bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Prescribed Burns and Bison (Bos Bison) Grazing on Breeding Bird Abundances in Tallgrass Prairie
Authors: Powell Alexis F. L A.
Published: September 2019

Grassland birds have declined more than any other avian assemblage in North America, with nearly every species showing negative population trends. In the Flint Hills of Kansas, the largest remnant of the tallgrass prairie biome, annual spring burning of rangeland has recently replaced burning every 2–3 years. I examined effects of different burning and bison (Bos bison) grazing regimes on June abundances of seven bird species using a 23-year data set from the Konza Prairie Biological Station. Fire significantly affected the abundances of six of the seven species. Effects varied among species but, notably, four grass-dependent species—Grasshopper Sparrow (Ammodramus savannarum), Henslow’s Sparrow (A. henslowii), Dickcissel (Spiza americana), and Eastern Meadowlark (Sturnella magna)— and the shrub-dependent Bell’s Vireo (Vireo bellii)—were least abundant or absent at sites in the breeding season immediately following burning. Upland Sandpipers (Bartramia longicauda) were most abundant at sites in the season following burning, whereas Brown-headed Cowbirds (Molothrus ater) exhibited no significant response. Bison grazing increased abundance of Upland Sandpiper and Grasshopper Sparrow, nearly eliminated Henslow’s Sparrow, and (in combination with recent fire) lowered the abundance of Dickcissel. Although fire and grazing are natural forces that maintain tallgrass prairie, their action was, until recently, intermittent and patchy, providing grassland birds with a variety of levels of disturbance. If the vast Flint Hills prairie is to serve as a grassland bird stronghold, the region-wide practice of annual burning with intensive grazing must be replaced with alternatives that restore heterogeneity to the landscape.

Efectos de las Quemas Programadas y del Pastoreo de los Bisontes sobre la Abundancia de Aves Reproductivas en Praderas de Pasto Alto
A Phylogenetic Perspective on the Evolution of Chromatic Ultraviolet Plumage Coloration in Grackles and Allies (Icteridae)
Authors: Eaton Muir D.
Published: September 2019

Plumage traits have been studied intensely for more than a century, especially bright and exaggerated plumage. A large body of evidence across a range of avian taxa supports sexual selection as a major evolutionary force acting on plumage colors. The discovery of ultraviolet (UV) coloration in avian plumage resulted in the extension of sexual selection hypotheses to explain the evolution of potential UV plumage traits. However, there have been no comparative evolutionary studies elucidating the origin of UV signals in birds. Here, I used a comparative phylogenetic approach to investigate the evolution of chromatic UV plumage colors in the grackles-and-allies clade of the New World blackbirds (Icteridae). On the basis of reflectance data collected from museum study skins, I have determined that UV plumage signals have evolved multiple times from an ancestral condition that lacked UV plumage signals, with very few unambiguous reversals. Although UV plumage has evolved in both males and females, there have been significantly more evolutionary changes in male UV plumage characters. Concentrated changes tests and correlations of independent contrasts reveal evidence for sexual selection of some male UV plumage characters, as well as an increase in UV plumage coloration for species found in open habitats. These results support the use of objective assessments of avian colors (i.e. spectrophotometry) to properly interpret patterns of plumage evolution generally, and they suggest the need for behavioral studies on the function of chromatic UV signals in several blackbird species.

Una Perspectiva Filogenética sobre la Evolución de la Coloración Ultravioleta en los Changos y Chamones (Icteridae)
Costs of Egg Punctures and Parasitism by Shiny Cowbirds (Molothrus Bonariensis) at Creamy-Bellied Thrush (Turdus Amaurochalinus) Nests
Authors: Astié Andrea A. , Reboreda Juan C.
Published: September 2019

Most studies on cowbird parasitism have focused on its effects on parasitized nests, whereas few have considered the costs at nests that cowbirds visit but at which they do not lay eggs. Shiny Cowbirds (Molothrus bonariensis) peck and puncture host eggs both in nests where they lay eggs and in unparasitized nests. We analyzed the effect of egg punctures in unparasitized and parasitized nests of a large host, the Creamy-bellied Thrush (Turdus amaurochalinus; hereafter “thrush”), as well as the costs of Shiny Cowbird eggs and chicks in this host’s nests. We determined thrush egg survival, hatching success, and chick survival in successful nests, and nest survival during the egg and nestling stages. Frequency of parasitism was 60%, and its intensity 1.6 ± 0.1 eggs nest−1. Number of host eggs punctured was positively associated with intensity of parasitism. The host’s eggs were frequently punctured in parasitized nests (71%) and in unparasitized nests (42%). Egg punctures reduced the number of eggs at hatching in 23% and 49% of unparasitized and parasitized nests, respectively. Nests with egg punctures had a lower survival rate than nests without them, but nest survival was not associated with parasitism. Presence of a Shiny Cowbird egg was associated with a decrease in the hatching success of host eggs, but presence of a Shiny Cowbird chick did not have any detrimental effect on either the survival and growth rate of host chicks in successful nests or the survival of the whole nest. Our results show that egg punctures were the primary determinant of thrush reproductive success. Consequently, comparison of unparasitized and parasitized nests gives an incomplete estimation of the effects of Shiny Cowbirds on host reproductive success, because the cost of egg punctures is also important in nests where there is no Shiny Cowbird egg laying.

