago, Illinois (14 September 1978), Cape May, New Jersey (11 September 1992), and Crescent Beach, Florida (3–5 September 1993). Estimated numbers of migrant dragonflies involved in these flights were approximately 1.2 million, >400,000, and 200,000, respectively. We also document other recent observations of large swarm migrations of dragonflies in eastern North America, review previous reports of this phenomenon, and compare these events to the flights at Chicago, Cape May and Crescent Beach. Records of large dragonfly migrations show several distinct patterns: (1) all reports fell between late July and mid-October, with a peak in September; (2) most of the large flights occurred along topographic leading lines such as coastlines and lakeshores; (3) massive swarm migrations generally followed the passage of synoptic-scale cold fronts; and (4) the common green darner (Anax junius) was the principal species involve...

To determine the generality of avian diversity patterns, we investigated patterns of elevational zonation shown by birds and mammals along the eastern slope of the Andes Mountains in southeastern Peru. The strong environmental gradient sampled, entirely within Peru's Manu National Park and Biosphere Reserve, supports highly diverse faunas. Elevational distributions of 901 bird species, 129 bat species, and twenty-eight species of native mice exhibit contrasting patterns in species richness, species composition, and species turnover. Birds and bats showed smooth declines of species richness with elevation, whereas the richness of mouse assemblages was unrelated to elevation. For all three groups, the greatest differences were between lowland and highland faunas, although cutoff points for this contrast varied among groups (≈ 500 m for birds, 750 m for bats, and 1000 m for mice). Differences in composition also separated bird and bat faunas on either side of c. 1400 m (the boundary between montance forest and cloud forest); for mice, this faunal transition may take place nearer to 2000 m. Bird and bat faunas lacked the more discrete zonations suggested for mouse assemblages, as indicated by elevational range profiles and nested subset analyses. Distinct highland assemblages are apparent in two-dimensional histograms of range limits of birds and mice, but not for bats. Highland bat species occupy broader elevational ranges than lowland bat species, but for both birds and mice, species at intermediate elevations had the broadest amplitudes. Finally, clumping of range maxima and minima along the gradient identified zones of pronounced species turnover in each group, but these were generally not strongly associated with the locations of ecotones. Differences in zonation of these groups appear to reflect their different biological attributes and phylogenetic histories. Such differences obviously complicate discussions of ‘general’ diversity patterns, and limit the usefulness of birds to forecast or predict diversity patterns in other more poorly known groups—other groups may show elevated diversity and endemism in areas where avian diversity patterns appear unremarkable. The pronounced contrasts between bats and mice, and the generally intermediate character of avian patterns, suggest that future analyses might profitably partition birds into finer, more homogeneous groups of historically and/or ecologically similar species. Group differences in zonation may ultimately prove explicable with information on both species-abundance patterns and resource distributions.

We describe a new species of tyrant flycatcher (Tyrannidae) based on nine specimens from the forested Andean foothills of southeastern Peru and one specimen from adjacent northern Bolivia. The new form appears most closely related to Phylloscartes flaviventris. We cite evidence that the latter species is endemic to the coast range of northern Venezuela. We hypothesize that these two sister-species are more distantly related to a third, P. superciliaris, which has a relictual distribution in midmontane forests of Middle America and the northern Andes. The new species is an obligate member of mixed-species flocks and forages high in the canopy of intact primary forest. In Peru it inhabits moist forest between 650 and 1,200 m elevation; elevational range may be somewhat lower in Bolivia, but even there the species is confined to the foothills. Conservation of large tracts of these vanishing forests is essential for the persistence of this and many other species narrowly restricted to the Andean foothills. Resumen. Decribimos una especie nueva de atrapamoscas (Tyrannidae), conocida de nueve ejemplares de los bosques humedos premontanos del sudeste de Peru, y un ejemplar del norte de Bolivia. El pariente mas cercano de la nueva especie es Phylloscartes flaviventris, que es endemico a las montanas de la costa venezolano. Nuestra hipotesis es que Phylloscartes superciliaris es el pariente mas cercano a esta par de especies. Phylloscartes superciliaris, tambien, tiene una patron de distribuci6n de tipo-reliquia en los bosques de elevaciones medias en America Central y los Andes al norte. La nueva especie es un miembro obligado de bandadas mixtas, y forrajea en las copas de bosque primario. En Peru, la distribucion elevacional esta limitada entre 650 y 1,200 m. La distribucion elevacional en Bolivia puede ser un poco mas baja, pero todavia la especie esta limitada a los bosques premontanos. Es esencial la conservacion de areas grandes de estos bosques, que son desapareciendo, para la persistencia de esta especie y muchas otras, que son especialistas dependientes de los bosques premontanos en los Andes. In 1899 the German collector Otto Garlepp obtained a small, yellowish tyrant flycatcher near the town of Marcapata, in the forested Andean foothills of southeastern Peru (male; depto. Cuzco, 1,000 m; collector's number 1398; Mus. Berlepsch no. 43968). Hellmayr (1927: 349) correctly predicted that this specimen would "doubtless prove to be an undescribed form," noting several ways in which it differed from the Venezuelan endemic, "Pogonotriccus" (= Phylloscartes) flaviventris. In 1972 John Terborgh and John Weske mist-netted, photographed, and released an unidentified tyrannid (see frontispiece), at their "Camp 0" on the Cordillera Vilcabamba, depto. Apurfmac, Peru (685 m). They suspected this to be the same form as Garlepp's specimen but did not encounter the species again (Terborgh, pers. comm.). In 1981 JWF located and collected several specimens of this same species in the lower Cosnipata Valley of southeastern Peru, and in 1982 DFS collected a single male near Puerto Bermudez, depto. Pasco, Peru. We later discovered the species to be a regular member of mixedspecies canopy flocks in foothill forests throughout southeastern Peru. Theodore A. Parker III also encountered the species at several localities in the foothills of southern Peru and in depto. La Paz, Bolivia, and in 1995 Bret Whitney, Alan Perry and Marcelo Hinojosa secured one specimen from depto. Beni, Bolivia.

