Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
R. Terry Chesser, Morton L. Isler, Andrés M. Cuervo, C. Daniel Cadena, Spencer C. Galen, Laura M. Bergner, Robert C. Fleischer, Gustavo A. Bravo, Daniel F. Lane, Peter A. Hosner
The Grallaria rufula complex is currently considered to consist of 2 species, G. rufula (Rufous Antpitta) and G. blakei (Chestnut Antpitta). However, it has been suggested that the complex, populations of which occur in humid montane forests from Venezuela to Bolivia, comprises a suite of vocally distinct yet morphologically cryptic species. We sequenced nuclear and mitochondrial DNA for 80 individuals from across the distribution of the complex to determine the extent of genetic variation between and within described taxa. Our results revealed 18 geographically coherent clades separated by substantial genetic divergence: 14 within rufula, 3 within blakei, and 1 corresponding to G. rufocinerea (Bicolored Antpitta), a species with distinctive plumage found to be nested within the complex. Neither G. rufula nor G. blakei as presently defined was monophyletic. Although 6 of the 7 recognized subspecies of G. rufula were monophyletic, several subspecies contained substantial genetic differentiation. Genetic variation was largely partitioned across recognized geographic barriers, especially across deep river valleys in Peru and Colombia. Coalescent modeling identified 17 of the 18 clades as significantly differentiated lineages, whereas analyses of vocalizations delineated 16 biological species within the complex. The G. rufula complex seems unusually diverse even among birds of the humid Andes, a prime location for cryptic speciation; however, the extent to which other dispersal-limited Andean species groups exhibit similar degrees of cryptic differentiation awaits further study.
Contemporary phenotypic trends associated with global change are widely documented, but whether such trends always denote trait optimization under changed conditions remains obscure. Natural selection has shaped the wings of long-distance migratory birds to minimize the costs of transport, and new optimal wing shapes could be promoted by migration patterns altered due to global change. Alternatively, wing shape could vary as a correlated response to selection on other traits favored in a changing environment, eventually moving away from the optimal shape for migration and increasing transport costs. Data from 20 yr of monitoring 2 Common Nightingale (Luscinia megarhynchos) populations breeding in central Spain, where environmental conditions for breeding have deteriorated during recent decades due to increased summer drought, show that birds have reduced wing length relative to body size over the period 1995–2014. However, long-winged nightingales survived their first round-trip migration better, and the shorter the average wing length of individuals, the stronger the survival-associated natural selection favoring longer wings. Maladaptive short wings may have arisen because the mortality costs of migration are outweighed by reproductive benefits accrued by short-winged nightingales in these populations. Assuming that the phenotypic integration of morphological and reproductive adaptations of migratory birds has a genetic basis, we hypothesize that the maladaptive trend towards shorter wings may be a correlated response to selection for moderate breeding investment in drying habitat. Our results provide evidence that contemporary phenotypic change may deviate average trait values from their optima, thereby increasing our understanding of the ecological constraints underpinning adaptation to rapid global change.
Acoustic signals used in animal communication play a key role in mate attraction, species recognition, and territory defense. Variation in acoustic signals may reflect population structure, lack of gene flow, and phylogenetic relationships. In birds, the study of geographic variation in acoustic signals has been useful for elucidating potential factors involved in phenotypic divergence and for establishing species limits. However, most of the studies on geographic variation have focused on calls and solo songs, with few studies focusing on complex behaviors such as duets. In this study, we investigated the variation in the duets of the Rufous-naped Wren (Campylorhynchus rufinucha). Our results suggest that duets vary across the distribution range of the species complex, matching the 3 taxonomic groups previously suggested (rufinucha, humilis, and capistratus). We also found a marked song sexual dimorphism in 2 groups, rufinucha and humilis, that is lacking in capistratus. At the local level, we found that duets also vary among sites within groups, but less than between groups. Our results suggest that groups rufinucha and humilis sing the most similar duets, whereas capistratus performs the most divergent duets of the 3 groups. Further, when comparing duet variation across geography, we found that birds living closer to each other sing more similar duets. We suggest that the existence of 3 vocal lineages is probably the result of historical geographic isolation followed by other selective (i.e. sexual selection, social selection, habitat structure) and/or non-selective factors (i.e. drift, isolation by distance), and that variation found within groups may be the result of cultural drift or social selection.
