bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological Role of a Tree (Gmelina Arborea) Plantation in Guatemala: An Assessment of an Alternative Land use for Tropical Avian Conservation
Authors: Rotenberg James A.
Published: September 2019

Established parks and nature reserves may be inadequate to preserve long-term biotic diversity, especially in tropical regions of Latin America where anthropogenic disturbance and land-conversion is an ongoing problem. Demand for economically productive land uses, such as cattle pastures or monoculture plantations, is one of the greatest threats to habitat and wildlife preservation. As a result, conservation biologists have turned to examining attributes of nonprotected lands to determine which land uses both support wildlife and make economic sense. I examined bird use of a plantation of Gmelina arborea (“white teak” or “melina” trees; hereafter “plantation”) in Guatemala to assess its suitability as bird habitat. Gmelina arborea is grown mainly for wood and paper pulp. Several compositionally different habitats were identified, based on the amount of natural vegetation grown within and among the plantation trees, forming a heterogeneous landscape. I detected 195 bird species from 45 families within this plantation-dominated landscape, and 144 species in plantation habitats combined. I observed a positive association between increased vegetative complexity and bird species richness; moreover, bird species richness attained levels statistically indistinguishable from those found in nearby forest fragments. Mixed plantation habitat containing 19–31% natural vegetative coverage supported bird communities that equaled or surpassed levels of species richness found by other researchers in shaded coffee (Coffea spp.) plantations. However, pure stands of G. arborea supported richness levels equal to those of grazed pasture; diversity levels associated with both these land uses were close to those reported for sun coffee plantations. Clearly, native vegetation played a significant role in enhancing bird species richness in the plantation habitat, and amounts of relative cover similar to or exceeding those in the plantation I studied should be considered in any management plan for G. arborea in Central America.

Rol Ecológico de Plantaciones de Árboles de Gmelina arborea en Guatemala: Una Evaluación de un Uso Alternativo del Suelo para la Conservación de las Aves Tropicales
Testosterone in Northern Cardinals (Cardinalis Cardinalis): Possible Influence of Prolonged Territorial Behavior
Authors: Jawor Jodie M.
Published: September 2019

Two attributes of many temperate passerine species are short-term territoriality and strongly fluctuating annual testosterone (T) profiles. Circulating T of temperate passerines can vary from undetectable levels in the nonbreeding season to higher, but fluctuating, levels during the breeding season. Males of many temperate species respond to territorial instability during the breeding season with transitory increases in T. In females, the hormonal response to aggression is more complex. Most temperate-zone passerine species that have been studied exhibit territoriality for less than three months. Here, I describe the year-round T profile of male and female Northern Cardinals (Cardinalis cardinalis), a temperate-zone species with prolonged territorial behavior (7+ months). Circulating levels of T in female Northern Cardinals is relatively stable. Males show variation in T levels over the year and they may respond to territorial intrusions with increases in T. Of particular interest are the relatively high levels of T observed in female Northern Cardinals throughout the year, and measurable amounts of T in both sexes in the winter.

Testosterona en Cardinalis cardinalis: Posible Influencia del Comportamiento Territorial Prolongado
High Level of Song Sharing in an Eastern Population of Song Sparrow (Melospiza Melodia)
Authors: Foote Jennifer R. , Barber Colleen A.
Published: September 2019

Using shared songs is believed to be an integral part of neighbor communication and territory establishment strategies among many avian species with repertoires. Previous studies of two western subspecies of Song Sparrows (Melospiza melodia) reported a high level of song sharing among neighboring males, whereas studies of an eastern subspecies have reported a very low level. The purpose of our study was to investigate another population of the eastern subspecies to determine whether higher song-sharing levels existed within its range. Every song in the repertoire of 29 males was compared with the songs of all other males to assess the number of shared songs. For each male, we calculated the mean song-sharing level with neighbors and non-neighbors. Males shared, on average, 33% of their repertoire with neighbors, significantly more than they shared with non-neighbors (27% of their repertoire). Two first-year males learned whole song types from several individuals and preferentially learned the song types shared among those individuals. Our results suggest that the eastern and western subspecies may not differ genetically in the way they learn songs, because song-sharing levels and song learning in our population were more similar to those of the western subspecies than to those of other populations within its own subspecies. Song-sharing differences among eastern populations may be explained instead by factors acting at the level of individual populations.

Niveau Élevé de Chants Partagés chez une Population de l'Est de Melospiza melodia
Tufted Puffins (Fratercula Cirrhata) Respond to Predation Danger During Colony Approach Flights
Authors: Addison BriAnne , Ydenberg Ronald C. , Smith Barry D.
Published: September 2019

In spite of their putative importance in the evolution of certain traits (e.g., nocturnality, coloniality, cliff nesting), the effects of aerial predators on behavior of adult seabirds at colonies have been poorly investigated. We hypothesized that Tufted Puffins (Fratercula cirrhata) respond to danger posed by aerial predators by modifying their behavior to mitigate danger. We observed Tufted Puffins making repeated colony fly-ins and departures and characterized (1) the timing of this behavior, (2) the activity rate (number of birds arriving or departing), and (3) the risk-level of activity, with respect to predation danger posed by Bald Eagles (Haliaeetus leucocephalus) and Peregrine Falcons (Falco peregrinus). As we predicted, we found that Tufted Puffins (1) dilute danger by synchronizing their fly-in and departure activities, (2) reduce fly-in and departure activity rates when predators are present, and (3) switch to lower-risk fly-in activities (e.g., staying over water where they have an escape route from an aerial attack) when predators are present.

