bluuebunny/crossref_metadata_2025_split huggingface dataset:
Male Badge Size Predicts Dominance Against Females in House Sparrows
Authors: Liker András , Barta Zoltán 
Published: September 2019

Abstract
We investigated dominance relationships and the use of male badge size as a status signal in a mixed-sex flock of House Sparrows (Passer domesticus). Specifically, we tested whether females differ from males in their fighting behavior or dominance status, and whether badge size predicts dominance and fighting success of males in male-female fights. We found that both sexes were involved frequently in aggressive encounters, and the mean dominance rank of males did not differ from the mean rank of females. Badge size was the only significant predictor of the dominance rank of males, and was a good predictor of their aggressiveness measured as the proportion of fights initiated. On the other hand, female dominance rank was correlated with body weight. In male-female fights, both the proportion of female-initiated aggressive interactions and the proportion of fights won by females decreased with increasing size of the opponent's badge. Large-badged males dominated more females in dyadic interactions than smaller-badged males. These correlational results suggest that male badge size may be used as a signal of dominance status between male and female House Sparrows in winter flocks.
Extra-Pair Paternity in the Common Murre
Authors: Birkhead Tim R. , Hatchwell Ben J. , Lindner Robert , Blomqvist Donald , Pellatt E. Jayne , Griffiths Richard , Lifjeld Jan T. 
Published: September 2019

Abstract
Multi-locus DNA fingerprinting was used to estimate the frequency of extra-pair paternity in the Common Murre (Uria aalge), a colonial, sexually monomorphic seabird that breeds at very high densities and in which extra-pair copulation is frequent. Common Murres produce a single chick. We detected 6 cases of extra-pair paternity in 77 families (7.8%). This value was higher than the proportion of successful extra-pair copulations (1.6%) estimated from behavioral data from an earlier study of the same population.
Aggressive Nest Intrusions by Male Humboldt Penguins
Authors: Taylor Sabrina S. , Leonard Marty L. , Boness Daryl J. 
Published: September 2019

Abstract
During observations at a breeding colony of Humboldt Penguins (Spheniscus humboldti), we noted five male penguins enter nests occupied by breeding pairs and engage in aggressive interactions with the resident adult. These nest intrusions resulted in egg loss or infanticide, and accounted for 11.1% of breeding failure in the colony. Two intruder males ultimately mated with respective resident females. This behavior had not been observed previously in Humboldt Penguins and we suggest that it may occur when males are unable to obtain mates through advertising at the nest. Intrusion behavior may slow down population recovery in this endangered species.
Female Responses to Intraspecific Brood Parasitism in the Tree Swallow
Authors: Whittingham Linda A. , Dunn Peter O. 
Published: September 2019

AbstractWe studied female responses to experimental intraspecific brood parasitism (IBP), or egg-dumping, in Tree Swallows (Tachycineta bicolor). Unlike other species of swallows, Tree Swallow nests are rarely parasitized by conspecifics. We experimentally parasitized nests of Tree Swallows to investigate how females respond to uncertain maternity. Host females accepted a parasitic egg if it was added to the nest within 3 days of the host's first egg (62%). In contrast, the host female buried the parasitic egg (24%) or deserted the nest (14%) when the parasitic egg was added 4 or more days before the host's first egg. The acceptance of parasitic eggs close to the host's own laying date is similar to the behavior reported for other species; however, egg burial and nest desertion appear to be rare as responses to intraspecific brood parasitism. We suggest that the low level of IBP in Tree Swallows has evolved as an indirect consequence of females defending their nest cavity against usurpation.
Context and Frequency of Infanticide in Communally Breeding Guira Cuckoos
Authors: Macedo Regina H. F. , Cariello Mariana , Muniz Laura 
Published: September 2019