Costos de la Perforación de Huevos y el Parasitismo por Molothrus bonariensis en Nidos de Turdus amaurochalinus
Testosterone Does not Increase in Response to Conspecific Challenges in the White-Bellied Antbird (Myrmeciza Longipes), A Resident Tropical Passerine
Authors: Fedy Bradley C. , Stutchbury Bridget J. M.
Published: September 2019

Resident tropical passerines that exhibit year-round territorial aggression do not fit well into the temperate-zone model, because testosterone does not increase substantially during the breeding season. We studied patterns of testosterone secretion in the White-bellied Antbird (Myrmeciza longipes), a resident tropical species in Panama that maintains territories year-round and is capable of aggression throughout the year, regardless of its stage of reproduction. Levels of plasma testosterone were low (mean = 0.30 ng mL−1) throughout the breeding and nonbreeding seasons and did not differ between them. Testosterone also did not increase in response to simulated conspecific intrusions. When we used temporary removal experiments to induce natural, extended conflict between males, testosterone levels did not increase in response to the extended social instability that resulted. White-bellied Antbirds demonstrate an apparent uncoupling of testosterone and territorial aggression throughout the year.

La Testosterona no Aumenta como Respuesta a Desafíos de Individuos Coespecíficos en Myrmeciza longipes, un Paserino Residente de la Zona Tropical
Fat Dynamics of Arctic-Nesting Sandpipers During Spring in Mid-Continental North America
Authors: Krapu Gary L. , Eldridge Jan L. , Gratto-Trevor Cheri L. , Buhl Deborah A.
Published: September 2019

We measured fresh body mass, total body fat, and fat-free dry mass (FFDM) of three species of Arctic-nesting calidrid sandpipers (Baird's Sandpiper [Calidris bairdii], hereafter “BASA”; Semipalmated Sandpiper [C. pusilla], hereafter “SESA”; and White-rumped Sandpiper [C. fuscicollis], hereafter “WRSA”) during spring stopovers in the Prairie Pothole Region (PPR) of North Dakota, and evaluated the contribution of stored fat to (1) energy requirements for migration to their Arctic-breeding grounds and (2) nutrient needs for reproduction. All spring migrant WRSA (n = 124) and BASA (n = 111), and all but 2 of 99 SESA we collected were ≥2 years old. Male and female BASA migrated through North Dakota concurrently, male SESA averaged earlier than females, and WRSA males preceded females. Fat indices (ratio of fat to FFDM) of male and female SESA and WRSA averaged approximately twice those of male and female BASA. Total body fat of male and female BASA increased with date in spring 1980, but not in 1981; slopes were similar for both sexes each year. Male and female SESA arrived lean in 1980 and 1981, and total body fat increased with date in both years, with similar slopes for all combinations of sex and year. Male and female WRSA arrived lean in 1980–1981 and 1981, respectively, and total body fat increased with date, whereas females arrived with fat reserves already acquired in 1980. Interspecific and sex differences in migration schedules probably contributed to variation in fat storage patterns by affecting maintenance energy costs and food availability. Estimated flight ranges of BASA suggest that few could have met their energy needs for migration to the breeding grounds exclusively from fat stored by the time of departure from North Dakota. Estimated flight ranges of SESA and WRSA, along with fresh body masses of both species when live-trapped on or near their breeding grounds in northern Canada, suggest that major parts of both populations stored adequate fat by departure from temperate mid-continental North America to meet their energy requirements for migration and part of their nutrient needs for reproduction.

Dinámica de la Grasa en Chorlos que Nidifican en el Ártico durante la Primavera en el Área Continental Central de América del Norte
A New Species of Hawaiian Finch (Drepanidini: Loxioides) From Makauwahi Cave, Kaua‘i
Authors: James Helen F. , Olson Storrs L.
Published: September 2019

A new species of Hawaiian finch is described from two fossil maxillae recovered from Holocene lacustrine sediments in Makauwahi Cave, island of Kaua‘i. The new species is assigned to Loxioides on the basis of characters defined in a previous study of drepanidine phylogeny. The maxilla of the new species resembles that of L. bailleui (the only other member of the genus) in its distinctly foreshortened shape, but differs in size and several qualitative characters. The species was sympatric with Loxioides cf. bailleui during the Holocene on Kaua‘i. Like L. bailleui, it may have been a resource specialist feeding mainly on leguminous pods. The radio-carbon chronology of the Makauwahi site indicates that the species became extinct in the late Holocene and, more tentatively, that it may have survived well beyond the time when humans first discovered and colonized Kaua‘i.