Réaction de Fratercula cirrhata au Danger de Prédation au cours des Vols d'Approche de la Colonie
Incorporating Availability for Detection in Estimates of Bird Abundance
Authors: Diefenbach Duane R. , Marshall Matthew R. , Mattice Jennifer A. , Brauning Daniel W.
Published: September 2019

Several bird-survey methods have been proposed that provide an estimated detection probability so that bird-count statistics can be used to estimate bird abundance. However, some of these estimators adjust counts of birds observed by the probability that a bird is detected and assume that all birds are available to be detected at the time of the survey. We marked male Henslow's Sparrows (Ammodramus henslowii) and Grasshopper Sparrows (A. savannarum) and monitored their behavior during May-July 2002 and 2003 to estimate the proportion of time they were available for detection. We found that the availability of Henslow's Sparrows declined in late June to <10% for 5- or 10-min point counts when a male had to sing and be visible to the observer; but during 20 May-19 June, males were available for detection 39.1% (SD = 27.3) of the time for 5-min point counts and 43.9% (SD = 28.9) of the time for 10-min point counts (n = 54). We detected no temporal changes in availability for Grasshopper Sparrows, but estimated availability to be much lower for 5-min point counts (10.3%, SD = 12.2) than for 10-min point counts (19.2%, SD = 22.3) when males had to be visible and sing during the sampling period (n = 80). For distance sampling, we estimated the availability of Henslow's Sparrows to be 44.2% (SD = 29.0) and the availability of Grasshopper Sparrows to be 20.6% (SD = 23.5). We show how our estimates of availability can be incorporated in the abundance and variance estimators for distance sampling and modify the abundance and variance estimators for the double-observer method. Methods that directly estimate availability from bird counts but also incorporate detection probabilities need further development and will be important for obtaining unbiased estimates of abundance for these species.

Incorporación de la Disponibilidad para la Detección en las Estimaciones de Abundancia de Aves
Postfledging Survival and Movement in Dickcissels (Spiza Americana): Implications for Habitat Management and Conservation
Authors: Berkeley Lorelle I. , McCarty John P. , Wolfenbarger L. LaReesa
Published: September 2019

When land managers incorporate the habitat needs of grassland birds into their planning, they typically rely on management recommendations based on habitat use by adults during nesting. Habitat requirements for other critical life stages are seldom known and may differ from those of nesting adults. Using radio-telemetry, we examined survival and habitat use by juvenile Dickcissels (Spiza americana) during the postfledging period. In 2003 and 2004, we monitored 60 fledgling Dickcissels for ≤30 days after they left the nest. Mortality rates were highest during the first week after leaving the nest, and only 33% of the fledglings survived the first four weeks after leaving the nest. Estimated mean survival times were 16.9 ± 1.6 days after birds left the nest. In both years, fledgling survival was positively associated with dense vertical and horizontal structure of forbs at nests. Survival tended to be positively associated with vertical grass density on adult territories and negatively associated with patchily distributed forbs on adult territories. Fledgling habitat use was restricted to areas where Dickcissels nested and adjacent fields. Habitats used included corn and soybean fields, grasslands, and wetlands. Our results suggest that the fledgling period is a critical stage for Dickcissels and that fledglings require habitat similar to habitat used for nesting.

Supervivencia Durante el Período Posterior al Emplumamiento en Spiza americana: Implicancias para el Manejo de Hábitat y Conservación
Population Structure and Mitochondrial Polyphyly in North American Gadwalls (Anas Strepera)
Authors: Peters Jeffrey L. , Omland Kevin E.
Published: September 2019

We examined population genetic structure in Gadwalls (Anas strepera) to test the prediction that female philopatry and fidelity to migratory flyways have contributed to the partitioning of mitochondrial variation across North America. Sequencing a 658–659 base-pair fragment of the mitochondrial DNA (mtDNA) control region from 348 Gadwalls, we found two distinct clades that were broadly intermixed across both breeding and nonbreeding populations. Clade A was abundant in North America as well as among published sequences from Eurasia. Clade B was sequenced from 5.5% of North American Gadwalls and was more similar to Asian Falcated Duck (A. falcata) haplotypes than to clade A haplotypes. Maximum likelihood indicated that Gadwall clade B haplotypes were a monophyletic group nested within Falcated Duck haplotypes, which suggests mtDNA introgression of clade B into Gadwalls. However, that topology was weakly supported, and we could not reject topologies that were consistent with incomplete lineage-sorting as the cause of mitochondrial polyphyly. Migratory flyways did not contribute significantly to population structure and, in general, we found a lack of genetic structure among most populations. However, Gadwalls sampled in Alaska and Washington were well differentiated from other populations. Coalescent analyses supported a historical population expansion for clade A, and this expansion could have contributed to the high genetic similarity among some populations but the strong differentiation of others. Female-mediated gene flow, along with both historical and contemporary population and range expansions, has likely contributed to the overall weak mtDNA structure in North American Gadwalls.