A number of bird species in southwestern Amazonia are associated with stands of bamboo. We studied the birds in bamboo in two regions, eastern Rondonia near the Rio Jiparana where a single small patch was located, and near Alta Floresta, in northern Mato Grosso, where several extensive bamboo stands were explored. We found a moderately large bamboo avifauna at each site, with eight species in Rondonia and ten at Alta Floresta. In species accounts, we discuss the significance of these records and provide notes on the ecology and behavior of these bamboo species. For most of these species, these records represented significant range extensions. Four species were recorded in Brazil for the first time. We also located a population of Poecilotriccus tricolor, previously known from a unique type, in Rondonia. We determined that it should be treated as a weakly differentiated subspecies of Poecilotriccus capitalis. Resumo. VaYias espe*cies de aves no sudoeste da Amazonia associam-se com bambuzais. Investigamos as aves de bambu em duas regioes: na regiao leste de Rondonia, perto ao no Jiparana* onde encontramos um pequeno bambuzal, e perto de Alta Floresta, no norte de Mato Grosso, onde emploramos v£rios bambuzias. Encontramos uma avifauna bastante diversa associada com bambus, composta de oito especies em Rondonia, e de dez em Atla Floresta. No relato de espe*cies, discutimos a importancia destes registros, e fornecemos imforma9oes sobre a ecologia e o comportamento destas especies. Para a maioria destas espe*cies, estes registros representam um aumento significante na drea de distribuic.ao. Quatro especies foram registradas no Brasil pela primeira vez. Tambe*m, localizamos uma populac^o de Poecilotriccus tricolor, antes conhecido s6mente do holotipo, em Rondonia. Determinamos que esta forma e" uma subespe*cie pouco differenciada de Poecilotriccus capitalis. During ornithological surveys in Rondonia and Mato Grosso, Brazil, in 1986 and 1989, we made observations on birds inhabiting tall, dense thickets of spiny bamboo (Guadua spp.) within both disturbed and undisturbed rainforests. Large species of bamboo occur patchily in southern Amazonia, primarily in floodplain forests along riverbanks or on natural landslides in hilly terrain. Guadua bamboos quickly invade clearings, and some bamboo-dwelling bird species may be spreading because of deforestation in SW Amazonia (Parker and Remsen 1987). On 6 and 11 November 1986, during an avifaunal survey in Rondonia conducted by the Field Museum of Natural History (FMNH) and the Museu de Zoologia, Universidade de Sao Paulo (MZUSP), Stotz and Fitzpatrick, together with T. S. Schulenberg, D. E. Willard, S. M. Lanyon and A. T. Peterson surveyed an isolated bamboo area of ca. 4 ha in partly disturbed terra firme forest at the edge of a recently planted corn field, along the road from Jam to Mac.adinho, ca. 40 km W of Cachoeira NazarS (9°44'S, 61°53'W), Rio Jiparana\ This was the only substantial

The ivory-billed woodpecker ( Campephilus principalis ), long suspected to be extinct, has been rediscovered in the Big Woods region of eastern Arkansas. Visual encounters during 2004 and 2005, and analysis of a video clip from April 2004, confirm the existence of at least one male. Acoustic signatures consistent with Campephilus display drums also have been heard from the region. Extensive efforts to find birds away from the primary encounter site remain unsuccessful, but potential habitat for a thinly distributed source population is vast (over 220,000 hectares).

