AbstractThe rails (Family Rallidae) are the most diverse and widespread group in the Gruiformes. Their extensive fossil history, global geographic distribution, and tendency to rapidly evolve flightless species on islands make them an attractive subject of evolutionary studies, but the rarity of modern museum specimens of so many rail species has, until recently, limited the scope of molecular phylogenetics

Seasonal migration is intrinsically connected to the balance of survival and reproduction, but whether migratory behavior influences species’ position on the slow-fast continuum of life history is poorly understood. We found that boreal-breeding birds that migrate long distances exhibit higher annual adult survival and lower annual reproductive investment relative to co-distributed boreal species that

AbstractMore than one-third of the bird species found in the Caribbean are endemic to a set of neighboring islands or a single island. However, we have little knowledge of the evolutionary history of the Caribbean avifauna, and the lack of phylogenetic studies limits our understanding of the extent of endemism in the region. The Sharp-shinned Hawk (Accipiter striatus) occurs widely across the Americas

There were 126 General Notes published in The Auk in 1921. Of those, only 23% dealt with something other than distribution. Natural history notes with personal stories often accompanied distributional lists of birds. Otherwise, there were reports of behavior (17), including subjects of song, foraging, nesting, and nest parasitism. There were mentions of elements of natural and anthropogenically driven

This is the 21st supplement since publication of the 7th edition of the Check-list of North American Birds (American Ornithologists’ Union [AOU] 1998). It summarizes decisions made between 15 April 2020 and 15 April 2021 by the American Ornithological Society’s (formerly American Ornithologists’ Union) Committee on Classification and Nomenclature—North and Middle America. The Committee has continued

The timing of events in birds’ annual cycles is important to understanding life history evolution and response to global climate change. Molt timing is often measured as an index of the sum of grown feather proportion or mass within the primary flight feathers. The distribution of these molt data over time has proven difficult to model with standard linear models. The parameters of interest are at

Cooperative breeding behavior in birds ranges from inducible to obligate strategies and has evolved across diverse taxa, in species that display a wide range of social and reproductive behavior. It is often thought to evolve when independent breeding is constrained, and cooperation increases fitness. Yet many systems show variable, even maladaptive, fitness effects. This observation, together with

AbstractWithin animal hybrid zones, parasites may determine competitive outcomes between host species and thus affect hybridization dynamics. We addressed this hypothesis by evaluating haemosporidian prevalence and community composition in a rapidly moving hybrid zone between Black-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (P. carolinensis). Using molecular methods, we screened

Birds of Maine by VickeryPeter D., DuncanCharles D., SheehanWilliam J., and WellsJeffrey V.. 2021. Princeton University Press and Nuttall Ornithological Society,Princeton, NJ, USA. x + 642 pp., 12 color plates, 29 color photographs, 79 color maps, 119 line drawings, 20 text figures. $45.00 (hardcover). ISBN 978-0-691-19319-9.

Incubation length and hatching asynchrony are integral elements of the evolved reproductive strategies of birds. We examined intra- and interpopulation variation in both traits for Eastern Kingbird (Tyrannus tyrannus) populations from New York (NY), Kansas (KS), and Oregon (OR) and found that both incubation length and hatching asynchrony were not repeatable among females, after controlling for a repeatable

AbstractAridland breeding bird communities of the United States are among the most vulnerable to drought, with many species showing significant population declines associated with decreasing precipitation and increasing temperature. Individual breeding bird species have varied responses to drought which suggests complex responses to changes in water availability. Here, we evaluated the influence of

AbstractThe family Thamnophilidae is a species-rich Neotropical radiation of passerine birds. Current classification of its 235 species is mostly based on morphological similarities, but recent studies integrating comprehensive phenotypic and phylogenetic data have redefined taxonomic limits of several taxa. Here, we assess generic relationships of Herpsilochmus, Sakesphorus, Thamnophilus, Biatas,

Most birds that show geographic variation in their songs discriminate between local and foreign songs, which may help them avoid unnecessary conflicts with vagrant individuals or similar-sounding congeners. However, some species respond equally to foreign and local songs, which may be useful if foreign individuals present territorial threats or if there are no sympatric congeners to avoid. Species

AbstractEnergy acquisition and storage are important for survival and fecundity of birds during resource-limited periods such as spring migration. Plasma-lipid metabolites (i.e. triglyceride [TRIG], β-hydroxybutyrate [BOHB]) have been used to index changes in lipid stores and, thus, have utility for assessing foraging habitat quality during migration. However, such an index may be affected by energetic

Mixed-species flocks constitute community modules that can help test mechanisms driving changes to community composition across environmental gradients. Here, we examined elevational patterns of flock diversity (species richness, taxonomic diversity, species, and guild composition) and asked if these patterns were reflections of the full bird community at a given elevation (open-membership hypothesis)

Storrs Olson in Uruguay, 2002 (photo courtesy of Christina Gebhard).