Estructura Poblacional y Polifilia Mitocondrial en Anas strepera
Patterns of Molecular and Morphological Variation in Some Solomon Island Land Birds
Authors: Smith Catherine E. , Filardi Christopher E.
Published: September 2019

The Solomon Archipelago is the largest and most biologically complex archipelago in northern Melanesia. We collected tissues and voucher specimens from codistributed bird species found on five island groups that provided the first opportunity to apply molecular methods to this avifauna. Using the mitochondrial marker ND2, we constructed a series of intraspecific phylogenies for 23 ecologically and taxonomically diverse species (13 families from 5 orders). Intraspecific comparisons across islands revealed a broad range of genetic differentiation, from 0% in widespread dispersive species such as Eurystomus orientalis and Nectarinia jugularis, to as high as 4–8% in species such as Ceyx lepidus and Dicaeum aeneum. Fifteen of the 23 species had well-supported phylogeographic structure, and for many of these, endemic and otherwise, molecular phylogenetic relationships closely matched those delineated by morphology. However, degrees of genetic differentiation appeared to be inconsistent across taxonomic designations, and the monophyly of some endemic taxa was not well supported. The data reveal the limits of morphology in tracking complex evolutionary histories and suggest that taxonomic revision of some Solomon Islands birds is warranted. As the first molecular analyses of this avifauna, results presented here create a platform for further biogeographic and evolutionary studies of bird diversity in this influential region.

Patrons de variation moléculaire et morphologique chez quelques oiseaux terrestres des îles Salomon
A Cautionary Tale: Cryptic Sexual Size Dimorphism in a Socially Monogamous Passerine
Authors: Murphy Michael T.
Published: September 2019

Among socially monogamous birds, standard metrics suggest that males are only ∼5% larger than females. An untested assumption is that, with the exception of reproductive systems, males and females are scaled mirror images of one another. I used external morphological and skeletal data, and information on muscle mass and organ size, to test this assumption in a population of breeding Eastern Kingbirds (Tyrannus tyrannus). Male and female Eastern Kingbirds exhibited no differences in body mass or standard measures of size, except in a longer (∼6%) wing chord and tail in males. However, keel length, a character rarely measured in the field, was 9.7% larger in males. In principal component analysis, overall body size (PC1) failed to differ between the sexes unless keel length was included. Analysis of 16 skeletal characters also showed that only the bones associated with flight were larger in males. However, the most significant differences between the sexes was that lean dry pectoral muscle mass (LDPMM) was nearly 30% greater in males, whereas the alimentary tract was 27.5% heavier in females. Females also carried more fat. In both sexes, LDPMM scaled in a positive allometric manner with body mass (i.e., slope > 1.0), but the significantly higher slope of males suggested especially strong selection for large muscle mass and, presumably, greater power generation during flight. Eastern Kingbirds thus exhibit pronounced cryptic sexual size dimorphism, but it is not clear whether natural or sexual selection is responsible. These data call for a broader perspective for measuring and a re-evaluation of sexual size dimorphism in other socially monogamous species.

Un Llamado de Atención: Dimorfismo Críptico en el Tamaño en un Paserino Socialmente Monógamo
Color Variation Among Nestling Brown-Headed Cowbirds (Molothrus Ater) Does Not Reflect Differential Success With Hosts in Texas
Authors: Ellison Kevin , Sealy Spencer G. , McGaha Hope R.
Published: September 2019

As brood parasites, nestling Brown-headed Cowbirds (Molothrus ater) may exhibit characters that improve their fledging success when reared alongside host young. The coloration of mouthparts of nestlings can influence adult care and, thus, the polymorphism of yellow or white rictal flanges among nestling Brown-headed Cowbirds may reflect differential success with different hosts on the basis of flange color. Moreover, because Brown-headed Cowbirds in the southern United States co-occur with Bronzed Cowbirds (M. aeneus), whose young have white flanges, cowbird nestlings' flange colors may reflect a means for reducing interspecific competition through partitioning of host species on the basis of nestling flange color. To determine whether flange color influences cowbird fledging success with hosts of either color, we recorded the flange colors of cowbirds and their hosts at a site in Texas. We also tested whether flange color was influenced by nestling sex. Most hosts of Brown-headed Cowbirds had young with yellow flanges (81%, n = 16 spp.), yet Brown-headed Cowbirds with white flanges were more common (61%, n = 107). Bronzed Cowbirds parasitized primarily species whose young had white flanges (86%, n = 348 eggs). Despite the differential use of hosts with regard to flange color, the frequencies of each were similar among nestling and juvenile Brown-headed Cowbirds. Likewise, the frequencies of each color did not differ significantly between the sexes. Therefore, we suggest that a flange color matching that of nestmates is not strongly selected for by hosts.

