bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Season and Frequency of Fire on Henslow's Sparrows (Ammodramus Henslowii) Wintering on Gulf Coast Pitcher Plant Bogs
Authors: Tucker James W. , Robinson W. Douglas 
Published: September 2019

Abstract
Henslow's Sparrow (Ammodramus henslowii) is a grassland bird that has suffered drastic population declines for over 30 years. Declining populations can be largely attributed to loss of breeding habitat, but loss of wintering habitat associated with longleaf pine (Pinus palustris) communities, especially pitcher plant (Sarracenia spp.) bogs, along the Gulf Coast also may be a contributing factor. Fire is critical for restoration and conservation of remaining longleaf pine communities, but the influence of fire on wintering Henslow's Sparrows has not been evaluated. We examined the influence of season and frequency (time since burning) of fire on use of pitcher plant bogs by Henslow's Sparrows wintering in the Conecuh National Forest, Alabama, and Blackwater River State Forest, Florida, during winters of 1999–2000 and 2000–2001. Density of Henslow's Sparrows was greatest on bogs the first winter after burning. Although significant effects for season of burning were not found, bogs burned during winter typically hosted Henslow's Sparrows for only one winter, whereas bogs burned during the growing season hosted sparrows for at least three winters. Growing-season fires may be more beneficial than dormant-season fires and will prevent forced abandonment of bogs burned during winter. Frequency of seed stalks of grasses and density of forbs were the most influential vegetation parameters affecting occurrence of Henslow's Sparrows at pitcher plant bogs. Henslow's Sparrows were found on bogs as small as 0.06 ha, but were found on bogs >0.25 ha more frequently than on smaller bogs. We conclude that burning pitcher plant bogs on an annual or biennial basis during the growing season will maximize the benefits to both wintering Henslow's Sparrows and the host of other organisms associated with those unique communities.
Evolution of Long-Distance Migration in and Historical Biogeography of Catharus Thrushes: A Molecular Phylogenetic Approach
Authors: Outlaw Diana C. , Voelker Gary , Mila Borja , Girman Derek J. 
Published: September 2019

AbstractWe addressed the evolution of long-distance migration in and the historical biogeography of Catharus thrushes within a phylogenetic framework. Catharus thrushes are a Nearctic–Neotropical genus consisting of five migrant and seven resident species. We reconstructed a molecular phylogeny using a combined analysis of cytochrome-b and ND2 genes. Phylogenetic reconstructions indicate the nonmonophyly of migratory Catharus species. The Neotropics are the most likely ancestral geographic area for the entire lineage, and migratory species are sister to resident taxa whose ranges are restricted to Central America, Mexico, or both. Resident behavior may be ancestral within the lineage, with migratory behavior evolving three times, although confidence in those reconstructions is equivocal in many cases. However, uncertainty in ancestral character states presents an interesting scenario including potential drop-offs of resident species from migratory ancestors.
Diet and Preparation for Spring Migration in Captive Hermit Thrushes (Catharus Guttatus)
Authors: Long Jennifer A. , Stouffer Philip C. 
Published: September 2019

AbstractSeasonal changes in food choice by migratory birds often reflect changes in relative food abundance and increased energetic demand. Hermit Thrushes (Catharus guttatus) in southeastern Louisiana are highly frugivorous during winter but forage exclusively on arthropods just prior to spring migration. We hypothesized that this switch to an exclusively arthropod diet would lead to an increase in fat reserves compared to a frugivorous diet, and that fat birds would initiate migration sooner and display more migratory activity than lean birds. We tested these hypotheses on captive Hermit Thrushes maintained on either an arthropod only diet or a mixed fruit and arthropod diet and measured changes in fat score, body mass, and nocturnal migratory activity (Zugunruhe) from February to April 2000. We found that the arthropod-only treatment led to greater body mass and greater amounts of subcutaneous fat than the mixed fruit and arthropod treatment by the third week of the experiment. Despite those differences, body mass was not correlated with intensity of Zugunruhe. We also did not find a significant difference in intensity or onset of Zugunruhe between treatments. We concluded that because Hermit Thrushes are short-distance migrants, large fat reserves are not crucial for their migration. Consequently, fruit and arthropods appear to be equivalent with respect to migratory behavior.
Relationship of Nutritional Condition of Permanent-Resident Woodland Birds With Woodlot Area, Supplemental Food, and Snow Cover
Authors: Doherty Paul F. , Grubb Thomas C. 
Published: September 2019