Una Nueva Especie de Pinzón de Hawaii (Drepanidini: Loxioides) de la Cueva Makauwahi, Kaua‘i
Point-Transect Surveys for Songbirds: Robust Methodologies
Authors: Buckland Stephen T.
Published: September 2019

Point-transect sampling is widely used for monitoring trends in abundance of songbirds. It is conceptualized as a “snapshot” method in which birds are “frozen” at a single location. With conventional methods, an observer records birds detected from a point for several minutes, during which birds may move around. This generates upward bias in the density estimate. I compared this conventional approach with two other approaches: in one, the observer records locations of detected birds at a snapshot moment; in the other, distances to detected cues (songbursts), rather than birds, are recorded. I implemented all three approaches, together with line-transect sampling and territory mapping in a survey of four bird species. The conventional method gave a biased estimate of density for one species. The snapshot method was found to be the most efficient of the point-sampling methods. Line-transect sampling proved more efficient than the point-sampling methods for all four species. This is likely to be generally true, provided that terrain and habitat allow easy use of a design with random transect lines. I concluded that the snapshot method is more appropriate than the conventional timed-count method for surveying songbirds. Although precision was rather poor with the cue-based method (partly because too few resources were devoted to cue rate estimation), it may be particularly useful for some single-species surveys. In addition, it is the only valid method for estimating abundance from surveys in which acoustic equipment is used to detect birds.

Muestreos en Transectos Puntuales para Aves Canoras: Metodologías Robustas
Salinity and Population Parameters of Bald Eagles (Haliaeetus Leucocephalus) in the Lower Chesapeake Bay
Authors: Watts Bryan D. , Markham A. Catherine , Byrd Mitchell A.
Published: September 2019

We evaluated the relationship between salinity and Bald Eagle (Haliaeetus leucocephalus) population parameters using 26 years of survey data for the lower Chesapeake Bay. Tidal tributaries within the study area were stratified according to the Chesapeake Bay Program's segmentation scheme, and segments with the same salinity classification were considered spatial replicates. Salinity categories included tidal fresh, oligohaline, mesohaline, and polyhaline. Four parameters— colonization rate, nesting density, projected carrying capacity, and productivity— were derived from nesting data within each shoreline segment and compared across the salinity gradient. The study-wide Bald Eagle population is exhibiting exponential growth, with an average doubling time of 7.9 years. All population parameters showed significant directional variation with salinity. Average population doubling time for tidal fresh reaches was <6 years, compared with >16 years for polyhaline areas. Current Bald Eagle nesting density is negatively related to salinity and varies by a factor of 4 across the gradient. Comparison of current densities with projected carrying capacity suggests that these differences will be stable or increasing as the geographic areas approach equilibrium densities. We suggest that fisheries within lower saline reaches, including spring spawning runs of anadromous Clupeidae (shad and herring), are the most likely explanation for salinity effects. Observed distribution patterns suggest that lands along low-salinity waters are the core of the Bald Eagle nesting population within the lower Chesapeake Bay and should be the focus of long-term programs designed to benefit nesting eagles.

Salinidad y Parámetros Poblacionales de Haliaeetus leucocephalus en la Bahia de Chesapeake
Egg Rejection in Marsh Warblers (Acrocephalus Palustris) Heavily Parasitized by Common Cuckoos (Cuculus Canorus)
Authors: Antonov Anton , Stokke Bård G. , Moksnes Arne , Røskaft Eivin
Published: September 2019

In the coevolutionary “arms race” between Common Cuckoos (Cuculus canorus) and their hosts, several adaptations and counter-adaptations have evolved. Here, we investigated natural parasitism and host sensitivity to egg rejection in Marsh Warblers (Acrocephalus palustris) in Bulgaria. The level of Common Cuckoo parasitism was high (28%), and average mimicry of Common Cuckoo eggs was good. Experimental parasitism with four egg-types that showed various degrees of mimicry of the host eggs revealed a generally high rejection rate of foreign eggs (37.5–100%). In addition, naturally laid Common Cuckoo eggs were rejected at a moderate rate (50%). The Marsh Warbler's ability to reject foreign eggs was strongly dependent on the degree of mimicry of the parasite egg but apparently not on differences in size between host and foreign eggs. Furthermore, intraclutch variation in host egg appearance was not related to the probability of egg rejection. The Marsh Warbler's highly developed egg-recognition ability and the good mimicry of Common Cuckoo eggs suggests that this poorly known host-parasite arms race has reached an advanced stage. The present study provides new insight into variables that are important for egg rejection in a heavily parasitized host population.

Rechazo de Huevos en Nidos de Acrocephalus palustris Fuertemente Parasitados por Cuculus canorus
Stable Isotope Evidence Links Breeding Geography and Migration Timing in Wood Warblers (Parulidae)
Authors: Kelly Jeffrey F.
Published: September 2019

Tracking seasonal movements of songbirds is a key step in understanding the annual cycle of migrants. To better understand autumn migration of wood warblers, I analyzed stable-hydrogen isotope ratios of feathers collected from three species captured during stopover at the Bosque del Apache National Wildlife Refuge, New Mexico. To assess the form and strength of the relationship between timing of migration and breeding origins, I regressed stable-hydrogen isotope ratios of feathers against date of capture. These analyses indicated that Orange-crowned Warblers (Vermivora celata) and Common Yellowthroats (Geothlypis trichas) breeding in the southern portion of these species' ranges precede their northern conspecifics in autumn migration. By contrast, Yellow Warblers (Dendroica petechia) from northern breeding sites arrived before more southerly breeding conspecifics. This pattern is similar to that reported previously in Wilson's Warbler (Wilsonia pusilla). These findings suggest that, among wood warblers, (1) timing of autumn migration is often strongly related to breeding location and (2) interspecific variation in the direction of this relationship is large. The direction and strength of these patterns have implications for our understanding of inter- and intraspecific geographic variation in the life histories of migrants.