La Variación del Color entre Polluelos de Molothrus ater no Refleja Éxito Diferencial al Ser Criados por Especies Hospederas en Texas
Flood Tides Affect Breeding Ecology of Two Sympatric Sharp-Tailed Sparrows
Authors: Shriver W. Gregory , Vickery Peter D. , Hodgman Thomas P. , Gibbs James P.
Published: September 2019

Breeding synchrony with the lunar cycle has been reported for many marine organisms but is essentially unknown for birds. Most organisms shown to breed synchronously with the lunar cycle provide no parental care to young, and such explosive breeding assemblages are usually promiscuous. Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus caudacutus) nest exclusively on salt marshes and are subjected to predictable, catastrophic flooding caused during flood tides every 28 days. Here, we show that Saltmarsh Sharp-tailed Sparrow males were nonterritorial and promiscuous and provided no parental care to young. Breeding behaviors of both sexes were synchronized with the lunar cycle. By contrast, males of a sympatric sister species, Nelson's Sharp-tailed Sparrow (A. nelsoni subvirgatus), consistently mate-guarded females, and breeding was not synchronized with the lunar cycle, yielding 21% lower reproductive success compared with Saltmarsh Sharp-tailed Sparrows. Saltmarsh and Nelson's sharp-tailed sparrows renested 2.9 ± 0.6 (SE) days and 10.3 ± 1.7 days after nest flooding, respectively. Patterns of vicariance between Nelson's and Saltmarsh sharp-tailed sparrows may explain the differences in social behavior and nesting ecology. Ancestral sharp-tailed sparrows diverged from Seaside Sparrows (A. maritimus) in tidal wetlands, and Nelson's Sharp-tailed Sparrows then diverged from Saltmarsh Sharp-tailed Sparrows in nontidal freshwater wetlands of interior North America. Nelson's Sharp-tailed Sparrows' range recently expanded into coastal salt marshes, where Saltmarsh Sharp-tailed Sparrows are better adapted to tidally influenced inundations. Adaptation to tidal flooding partially explains the evolution of the unique Saltmarsh Sharp-tailed Sparrow mating system.

Las Inundaciones Mareales Afectan la Ecología Reproductiva de Dos Especies Simpátricas de Ammodramus
King Eider (Somateria Spectabilis) Brood Ecology: Correlates of Duckling Survival
Authors: Mehl Katherine R. , Alisauskas Ray T.
Published: September 2019

Events during duckling growth can influence waterfowl population dynamics. To gain insight into King Eider (Somateria spectabilis) brood ecology, we monitored 111 and 46 individually marked ducklings from broods of 23 and 11 radiomarked King Eiders during 2000 and 2001, respectively. We used capture-mark-resight data to model apparent survival of King Eider ducklings and broods, and multistratum analysis to estimate probabilities of (1) movement among habitats and (2) apparent survival of ducklings that used various habitats. In addition, we recorded length of stay for 7 and 18 radiomarked females with failed nesting attempts during 2000 and 2001, respectively. Complete loss of individual broods accounted for 84% of all duckling mortality (106 of 126 mortalities), with most brood loss (74%; 17 of 23 broods lost) within the first two days after hatch. Estimated apparent survival of ducklings to 24 days of age was 0.10 (95% CI: 0.05 to 0.15). Apparent survival of broods was estimated to be 0.31 (95% CI: 0.13 to 0.50). Our data suggested an interaction between female size and hatch date, whereby larger females whose ducklings also hatched earlier raised more ducklings than either small females or those with ducklings that hatched later. Overland brood movements ≥1 km occurred in both years, and survival was greatest for ducklings on smaller ponds away from the central nesting area at Karrak Lake, Nunavut. Females that experienced nest failure and total brood loss left the study area earlier than females with surviving ducklings.

Écologie d'élevage des couvées de Somateria spectabilis : Corrélations avec la survie des canetons
Nest Light Environment and the Potential Risk of Common Cuckoo (Cuculus Canorus) Parasitism
Authors: Muñoz A. Román , Altamirano Maria , Takasu Fugo , Nakamura Hiroshi
Published: September 2019

Brood parasitism represents a significant cost in reproduction; thus, natural selection should favor the evolution of host defenses, which in turn may favor evolution of more sophisticated techniques by the parasite to overcome host defenses. These host defenses include egg rejection, attacking parasites near the nest, and avoiding parasitism by concealing nest sites. In all these antiparasitism strategies, nest light environment may play an important role. In the present study, the risk of Common Cuckoo (Cuculus canorus) parasitism for the Great Reed Warbler (Acrocephalus arundinaceus) was modeled in relation to the in situ nest light environment, from far ultraviolet (UV) to infrared (IR) radiation (280–1,100 nm), and nest situation and structure. The percentage of photosynthetically active radiation (PAR) plus IR radiation (400–1,100 nm) falling on the nest, maximum nest width, and distance between the nest and the nearest active conspecific neighbor were significantly related to the risk of parasitism. Photosynthetically active radiation alone explained 65% of variation in parasitism risk in the final model. Although solar radiation levels in nests were low (<4% for UV-B and UV-A radiation, 5% for PAR, and 22% for PAR plus IR radiation when cloudless), UV-B, UV-A, and visible-plus-IR radiation levels were significantly lower in nonparasitized nests. These findings provide the first evidence of a relationship between parasitism risk and nest concealment related to microhabitat light environment, with brighter nests suffering a higher risk of parasitism.