Relationships of the Neotropical finches in the genera Euphonia and Chlorophonia (Fringillidae: Euphoniinae) have been clarified by recent molecular studies, but species-level relationships within this group have not been thoroughly addressed. In this study, we sampled specimens representing every recognized species of these genera, in addition to 2 outgroup taxa, and used target enrichment to sequence thousands of ultraconserved element (UCE) loci, as well as mitochondrial DNA reconstructed from off-target reads, from each specimen to infer these relationships. We constructed both concatenation and coalescent-based estimates of phylogeny from this dataset using matrices of varying levels of completeness, and we generated a time-scaled ultrametric tree using a recently published fossil-based external calibration. We found uniformly strong support for a monophyletic subfamily Euphoniinae and genus Chlorophonia, but a paraphyletic Euphonia across UCEs and mitochondrial genomes. Otherwise, our inferred relationships were largely concordant with previous studies. Our time-tree indicated a stem divergence time of 13.8 million years ago for this lineage, followed by a relatively young crown age of only 7.1 myr. Reconstructions of biogeographic history based on this tree suggest a South American origin for crown Euphoniinae, possibly resulting from a transoceanic dispersal event from the Eastern Hemisphere, followed by 2 dispersal events into the Caribbean and as many as 6 invasions of North America coinciding with recent estimates of the age at which the Isthmus of Panama had completely formed. We recommend splitting Euphonia and resurrecting the genus Cyanophonia for the 3 blue-hooded species more closely related to Chlorophonia. Based on our results, we suspect that there is undescribed species-level diversity in at least one, possibly many, widespread and phenotypically diverse species.
The vertical structure and composition of vegetation can influence the quantity and quality of potential nesting sites for birds. Interspecific competition for high-quality nesting habitat may force some individuals into suboptimal habitat and lead to reduced reproductive success, eventually leading to changes in distribution or abundance. Large climate-mediated shifts in vegetation, including the rapid expansion of shrubs onto tundra, are occurring in the Arctic across important breeding grounds of many shorebird species of conservation concern. We investigated effects of vegetation structure and composition on nest-site selection and nest success of sympatrically breeding American Golden-Plovers (Pluvialis dominica) and Pacific Golden-Plovers (P. fulva), which nest along an elevational gradient ranging from coastal tundra meadows to alpine tundra. Both species strongly selected nest sites with less cover of tall shrubs and other tall vegetation than available at random sites within their territories. American Golden-Plovers selected territories and nest sites that were higher in elevation and had more rocky substrates and less graminoid vegetation than those selected by Pacific Golden-Plovers. The daily nest survival rate was equivalent in the 2 species (0.966, 95% CI: 0.955, 0.975) and similar to that found in other Arctic-breeding shorebirds; however, contrary to predictions, nest survival was not associated with habitat features selected for nest sites for either species. Strong selection of open habitat for nest sites suggests that continued climate-related shrub expansion may reduce the amount of suitable breeding habitat for both species, but partitioning along the elevational gradient and differences in body size suggest that impacts may be more severe for Pacific Golden-Plovers. Additional research is needed to determine if differential selection of nesting habitat is related to survival of the adults or their young.
The mass of a bird's egg is a critical attribute of the species' life history and represents a fundamental component of reproductive effort. Indeed, the tradeoff between the number of eggs in a clutch and clutch mass lies at the heart of understanding how environmental attributes such as nest predation or adult mortality influence reproductive investment. However, egg masses have not been reported for the majority of avian species. We capitalized on the strong allometric relationship between avian body mass and egg mass to produce egg mass estimates for over 5,500 species previously lacking such information. These estimates are accompanied by measures of the robustness of the regressions used to produce them (e.g., sample size, root mean square error [RMSE] of estimation, coefficient of determination, and degree of extrapolation), thus allowing independent evaluation of the suitability of any estimate to address a particular research question relating to avian life history. Most estimates (∼5,000) were based on family-level egg mass–body mass regressions, with the remainder derived from other relationships such as ordinal regressions. We compared estimating regressions based on adult vs. female body masses and, after finding little difference between the 2, based our final estimates on adult masses as those were more numerous in the literature. What small differences between adult- and female-based regressions that did occur were not related to sexual size dimorphism across families. These new estimates, coupled with ∼5,000 egg masses reported in the literature, provide a foundation of over 10,000 species for wider investigations assessing variation in reproductive effort in birds over a broad array of ecological and evolutionary contexts.