AbstractWe studied the context of brood reduction through infanticide by communally breeding Guira Cuckoos (Guira guira) in central Brazil. During seven reproductive seasons, we monitored 142 nests from egg laying until fledging. Almost all nests (97%) lost eggs through ejection, and chick deaths occurred in 72% of all nests with hatchlings. There was evidence for infanticide in 38% of the nests that exhibited some mortality. We compared egg and chick mortality in the early part of the season with the later part, when insect abundance declines, but found no significant differences. Less than one-third of all nests monitored showed asynchronous hatching of eggs, and in those that did, chick death was not in reverse hatch order. Although there are several plausible explanations for infanticide, we highlight one likely candidate, which is its interpretation as a sexually selected trait where individuals gain reproductive benefits by provoking the group's nesting failure.
Differences in Depredation by Small Predators Limit the Use of Plasticine and Zebra Finch Eggs in Artificial-Nest Studies
Authors: Maier Thomas J. , Degraaf Richard M. 
Published: September 2019

AbstractSmall mammals, such as mice and voles, have been implicated as major egg predators of Neotropical migrant passerines by field studies using soft plasticine eggs or the very small eggs of Zebra Finch (Taeniopygia guttata). Nevertheless, the effort required to depredate these commonly used egg surrogates may be less than that required to depredate the larger, thicker-shelled eggs of most passerine species. To compare the depredation of these surrogates to that of the eggs of a mid-sized passerine by a ubiquitous small predator, we exposed dissimilar pairs of plasticine, Zebra Finch, and House Sparrow (Passer domesticus) eggs to captive white-footed mice (Peromyscus leucopus). Plasticine eggs were marked by mice more than either kind of real egg, and Zebra Finch eggs were breached more often than House Sparrow eggs. We conclude that the use of either plasticine or Zebra Finch eggs may lead to overestimation of the ability or proclivity of small mammals to actually depredate the eggs of most passerines.
Assessing Raptor Diet: Comparing Pellets, Prey Remains, and Observational Data at Hen Harrier Nests
Authors: Redpath Stephen M. , Clarke Roger , Madders Mike , Thirgood Simon J. 
Published: September 2019

AbstractWe compared techniques to assess diet at 17 Hen Harrier (Circus cyaneus) nests. Diet was measured directly from observations and compared to estimates from pellets, prey remains and a combination of pellets and remains. For data pooled across nests, pellets over-represented mammalian prey and under-represented avian prey. Prey remains over-represented large prey and under-represented small prey. Combining pellet and remains data did not eliminate these biases. Pellets gave higher diversity values than direct observations and detected more small prey species. For data analyzed on a nest by nest basis, estimates from pellets were significantly related to estimates from direct observations for three prey types by frequency and all types by biomass. These linear relationships were used to predict frequencies and biomass of prey types in the observed diet at five new nests. Our findings suggest that pellets are useful for estimates of prey diversity and as an index of the frequency of certain prey types in the diet, but direct observations are necessary to help quantify the biases inherent in diet estimates.
Size Characteristics of Stones Ingested by Common Loons
Authors: Franson J. Christian , Hansen Scott P. , Pokras and Mark A. , Miconi Rose 
Published: September 2019

Abstract
Common Loon (Gavia immer) carcasses recovered in New England had more stones of greater combined mass in their stomachs than loons from the southeastern United States. Stones retained in sieves with mesh sizes between 4.75 and 8.00 mm accounted for the greatest percentage (by mass) of grit in loon stomachs. The median longest dimension of the largest single stone in each stomach was 12.5 mm in loons from New England and 10.7 mm in loons from the southeast (maximum = 23.1 mm and 16.8 mm, respectively). A recent national proposal to restrict the use of certain fishing weights in the United States called for a ban on lead fishing sinkers of 25.4 mm or less in any dimension. Our findings suggest it is unlikely that Common Loons would ingest lead fishing weights greater than 25.4 mm in any dimension, if such ingestion was solely the result of their search for replacement stones for their stomachs. However, this does not preclude the possibility that loons may ingest larger fishing weights under other circumstances, such as the consumption of fish with attached sinkers.
Egg Size, Body Size, Locomotion, and Feeding Performance in Captive King Eider Ducklings
Authors: Anderson Vanessa R. , Alisauskas Ray T. 
Published: September 2019