Ambiente Lumínico del Nido y el Riesgo Potencial de Parasitismo por Parte de Cuculus canorus
Validation of Thamnophilus Capistratus Lesson, 1840 (Passeriformes: Thamnophilidae)
Authors: Assis Claydson P. , Raposo Marcos A. , Stopiglia Renata , Parrini Ricardo
Published: September 2019

We reviewed the taxonomic status of Thamnophilus doliatus capistratus Lesson, 1840, which is endemic to eastern Brazil. The analyses of skins focused on plumage coloration and measurements. Morphometric skin analyses included descriptive statistics, analyses of variance, and discriminant-function analysis. The results provided a consistent morphological and morphometric diagnosis, and consequently validated Thamnophilus capistratus.

Validação de Thamnophilus capistratus Lesson, 1840 (Passeriformes: Thamnophilidae)
Waterfowl Ecology and Management
Authors: Krapu Gary L.
Published: September 2019

The following critiques express the opinions of the individual evaluators regarding the strengths, weaknesses, and value of the books they review. As such, the appraisals are subjective assessments and do not necessarily reflect the opinions of the editors or any official policy of the American Ornithologists' Union.
Birds of Mexico and Central America
Authors: de Silva Héctor Gómez
Published: September 2019

The following critiques express the opinions of the individual evaluators regarding the strengths, weaknesses, and value of the books they review. As such, the appraisals are subjective assessments and do not necessarily reflect the opinions of the editors or any official policy of the American Ornithologists' Union.
A New Species of Smoky Honeyeater (Meliphagidae: Melipotes) From Western New Guinea
Authors: Beehler Bruce M. , Prawiradilaga Dewi M. , de Fretes Yance , Kemp Neville
Published: September 2019

We describe a new species of smoky honeyeater from the Foja Mountains, an isolated range in western New Guinea (Papua Province, Indonesia). A common inhabitant of montane forest and forest-edge in this little-known north coastal range, this species possesses a fleshy pendant suborbital wattle, unique in the genus Melipotes, among other characteristics that distinguish it from all congeners. This fleshy wattle provides a morphological link between Melipotes and the monotypic genus Macgregoria, an alpine inhabitant of the Central Ranges of New Guinea, traditionally treated as a bird of paradise (e.g., Frith and Beehler 1998) but now regarded as the sister genus to Melipotes (Cracraft and Feinstein 2000). The presence of an endemic meliphagid species in the Foja Mountains highlights the biogeographic significance and conservation importance of this geographically isolated upland forest tract, which is also home to the endemic Golden-fronted Bowerbird (Amblyornis flavifrons) and Berlepsch's Parotia (Parotia berlepschi), a distinctive, recently rediscovered species of six-wired bird of paradise (B. M. Beehler unpubl. data).

Una Especie Nueva de Melipotes (Meliphagidae) del Oeste de Nueva Guinea
Lifetime Reproductive Success of Female Eastern Kingbirds (Tyrannus Tyrannus): Influence of Lifespan, Nest Predation, and Body Size
Authors: Murphy Michael T.
Published: September 2019

I report on the lifetime reproductive success (LRS) of female Eastern Kingbirds (Tyrannus tyrannus) in central New York. I investigated the major correlates of LRS and specifically tested the hypothesis that small body size yields reproductive benefits. Lifetime reproductive success varied widely: 15–20% of females failed to fledge young over their life, whereas 50% of young were fledged by 20% of females. Female lifespan varied between one and eight years, and females that died after one breeding season tended to be smaller-bodied than long-lived females (≥2 seasons). I therefore conducted analyses of LRS for the entire sample and for longer-lived females separately. As in other species, lifespan was the strongest predictor of LRS, followed by the proportion of eggs laid that resulted in fledged young (P). Lifetime reproductive success varied positively with clutch size and, as predicted, inversely with body size (i.e., tarsus length) of females. However, variance partitioning indicated that most variation in LRS was attributable to the effects of lifespan and P, but that a substantial negative covariance existed between lifespan and P. The latter result was consistent with experimental evidence of a cost of reproduction in Eastern Kingbirds. Analysis of the correlates of lifespan, P, and clutch size showed that over a female's lifetime, (1) the longest-lived birds fledged an intermediate proportion of the eggs that they laid, (2) the most productive birds were of intermediate wing length, and (3) females with small tarsi produced the largest clutches and lost the fewest nests to predators. Hence, although lifespan was the dominant influence on LRS, negative effects of large female size appeared to be expressed through the influence of body size on other demographic parameters that contribute to LRS.

Éxito Reproductivo Completo de Vida de Hembras de Tyrannus tyrannus: Influencia de la Duración de la Vida, la Depredación de Nidos y el Tamaño Corporal
Survival and Natal Dispersal of Juvenile Snowy Plovers (Charadrius Alexandrinus) in Central Coastal California
Authors: Stenzel Lynne E. , Page Gary W. , Warriner Jane C. , Warriner John S. , George Douglas E. , Eyster Carleton R. , Ramer Bernadette A. , Neuman Kristina K.
Published: September 2019