Fred Gehlbach, whose teaching inspired many students and whose research in ecology contributed significantly to our understanding of natural systems.

Grinnell: America’s Environmental Pioneer and His Restless Drive to Save the West by TaliaferroJohn. 2019. Liveright Publishing Corporation, A Division of W.W. Norton & Company, New York, New York and London, England. 606 pp. $35.00 (hardcover). ISBN 9781631490132.

Prinias (Cisticolidae: Prinia) are resident warblers of open areas across Africa and Asia and include many polytypic species whose species limits have not been seriously reevaluated recently. Based on an integrative taxonomic analysis of morphology, song, and mitochondrial DNA (mtDNA), we suggest that 2 species should be recognized in the Graceful Prinia (Prinia gracilis) complex. In addition, our

The following figures and figure captions contained errors outlined here in this correction document: (1) the y axis for Figure 2 was incorrectly labelled as “Discrimination Ratios”, and (2) the y axes and figure captions for Figures 3, 4, and 5 were incorrectly labelled (axes) and written (figure captions) as “Percent response”. The corrected figures and figure captions appear below. None of these

AbstractIdentifying population genetic structure is useful for inferring evolutionary process and comparing the resulting structure with subspecies boundaries can aid in species management. The American Kestrel (Falco sparverius) is a widespread and highly diverse species with 17 total subspecies, only 2 of which are found north of U.S./Mexico border (F. s. paulus is restricted to southeastern United

AbstractExamining differences among recently diverged populations can provide insight into the traits and evolutionary mechanisms that drive or maintain divergence. The genus Sturnella includes 2 recently diverged species, Sturnella magna (Eastern Meadowlark) and S. neglecta (Western Meadowlark), the former of which has a complex of subspecies distributed across the Americas. Of the S. magna subspecies

Elevational migration can be defined as roundtrip seasonal movement that involves upward and downward shifts in elevation. These shifts incur physiological challenges that are proportional to the degree of elevational change. Larger shifts in elevation correspond to larger shifts in partial pressure of oxygen, air density, temperature, and ultraviolet (UV) exposure. Although most avian examples of

Major articles appearing in the 38th volume of The Auk in 1921 included accounts of life history and behavior (11); systematics and nomenclature (10); bird lists by region (8); migration, irruption, and range expansion (3); bird banding (2); oology (1); a memorial; and annual reports of the secretary. Alfred Otto Gross (1883–1970) authored the lead article, an account of the life history of the Dickcissel

AbstractAccurately determining avian species limits has been a challenge and a work in progress for most of a century. It is a fascinating but difficult problem. Under the biological species concept, only lineages that remain essentially independent when they are in sympatry are clearly species. Otherwise, there is no clear line yet found that marks when a pair of diverging lineages (e.g., in allopatry)

The ornithological world has 4 global checklists (as of early 2020). While 3 follow the results of peer-reviewed research at varying pace and conservatism, the HBW/BirdLife checklist, which is adopted by the global Red List authority, has implemented Tobias et al.’s (2010) 7-point scoring system to overhaul global ornithological treatment. Critically received in some academic quarters, this scoring

Studying macroevolutionary patterns of phenotypic variation and their driving forces in large radiations can shed light on how biodiversity is generated across broad spatiotemporal scales. In this study, we integrated song and morphological variation across more than 300 species representing the largest family of songbirds, the tanagers (Thraupidae), to uncover how morphological variables of the vocal

AbstractFour main challenges that can underpin ongoing, intransigent debates about species limits in birds are reviewed: allopatry (population subdivision vs. speciation), geographically widespread introgression of mitochondrial DNA (mtDNA), recent speciation, and selection. Examples from birds of the Australian region show how these challenges, their interplay, and the molecular-phenotypic discordance

AbstractSex allocation theory predicts that parents should adjust their brood sex ratio to maximize fitness returns in relation to parental investment. Adaptive adjustment of sex ratio may be driven by differential costs of rearing sons and daughters or differential benefits of investing limited resources into offspring of different sex. In both cases, possible sex ratio bias should depend on parental