Abstract
In a previous study we found that survivorship of several species of permanent-resident, temperate-zone birds was positively related to forest fragment size and presence of supplemental food, and negatively related to extent of snow cover (Doherty and Grubb 2002). Here, we test the hypothesis that such trends are related to differential nutritional condition during winter. Employing rate of growth of induced feathers, we found that woodlot size and presence of supplemental food interacted to increase the nutritional condition of Carolina Chickadees (Poecile carolinensis) and that Tufted Titmouse (Baeolophus bicolor) nutritional condition was reduced in years with high snow cover. Assuming that nutritional condition is positively related to survivorship, these results have possible implications for the viability of permanent-resident birds in small woodlots, with the effects on subordinate species in foraging flocks in very small woodlots possibly being the most severe.
Influence of Diet on Fatty-Acid Composition of Depot Fat in Western Sandpipers (Calidris Mauri)
Authors: Egeler Oliver , Seaman Dana , Williams Tony D. 
Published: September 2019

Abstract
Western Sandpipers (Calidris mauri) have been previously shown to undergo seasonal changes in the fatty acid composition of their fat stores, even though they do not show the marked seasonal variation in diet common to many migratory passerines. We investigated the effect of dietary fatty acid composition on the fatty acid composition of adipose tissue in captive Western Sandpipers by feeding birds experimental diets with different fatty acid composition. In addition, we determined the effect of total percentage of fat content of the diet (5 vs. 10%) on fatty acid composition of depot fat. Birds maintained normal body mass (24–27 g) throughout all experimental treatments. Most adipose fatty acids were sensitive to dietary manipulation to some extent. Changes in fatty acid composition of the diet had the largest effect on adipose tissue composition for the essential polyunsaturated fatty acid linoleate (18:2), whereas it had the least effect for the monounsaturated fatty acid oleate (18:1). The saturated fatty acid palmitate (16:0) demonstrated an intermediate capacity to alter fatty acid composition of adipose tissue. Total amount of fat in the diet did not influence the effect of diet on fatty acid deposition. Results of dietary manipulations in this study suggest that diet does explain some of the variation in fatty acid composition observed during migration in Western Sandpipers, but that certain fatty acids can be modulated independently of diet (probably through de novo synthesis, postabsorption modification, or both).
Phylogeography of the California Thrasher (Toxostoma Redivivum) Based on Nested-Clade Analysis of Mitochondrial-DNA Variation
Authors: Sgariglia Erik A. , Burns Kevin J. 
Published: September 2019

AbstractDistribution of genealogical lineages within a species is likely the result of a complicated series of ecological and historical events. Nested-clade analysis is specifically designed as an objective phylogeographic approach for inferring evolutionary processes on a spatial and temporal scale for small subclades within a larger set of intraspecific relationships. Here, we use nested-clade analysis as well as other phylogeographic methods to investigate the evolutionary history of California Thrasher (Toxostoma redivivum) populations. Inferences resulting from nested clade analysis suggest a history that includes past fragmentation, range expansion, and isolation-by-distance. Along with root information, those inferences enable the construction of a biogeographic scenario for this species involving general southern ancestry, an early north–south division, northward range expansion, and a southward back-expansion into an already populated southern region. Isolation-by-distance is also identified, particularly in southern California, indicating that gene flow between localities does occur but is restricted. Many conclusions drawn from this study are concordant with geologic data as well as phylogeographic scenarios drawn for other codistributed California taxa.
Male Parental Care in Greater Rheas (Rhea Americana) in Argentina
Authors: Fernández Gustavo J. , Reboreda Juan C. 
Published: September 2019

AbstractGreater Rheas (Rhea americana) are precocial birds that show uniparental male care. We evaluated the extent of nest attention by males and estimated its effect on viability and survival of eggs. We assessed whether male absences during incubation were constrained to avoid embryos reaching lethal temperatures or to minimize risk of egg predation. We estimated (1) effect of nest attention on viability of eggs by comparing egg temperature in nests with and without male attention; and (2) effect of male care on egg predation, by comparing survival of eggs in nests with and without male care. Rhea males attended the eggs for 42 days, but effective incubation started 5–7 days after laying of the first egg. The proportion of time that males spent at the nest increased from 64% during egg laying (days 1–10) up to 97.5% during mid and late incubation (days 20–40). Male absences occurred at the warmest hours of the day and their lengths were positively correlated with the temperature of the environment. Male nest attention reduced the rate of egg losses and kept eggs above lower lethal temperatures for embryos during the night. We also estimated relative cost of parental care after hatching by comparing the time allocated to feeding and vigilance by males with chicks, males in nonreproductive groups, and nonreproductive solitary males. Males took care of the chicks for 4–6 months. They allocated less time to feeding and more time to vigilance than males in groups of adults or solitary males. Investment in vigilance decreased as chicks aged. Our results indicate that Greater Rhea males would require high levels of energetic reserves to start a breeding attempt. That high demand could explain why less than only 20% of the males attempt to nest during a breeding season.
Snag use by Foraging Black-Backed Woodpeckers (Picoides Arcticus) in a Recently Burned Eastern Boreal Forest
Authors: Nappi Antoine , Drapeau Pierre , Giroux Jean-François , Savard Jean-Pierre L. 
Published: September 2019