Juvenile survival and dispersal rates are important demographic parameters in predicting the viability of avian populations, but estimates are seldom available because mortality is usually confounded with permanent natal dispersal in analyses of live-encounter data. We used the Barker model for combined captures, recoveries, and resightings to estimate juvenile survival in fledgling Snowy Plover (Charadrius alexandrinus) for the 6.5-to-10.5-month period between fledging at 28 days and 1 April the following year, on the central California coast, for a 16-year period, 1984-1999. By using a large body of year-round sighting data from throughout the species' Pacific-coast range, we estimated true survival and quantified natal dispersal rates and distances. Juvenile survival estimates varied annually between 0.283 ± 0.028 (mean ± SE) and 0.575 ± 0.061 with no trend over the study, and paralleled higher adult survival in our most parsimonious models. In comparison, annual survival of banded chicks from hatching to fledging at age 28 days was 0.285–0.483 (x̄ = 0.382 ± 0.014 SE) for those 16 years. Males were more likely to disperse from Monterey Bay for winter and females were more likely to disperse for breeding. Dispersal distances to breeding sites were usually within 10 km of natal sites (64%) and seldom >50 km (16%). The present study provides the first estimate of true survival for a juvenile shorebird and new information on survival and dispersal rates that will be useful for modeling Snowy Plover population viability. Studies of local winter residents, focused on predator pressure and weather conditions, could further advance our understanding of factors determining Snowy Plover survival.

Supervivencia y Dispersión Natal de Juveniles de Charadrius alexandrinus en la Costa Central de California
Detecting Population Trends in Migratory Birds of Prey
Authors: Farmer Christopher J. , Hussell David J. T. , Mizrahi David
Published: September 2019

Counts of visible migrants at traditional watchsites throughout North America provide an opportunity to augment population-monitoring efforts for birds of prey. We analyzed hourly counts of migrating raptors at one inland (Hawk Mountain Sanctuary, Pennsylvania) and one coastal (Cape May Point, New Jersey) watchsite in northeastern North America. Hourly counts of migrants have been collected for 38 years at Hawk Mountain Sanctuary and for 28 years at Cape May Point. We compared effort-adjusted, arithmetic-mean passage rates to five geometric-mean indexes for 12 species. We used reparameterized polynomial regression to estimate trends in the indexes and to test the significance of trends from 1976–1978 (average index over three-year period) to 2001–2003. Effort-adjusted, arithmetic-mean indexes corresponded to more sophisticated indexes on the complete data sets but did not perform well on simulated data with missing observation days. We recommend the use of a regression-based, date-adjusted index for the analysis of hawk-count data. This index produced trends similar to other geometric-mean indexes, performed well on data sets simulating reduced sampling frequency, and outperformed other indexes on data sets with large blocks of missing observation days. Correspondence between trends at the watchsites and trends from Breeding Bird Surveys (BBSs) suggests that migration counts provide robust estimates of population trends for raptors. Furthermore, migration counts allow the monitoring of species not detected by BBS and produce trends with greater precision for species sampled by both methods. Analysis of migration counts with appropriate methods holds considerable promise for contributing to the development of integrated strategies to monitor raptor populations.

Detección de Tendencias Poblacionales en Aves de Presa Migratorias
Stopover Habitat use by Spring Migrant Landbirds: The Roles of Habitat Structure, Leaf Development, and Food Availability
Authors: Rodewald Paul G. , Brittingham Margaret C.
Published: September 2019

Stopover habitat quality may influence the abundance of migrant landbirds, yet little is known about how spatial and temporal changes in stopover habitat quality influence the use of habitats by migrant landbirds. From late April to late May, 1997–1999, we surveyed migrant landbirds within five habitats (early successional shrub-sapling-stage forest, midsuccessional pole-stage forest, mature forest interior, mature forest-agricultural edge, and mature suburban forest) in central Pennsylvania. To assess relative quality of stopover habitats, we measured species abundance, species richness, and foraging behavior of Yellow-rumped Warblers (Dendroica coronata). We measured vegetation structure and phenology to examine proximate cues of potential importance in habitat selection. Of nine transient (nonbreeding) species analyzed, seven-Least Flycatcher (Empidonax minimus), Nashville Warbler (Vermivora ruficapilla), Northern Parula (Parula americana), Magnolia Warbler (D. magnolia), Black-throated Blue Warbler (D. caerulescens), Yellow-rumped Warbler, and Blackpoll Warbler (D. striata)-were most abundant in mature forests, and especially edge-dominated mature forests (forest-agricultural edge and suburban forest). Habitats used by mature-forest-breeding transients changed between years, but edge-dominated forest types were used most frequently in all three years. Although canopy leaf development at mature forest sites showed little relationship to site use by mature-forest-breeding transients within weekly intervals, year-to-year differences in leaf phenology were consistent with year-to-year changes in habitat use by migrant landbirds. Foraging behavior of Yellow-rumped Warblers suggested higher food availability and quality in forest-agricultural edges, compared with suburban forest and forest interior. Mature-forest-breeding transients were positively associated with sites that had large trees (>38 cm diameter at breast height) and denser understory vegetation (stems 0–2.5 cm in diameter). Extensive use of mature edge-dominated forests by migrating forest birds during spring suggests that these habitats may be important for the conservation of migrant landbirds.