Evidencia de Isótopos Estables Conecta la Geografía de Nidificación con el Momento de la Migración en Especies de Parulidae
Are Point Counts of Boreal Songbirds Reliable Proxies for More Intensive Abundance Estimators?
Authors: Toms Judith D. , Schmiegelow Fiona K. A. , Hannon Susan J. , Villard Marc-André
Published: September 2019

Point counts are often used to provide information on abundance of songbirds. If data from point counts are to be compared in space or time, however, any bias in the estimate should be consistent and linearly related to the true abundance. Several studies have suggested that this assumption may be violated for songbirds. Here, we used double sampling to test whether point counts are linearly related to true abundance, as estimated from spot mapping, for 12 songbird species in the boreal mixed-wood forest of northern Alberta, Canada. We found that total abundance of birds across several point-count stations was positively correlated with the number of territories and confirmed that point counts were linearly related to spot-mapping abundance for the species tested. However, large sampling errors masked this relationship at the scale of a single point-count station (100-m fixed-radius plot). Double-sampling models that accounted for differences in abundance between spot-mapping grids using random effects improved prediction for most species. We found no year effect on detectability. Maximum abundance over point-count rounds was a more sensitive index of abundance than mean abundance and tended to produce better-fitting models. Point-count abundance was more closely related to true abundance in species with relatively small territories, or those with large spatial or temporal variation in density. Our results further suggest that point-count abundance may be proportional to the total length of territorial boundaries in the plot rather than the total fraction of territories in the plot. Our analysis suggests that point counts provide a reasonable index of abundance, even though individual point-count stations are not consistently effective in estimating the density of territorial individuals.

Est-ce que les Points D'Écoute de Passereaux Boréaux Constituent une Méthode Fiable pour L'Obtention D'Estimateurs D'Abondance Plus Avancés?
Phylogenetic Tests of Hypotheses for the Evolution of Avian Migration: A Case Study Using the Motacillidae
Authors: Outlaw Diana C. , Voelker Gary
Published: September 2019

The evolution of avian migration continues to be an intriguing research subject, even though relationships between migration and factors such as seasonality clearly exist. The question remains whether these relationships are evident within phylogenies containing both sedentary and migratory taxa. We explore the evolution of migration in the family Motacillidae by evaluating existing hypotheses for the evolution of migration in a comparative, phylogenetic framework at the interspecific level. Many hypotheses to explain the evolution of avian migration—such as the “evolutionary precursor” hypothesis (Levey and Stiles 1992, Chesser and Levey 1998) and the “stepping-stone” hypothesis (Cox 1968, 1985)—are based on New World migratory systems. The central components of these hypotheses should apply across biogeographic realms (i.e. the Old World), given that seasonality and habitat regimes are similar in the New and Old worlds. Using a molecular phylogeny containing most species in the Motacillidae, we investigated the potential interactions of seasonality and ecology with migratory and sedentary behavior. Our results suggest that habitat and migration are not correlated in the manner predicted by the evolutionary precursor hypothesis, but they also suggest the importance of increasing seasonality in explaining the patterns of the evolution of migration, an expected but previously unexamined evolutionary relationship. While understanding the limitations of applying generalizations to a complex evolutionary system such as migration, we have delineated here a broad methodology for testing hypotheses about the evolution of migration within a phylogenetic context.

Pruebas Filogenéticas de Hipótesis sobre la Evolución de la Migración: Un Estudio de Caso en la Familia Motacillidae
Home-Range Characteristics, Age, Body Size, and Breeding Performance of Female Mallards (Anas Platyrhynchos)
Authors: Mack Glenn G. , Clark Robert G.
Published: September 2019

Understanding reproductive and survival consequences of space use is of general interest to ecologists and vital to successful conservation planning. Hypothesized effects of home-range habitat composition and female attributes on these vital rates have not been adequately evaluated in breeding female Mallards (Anas platyrhynchos). Thus, we investigated reproductive and survival consequences of home-range variability and individual characteristics for 126 female Mallards studied on 12 study areas in the Canadian prairie parklands, 1995–1998. We used nine variables to discriminate between three reproductive categories (females that did not nest, nested but failed, or nested successfully) and two survival categories (killed by predator and survived the nesting season). Discriminant function analysis separated females that nested successfully from those that did not, with successful females having higher percentages of wood-shrub and planted grass habitat within their home ranges, a lower percentage of seasonal and semipermanent wetlands, smaller home-range sizes, and a higher percentage of wetlands at the study-area scale. We also distinguished females that did not nest from failed nesters; females that did not nest were younger and smaller and had larger home-range sizes, with a higher percentage of seasonal and semipermanent wetlands. Females that were killed did not differ from nesting-season survivors of either individual or home-range characteristics.