LAY SUMMARY
The mass of a bird's egg is a critical attribute of the species' life history but has not been reported for the majority of avian species.
We capitalized on the strong statistical relationship between egg mass and avian body mass (known for almost all bird species) to produce new egg mass estimates for over 5,500 species previously lacking such information.
Most estimates (∼5,000) were based on family level regressions of egg mass on body mass, with the remainder derived from other relationships such as order regressions.
We found little difference between egg mass relationships calculated from adult vs. female-only body masses and based our final estimates on adult masses as those were more numerous in the literature.
These new estimates, coupled with ∼5,000 egg masses reported in the literature, provide a foundation of over 10,000 species for wider investigations examiniing variation in reproductive effort in birds over a broad array of ecological and evolutionary contexts.
Studying the avian egg, its shape, and other aspects of its morphology, has recently undergone a renaissance. Yet most studies rely solely on 2, albeit multicomponent, metrics for the quantification of egg shape: elongation and asymmetry. The difficulty of quantifying an additional trait, the curvature, of an eggshell has yielded many attempts, including several with complex equations or spatial modeling techniques based on digitized images. Yet most of these approaches have lacked an independent single-variable metric, hampering comparative studies especially. We propose a metric for one common quality of egg shape, conicality, which is notably variable across different species' calcareous shells, including shorebirds and non-avian theropods. This metric utilizes multiple measurements of the slope along an egg's profile to produce a distribution of angular measurements, which can be analyzed with a kurtosis value. We tested this metric with sets of computer-generated and 3-dimensional-printed egg forms, where elongation, the percentage of conicality, and the relative curvature of the shell profile were systematically manipulated. For applicability to natural eggs and their diversity across taxa, the kurtosis value was used to quantify the gradient of conicality across a focal avian family, Alcidae, where the extreme ranges of kurtosis values successfully identified eggs qualitatively described as most conical in previous studies. Given the significance of egg morphology and profile curvature to eggshells' structural integrity, surface area-to-volume ratio, mobility/stability, nesting behavior, embryonic development, and individual recognition, our proposed measure of conicality could prove a useful variable to the study of avian and non-avian egg-producing species.
LAY SUMMARY
Avian eggs are shaped in diverse ways and the form of bird's eggshell can be influenced by its nesting requirements, parenting strategies and flight abilities.
Most previous studies used only 2 metrics to study avian egg shape: (1) the width-to-length ratio and (2) the position along its length where the widest part of the egg is located (asymmetry).
We propose a novel metric (conicality) for quantifying how straight/curved the profile of an eggshell is between its outermost dimensions by assessing how much either half of the profile resembles a cone.
The novel conicality measure was also applied to a group of closely related birds with eggs that ranged from more elliptical to more conical. This new conicality metric successfully predicted the relative level of curvature known from casual observations of each species, which supports the method's validity.
Declines in reproductive performance among older age classes have been reported in many bird and mammal species, and are commonly presented as demonstrating reproductive senescence. However, no declines in performance could be demonstrated in studies of several bird species. We measured reproductive performance in Common Terns (Sterna hirundo) of known age (2–28 yr) during a 19-yr period at a site in Buzzards Bay, Massachusetts, USA. We measured 6 components of reproductive performance and used generalized additive mixed models (GAMMs) in a Bayesian framework to analyze dependence of each measure on parental age, while controlling for variations among years and indices of individual quality. Four measures of performance improved (earlier laying date, higher values of clutch size, fledging success, and productivity) with age, most rapidly between ages 2 and 10 yr; egg mass and hatching success varied only slightly with age. No measure of performance showed reversals among the older age classes; fledging success and productivity continued to increase through at least age 22 yr. These findings are consistent with results from an earlier study of the same species. Continued increase in reproductive performance through the oldest age classes is not incompatible with “reproductive senescence” (decline in physiological or other functions required for successful reproduction) if either reproductive effort or efficiency continue to increase. Studies within our population have yielded no evidence for age-related increase in reproductive effort, but 3 studies have suggested that older Common Terns can raise chicks more successfully than younger birds without increasing reproductive effort, probably by more efficient foraging and chick provisioning. Our findings suggest that Common Terns offset reproductive senescence by continuing to improve efficiency through at least age 22 yr. Age-related changes in efficiency should be investigated in other species with similar life-history traits.
LAY SUMMARY
We studied Common Terns (Sterna hirundo) at a breeding colony in Massachusetts from 1970 until 2003: we banded chicks when they hatched so that we could determine their age when they returned to breed at the same site in subsequent years.