Uso de Hábitat durante las Escalas Migratorias por Aves Migratorias Terrestres: el Papel de la Estructura del Hábitat, el Desarrollo de las Hojas y la Disponibilidad de Alimento
Parrots of the World: An Identification Guide.
Authors: Iñigo-Elias Eduardo E.
Published: September 2019

The following critiques express the opinions of the individual evaluators regarding the strengths, weaknesses, and value of the books they review. As such, the appraisals are subjective assessments and do not necessarily reflect the opinions of the editors or any official policy of the American Ornithologists' Union.
Extinction & Biogeography of Tropical Pacific Birds
Authors: Simberloff Daniel
Published: September 2019

The following critiques express the opinions of the individual evaluators regarding the strengths, weaknesses, and value of the books they review. As such, the appraisals are subjective assessments and do not necessarily reflect the opinions of the editors or any official policy of the American Ornithologists' Union.
A Distinctive New Species of Tyrant Flycatcher (Passeriformes: Tyrannidae: Cnipodectes) From Southeastern Peru
Authors: Lane Daniel F. , Servat Grace P. , Valqui H. Thomas , Lambert Frank R.
Published: September 2019

We describe a distinctive new species of twistwing (Tyrannidae: Cnipodectes) from southeastern Peru. Despite extensive ornithological research in the region, this species has escaped notice, which suggests that it may be restricted to larger blocks of forest dominated by bamboo (Guadua spp.), a habitat poorly surveyed in Amazonia. Currently known from only a few sites in the departments of Madre de Dios and Cuzco, the species appears to be a Guadua specialist, though its life history is very poorly known. To date, the only other species of Cnipodectes, C. subbrunneus (Brownish Twistwing), is not known from most of southeastern Peru.

Una Nueva Especie Distintiva del Género Cnipodectes (Passeriformes: Tyrannidae) del Sureste de Perú
Short-Term Response of Forest Birds to Experimental Clearcut Edges
Authors: Villard Marc-André , Schmiegelow Fiona K. A. , Trzcinski M. Kurtis
Published: September 2019

Numerous studies have addressed the potential consequences of increasing the density of edges through human activities, but most have documented responses to existing edges. Here, we monitored the response of seven forest bird species to experimentally created edges around five plots (10 ha, n = 3; 25 ha, n = 2) in the boreal mixed-wood forest of Alberta, Canada. We also mapped bird detections in six control plots (10 ha, n = 5; 25 ha, n = 1). The focal species were Least Flycatcher (Empidonax minimus), Red-eyed Vireo (Vireo olivaceus), Yellow-rumped Warbler (Dendroica coronata), Black-throated Green Warbler (D. virens), Ovenbird (Seiurus aurocapilla), Mourning Warbler (Oporornis philadelphia), and White-throated Sparrow (Zonotrichia albicollis). In the two breeding seasons following experimental clearcutting, we quantified birds' responses to edges in the absence of substantial edge-induced changes in vegetation by comparing the distribution of detections between treatment and control plots. We predicted that forest-edge specialists would be attracted to edges, forest-interior specialists would avoid them, and interior-edge generalists would show a neutral response. None of these predictions was consistently supported among plots and years, except in the Mourning Warbler. However, none of the significant responses was the opposite of predictions. We also predicted that postharvest colonization of treated plots would mainly involve forest-edge specialists, whereas most local extinctions would involve forest-interior specialists. Only the colonization of 10-ha fragments followed the predicted pattern. The relatively neutral response to forest edges we observed suggests that, in general, boreal forest birds do not respond to the edge itself or to proximate cues of edge proximity. Rather, significant responses may be delayed until edge-to-interior gradients in vegetation are established.

Respuestas a Corto Plazo de las Aves de Bosque a Bordes Creados Experimentalmente por Tala Rasa
Behavioral Paternity Predicts Genetic Paternity in Satin Bowerbirds (Ptilonorhynchus Violaceus), A Species With a Non-Resource-Based Mating System
Authors: Reynolds Sheila M. , Dryer Katie , Bollback Jonathan , Uy J. Albert C. , Patricelli Gail L. , Robson Timothy , Borgia Gerald , Braun Michael J.
Published: September 2019

The potential for differences between genetic paternity and paternity inferred from behavioral observation has long been recognized. These differences are associated with the challenge for females of seeking both genetic and material benefits; this challenge is less severe in species with polygynous, non-resource-based mating systems (such as leks) than in those with resource-based systems. We present the first study of paternity patterns in a non-resource-based species that does not form true leks. We compared paternity inferred from observed mating behavior to genetically assigned paternity in the Satin Bowerbird (Ptilonorhynchus violaceus) using eight microsatellite markers. Mating behavior was observed and recorded via automated video-cameras positioned at all bowers (29–34 bowers each year) in the study site throughout each mating season. We obtained blood samples and identified mothers for 11 chicks in 9 nests. For all chicks, the most likely genetic father had been observed to mate with the mother in the year the chick was sampled. All most likely genetic fathers were assigned with high confidence and all were bower-holding males. These results demonstrate that genetic paternity can be inferred from observed mating behavior with reasonable confidence in Satin Bowerbirds. Observed male mating-success is therefore a reliable predictor of reproductive success, and this suggests that high skew in observed male mating-success translates directly to high skew in reproductive success.