Características del Rango de Hogar, Edad, Tamaño Corporal y Desempeño Reproductivo de las Hembras en Anas platyrhynchos
Seasonal Fecundity of Sagebrush Brewer's Sparrow (Spizella Breweri Breweri) at The Northern Edge of its Breeding Range
Authors: Mahony Nancy A. , Krannitz Pamela G. , Martin Kathy
Published: September 2019

We examined the effects of environmental and ecological factors associated with seasonal fecundity on spatial and temporal patterns of productivity in Sagebrush Brewer's Sparrow (Spizella breweri breweri) in British Columbia, the northwestern edge of its breeding range. This study is the first examination of seasonal fecundity in this species. Seasonal fecundity of females varied from 1998 to 2000. It was highest in 2000, when nest predation was lowest and number of clutches per female was intermediate, and lowest in 1998, when nest predation and number of clutches per female were the highest and warm El Niño conditions led to early breeding. Potential fecundity gains from early breeding were diminished by the interaction of shifting predation rates and variable effects of weather at different elevations. Early breeding in 1998 proved an advantage only at the low-elevation site, because an early spring storm destroyed 43% and 20% of first nests at two high-elevation sites. High seasonal fecundity varied between the sites, such that the best site in 1998 became the least productive in 1999 and vice versa. The overriding factor driving spatiotemporal variation was shifting rates of nest predation, though the elevation-related storm effects and variation in number of clutches were partly responsible. To maintain high productivity for Sagebrush Brewer's Sparrow at the northern edge of its range, where conditions are unpredictable and where there is no consistently best or worst site in terms of productivity, managers must protect sites from habitat loss or alteration across a range of elevations and conditions.

Fécondité Saisonnière de Spizella Breweri Breweri à la Limite Nord de Son Aire de Reproduction
Mate Opportunity Hypothesis and Extrapair Paternity in Waved Albatrosses (Phoebastria Irrorata)
Authors: Huyvaert Kathryn P. , Anderson David J. , Parker Patricia G.
Published: September 2019

Early arrival at breeding sites can influence reproductive success through enhanced access to critical resources such as nest sites or mates. One hypothesis explaining protandry, or male-first arrival at breeding sites, proposes that males arrive earlier to increase their extrapair copulation (EPC) opportunities, which may, in turn, enhance males' reproductive success through extrapair fertilizations (EPFs) (“mate opportunity hypothesis”). Extrapair behavior is unexpected in long-lived birds, in which the male is expected to abandon a brood of uncertain paternity, because his probability of future reproduction is high. A previous study of the Waved Albatross (Phoebastria irrorata), a long-lived, socially monogamous seabird, showed evidence of EPFs in 4 of 16 (25%) families. Here, we combined behavioral observations of copulations with additional molecular genetic evidence of EPFs in Waved Albatross families to investigate the fitness consequences of protandry under the mate opportunity hypothesis. During three breeding seasons, we documented 3,661 attempted copulations between birds of known identity; >60% of copulations that involved at least one breeding bird were classified as EPCs. Protandry was pronounced in all three study years: 76.3–96.6% of males arrived before (typically, 6–10 days before) their social mates. Early arrival was associated with increased opportunities for copulations: individual EPC frequencies were higher for breeding males than for breeding females, and males that arrived earlier than their social mates engaged in the most EPCs. Extrapair fertilizations were also regular in our study population; social fathers were excluded as the genetic sire in 14–21% of families. Egg laying dates of EPFs tended to be earlier in the season than those of within-pair fertilizations (WPFs). However, earlier arrival by a male did not translate into a higher probability of siring either within-pair or extrapair offspring, nor did cuckolding males have enhanced reproductive success. Although the fitness consequences of early arrival remain unclear, these findings suggest alternative advantages of early arrival for male Waved Albatrosses.

La Hipótesis de Oportunidad de Apareamiento y Paternidad Extra-pareja en Phoebastria irrorata
Song Sparrow (Melospiza Melodia) Song Varies with Urban Noise
Authors: Wood William E. , Yezerinac Stephen M.
Published: September 2019

In urban environments, anthropogenic noise may mask bird song, especially the notes occurring at lower frequencies (1–2 kHz). Birds living in urban environments may modify their songs, particularly the low-frequency portions, to minimize masking by anthropogenic noise. Such modifications have been observed in Great Tits (Parus major) in The Netherlands, as well as in some mammals. We studied Song Sparrows (Melospiza melodia), which are common in both urban and rural environments in much of North America, and recorded the songs of 28 free- living males in Portland, Oregon. We also measured the amplitude and spectrum of ambient noise at singing locations. Song Sparrows singing at noisier locations exhibited higher-frequency low notes and had relatively less energy (amplitude) in the low-frequency range of their songs (1–4 kHz), where most anthropogenic noise also occurred. Although the mechanism(s) producing the correlation are as yet undetermined, the observed match between song and noise may result from behavioral plasticity. We discuss explanations for these patterns and how to test them.