The terns' breeding success continued to improve with age throughout their lives and was still increasing among birds that were 22 years old.
Common Terns continually improve their skills at finding fish and provisioning their chicks, even after 20 years of practice.
Together, puffbirds (Bucconidae) and jacamars (Galbulidae) form the suborder Galbulae, sister group of all other Piciformes. Hitherto, the Galbulae had no ascertained pre-Pleistocene fossil record, and all previous alleged candidates have been refuted, except possibly the Sylphornithidae. Here we describe a wing of a tiny fossil bird from the early Oligocene of the Luberon region (southern France), which we assign to the Galbulae, as a new genus and species. Several characters, especially of the ulna and wing phalanx 1 of digit II, exclude the Passeriformes and Zygodactylidae, and indicate a representative of the Piciformes. Among Piciformes, absence of papillae remigales caudales and several characters of the wing phalanx 1 of digit II make it possible to assign the fossil to the Galbulae, and exclude all other clades. The fossil Sylphornithidae, with the carpometacarpus of Sylphornis being available, show some similarity with the Luberon fossil. The combination of features of the wing elements leads to the placement of the new fossil as stem Galbulae, and tentatively within the family Sylphornithidae. As such, it fills a gap and permits to better assign the whole enigmatic tiny sylphornithids, otherwise essentially known from leg bones. This yields the first firm pre-Pleistocene fossil record for the Galbulae. Today, both the Bucconidae and Galbulidae live exclusively in tropical America. The presence of stem Galbulae in the Oligocene of Europe, and probably the late Eocene, is a new example of a present-day Neotropical clade that had stem representatives in the Paleogene of Europe.
LAY SUMMARY
A new fossil bird, named Jacamatia luberonensis, found in France and aged 30 myr, is the first pre-Pleistocene fossil for the whole suborder Galbulae (jacamars and puffbirds).
The evolution of the total group Galbulae, now an exclusively tropical American clade, involved the Old World.
Tentative placement of Jacamatia luberonensis in the fossil family Sylphornithidae helps to clarify the position of the latter enigmatic group of tiny, long-legged piciform birds.
Gloger's rule is a classic ecogeographical principle that, in its simplest version, predicts animals should be darker in warmer and wetter climates. In a rarely tested more complex version, it also predicts animals should be more rufous in warmer and drier climates. The Variable Antshrike (Thamnophilus caerulescens) is a widely distributed South American passerine that presents an impressive amount of plumage color variation and occupies a wide variety of climatic conditions. Moreover, genetic and vocal evidence indicate ongoing hybridization in south-central Bolivia among 3 populations with very distinct plumages. We collected color data from 232 specimens from throughout this species' distribution to test the predictions of Gloger's rule. We found a negative correlation between brightness and precipitation, consistent with the simple version of Gloger's rule. In contrast, we found that birds were darker in cooler climates, contrary to the simple version of Gloger's rule, but consistent with recent findings in other taxa. We found support for both predictions of the complex Gloger's rule and suggest it might be driven by background matching. We conclude by concurring with a recent suggestion that the simple version of Gloger's rule should be reformulated exclusively in terms of humidity.
LAY SUMMARY
Almost 200 years ago, the German naturalist Constantin Gloger predicted that birds that live in warm and rainy areas tend to be darker than those that in live in cool and dry areas. He also predicted that birds tend to be browner when they live in dry areas. This pattern has come to be known as Gloger's rule.
South America has the world's greatest bird diversity, but Gloger's rule has almost never been studied in South American birds. This is an important question to address because it can help us learn about how species evolve respond to their environments. It becomes even more important in our era of human-induced climatic changes.
We studied Gloger's rule in the aptly named Variable Antshrike. This small South American bird species varies geographically in color from almost all black to almost all white. We used a technique called reflectance spectrophotometry, which allows us to precisely quantify the colors of feathers. We measured over 200 specimens kept in natural history collections. The majority of those specimens were collected by one of us (Brumfield) in Bolivia in the early 2000s. This is the largest sample size ever used to study Gloger's rule in a tropical bird.
As predicted by Gloger, we found that the Variable Antshrike tends to be darker in rainier areas, and it tends to be browner in drier and warmer areas. But contrary to Gloger's ideas, we found that it tends to be darker in cooler, not warmer, areas. We suggest that this might be because being dark in cooler places helps birds maintain warm body temperatures. We also suggest that being brown in dry areas helps the birds camouflage amidst sparse vegetation.