La Paternidad Comportamental Predice la Paternidad Genética en Ptilonorhynchus violaceus, una Especie con un Sistema de Apareamiento que No Está Basado en los Recursos
Flyway-Scale Variation in Plasma Triglyceride Levels as an Index of Refueling Rate in Spring-Migrating Western Sandpipers (Calidris Mauri)
Authors: Williams Tony D. , Warnock Nils , Takekawa John Y. , Bishop Mary Anne
Published: September 2019

We combined radiotelemetry, plasma metabolite analyses, and macro-invertebrate prey sampling to investigate variation in putative fattening rates (estimated as plasma triglyceride levels) at the flyway scale in Western Sandpipers (Calidris mauri) migrating between Punta Banda, Mexico (31°N), and Hartney Bay, Alaska (60°N), a distance of 4,240 km. Birds were caught at a wintering site (San Francisco Bay) and eight stopover sites along this Pacific Flyway. Body mass was higher in females than in males at six sites, but variation was not correlated with latitude for either sex, and the relationship of change in mass by date within sites was uninformative with regard to possible latitudinal variation in fattening rates. At San Francisco Bay, triglyceride levels were higher in the spring than in the winter. Mean plasma triglyceride varied among stopover sites, and there was a significant linear trend of increasing triglyceride levels with latitude as birds migrated north. At San Francisco Bay, length of stay was negatively related to triglyceride levels. However, plasma triglyceride levels at wintering or initial stopover sites (San Francisco and Punta Banda) did not predict individual variation in subsequent rates of travel during migration. We found no significant relationship between triglyceride levels and prey biomass at different stopover sites, which suggests that the latitudinal pattern is not explained by latitudinal changes in food availability. Rather, we suggest that differences in physiology of migratory birds at southern versus northern stopover sites or behavioral differences may allow birds to sustain higher fattening rates closer to the breeding grounds.

Variación a la Escala de Corredores de Vuelo en los Niveles de Triglicéridos Plasmáticos como un Índice de la Tasa de Reabastecimiento durante la Migración de Primavera en Calidris mauri
Early Infestation by Bot Flies (Philornis Seguyi) Decreases Chick Survival and Nesting Success in Chalk-Browed Mockingbirds (Mimus Saturninus)
Authors: Rabuffetti Fabián L. , Reboreda Juan C.
Published: September 2019

Bot flies (Diptera: Muscidae: Philornis spp.) are a group of flies comprising mostly species with a Neotropical distribution. Their larvae parasitize several species of birds, living subcutaneously on altricial chicks. We investigated the effect of parasitism by bot flies (P. seguyi) on the reproductive success of Chalk-browed Mockingbirds (Mimus saturninus) in temperate grasslands near the southern limit of bot fly distributions. We analyzed seasonal variation of bot fly prevalence during three consecutive years and how the timing and intensity of bot fly infestation affected growth and survival of Chalk-browed Mockingbird nestlings. Bot fly prevalence was 58.3%, 30.7%, and 45.5% each year, and in all years, it increased with time of breeding. Most of the infested nests fledged no chicks. In these nests, chicks had a lower tarsus growth rate than in noninfested nests and died 3–4 days after parasitism. The average time from hatching of the first chick until infestation was 4.4 days. The age of the chicks at the time of infestation was associated positively with nesting success and negatively with intensity of parasitism. Bot fly parasitism also reduced the survival of Shiny Cowbird (Molothrus bonariensis) chicks present in Chalk-browed Mockingbird nests, but the presence of Shiny Cowbird chicks did not affect timing of infestation or fledging success of Chalk-browed Mockingbird chicks. Our results show that an intermediate prevalence of bot fly parasitism produces an important decrease in the reproductive success of Chalk-browed Mockingbirds and suggest that bot flies may play an important role as selective agents in the evolution of host life-history strategies.

La Infestación Temprana con Larvas de Philornis seguyi Disminuye la Supervivencia de los Pichones y el Éxito de Nidificación de Mimus saturninus
Use of Juvenal Plumage in Diagnosing Species Limits: An Example Using Buntings in the Genus Plectrophenax
Authors: Maley James M. , Winker Kevin
Published: September 2019

Species limits in the genus Plectrophenax have been difficult to assess. McKay’s Buntings (Plectrophenax hyperboreus) are very similar both morphologically and behaviorally to Snow Buntings (P. nivalis). However, their breeding ranges are allopatric, and there is limited evidence of gene flow. The juvenal plumage of McKay’s Buntings has never been described as different from that of Snow Buntings. Comparison of a series of McKay’s Buntings in juvenal plumage with a series of Snow Buntings in juvenal plumage showed clear differences between the two forms. We used color spectrophotometry to quantify the differences between the two taxa in two areas of the body that appeared to be consistently different, the throat and back. The relative magnitude of the difference between McKay’s and Snow buntings was greater than homologous differences between two subspecies of Snow Bunting (P. n. nivalis and P. n. townsendi). Four out of six variables were significantly different between McKay’s and Snow buntings, whereas none of the variables were significantly different between the two subspecies of Snow Bunting. Bonferroni corrected t-tests of sexual dimorphism and regression of the variables against year of collection showed that these factors were not associated with these differences. Discriminant analysis accurately separated 100% of the specimens into their respective groups. These differences are notable given the evolutionarily conservative nature of juvenal plumage. Our results support continued recognition of McKay’s Bunting as a species and reconfirm the use of juvenal plumage to help determine species limits.

Uso del Plumaje Juvenil para Diagnosticar los Límites entre Especies: un Ejemplo en el Género Plectrophenax