AbstractSpecies delimitation requires a broad assessment of population-level variation using multiple lines of evidence, a process known as integrative taxonomy. More specifically, studies of species limits must address underlying questions of what limits the distribution of populations, how traits vary in association with different environments, and whether the observed trait differences may lead

Species are fundamental to biology, conservation, and environmental legislation; yet, there is often disagreement on how and where species limits should be drawn. Even sophisticated molecular methods have limitations, particularly in the context of geographically isolated lineages or inadequate sampling of loci. With extinction rates rising, methods are needed to assess species limits rapidly but robustly

Despite the acknowledged importance of defining avian species limits to scientific research, conservation, and management, in practice, they often remain contentious. This is true even among practitioners of a single species concept and is inevitable owing to the continuous nature of the speciation process, our incomplete and changing understanding of individual cases, and differing interpretations

The Sensory Ecology of Birds by MartinGraham R.. 2017. Oxford University Press, Oxford, England. 320 pp. $105.00 (hardcover). ISBN 978-0-199-694532. $53.00 (paperback). ISBN 978-0-199-694549.

AbstractAlthough primary cavity-nesting species are capable of excavating new cavities, they often reuse old ones. To determine potential factors driving such reuse, we studied nest-cavity reuse in the Acorn Woodpecker (Melanerpes formicivorus), a cooperatively breeding species that reuses old cavities for 57.2% of nests at Hastings Reservation in central coastal California, USA. We found no evidence

Africa’s montane ecosystems are noteworthy not only for their isolation but for their morphologically similar bird populations that inhabit geographically disparate localities. Many species possess range disjunctions in excess of 2,000 km and appear to represent populations that have been isolated since at least the last Ice Age, including the Northern Double-collared Sunbird (Cinnyris reichenowi)

Millicent Ficken releasing a Golden-crowned Kinglet at the University of Wisconsin-Milwaukee Field Station (2005) (photo by Gretchen Meyer).

Habitat selection decisions can impact individual fitness and ultimately scale up to mediate population dynamics. Understanding how birds select habitat is thus critical for discerning the biological processes structuring populations and for developing conservation strategies, particularly for species in decline. Marbled Murrelet (Brachyramphus marmoratus; hereafter murrelet) populations have declined

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 impact avian survival and reproduction. However, the mechanisms

Understanding the evolutionary and ecological mechanisms that shape the spatial divergence of signals involved in reproductive isolation is a central goal in studies of speciation. For birds with innate songs, such as the suboscine passerine birds, the integration and comparison of both genetic and ecological factors in explaining song variation at the microevolutionary scale are rare. Here, we evaluated

Migrating animals occur along a continuum from species that spend the nonbreeding season at a fixed location to species that are nomadic during the nonbreeding season, essentially continuously moving. Such variation is likely driven by the economics of territoriality or heterogeneity in the environment. The Snowy Owl (Bubo scandiacus) is known for its complex seasonal movements, and thus an excellent

AbstractGiven the availability of genomic data to identify separately evolving groups of organisms, many researchers establish species limits based on assessments of the extent of gene flow among populations and often use analytical approaches to identify species in which gene flow is explicitly disallowed. Strictly considering lack of—or limited—gene flow as the main or only criterion to delimit species

We compared support for 3 hypotheses that might explain observed morphological variation among islands of 4 species of Caribbean land birds: ecological release from competition and predation pressure, predation pressure from 1 novel predator species (small Indian mongoose, Herpestes auropunctatus), and climate. We measured wing chord, tarsus length, bill length, and mass of Bananaquits (Coereba flaveola)

AbstractDo birds detect and respond to forces acting on feathers through filoplumes, which appear to be unique mechanosensory feathers? If filoplumes function as sensors, their morphology should covary with the morphology of their companion feather to better detect feather movements and position. We explore covariation in filoplumes and primaries across 5 species of birds that vary in body size, molt

Migratory birds engage in 2 periods of endurance flight annually as they travel between summer breeding and overwintering grounds, and such endurance flights likely incur oxidative costs. These costs may differ between fall and spring migration, especially for females who must prepare for breeding and egg laying in spring. The objective of this study of a migratory bird was to test proposed hypotheses

AbstractEcological traits related to pace of life, such as foraging strategies and activity levels, influence daily energy expenditure (DEE) and can affect fitness. A fast pace of life tends to be supported by high-energy aerobic activity and is positively correlated with high DEE and basal and maximal metabolic rates in some endotherms. Given that maximal capacities for exercise and thermogenesis

Ludwik Tomiałojć, Radziądz, Poland, 2013 (photo by A. Wuczyński)

James Denis Summers-Smith, a professional tribologist who made significant contributions to ornithology as a highly skilled amateur, died May 5, 2020. His pioneering studies of the lowly House Sparrow and other species in the genus Passer resulted in numerous articles in peer-reviewed ornithological journals as well as four influential books on sparrows, and a fifth book chronicling his life pursuing

Bird is the Word: An Historical Perspective on the Names of North American Birds by MeiterGary H.. 2020. McDonald and Woodward Publishing, Newark, Ohio, USA. 437 pp. $39.95 (softcover). ISBN 978-1-9357-7842-4.