Studies comparing dispersal in fragmented versus unfragmented landscapes show that habitat fragmentation alters the dispersal behavior of many species. We used two complementary approaches to explore Florida Scrub-Jay (Aphelocoma coerulescens) dispersal in relation to landscape fragmentation. First, we compared dispersal distances of color-marked individuals in intensively monitored continuous and fragmented landscapes. Second, we estimated effective dispersal relative to the degree of fragmentation (as inferred from two landscape indexes: proportion of study site covered with Florida Scrub-Jay habitat and mean distance to nearest habitat patch within each study site) by comparing genetic isolation-by-distance regressions among 13 study sites having a range of landscape structures. Among color-banded individuals, dispersal distances were greater in fragmented versus continuous landscapes, a result consistent with other studies. Nevertheless, genetic analyses revealed that effective dispersal decreases as the proportion of habitat in the landscape decreases. These results suggest that although individual Florida Scrub-Jays may disperse farther as fragmentation increases, those that do so are less successful as breeders than those that disperse short distances. Our study highlights the importance of combining observational data with genetic inferences when evaluating the complex biological and life-history implications of dispersal.

Cercomacra manu is a distinctive new species in the family Formicariidae. The species is distributed locally in southeastern Peru and adjacent Bolivia at elevations below 1,200 meters. C. manu is secretive and restricted largely to extensive bamboo thickets. The female is gray below; this unusual feature-along with other plumage and vocal characteristics-places C. manu within a species group that contains four other, allopatric South American taxa. We suggest that manu is closest to C. melanaria of eastern Bolivia and Mato Grosso, Brazil. Received 7 March 1989, accepted 23 October 1989. IN 1975 we encountered an unusual antbird several times in mist nets set among dense riparian vegetation near the Manu River, well inside the Manu National Park of southeastern Peru (Terborgh et al. 1984). We tentatively identified these birds as Cercomacra nigricans, a species then thought to occur in the Amazon basin on the basis of one specimen taken by J. A. Feduccia and J. P. O'Neill at Balta, Department Ucayali, Peru, in 1964 (LSUMZ 34211; O'Neill 1969). Because the collection of specimens inside the Manu National Park is prohibited, our identification could not be confirmed. Subsequently we obtained other specimens of this antbird during intensive surveys of the lower Manu River, the banks of the Alto Madre de Dios River, and adjacent Andean foothills. These specimens confirm that these birds are members of a distinctive new species of Cercomacra, to which the Balta specimen also belongs. The species is virtually restricted to dense bamboo thickets, as discussed more fully below. 1 Present address: Archbold Biological Station, Box 2057, Lake Placid, Florida 33852 USA. Cercomacra manu sp. nov. Manu Antbird Holotype.-Field Museum of Natural History no. 310653; adult female (skull 80% pneumatized), taken 12 river km downstream from Shintuya on left bank of Alto Rio Madre de Dios, Dept. Madre de Dios, Peru, 12?33'S, 71?17'W, elevation 420 m; collected 17 August 1980 by John W. Fitzpatrick, field number 80221. Diagnosis. -Medium-sized antbird, identifiable as Cercomacra by graduated tail with whitetipped rectrices, long bill with broad base and slightly hooked tip, and gray-bellied female plumage. Within the gray-bellied species group (see below), manu females are unique in having dull olive crown and dorsal plumage, rather than blackish or grayish upperparts. Males are extremely similar to C. nigricans, carbonaria, melanaria, and ferdinandi, but are dark sooty gray to dull black rather than deep, glossy black over most of their plumage. Flank plumes are dark gray, and suffused with olive in some specimens, rather than pure black as in the other similar species. White tips of rectrices, though variable, are narrower than in nigricans, ferdi239 The Auk 107: 239-245. April 1990 This content downloaded from 207.46.13.64 on Sun, 04 Sep 2016 06:32:25 UTC All use subject to http://about.jstor.org/terms 240 FITZPATRICK AND WILLARD [Auk, Vol. 107 nandi, and carbonaria. Rictal, loral, and supraorbital bristles are longer, stiffer, and more numerous in manu than in the four related species; the longest are 6-8 mm and have basal barbs. All five members of this species group are allopatric (see below). Description of holotype. -Overall appearance is "two-toned," with olive-brown above and neutral gray below. Crown, dorsum, and outer webs of remiges dull olive-brown, between Olive (Color 30) and Olive-Green (Color 48; capitalized colors are from Smithe [1975, 1981]). Concealed interscapular patch white. Marginal coverts from shoulder to wrist white, producing a semiconcealed white "shoulder patch." Wing linings white; lesser and median secondary coverts black, broadly tipped white; greater secondary coverts, primary coverts, and alula dusky brown, tipped white and with outer margins olive like back. Tail graduated; rectrices uniformly dark gray-brown, closest to Blackish Neutral Gray (Color 82), each narrowly tipped with white crescent, broadest on outermost (shortest) pair and reduced to a few white barbs at the tips of the central pair. Eyering, lores, cheeks, and entire underparts uniform neutral gray, between Medium and Dark Neutral Gray (Colors 84 and 83); chin and throat slightly paler, faintly streaked with whitish; long flank plumes gray, suffused with dull olive. Long, black rictal bristles about eyes, face and gape. Soft part colors in life: irises pale sandy brown, maxilla black, mandible silvery gray mottled darkish; tarsi and feet pale gray. Measurements of holotype (mm).