Le Chant de Melospiza melodia Varie avec le Bruit Urbain
Molecular Systematics and Patterns of Diversification in Pyrrhura (Psittacidae), with Special Reference to the Picta-Leucotis Complex
Authors: Ribas Camila C. , Joseph Leo , Miyaki Cristina Y.
Published: September 2019

Parakeets in the genus Pyrrhura occur in Amazonia and in almost all other major Neotropical forests. Their uneven distribution (with some widespread and several geographically restricted endemic taxa) and complex patterns of plum- age variation have long generated a confused taxonomy. Several taxonomically difficult polytypic species are usually recognized. Here, we present a mitochondrial DNA (mtDNA) phylogenetic analysis of Pyrrhura, with emphasis on the especially problematic picta-leucotis complex, to provide a more robust basis for interpreting the systematics and historical biogeography of the group. Our main findings are that (1) Pyrrhura can be divided into three main evolutionary lineages, one comprising P. cruentata, an Atlantic Forest endemic, the second comprising the picta-leucotis complex, and the third comprising the remaining species; (2) the traditionally recognized species P. picta and P. leucotis are not monophyletic; and (3) most of the species recognized by Joseph (2000, 2002) are diagnosable as independent evolutionary units, with the exception of the following species pairs: P. snethlageae and P. amazonum, P. leucotis and P. griseipectus, and P. roseifrons and P. peruviana. Other than P. cruentata, the two clades that constitute Pyrrhura appear to have radiated and evolved their present mtDNA diversity over short periods during the Plio-Pleistocene.

Sistemática Molecular y Patrones de Diversificación en Pyrrhura (Psittacidae), con Énfasis en el Complejo Picta-Leucotis
Assessing the Effects of Introduced Norway Rats (Rattus Norvegicus) on Survival and Productivity of Least Auklets (Aethia Pusilla)
Authors: Major Heather L. , Jones Ian L. , Byrd G. Vernon , Williams Jeffrey C.
Published: September 2019

We assessed potential effects of introduced Norway rats (Rattus norvegicus) on Least Auklets (Aethia pusilla) breeding at Sirius Point on Kiska Island, the largest auklet colony in the Aleutian Islands, Alaska. We compared productivity, chick growth, and adult survival of Least Auklets during 2001-2003 at Kiska and two nearby, rat-free Least Auklet colonies on Buldir and Kasatochi islands. During 2001 and 2002 (when rats were abundant), productivity at Kiska was the lowest ever recorded for this species (0.09–0.16 chicks fledged per eggs laid), primarily because of high mortality of newly hatched chicks. Growth rates and mean fledging mass were both lower on Kiska than on rat-free islands, though there were some interannual differences in these patterns. Adult survival rates were highly variable among years but strongly concordant among colonies, and survival from 2001 to 2002 on Kiska (0.881 ± 0.033) did not differ significantly from long-term averages on either Buldir (0.853 ± 0.014, 1990-2003) or Kasatochi (0.893 ± 0.027, 1996-2003) islands. Although we found little evidence at nesting crevices of predation on adults, eggs, or chicks, low productivity and slow chick growth were both consistent with disturbance caused by rats, particularly through disruption of adults attempting to brood or provision young chicks. Breeding failure may have been exacerbated by low prey availability for chick provisioning, but the lack of concordance in either productivity or chick growth rates between Kiska Island and nearby rat-free Buldir Island cast doubt on this possibility.

Évaluer les Effets de Rattus norvegicus Introduits sur la Survie et la Productivité de Aethia pusilla
A New Equation for Calculating Reproductive Success of Clutches as a Function of the Day on Which Incubation Starts: Some Implications
Authors: Murray Bertram G.
Published: September 2019

Many species of birds start incubation before the last egg of a clutch is laid, which often results in asynchronous hatching and fledging. The incubation pattern favored by natural selection should lead to greater reproductive success than alternative patterns. Equations for calculating the reproductive success of a clutch as a function of the start of incubation have been proposed by Clark and Wilson (1981) and Hussell (1985). Both equations predicted a greater frequency of an earlier start of incubation than occurs in nature. Here, I present a new equation in which the relevant parameters determining reproductive success as a function of the start of incubation are (1) the probability of any young leaving a nest and (2) the post-first- fledging daily survival rates of the remaining nestlings. This equation is universally applicable and accounts for the greater frequency of incubation starting later, rather than earlier, in the laying sequence of most birds. I use the equation to evaluate various hypotheses regarding the evolution of incubation patterns.

Una Nueva Ecuación para Calcular el Éxito Reproductivo de Nidadas en Función del Día en que Comienza la Incubación: Algunas Implicaciones
Estimating Detection Probability and Density from Point-Count Surveys: A Combination of Distance and Double-Observer Sampling
Authors: Kissling Michelle L. , Garton Edward O.
Published: September 2019