Hybrids with different combinations of traits can be used to identify genomic regions that underlie phenotypic characters important to species identity and recognition. Here, we explore links between genomic and plumage variation in Blue-winged Warbler x Golden-winged Warbler (Vermivora cyanoptera x V. chrysoptera) hybrids, which have traditionally been categorized into 2 discrete types. “Lawrence's” hybrids are yellow overall, similar to Blue-winged Warblers, but exhibit the black throat patch and face mask of Golden-winged Warblers. “Brewster's” hybrids are similar to Golden-winged Warblers, but lack the black throat patch and face mask, and sometimes have yellow on their underparts. Previous studies hypothesized that (1) first generation hybrids are of the Brewster's type and can be distinguished by the amount of yellow on their underparts, and that (2) the throat patch/mask phenotype is consistent with Mendelian inheritance and controlled by variation in a locus near the Agouti-signaling protein (ASIP) gene. We addressed these hypotheses using whole genome re-sequencing of parental and hybrid individuals. We found that Brewster's hybrids had genomic hybrid index scores indicating this phenotype can arise by majority ancestry from either parental species, that their plumage varied in levels of carotenoid pigmentation, and individuals captured in multiple years grew consistently less yellow over time. Variation in carotenoid pigmentation showed little relationship with genomic hybrid index score and is thus inconsistent with previous hypotheses that first generation hybrids can be distinguished by the amount of yellow in their plumage. Our results also confirm that variation near ASIP underlies the throat patch phenotype, which we refined to an ∼10–15 Kb region upstream of the coding sequence. Overall, our results support the notion that traditional categorization of hybrids as either Lawrence's or Brewster's oversimplifies continuous variation in carotenoid pigmentation, and its inferred underlying genetic basis, and is based primarily on one discrete trait, which is the throat patch/mask phenotype.
LAY SUMMARY
We used whole genome sequences of hybrid Vermivora warblers to examine the genetic basis and inheritance of plumage pigmentation.
Yellow carotenoid pigmentation varied among hybrids, decreased between years, and showed no clear relationship with degree of admixture, suggesting a complex genetic basis.
The ASIP gene was previously linked to melanic (black) throat pigmentation and we refined the causal region to ∼10–15 Kb upstream of the coding sequence.
We conclude that first generation hybrids in this system may not be readily distinguished by their degree of carotenoid pigmentation.
Individual recognition is a social behavior that occurs in many bird species. A bird's ability to discriminate among familiar and unfamiliar conspecifics is critical to avoid wasting resources such as time and energy during social interactions. Black-capped Chickadees (Poecile atricapillus) are able to discriminate individual female and male chick-a-dee calls, potentially male and female tseet calls, and male fee-bee songs. In the current study, we used an operant discrimination go/no-go paradigm to determine whether female and male chickadees could discriminate between fee-bee songs produced by individual female chickadees as well as test which song component(s) enable this discrimination. Birds trained on natural categories—the songs of different females—learned to respond to rewarded stimuli more quickly than birds trained on random groupings of female songs and were able to transfer this learning to new songs from the same categories. Chickadees were also able to generalize their responding when exposed to the bee note of the fee-bee song of rewarded individuals; they did not generalize to fee notes. Our results provide evidence that Black-capped Chickadees can use female-produced fee-bee songs for individual recognition. However, the acoustic features underlying individual recognition require further investigation.
LAY SUMMARY
The current study used an operant conditioning paradigm to test whether Black-capped Chickadees can distinguish between the songs of individual female Black-capped Chickadees.
Research on female song in Black-capped Chickadees has shown that female song differs from male song in sound and perception, and chickadees can distinguish between male and female song.
We found that male and female chickadees can distinguish between females by listening to their song, and can do so using the whole song and only part of the song.
A chickadee's ability to distinguish song by sex as well as by the individual female suggests that female song does serve a function in Black-capped Chickadees.