-Wing chord 64.0, central rectrices 66.5, outermost rectrices 46.0, culmen from base 19.0, culmen from anterior edge of nostril 10.0, tarsus 22.0; mass 17.0 g. Distribution. -Cercomacra manu occurs (Fig. 1) locally in bamboo thickets and associated habitats in the lowlands and lower Andean slopes (up to 1,200 m, above Pilcopata, Dept. Cusco) of southeastern Peru, and extreme northwestern Bolivia along the Rio Tahuamanu (2 km W Porvenir, Dept. Pando, 300 m). The northernmost record is the single specimen from Balta, Dept. Ucayali. The species is regularly encountered in bamboo along the banks of the Rio Manu and the Rio Madre de Dios. Numerous sight records exist from the Tambopata Reserve near Puerto Maldonado, and from the Rio Heath at the Bolivian border (T. A. Parker III pers. comm.). The species is not recorded from Brazil, but almost certainly occurs in proper habitat in the state of Acre (Parker and Remsen 1987). Etymology-We are pleased to name this species in honor of the Manu National Park, one of the most important reservoirs of biological diversity on earth. Encompassing nearly 1.5 million hectares of pristine rain forest, cloud forest, and puna grassland, the park protects the richest avifauna in the world. To date more than 870 bird species are recorded from the vicinity of the park. The total species within the park is probably near 1,000. By honoring the historical and present-day importance of this region and park, we also honor the efforts of the Peruvian government and the World Wildlife Fund in protecting it for future generations. Cercomacra manu is a regular inhabitant of extensive bamboo thickets at lower elevations in the Manu region. Specimens examined.-We examined the following specimens from Museu de Zoologia, Universidade de Sao Paulo (MZUSP), Museu Nacional, Rio de Janeiro (MNRJ), Field Museum of Natural History (FMNH), Academy of Natural Science of Philadelphia (ANSP), American Museum of Natural History (AMNH), Los Angeles County Museum of Natural History (LACM), and Louisiana State University Museum of Natural Science (LSUMZ): C. manu (14 males, 10 females): Peru-Dept. Ucayali: Balta (LSUMZ 16); Dept. Madre de Dios: Cerro de Pantiacolla, E slope, 5 km NNE Shintuya (FMNH 16, 1Q); Alto Rio Madre de Dios, left bank: 17 km downstream from Shintuya (FMNH 16 [plus 1 skeleton, 1 in alcohol], 2Q), 12 km downstream from Shintuya (FMNH 26), 10 km downstream from Shintuya (FMNH 1Q? in alcohol), 7 km downstream from Shintuya (FMNH 16); Rio Palotoa, left bank, 12 km from mouth (FMNH 16?); ridge above Hacienda Amazonia (FMNH 16, 1Q); lower Rio Manu, left bank (AMNH 16, 1Q); Dept. Cuzco: Consuelo (km #165), 17 road km above Pilcopata (FMNH 1Y). Bolivia-Dept. Pando: 2 km W Porvenir (LSUMZ 26 [plus 1 skeleton], 1Q [plus 1Q? in alcohol]). C. melanaria (30 males, 8 females): BrazilMato Grosso: Agua Blanca de Corumba (AMNH 16); Faz. San Juan, R. Cuyaba (AMNH 26, 1Q); Cuiaba (MZUSP 16); Descalvados (FMNH 26; AMNH 16; ANSP 26, 1Q); rio Sao Lorenzo (AMNH 26, 1Q); Chapada (AMNH 1Q); Porta Esperanza (MZUSP 16); Miranda (MZUSP 26, 19); R. Paraguay (MZUSP 16); Xarqueada Ottilia, R. This content downloaded from 207.46.13.64 on Sun, 04 Sep 2016 06:32:25 UTC All use subject to http://about.jstor.org/terms April 1990] New Amazonian Antbird 241 X t m ela n u f ei a n, d Fig. 1. Northwestern South America and the Amazon drainage basin, showing distributions in the "Cercomacra nigricans" species group: nigricans (hatched areas), carbonaria (squares), ferdinandi (diamonds), melanaria (triangles), and manu (closed circles = specimen localities, open circles = sight records). Northernmost plotted locality for ferdinandi is uncertain (see text). Paraguay (MNRJ 16); Rio Piquiri (MNRJ 16); Porto Esperidiao (MNRJ 16); Salobra (MZUSP 16, MNRJ 18); Caceres (MZUSP 16); Santo Antonio (MZUSP 16, 1Q). Bolivia-Dept. Santa Cruz: Buena Vista (LSUMZ 16); Isama (LSUMZ 19); Dept. Beni: Rio Yacuma, 2 km from mouth (AMNH 16); Rio Tijamuchi, 4 km from mouth (AMNH 16); Laguna Suarez, 5 km SW of Trinidad (FMNH 16); 6 road km SE of Trinidad (LSUMZ 16 [alcohol], 19); Dept. Cochabamba: mouth of Rio Chapare (ANSP 26); Todos Santos, Rio Chapare (ANSP 16). C. carbonaria (11 males, 3 females): BrazilRoraima: Rio Mucajai, S of Boa Vista (LACM 66, 29; FMNH 26; MZUSP 16); Ilha Sao Jose, Rio Branco (FMNH 19); Forte do Rio Branco (AMNH 16); Caracarahy, Rio Branco (AMNH 16). C. ferdinandi (6 males, 6 females): BrazilGoiaz: Ilha do Bananal (MZUSP 19); Santa Isabel do Morro, Ilha do Bananal (MNRJ 16, 19); Furo de Pedra, Ilha do Bananal (MNRJ 46, 39); Araguatins (MZUSP 16, 19). C. nigricans: more than 100 specimens, from Ecuador, Colombia, Venezuela, Middle Amer