AbstractPhylogeographic structure within high-latitude North American birds is likely shaped by a history of isolation in refugia during Pleistocene glaciations. Previous studies of individual species have come to diverse conclusions regarding the number and location of likely refugia, but no studies have explicitly tested for biogeographic concordance in a comparative phylogeographic framework. Here

AbstractDisjunct distributions within a species are of great interest in systematics and biogeography. This separation can function as a barrier to gene flow when the distance among populations exceeds the dispersal capacity of individuals, and depending on the duration of the barrier, it may eventually lead to speciation. Here, we describe patterns of geographic differentiation of 2 disjunct populations

The Bird Way: A New Look at How Birds Talk, Work, Play, Parent, and Think by AckermanJennifer. 2020. Penguin Press, New York, New York. 355 pp. $28.00 (hardcover). ISBN 9780735223011.

AbstractArmy-ants (particularly swarm-raiding species Eciton burchellii and Labidus praedator) are keystone predators in Neotropical forests. Hundreds of associated species from diverse taxa depend on them for survival, the most conspicuous of which are the ant-following birds. These birds forage on cryptic arthropods and vertebrates as they attempt to escape raiding army-ants. Despite capturing the

AbstractThe slow-paced life history of many Neotropical birds (e.g., high survival and low fecundity) is hypothesized to increase lifetime fitness through investments in self-maintenance over reproduction relative to their temperate counterparts. Molt is a key investment in self-maintenance and is readily shaped by environmental conditions. As such, variation in molt strategies may be a key mechanism

We explored adaptive factors affecting the preformative molt in the passerine family Cardinalidae, and concluded that the ancestor inhabited forest habitats and underwent a partial preformative molt that included wing coverts but not primaries. Later radiations within the family appeared to be characterized by transitions from forests toward more open habitats, and such transitions also correlated

AbstractRapid high-intensity molt of flight feathers occurs in many bird species and can have several detrimental consequences, including reductions in flight capabilities, foraging performance, parental care, and plumage quality. Many migratory New World warblers (family Parulidae) are known to have intense remigial molt, and recent work has suggested that simultaneous replacement of the rectrices

AbstractAnimal culture changes over time through processes that include drift, immigration, selection, and innovation. Cultural change has been particularly well-studied for animal vocalizations, especially for the vocalizations of male animals in the temperate zone. Here we examine the cultural change in the vocalizations of tropical Rufous-and-white Wrens (Thryophilus rufalbus), quantifying temporal

AbstractCo-infection with microparasites (e.g., bacteria) and macroparasites (e.g., helminths) is often the natural state for wild animals. Despite evidence that gut helminths can bias immune responses away from inflammatory processes, few field studies have examined the role that helminths, or their potential interactions with internal microbial communities, play in modulating immunity in free-living

AbstractEastern (Vireo gilvus gilvus) and western (V. g. swainsoni) forms of the Warbling Vireo have essentially allopatric breeding ranges across north-central North America, but come into contact in central Alberta, Canada. In 1986, Jon Barlow presented preliminary morphological and song evidence suggesting that the Warbling Vireo complex might comprise more than one valid species. However, to date

Welcome to the first issue of Ornithology. While the title is new, this issue opens the 138th volume of an unbroken record of peer-reviewed, ornithological research that extends from The Auk’s first volume in 1884 (Figure 1) and, ultimately, from the 8 volumes of the Bulletin of the Nuttall Ornithological Club, started in 1876 (Allen et al. 1883). The new title is part of a long-term effort to increase

The annual meeting of the American Ornithologists’ Union (AOU) convened in Philadelphia at the Academy of Natural Sciences on November 7, 1921. Attendance was near 125. Among those present were 24 Members and 25 Fellows, of which 2 were founders, C. F. Batchelder (1856–1954) and A. K. Fisher (1856–1948). Also present were Retired Fellows W. K. Fisher (1878–1953) and N. T. Lawrence (1855–1928), as well