Abstract
We studied snag use for foraging by Black-backed Woodpeckers (Picoides arcticus) one year after a fire in an eastern black spruce (Picea mariana) boreal forest in Quebec, Canada. We searched for signs of foraging (bark flaking and excavation holes) by Black-backed Woodpeckers on 6,536 snags sampled in 56 plots located in portions of the burned forest that had not been salvage logged. A logistic regression model was developed based on the presence or absence of foraging signs. Results showed that Black-backed Woodpeckers used larger snags that were less deteriorated by fire (qualified as high-quality snags). Direct field observations of individuals foraging on 119 snags also indicated that used snags corresponded to those of high predicted quality. Finally, we assessed the relationship between food availability and snag characteristics by measuring the density of wood-boring beetle larvae holes on 30 snags of different size and deterioration classes. High-quality snags contained higher prey densities (wood-boring beetle holes) than smaller and more deteriorated snags. We recommend that forest blocks characterized by large and less deteriorated trees be preserved from salvage logging in recently burned boreal forests in northeastern North America.
Using Vitellogenin to Identify Interannual Variation in Breeding Chronology of Marbled Murrelets (Brachyramphus Marmoratus)
Authors: Tranquilla Laura Mcfarlane , Williams Tony , Cooke Fred 
Published: September 2019

AbstractVitellogenin is a lipophosphoprotein found in plasma of egg-producing birds prior to laying that may be used to identify fecund females whose reproductive status is otherwise unknown. We captured Marbled Murrelets (Brachyramphus marmoratus) at sea in Desolation Sound, British Columbia, and used vitellogenin to (1) identify variation in egg production between 1999 and 2000, (2) predict timing of subsequent breeding stages on the basis of egg production, and (3) describe proportion of captured females producing eggs. We also used vitellogenin to investigate a capture bias previously detected in mist-netted birds in the study area and found a corresponding bias in number of egg producers caught. Dates that egg producers were present (27 April to 6 July 1999, 20 April to 6 July 2000) indicate that breeding is highly asynchronous in that species but was similar in both years. Predicted chick-fledging based on vitellogenin analyses was within one day of first sightings of fledglings at sea in both years, confirming that the vitellogenin technique provides accurate information on breeding chronology. Percentage of egg producers (54% in 1999, 56% in 2000) were similar in both years. Vitellogenin analyses provided a chronology very similar to that previously estimated using multiple techniques in the same study area (1996–1998), confirming that vitellogenin analyses alone may be used to describe chronology when sampling encompasses the entire laying period. We recommend that technique for use in other studies of secretive species where egg production cannot normally be monitored by direct observation.
Climate Change, Spring Temperatures, and Timing of Breeding of Tree Swallows (Tachycineta Bicolor) in Southern Ontario
Authors: Hussell David J. T. 
Published: September 2019

AbstractSeveral European studies have indicated advances in breeding dates of birds in the last 30 years, which authors attributed to climate change. In North America, Dunn and Winkler (1999) reported a continent-wide advance of five to nine days in breeding dates of Tree Swallows (Tachycineta bicolor) between 1959 and 1991. I present results of an intensive study of Tree Swallows breeding on and near Long Point, Ontario, at four sites monitored 1969–2001, 1977–1986, 1978–2001, and 1987–2001. Local air temperatures varied among sites, according to distance from Lake Erie, but there was no significant regional trend in April and May temperatures between 1969 and 2000. Median and 10th percentile dates of clutch initiation by females that were at least two years old varied among years by up to 20 days overall and 18 days within sites, and differed by 0–14 days between sites in the same year. There were no significant differences in average timing of laying among the 1970–1980, 1980–1990, and 1990–2000 periods. Nevertheless, there was a significant trend towards earlier laying in 1990–2000, which was attributable to exceptionally early laying and warm May weather in 1998–2001. Across all sites, median dates of clutch initiation were strongly correlated with average daily maximum temperatures in the first four, five-day periods in May, but clutches at one site were initiated three days earlier than predicted by temperatures alone. I estimate that climate warming of 5°C in May could result in an average advance of about seven days in the median date of laying of Tree Swallows at those sites. My results indicate that spring temperatures are strongly correlated with timing of laying, but show that spring temperatures have not increased in the Long Point region and timing of the breeding season has not advanced throughout North America.
Effects of Scaley-Leg Mite Infestations on Body Condition and Site Fidelity of Migratory Warblers in The Dominican Republic
Authors: Latta Steven C. 
Published: September 2019