1. Using data on breeding birds from a 35-year study of Florida scrub-jays Aphelocoma coerulescens (Bosc 1795), we show that survival probabilities are structured by age, birth cohort, and maternal family, but not by sex. Using both accelerated failure time (AFT) and Cox proportional hazard models, the data are best described by models incorporating variation among birth cohorts and greater mortality hazard with increasing age. AFT models using Weibull distributions with the shape parameter1 were always the best-fitting models. 2. Shared frailty models allowing for family structure greatly reduce model deviance. The best-fitting models included a term for frailty shared by maternal families. 3. To ask how long a data set must be to reach qualitatively the same conclusions, we repeated the analyses for all possible truncated data sets of 2 years in length or greater. Length of the data set affects the parameter estimates, but not the qualitative conclusions. In all but three of 337 truncated data sets the best-fitting models pointed to same conclusions as the full data set. Shared frailty models appear to be quite robust. 4. The data are not adequate for testing hypotheses as to whether variation in frailty is heritable. 5. Substantial structured heterogeneity for survival exists in this population. Such structured heterogeneity has been shown to have substantial effects in reducing demographic stochasticity.

Cadmium is known to be both extremely toxic and ubiquitous in natural environments. It occurs in almost all soils, surface waters and plants, and it is readily mobilized by human activities such as mining. As a result, cadmium has been named as a potential health threat to wildlife species; however, because it exists most commonly in the environment as a trace constituent, reported incidences of cadmium toxicity are rare. Here we have measured trace metals in the food web and tissues of white-tailed ptarmigan (Lagopus leucurus) in Colorado. Our results suggest that cadmium toxicity may be more common among natural populations of vertebrates than has been appreciated to date and that cadmium toxicity may often go undetected or unrecognized. In addition, our research shows that ingestion of even trace quantities of cadmium can influence not only the physiology and health of individual organisms, but also the demographics and the distribution of species.

John James Audubon's monumental Birds of America holds a place among the greatest artistic achievements of any era, and his writings provide a rich chronicle of North American natural history before the industrial revolution. Yet Audubon remains victim of a legend that paints him as a bumbling businessman and dandy, who deserted his family to live in the woods and sketch birds. In a major biography reviewed in Nature this week, historian and novelist Richard Rhodes separates fact from fiction to draw a rounded picture of Audubon the man.