AbstractWe studied the effect of egg volume and body size on swimming speed, endurance, and feeding rate in captive King Eider (Somateria spectabilis) ducklings in the Canadian arctic. Sprint speed, endurance, and feeding rate were positively related to egg size and body size. Large ducklings from large eggs performed better than small ducklings from small eggs. Ducklings that are more capable swimmers and have higher feeding rates may grow more quickly and be more effective at predator evasion. Thus, ducklings from large eggs may have a survival advantage over those from small eggs under conditions where predation and nutrition may constrain survival.
Seasonal Fluctuations of Birds, Fruits, and Flowers in a Subtropical Forest of Argentina
Authors: Malizia Lucio R. 
Published: September 2019

AbstractI quantified monthly variation in species composition and captures of birds in a premontane forest of northwestern Argentina. Seasonal patterns of frugivore-insectivores and nectarivores were compared with fruit and flower abundances, respectively. The composition of the entire bird community fluctuated seasonally; frugivore-insectivores showed a peak in captures during the wet season, insectivores peaked at the end of the dry season, and nectarivores peaked during the dry season. At a local scale (∼50 ha), captures of frugivore-insectivores were not correlated with number of plant species with ripe fruits for any vegetation stratum considered, but were correlated with a fruit phenology index that considers crop size. At a plot scale (∼7.5 ha), only understory flower abundance and captures of nectarivores were correlated, but only in the plot where both were more abundant. At a net-site scale (50 m2), captures of the Rufous-bellied Thrush (Turdus rufiventris) were correlated with understory fruit abundance, but only in the plot where fruits were more abundant. These results suggest that seasonal fluctuations in birds may be driven to some extent by their food resources. Premontane forest provides habitat for many migrants and also presumably acts as a source of birds that emigrate to disturbed areas. Although premontane forests should be a conservation priority for the region, they are poorly protected and suffering high deforestation.
Reproductive Biology of Sabine's Gull in the Canadian Arctic
Authors: Stenhouse Iain J. , Grant Gilchrist H. , Montevecchi William A. 
Published: September 2019

Abstract
We studied the reproductive biology of Sabine's Gulls (Xema sabini) breeding on Southampton Island, in the eastern Canadian Arctic, from May to August in 1998 and 1999, and compared our results to information collected from the same region in 1980. Breeding phenology was 10 days earlier in 1998 than in these other years, and reflects an earlier onset of snowmelt in that year. Nests were dispersed, with a density of 7.6 to 8.7 nests per km2. Sabine's Gulls exhibited strong interannual fidelity to breeding sites. Mean clutch size was lower in 1999 than 1998, and lower in both these years than in 1980. Hatching success was 63% in 1998, but only 21% in 1999 due to increased predation, most likely by arctic fox (Alopex lagopus). Adult gulls and chicks abandoned nest-sites within a few hours of the hatching of the last chick and relocated to coastal ponds, where adults continued to attend chicks. In comparisons of the reproductive biology of Sabine's Gull to closely related “tern-like” gull species and other “black-headed” gulls, Sabine's Gull showed a number of distinct ecological and behavioral differences and represents an ecological outlier within the Laridae.
Provisioning Rate and Attendance Patterns of Wandering Albatrosses at Bird Island, South Georgia
Authors: Berrow Simon D. , Croxall John P. 
Published: September 2019

Abstract
We investigated foraging behavior of Wandering Albatrosses (Diomedea exulans) breeding at South Georgia to assess how sex and season-specific foraging patterns relate to provisioning performance. We estimated Wandering Albatross chicks require 60–65 kg of food over the chick-rearing period; males deliver 54% of this total. Meal size delivered by both sexes remained essentially constant throughout the post-brooding chick-rearing period, but foraging trip duration varied considerably. Females made consistently longer foraging trips and delivered smaller meals but transported an average load that was 20% heavier in proportion to their body mass than males. We suggest that chick-rearing places greater demands on females compared with males and Wandering Albatrosses work hard to deliver food during the first half of chick rearing (at the expense of their own condition), thereafter reduce their work rate, presumably so as not to compromise their survival.
Food Supply and the Consequences of Egg Size in the Thick-Billed Murre
Authors: Hipfner J. Mark , Gaston Anthony J. , Storey Anne E. 
Published: September 2019

Abstract
We examined the effect of egg size on post-hatching development in the Thick-billed Murre (Uria lomvia), an Arctic seabird that lays a one-egg clutch, at a colony where food availability during chick-rearing was low (Digges Island, Nunavut, Canada). We compared our results to those of a previous study conducted at a colony where food availability was higher (Coats Island, Nunavut). To control for underlying phenotypic correlations between egg size and parental quality, we switched eggs at random among pairs. Egg size positively affected the rate of early wing-feather growth, but contrary to prediction, the advantage enjoyed by chicks from large eggs over those from small eggs at Digges Island (1.6 days' feather growth on average) was no greater than at Coats Island (2.0 days). Egg size had no effect on the rate at which chicks gained mass at Digges Island, but young from large eggs tended to remain heavier than those from small eggs. At Coats Island, this occurred only in a year in which chicks grew relatively slowly, offering some support for the hypothesis that a large egg confers greater advantage when feeding conditions are unfavorable. Adults at Digges Island invested heavily in provisioning their chicks, but there was no evidence of a trade-off between egg size and provisioning. As costs associated with large eggs have not been detected in Thick-billed Murres, the existence of considerable variation in egg size, beyond that associated with female age or experience, remains unexplained.
Phylogenetic Relationships in Bearded Manakins (Pipridae: Manacus) Indicate That Male Plumage Color is a Misleading Taxonomic Marker
Authors: Brumfield Robb T. , Braun Michael J. 
Published: September 2019

AbstractThe piprid genus Manacus is composed of four allospecies that are readily distinguishable by differences in male plumage color. Electrophoretic data for two populations of each of the four forms plus seven outgroup piprid taxa were collected from 32 isozyme loci and used to infer phylogenetic relationships. Each Manacus form was monophyletic, with the exception of M. manacus, in which the trans-Andean (west of the Andes) population was sister to M. vitellinus, rather than to its conspecific cis-Andean (east of the Andes) population. This controversial relationship, supported by the synapomorphic allele PGM-2b as well as allele frequencies at ADA, GOT-1 and LGG, is consistent with general biogeographic patterns in the region, but indicates that male plumage color is an unreliable taxonomic marker. Reconstruction of male plumage color on the tree confirms that gold plumage is a derived state in M. vitellinus, a finding consistent with the possibility that gold plumage is an evolutionary novelty in vitellinus which has spread recently under positive selection. Among piprids, there was strong support for a group composed of Antilophia, Chiroxiphia, and Corapipo, and for a group composed of Pipra mentalis, P. fasciicauda, and Dixiphia pipra. Manacus is more closely related to the P. mentalis + P. fasciicauda + D. pipra group. The isozymes supported Lepidothrix as the basal taxon of those examined.
A Half-Century Comparison of Breeding Birds in the Southern Appalachians
Authors: Haney J. Christopher , Lee David S. , Wilbert Mark 
Published: September 2019

AbstractWe evaluated long-term (∼50-year) change in a bird community of an extensively forested region of the southern Appalachian mountains in North Carolina and Tennessee. A species accumulation curve for a 1996–1998 survey identified a core of 50 breeding species in upper elevations of the Unicoi Mountains. Since a 1944–1946 survey, dominant species have remained identical, no species have disappeared, and mean ranked abundance of both short and long-distance migrants has not changed. Permanent residents, however, had decreased in rank by the late 1990s. Three “new” disturbance-dependent species, American Crow (Corvus brachyrhynchos), Indigo Bunting (Passerina cyanea), and Song Sparrow (Melospiza melodia), expanded into interior forest along a recently constructed parkway. Largest apparent increases in ranked abundance of individual species occurred in eight Neotropical migrants that rely upon mature, forest-interior habitat, whereas largest apparent declines in ranked abundance occurred in land-use generalists, cavity nesters, and three other Neotropical migrants. Modifications to land-use were reasonable explanations for changes in most species. Little change in community structure, greater representation of many Neotropical migrants, and virtual absence of Brown-headed Cowbirds (Molothrus ater) suggest that this large, continuous forest retained and probably regained functional integrity for forest birds during the latter half of the twentieth century.
Species Limits in Antbirds: The Thamnophilus Punctatus Complex Continued
Authors: Isler Morton L. , Isler Phyllis R. , Whitney Bret M. , Walker Barry 
Published: September 2019