AbstractRates of infestation by the scaley leg mite (Knemidokoptes jamaicensis) were examined on two overwintering Nearctic-Neotropical migrants, Palm Warbler (Dendroica palmarum) and Prairie Warbler (D. discolor), in low-elevation desert thorn scrub and high-elevation pine forest in the Dominican Republic. Ectoparasites were common on birds in the dry thorn scrub where birds roosted communally, but were never found on birds in the moister pine forest where communal roosting was not detected. Prevalence of ectoparasites varied between years and generally increased in prevalence within winters, with mean rates of infestation reaching as high as 25% among Palm Warblers in late-winter. Parasitized Palm Warblers showed significant decreases in mean pectoral muscle mass scores indicating a negative effect on body condition and physiological stress. Infestation had a significant effect on overwinter site persistence and annual return rates; no infected individuals ever returned the following year. Results of a path analysis indicated that mite infestation was more important than general physiological condition (as represented by pectoral muscle score) in determining annual return. Data suggest that environmental variables and host behavior may affect parasite infestation rates, and further attention should be given to the potential contribution of parasite infestation to winter limitation of avian populations.
Effect of Northern Pygmy-Owl (Glaucidium Gnoma) Eyespots on Avian Mobbing
Authors: DEPPE CAROLINE , HOLT DENVER , TEWKSBURY JOSH , BROBERG LEN , PETERSEN JULIE , WOOD KRISTIN 
Published: September 2019

AbstractEyespots (color patterns resembling eyes) are present in many taxa and often have important ecological functions. In some taxa, potential functions of eyespots have not been extensively examined, as is the case with pygmy-owls (Glaucidium spp.), many of which bear a conspicuous eye-like pattern on their nape. Using wooden replicas of Northern Pygmy-Owls (G. gnoma), with and without eyespots, we tested one potential function: whether eyespots affect mobbing behaviors of small forest birds. We measured the orientation of mobbing behaviors (where birds perched and flew at the model) and intensity of mobbing bouts (duration of bouts and number of mobbing individuals). Eyespots affected the most proximal behavior, close passing (flights directly at the model, resulting in an approach within 0.5 m). When eyespots were present, mobbers shifted away from eyespots, providing the first empirical evidence for a link between eyespots and avian mobbing.
How do Brown-Headed Cowbirds (Molothrus Ater) CAUSE NEST FAILURES IN SONG SPARROWS (MELOSPIZA MELODIA)? A REMOVAL EXPERIMENT
Authors: Smith James N. M. , Taitt Mary J. , Zanette Liana , Myers-Smith Isla H. 
Published: September 2019

AbstractA removal experiment was conducted to measure how much and by what mechanisms brood parasitic Brown-headed Cowbirds (Molothrus ater) cause nest failures in a commonly used host, the Song Sparrow (Melospiza melodia). When numbers of female cowbirds were reduced experimentally, nest failures fell from 65.0% (n = 663 nests) to 49.9% (n = 331). Cowbird reduction reduced the frequency of nest failure to one-third of control levels in Song Sparrows during the last 80 days of the sparrow's breeding season, the period when most parasitic laying took place. Cowbird reduction decreased nest failures strongly at the egg stage, and weakly at the nestling stage. Daily nest-failure rates were independent of whether or not a nest was parasitized by cowbirds. Two hypotheses were tested to explain how cowbirds cause host nests to fail: first, egg removal by female cowbirds lowers clutch size below a threshold where the host deserts; second, cowbirds cause host nests to fail by destroying entire clutches or broods. In support of the first hypothesis, desertion following parasitism and egg removal was less frequent when cowbird numbers were reduced (8.9% of n = 158 nests) than for unmanipulated controls (16.5% of n = 424 nests). In support of the second hypothesis, there were fewer cases where young were killed in the nest, or found dead near it, after cowbird numbers were reduced (2.5% of 158 nests) than in controls (4.7% of 424 control nests). In contrast, proportions of nests that failed after the disappearance of all eggs, young, or both, and after unparasitized clutches were deserted, increased when cowbird numbers were reduced. Although our study supports both hypotheses, cowbird-induced desertion had a greater effect on nest failure rates than did cowbird predation. Our study suggests that cowbird removal programs are likely to benefit commonly used and endangered hosts by reducing rates of nest failure.
Effects of Body Size and Sex on Foraging Territoriality of the Little Egret (Egretta Garzetta) in Japan
Authors: Nota Yukiko 
Published: September 2019

Abstract
I studied the characteristics of foraging territoriality in the Little Egret (Egretta garzetta) and effects of body size and sex on territoriality. Sixty-eight birds were captured and sexed, and foraging behavior (usage of area, defense rate, and foraging efficiency) of 26 birds identified by color bands was observed in detail for 3 years. I categorized territoriality within the foraging area into three types according to the birds' exclusiveness and attachment to the area: high exclusiveness and strong attachment to the same area for a long period, moderate exclusiveness and attachment, and minimal exclusiveness and attachment. Body size was largest and feeding efficiency was highest in the first type. I propose a model that predicts a relationship between body size and defense rate to explain the behavior of egrets.