Point counts are the method most commonly used to estimate abundance of birds, but they often fail to account properly for incomplete and variable detection probabilities. We developed a technique that combines distance and double-observer sampling to estimate detection probabilities and effective area surveyed. We applied this paired-observer, variable circular-plot (POVCP) technique to point-count surveys (n = 753) conducted in closed-canopy forests of southeast Alaska. Distance data were analyzed for each species to model a detection probability for each observer and calculate an estimate of density. We then multiplied each observer's density estimates by a correction factor to adjust for detection probabilities <1 at plot center. We compared analytical results from four survey methods: single-observer fixed-radius (50-m) plot; single-observer, variable circular-plot (SOVCP); double-observer fixed-radius (50-m) plot; and POVCP. We examined differences in detection probabilities at plot center, effective area surveyed, and densities for five bird species: Pacific-slope Flycatcher (Empidonax difficilis), Winter Wren (Troglodytes troglodytes), Golden-crowned Kinglet (Regulus satrapa), Hermit Thrush (Catharus guttatus), and Townsend's Warbler (Dendroica townsendi). Average detection probabilities for paired observers increased ≈8% (SE = 2.9) for all species once estimates were corrected for birds missed at plot center. Density estimators of fixed-radius survey methods were likely negatively biased, because the key assumption of perfect detection was not met. Density estimates generated using SOVCP and POVCP were similar, but standard errors were much lower for the POVCP survey method. We recommend using POVCP when study objectives require precise estimates of density. Failure to account for differences in detection probabilities and effective area surveyed results in biased population estimators and, therefore, faulty inferences about the population in question.

Estimaciones de la Densidad y de las Probabilidades de Detección a Partir de Muestreos Utilizando Conteos en Puntos: Una Combinación de Muestreos de Distancia y de Doble Observador
Effects of Chronic Avian Malaria (Plasmodium Relictum) Infection on Reproductive Success of Hawaii Amakihi (Hemignathus Virens)
Authors: Kilpatrick A. Marm , LaPointe Dennis A. , Atkinson Carter T. , Woodworth Bethany L. , Lease Julie K. , Reiter Matthew E. , Gross Kevin
Published: September 2019

We studied the effects of chronic avian malaria (Plasmodium relictum) infections on the reproductive success of a native Hawaiian honeycreeper, Hawaii Amakihi (Hemignathus virens). Chronic malaria infections in male and female parents did not significantly reduce reproductive success as measured by clutch size, hatching success, fledging mass, number of nestlings fledged, nesting success (daily survival rate), and minimum fledgling survival. In fact, nesting success of pairs with chronically infected males was significantly higher than those with uninfected males (76% vs. 38%), and offspring that had at least one parent that had survived the acute phase of malaria infection had a significantly greater chance of being resighted the following year (25% vs. 10%). The reproduction and survival of infected birds were sufficient for a per-capita population growth rate >1, which suggests that chronically infected Hawaii Amakihi could support a growing population.

Efectos de las Infecciones Crónicas de Malaria Aviaria (Plasmodium relictum) en el Éxito Reproductivo de Hemignathus virens
Effects of Flipper Bands on Foraging Behavior and Survival of Adélie Penguins (Pygoscelis Adeliae)
Authors: Dugger Katie M. , Ballard Grant , Ainley David G. , Barton Kerry J.
Published: September 2019

Since the 1950s, flipper bands have been used widely to mark penguins (Spheniscidae), but not without concerns regarding possible negative effects on survival and fitness. As part of a demographic study of Adélie Penguins (Pygoscelis adeliae) in the western Ross Sea, Antarctica, we investigated effects of flipper bands on foraging-trip duration and food loads, as well as apparent survival, during four breeding seasons (2000-2003), using mark-recapture and radio-frequency identification (RFID) technology. Foraging-trip durations were ∼8% (3.5 h) longer, on average, for banded compared with unbanded birds, but the effect varied among years. Food loads did not differ between banded and unbanded birds, but males carried heavier food loads than females. Flipper bands decreased apparent annual survival by 11–13% during 2000-2003, but over a longer time period (1996-2003) we observed high annual variability, including years of high survival for banded birds. Males had slightly higher survival than females in both banded and unbanded birds. Mechanisms resulting in band effects on foraging behavior and survival, the variable effect of bands by season, and the potential ameliorating effect of age or experience on the effects of bands need further investigation in Adélie and other penguin species. We recognize a need to understand and balance the negative consequences of flipper bands for penguins against the beneficial gains in information associated with their use.

Effets du Baguage à l'Aileron sur le Comportement de Recherche Alimentaire et la Survie de Pygoscelis adeliae
Interspecies Comparison of Pentosidine Accumulation and its Correlation with Age in Birds
Authors: Fallon Jesse A. , Cochrane Robert L. , Dorr Brian , Klandorf Hillar
Published: September 2019

Recent studies suggest that a linear correlation exists between the age of individual birds and accumulation of the advanced glycation endproduct pento- sidine (Ps). We compared Ps accumulation in skin tissue of Ruffed Grouse (Bonasa umbellus) and Double-crested Cormorants (Phalacrocorax auritus). Skin samples were taken from the breasts of 52 Ruffed Grouse of known ages ranging from a few days to 10 years. Skin was cleaned of feathers and adipose tissue, acid hydrolyzed, and measured for collagen content via hydroxyproline spectrophotometric assay. Pentosidine concentrations were determined using reverse-phase high-performance liquid chromatography. Fluorescent detection (excitation: 310 nm, emission: 385 nm) revealed that concentrations of Ps per milligram of collagen increased curvilinearly with age (r2 = 0.87, P < 0.0001). Additionally, a blind study of 19 Double-crested Cormorants revealed a linear relationship between Ps concentrations and age (r2 = 0.93). Comparison of these two species revealed a more rapid accumulation of Ps in Ruffed Grouse. Accurate age information could aid species recovery programs and provide insights into longevity, now understood entirely from banding programs and captive birds.

Comparación entre Especies de la Acumulación de Pentosidina y su Correlación con la Edad de las Aves
Postfledging Dependence Period of Migratory Golden Eagles (Aquila Chrysaetos) in Denali National Park and Preserve, Alaska
Authors: McIntyre Carol L. , Collopy Michael W.
Published: September 2019

The postfledging dependence period is not well documented for many species of raptors, including Golden Eagles (Aquila chrysaetos). From 1997 to 1999, we used satellite telemetry to estimate the length of the postfledging dependence period, and the finite survival rate of fledglings during that period, for migratory Golden Eagles in Denali National Park and Preserve, Alaska. Length of the postfledging dependence period averaged 50.1 days and ranged from 39 to 63 days. The post- fledging dependence period was longer for Golden Eagles that hatched earlier, but hatching date did not influence the date they departed their natal area. Average date of departure from the natal area was 25 September. The departure period spanned a 17-day period from 15 September to 5 October, and coincided with a series of environmental changes including decreases in day length, temperature, and prey diversity. Probability of survival during the postfledging dependence period was 0.98 (95% CI = 0.94 to 1.00).

Período de Dependencia Posterior al Emplumamiento de Aquila chrysaetos en el Parque Nacional y Reserva Denali, Alaska
Birds in Europe: Population Estimates, Trends and Conservation Status
Authors: Peterjohn Bruce
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.
The Gyrfalcon
Authors: Cade Tom J.
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.
Nest Weight and Female Health in the Blue Tit (Cyanistes Caeruleus)
Authors: Tomás Gustavo , Merino Santiago , Moreno Juan , Sanz Juan J. , Morales Judith , García-Fraile Sonia
Published: September 2019

We explored two hypotheses that may explain intraspecific variability in nest size. The “thermoregulatory” hypothesis states that species adjust nest size to maintain egg temperature and minimize temperature fluctuations in the nest. Recently, the suggestion has been made that nest size may reflect the health status or phenotypic quality of the builder, potentially making it a sexually selected trait (“sexual selection” hypothesis). For two years, we weighed nests of Blue Tit (Cyanistes caeruleus) at initiation of reproduction in a nest-box breeding population in central Spain. We recorded laying date, clutch size, incubation period, and hatching success. We measured and took blood samples of adult females when nestlings reached three days of age. General regression models controlling for potential variables that could affect nest weight revealed that prevalence of Trypanosoma avium and immunoglobulin levels in females were significantly related to nest weight in only one of the study years. Females not infected with Trypanosoma avium built heavier nests than infected ones, whereas female immunoglobulin levels were negatively associated with nest weight. Hatching success and duration of the incubation period were not related to nest weight in either year. Thus, our results do not support the thermoregulatory hypothesis and show that certain measures of female health are related to nest-building effort in some years, probably depending on environmental conditions.

Peso del Nido y Estado de Salud de la Hembra en el Cyanistes caeruleus
Nesting With The Wasp Ropalidia Cincta Increases Nest Success of Red-Cheeked Cordonbleu (Uraeginthus Bengalus) in Ghana
Authors: Beier Paul , Tungbani Agba Issahaku
Published: September 2019

Associations between birds and social Hymenoptera (ants, wasps, bees) are common in tropical regions and are usually assumed to be commensal relationships that benefit birds but neither help nor harm the arthropods. However, benefits to birds have been documented in only four such associations, and no previous research has rigorously investigated costs or benefits to associated hymenopterans. We followed the nesting cycles of an estrildid finch, the Red-cheeked Cordonbleu (Uraeginthus bengalus), and a common nesting associate, the wasp Ropalidia cincta, during 2002 and 2003 in northern Ghana to compare reproductive success of birds and wasps nesting in association with that of birds and wasps nesting separately. Red-cheeked Cordonbleus and wasps nested together in the same tree 3.7 × as often as expected if nesting decisions were made independently, with 74% of bird nests and 74% of wasp colonies occurring in associations. Bird nesting was initiated ≈33 days after founding of an associated wasp colony; bird nests and wasp colonies were, on average, 42 cm apart. In both years, Red-cheeked Cordonbleus in nesting associations with wasps were twice as likely to fledge young as birds nesting in trees without wasps. Reduced predation was apparently a major reason for increased fledging success: we documented four cases of nest predation on 122 Red-cheeked Cordonbleu nests associated with wasps, and 11 cases on 90 nests not associated with wasps. Association with birds did not affect the success of wasp colonies. Although our observational study cannot rule out the possibility that both species coincidentally shared a preference for a habitat feature in limited supply, suitable nest sites did not appear to be limiting (74% of potential nest trees had neither bird nor wasp nests). Reproductive success of Red-cheeked Cordonbleu populations in this region may be limited by the number of available wasp colonies. By designing our study to address four working hypotheses (commensalism, mutualism, parasitism, coincidence of habitat preference), we have provided strong evidence that this relationship is commensal.

Augmentation du Succès de Nidification de Uraeginthus bengalus Nichant avec des Guêpes Ropalidia cincta au Ghana