Abstract
In a previous study (Isler et al. 1997) we examined species limits in the Thamnophilus punctatus complex of the Neotropics. We recommended that six taxa be considered species, but were unable to make recommendations regarding two morphologically distinct and geographically restricted taxa, leucogaster and huallagae, due to the lack of vocal recordings which were essential to our methodology. Analysis of newly obtained recordings has found that vocal differences support the separation at the species level of leucogaster and huallagae from five of the six species in the complex (T. atrinucha, T. stictocephalus, T. sticturus, T. pelzelni, and T. ambiguus). However, leucogaster and huallagae could not be distinguished vocally from each other nor from nominate punctatus to an extent that supported species status, and they are retained as subspecies under our recommended guidelines (Isler et al. 1998, 1999). The Thamnophilus punctatus complex affords an interesting opportunity for future molecular studies that compare the genetic distances among populations that have differentiated vocally and those that have not. The question of species status of leucogaster and huallagae is pressing because the ranges of both taxa are limited to sub-Andean basins in northwestern Peru and southwestern Ecuador that increasingly are under cultivation.
Geographical Variation in the Calls of the Choughs
Authors: Laiolo Paola , Rolando Antonio , Delestrade Anne , de Sanctis Augusto 
Published: September 2019

Abstract
The calls of 22 populations of the Red-billed Chough (Pyrrhocorax pyrrhocorax) and the Alpine Chough (P. graculus) were sampled throughout the Palearctic region. In both species calls differed in frequencies, either by latitude or longitude in the Red-billed Chough and mostly by longitude in the Alpine Chough. Frequencies varied according to body size, being higher in smaller-bodied populations and lower in larger-bodied ones, as predicted by the inverse relationship between body size and frequency. We hypothesize that, besides the effect of physical constraints determining frequencies, past climatic events and the geomorphological history of the Pleistocene also have influenced the present pattern of diversification. We also hypothesize that gene flow and ‘cultural’ flow have constrained the evolution of clear-cut population differences between European and North African populations, whose segregation could be quite recent.
Lekking Behavior of the Round-Tailed Manakin
Authors: Tello Jose G. 
Published: September 2019

AbstractAlong the Rio Manu in southeastern Peru, Round-tailed Manakins (Pipra chloromeros) breed mainly from August to November. Male P. chloromeros have a dispersed lek breeding system, with each lek composed of two to five territorial males. Sites used by males for display had significantly higher densities of shrubs, vines, and small trees than did non-display sites. Interlek distances ranged from 220 to 1000 m. Within leks, most males occupied territories within auditory range, but not visual range. Distance to the closest neighbor's display perch varied from 8 to 87 m. Males vigorously defended territories that ranged from 20 to 50 m in diameter. Males progress in social status within the lek (from immature to non-territorial adult to territorial adult). Territorial adult males were always dominant to males of the other two categories. Territorial males engaged in daily ritualized encounters at the borders of their territories. Encounters involved slow, coordinated displays reminiscent of those performed toward females. Such interactions may help maintain dominance relationships within the lek, but an analysis of interaction outcomes failed to show clear dominance relationships among males. Female visitation was most frequent in early afternoon, during males' maximum territory attendance and display activity. Lekking P. chloromeros employ ten display elements, six vocalizations, and one mechanical noise. One display element has not been observed in any other species of Pipra. The displays and sounds in the P. erythrocephala clade are compared from the perspective of understanding the evolution of display behavior in this group.