The biodiversity of the Neotropics is considerable, but it is likely underestimated owing to gaps in sampling effort and a focus on using morphological features of animals to determine species differences rather than divergence in their mating signals and behavior. Recent multi-trait analyses incorporating morphological, plumage, and vocal data have allowed for more accurate quantification of tropical biodiversity. We present a comprehensive study of morphological features, plumage, and vocalizations of the Neotropical resident Rufous-capped Warbler (Basileuterus rufifrons). This species' taxonomic status is controversial because the B. r. salvini subspecies is intermediate in plumage coloration between the neighboring B. r. delattrii and B. r. rufifrons subspecies. Using morphological and spectral plumage measurements of field and museum specimens, as well as analyses of vocalizations from field recordings and sound libraries, we compared phenotypes of all 8 currently recognized Rufous-capped Warbler subspecies, with an emphasis on delattrii, rufifrons, and salvini. We found that delattrii and rufifrons differ significantly in morphology and plumage, and that salvini is similar to rufifrons in morphology and some plumage features. Vocalizations fall into 2 distinct groups, delattrii and rufifrons-salvini, which differ in multiple spectro-temporal characteristics with no overlap between them, even among individuals in the delattrii–rufifrons zone of sympatry. Our results therefore suggest that Rufous-capped Warblers comprise 2 distinct groups: Rufous-capped Warblers (B. r. rufifrons and salvini as well as B. r. caudatus, dugesi, and jouyi) and Chestnut-capped Warblers (B. r. delattrii as well as B. r. actuosus and mesochrysus). Future genomic analysis of samples from multiple sites in Mexico and Central America will further refine our assessment of range-wide phenotypic and genetic divergence in this species complex.
LAY SUMMARY
The taxonomy of Rufous-capped Warblers is controversial: 8 subspecies exhibit divergent plumage color and songs and consequently they are sometimes treated as 2 separate species.
Using field data, museum specimens, and sound archives, we compared the body size, plumage color, and songs of all 8 Rufous-capped Warbler subspecies
Seven of 8 subspecies comprised 2 groups with different color, songs, and body size: the northern, white-bellied rufifrons group and the southern, yellow-bellied delattrii group.
The eighth subspecies, salvini, showed similarity to the rufifrons group, rather than being intermediate between the 2 groups as described in previous studies.
We found that Rufous-capped Warblers comprise 2 separate groups, which improves our knowledge of Neotropical avian biodiversity.
R. Terry Chesser, Shawn M. Billerman, Kevin J. Burns, Carla Cicero, Jon L. Dunn, Andrew W. Kratter, Irby J. Lovette, Nicholas A. Mason, Pamela C. Rasmussen, J. V. Remsen Jr, Douglas F. Stotz, Kevin Winker
Hermit Warblers (Setophaga occidentalis) sing a formulaic, type I song to attract mates, in contrast to a repertoire of more complex, type II songs to defend territories. A single, dominant type I song, or a low diversity of type I songs, often occur within a geographic area. We provide the first comprehensive description of Hermit Warbler type I song variants throughout California, USA. We recorded type I songs from 1,588 males across 101 study sites in the state from April through July 2009–2014. Using those locations and a pre-existing range map of the species, we created a maximum entropy-based breeding habitat suitability map and classified the songs into 35 variants using a typological rubric. We validated consistent classification of songs for 87.5% of the birds. We then modeled the effects of recent fire history at the local scale (10 yr, 315 km2), the amount of breeding habitat at the regional scale (8,000 km2), and the distance between territories to examine factors involved in song sameness at the local scale. We found that the probability of different birds singing the same form declined with the amount of local fire, regional habitat, and distance, and that these findings were robust to uncertainty in our song classification rubric. Using a longitudinal analysis including additional data from 10 study areas revisited in 2019, we showed that song structure within forms had drifted since our initial visits 5–10 yr earlier, and that the evenness (e.g., Simpson's measure) of song forms increased at locations that had been burned by wildfire between visits. Taken together, the results suggest that wildfires and the mass effects of dispersal of birds singing rival song forms disrupt the uniformity of type I songs locally. The results demonstrate how species traits, such as birdsong, can be used to disentangle the ecological processes that regulate observed patterns in biodiversity. Further investigation is recommended to determine whether song pattern dynamics reflect underlying genetic differences and habitat specializations among subpopulations.
LAY SUMMARY
The diversity of song dialects sung by Hermit Warblers in California forests is influenced by fire history.
After exhaustive surveys of >1,500 birds, we mapped the distribution of 35 song dialects throughout the state.
Our results suggest that differences among these songs were generated as an epiphenomenon of different subpopulations specializing on different forest types.
Dispersal due to fire, and the mass effects of birds from surrounding forests, likely disrupts the uniformity of song dialects within locations, thereby promoting dynamic diversity over the longer term.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere