bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Postfire Salvage Logging on Cavity-Nesting Birds
Authors: Hutto Richard L. , Gallo Susan M. 
Published: September 2019

Abstract

Abstract
We investigated the effects of postfire salvage logging on cavity-nesting birds by comparing nest densities and patterns of nest reuse over a three-year period in seven logged and eight unlogged patches of mixed-conifer forest in the Blackfoot-Clearwater Wildlife Management Area, Montana. We found 563 active nests of 18 cavity-nesting birds; all species were found nesting in the uncut burned forest plots, but only eight nested in the salvage-logged plots. All except one species nested at a higher density in the unlogged areas, and half of the species were significantly more abundant in the unlogged plots. Every timber-drilling and timber-gleaning species was less abundant in the salvage-logged plots, including two of the most fire-dependent species in the northern Rocky Mountains—American Three-toed (Picoides dorsalis) and Black-backed (P. arcticus) Woodpeckers. Lower abundances in salvage-logged plots occurred despite the fact that there were still more potential nest snags per hectare than the recommended minimum number needed to support maximum densities of primary cavity-nesters, which suggests that reduced woodpecker densities are more related to a reduction in food (wood-boring beetle larvae) than to nest-site availability. Because cavities were present in only four of 244 randomly selected trees, and because frequency of cavity reuse by secondary cavity-nesters was higher in salvage-logged than in unlogged plots, nest-site limitation may be a more important constraint for secondary cavity-nesters in salvage-logged areas. These results suggest that typical salvage logging operations are incompatible with the maintenance of endemic levels of most cavity-nesting bird populations, especially populations of primary cavity-nesting species.
Factors Influencing Nest Success of Songbirds in Aspen and Willow Riparian Areas in the Great Basin
Authors: Heltzel Jeannie M. , Earnst Susan L. 
Published: September 2019

AbstractAbstractRecent studies have examined the effects oflivestock grazing, agriculture, and humanhabitation on nest predation and brood parasitismin riparian areas in the western United States.However, we know little about factors influencingnest success in riparian areas lacking suchanthropogenic influences, in part because theinfluences are so pervasive. We studied riparianbird communities in a 115 000 hawildlife refuge where livestock grazing wasdiscontinued >10 years ago, and which haslittle nearby agriculture or human habitation. Wemonitored nests on 24 aspen (Populustremuloides) and 10 willow(Salixspp.) plots. Brood parasitism rates weresubstantially lower than at other western sites anddid not differ between aspen and willow habitats.Nest success in aspen was relatively high comparedto that reported for other western sites and higherthan in willow. Predators may have been able tofind nests more efficiently in willow than in aspenbecause territory densities were higher in willow(40 versus 30 pairs per ha,respectively), because willow had lessstructural heterogeneity, or both. We did not findstrong evidence that nest success was influenced byaspen patch size or distance to riparian edge,indicating that even small aspen patches providevaluable nesting habitat. Weather was an importantcause of nest failure, particularly at higherelevations during late-spring snowstorms. Ourresults indicate that riparian areas without majoranthropogenic impacts, especially aspen stands,constitute high-quality breeding habitat andwarrant conservation focus.
Ecological and Physiological Variance in T-Cell Mediated Immune Response in Cory's Shearwaters
Authors: Forero Manuela G. , González-Solis Jacob , Igual José M. , Hobson Keith A. , Ruíz Xavier , Viscor Ginés 
Published: September 2019

Abstract

Abstract
T-cell mediated immune response (CMI) hasbeen widely studied in relation to individual andfitness components in birds. However, few studieshave simultaneously examined individual and socialfactors and habitat-mediated variance in theimmunity of chicks and adults from the samepopulation and in the same breeding season. Weinvestigated ecological and physiological variancein CMI of male and female nestlings and adults in abreeding population of Cory's Shearwaters(Calonectrisdiomedea) in theMediterranean Sea. Explanatory variables includedindividual traits (body condition, carbon andnitrogen stable isotope ratios, plasma totalproteins, triglycerides, uric acid, osmolarity,β-hydroxy-butyrate, erythrocyte meancorpuscular diameter, hematocrit, andhemoglobin) and burrow traits(temperature, isolation, and physicalstructure). During incubation, immune responseof adult males was significantly greater than thatof females. Nestlings exhibited a lower immuneresponse than adults. Ecological and physiologicalfactors affecting immune response differed betweenadults and nestlings. General linear models showedthat immune response in adult males was positivelyassociated with burrow isolation, suggesting thatmales breeding at higher densities suffer immunesystem suppression. In contrast, immune response inchicks was positively associated with bodycondition and plasma triglyceride levels.Therefore, adult immune response appears to beassociated with social stress, whereas a trade-offbetween immune function and fasting capability mayexist for nestlings. Our results, and those fromprevious studies, provide support for anasymmetrical influence of ecological andphysiological factors on the health of differentage and sex groups within a population, and for theimportance of simultaneously considering individualand population characteristics in intraspecificstudies of immune response.
Large-Scale Movements and Habitat Characteristics of King Eiders Throughout the Nonbreeding Period
Authors: Phillips Laura M. , Powell Abby N. , Rexstad Eric A. 
Published: September 2019

AbstractAbstractKing Eiders (Somateriaspectabilis) breeding inwestern Canada and Alaska molt wing feathers andspend the winter in remote areas of the Bering Sea,precluding direct observation. To characterizetiming of migration and habitat used by King Eidersduring the nonbreeding period, we collectedlocation data for 60 individuals (27 femalesand 33 males) over three years from satellitetelemetry and utilized oceanographic informationobtained by remote sensing. Male King Eidersdispersed from breeding areas, arrived at wing moltsites, and dispersed from wing molt sites earlierthan females in all years. Males arriving earlierat wing molt sites molted flight feathers at higherlatitudes. Distributions of molt and winterlocations did not differ by sex or among years. Ofthe variables considered for analysis, distance toshore, water depth, and salinity appeared to bestdescribe King Eider habitat throughout thenonbreeding period. King Eiders were located closerto shore, in shallower water with lower salinitythan random locations. During the winter, lower iceconcentrations were also associated with King Eiderlocations. This study provides some of the firstlarge-scale descriptions of King Eider migrationand habitat outside the breeding season.
Correlated Growth and Survival of Juvenile Spectacled Eiders: Evidence of Habitat Limitation?
Authors: Flint Paul L. , Morse Julie A. , Grand J. Barry , Moran Christine L. 
Published: September 2019

AbstractAbstractWe studied the growth andsurvival of Spectacled Eider (Somateriafischeri) ducklings to30 days of age along the lower KashunukRiver on the Yukon-Kuskokwim Delta from 1995 to2000. We replicated this study at a second site,Kigigak Island, in 1999 and 2000. Age-adjustedestimates of duckling mass and survival at30 days posthatching were highly variable.Duckling survival was consistently higher onKigigak Island in 1999 and 2000, averaging67%, while survival on the Kashunuk Riveraveraged 45% during the same time period.Duckling survival was negatively related tohatching date. At the Kashunuk River site our datasupported models that indicated age-adjusted massvaried with habitat type and declined with hatchingdate. Ducklings from Kashunuk River were heavier in1999, while ducklings from Kigigak Island wereheavier in 2000. However, we found a positivecorrelation between 30-day duckling survival andage-adjusted mass, suggesting a localizedenvironmental effect on both parameters. Weconclude that predation may be the proximatemechanism of mortality, but habitat conditions arelikely the ultimate factors influencing ducklingsurvival. Geographic variation in rates of ducklingsurvival and apparent growth suggest that spatialheterogeneity in population vital rates isoccurring at multiple levels.
Trends in Radar-Based Counts of Marbled Murrelets on the Olympic Peninsula, Washington, 1996–2004
Authors: Cooper Brian A. , Raphael Martin G. , Peery M. Zachariah 
Published: September 2019

AbstractAbstractThe Marbled Murrelet (Brachyramphusmarmoratus) is a highprofile, federally threatened seabird, but noreliable estimates of population trends at inlandbreeding areas exist for this species. We conductedland-based radar studies of Marbled Murrelets at3–7 sites on the Olympic Peninsula,Washington, in 1996–2002 and 2004 to estimatepopulation changes and to examine relationshipsbetween our counts and oceanographic conditions,murrelet productivity, and regional at-sea countsof murrelets. Morning radar counts of murreletsvaried significantly among and within sites but didnot decline from 1996–2004, suggesting thatthe inland breeding population of murrelets isstable in this area. A retrospective power analysisindicated that we had a 25% and 56%chance of detecting 2% and 4% annualdeclines, respectively. Thus, if relatively smallannual declines did occur during our study period,there is a high probability that they would havegone undetected, even though they could add up to abiologically important decline over time. It isunlikely that murrelets on the Olympic Peninsuladeclined by ≥6% annually, however,because retrospective analyses indicated that powerto detect such declines was >88%. Therewas no significant relationship between radarcounts and at-sea counts or productivity ofmurrelets in the nearby San Juan Islands during thestudy period. We also did not detect a relationshipbetween radar counts and mean sea-surfacetemperatures or the Northern Oscillation Index,suggesting that variation in oceanographicconditions (e.g., the strong 1998 ElNiño event) was not associated withvariation in morning radar counts of MarbledMurrelets. A prospective power analysis indicatedthat small (2%–4%)annual declines could be detected with reasonablyhigh power (≥80%) with thecurrent radar sampling design by extending thestudy to 11–15 years.
Numerical Discrimination by Wild Northern Mockingbirds
Authors: Farnsworth George L. , Smolinski Jennifer L. 
Published: September 2019

Abstract

Abstract
Optimal foraging theory predicts that birds, when faced with alternative foraging options, will choose the one that provides the greatest rate of return. We tested if wild, free-living Northern Mockingbirds (Mimus polyglottos) could solve a novel foraging problem to attain food rewards with the least amount of effort. We introduced five subjects to experimental feeders in their winter territories in an urban habitat. Feeders contained different numbers of bamboo sticks at each of two ends. Birds could access a food reward (Tenebrio larvae) by removing all sticks from either end; therefore, the optimal choice was to remove sticks from the end with fewer sticks. Each subject was tested in repeated trials to determine if it preferentially chose the end with fewer sticks. All five birds successfully discriminated between one stick and six sticks as well as between two sticks and five sticks. However, all five birds failed to discriminate between three sticks and four sticks. Wild Northern Mockingbirds thus appear to have a limited capacity to solve novel foraging problems by minimizing the number of obstacles to be removed.
Laboratory Metabolism of Incubating Semipalmated Plovers
Authors: Williamson Mark , Williams Joseph B. , Nol Erica 
Published: September 2019

AbstractAbstractThe Semipalmated Plover (Charadriussemipalmatus), anarctic-nesting migratory shorebird, regularlyencounters low temperatures during the breedingseason. We measured the basal metabolism of adultsduring incubation at Churchill, Manitoba, Canada todetermine basal metabolic rate (BMR),lower critical temperature(Tlc), total evaporative waterloss (TEWL), and dry thermal conductance(Cm). BMR and Tlcwere 47.4 kJ day−1and 23.3°C, respectively, TEWL was2.5 mL H2O−d,and Cm was1.13 mW g−1 °C−1.Measured BMR and Tlc were consistentwith high values found for other shorebird speciesbreeding in the Arctic, while Cm was18% higher than predicted from allometricequations. These metabolic data suggest thatSemipalmated Plovers are adapted to balance therequirements of incubation against energetic andthermoregulatory demands in the Arctic, especiallyin harsh early breeding season conditions.
Egg Composition in Northern Flickers
Authors: Wiebe Karen L. 
Published: September 2019

AbstractAbstractThere have been several studies on egg compositionin birds, but none on woodpeckers. Woodpeckers(Picidae) have among the smallest eggsrelative to their body size of any bird. Idissected Northern Flicker (Colaptesauratus) eggs into shell,yolk, and albumen components, and determined thelipid content of the yolk. The proportional size ofthe yolk in flicker eggs (16%) wasamong the smallest described for any bird. However,the yolk contained a similar amount of lipid(58%) as the yolks of otheraltricial species. The overall energy density inflicker eggs, 3.8 kJ g−1,was also among the lowest reported in birds. Therelative size of the yolk tended toward negativeallometry with increasing total egg mass while theamount of albumen showed positive allometry, butthe confidence intervals for the regression slopesshowed that isometry of these components could notbe excluded. These results demonstrate that flickereggs contain relatively little energy and, comparedto other species, eggs may be relatively cheap forflicker females to produce.
Growth and Plumage Development of Nestling Long-Eared Owls
Authors: Seidensticker Mathew T. , Flockhart D. T Tyler , Holt Denver W. , Gray Kathy 
Published: September 2019

AbstractAbstractWe report the growth rates and plumage development of Long-eared Owls (Asio otus) in two developmental stages from hatching to fledging, the nestling period (1–22 days) and prefledging period (23–37 days). We used the logistic growth equation to model nestling mass gain. Mass gain was most rapid during the nestling period. Average mass gain per day was highest between seven and 13 days of age. At 16 days of age nestlings displayed defined facial disks and complete second down. Nestlings left the nest at 22 days of age. Mass gain slowed considerably after nest departure and continued to slow up to fledging. Appearance of defensive and concealment behaviors occurred nearly simultaneously with departure from the nest. To our knowledge this is the first detailed report of nestling growth rates and plumage development for Long-eared Owls in North America.
Old Burns as Source Habitats for Lewis's Woodpeckers Breeding in the Black Hills of South Dakota
Authors: Gentry Dale J. , Vierling Kerri T. 
Published: September 2019

AbstractAbstractCrown-burned pine forests are an important breeding habitat for many cavity-nesting birds, and can serve as a source habitat for some woodpecker species. However, it is unclear if this function continues with postburn succession as predators recolonize burned habitats and snag density declines. Lewis's Woodpeckers (Melanerpes lewis) are considered “burn specialists” and are a species of conservation concern. We monitored Lewis's Woodpeckers nesting in ponderosa pine (Pinus ponderosa) forests to determine the source or sink function of old-burn habitats in the Black Hills of South Dakota (study units burned in 1988 and 1991); concurrently, we examined avian and mammalian predator communities within burned and unburned areas. Between 2002 and 2005 we found 55 Lewis's Woodpecker nests, 51 of which were successful. Using adult and juvenile mortality rates for other melanerpine species taken from the literature, we determined that the old-burn habitats we sampled were acting as sources for Lewis's Woodpeckers. Point counts and tracking tube surveys suggested that both avian and mammalian predators had successfully recolonized these old-burn habitats, as both groups were common in old burns and in unburned forests. The unusually high nesting success of Lewis's Woodpeckers in the Black Hills is likely due to the absence of some common nest predators. While the high success rates might continue, we suggest that the overall contribution of young to the region from these burned sites will decline as suitable habitat components (such as snags) decline with the continuation of postfire succession.
The Effects of Permanent Local Emigration and Encounter Technique on Stopover Duration Estimates as Revealed by Telemetry and Mark-Recapture
Authors: BÄCHLER Erich , Schaub Michael 
Published: September 2019

Abstract

Abstract
Studies of stopover durations of migrating birds using mark-recapture and resighting techniques are usually restricted to only a part of a stopover site. Therefore, estimates of stopover duration may be negatively biased if birds leave the trapping area permanently, but remain within the stopover site (permanent local emigration). We tested this possible effect by comparing stopover durations of Orphean Warblers (Sylvia hortensis) estimated from recapture and resighting data obtained from a trapping area covering only a part of a stopover site with durations estimated from relocation data of radio-marked individuals sampled over the entire stopover site. To test a possible effect of the different reencounter techniques on stopover duration estimates we compared estimates of stopover duration derived from the recapture and resighting data with those derived from the relocation data restricted to the same trapping area. Stopover duration estimated from relocation data obtained from the entire stopover site was twice as long as stopover duration estimated from recapture and resighting data. While similar estimates of stopover duration were obtained from relocation data when data from only the restricted trapping area were used, the proportion of transients was different between the two data sets. The different estimates of stopover duration were most likely not due to permanent local emigration, but rather to violations of essential model assumptions, such as equal catchability or that the probability of staying for another day is independent of the time a bird has already spent at the stopover site.
Display Behavior and Spatial Distribution of the White-Crowned Manakin in the Atlantic Forest of Brazil
Authors: Castro-Astor Ivandy N. , Alves Maria Alice S. , Cavalcanti Roberto B. 
Published: September 2019

AbstractAbstractWe studied the display behavior and spatial distribution of the White-crowned Manakin (Dixiphia pipra, formerly in the genus Pipra) in the Atlantic Forest of the state of Rio de Janeiro, Brazil. The study area included three leks, two apparently solitary display sites, and two “collective display sites,” where definitive-plumaged males, predefinitive-plumaged males, and birds of undetermined sex displayed. The average distance between display sites was 68.0 ± 24.4 m (n  =  8, range  =  41–113 m). Males occupied the same display sites among years. The dispersion pattern of males was typical of exploded or dispersed leks. Males did not display in auditory or visual contact, except at the two display sites that were closest to each other. Lekking White-crowned Manakins used 11 display behaviors and two vocalizations. Four of the 11 display behaviors were recorded only at the collective display sites. We only observed males displaying in the presence of other individuals, regardless of whether it was a collective or solitary display site. Definitive- and predefinitive-plumaged males and birds of indeterminate sex all displayed together. The White-crowned Manakin repertoire of 11 display behaviors indicates a more complex display behavior than previously described.
Free-Living Male Mountain White-Crowned Sparrows Exhibit Territorial Aggression Without Modulating Total or Free Plasma Testosterone
Authors: Lynn Sharon E. , Hahn Thomas P. , Breuner Creagh W. 
Published: September 2019

AbstractAbstractIn some species, expression of territorial aggression is accompanied by a rise in testosterone secretion, but in others aggressive behavior is expressed while testosterone levels remain unchanged. Corticosteroid binding globulin (CBG) binds both corticosterone and testosterone in avian plasma. Thus, increasing corticosterone may result in fluctuations in unbound (“free”) testosterone; this could result in greater biological activity of testosterone without an increase in testosterone secretion. We investigated whether such plasma interactions of testosterone, corticosterone, and CBG might result in alterations of free testosterone in male Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha). We conducted simulated territorial intrusions during incubation and compared total and free testosterone of males captured immediately following a simulated territorial intrusion with that of males captured passively. All experimental males showed aggressive behavior, but apparently did not modulate total or free testosterone relative to controls.
Using a Commercially Available Enzyme Immunoassay to Quantify Testosterone in Avian Plasma
Authors: Washburn Brian E. , Millspaugh Joshua J. , Morris Dana L. , Schulz John H. , Faaborg John 
Published: September 2019

Abstract

Abstract
Using a commercially available testosterone enzyme immunoassay (EIA), we developed and validated an assay procedure for determining testosterone levels in small-volume (20 µL) avian plasma samples. We evaluated this EIA's utility by measuring plasma testosterone levels in Mourning Doves (Zenaida macroura), White-eyed Vireos (Vireo griseus), Red-eyed Vireos (Vireo olivaceus), and Indigo Buntings (Passerina cyanea). Standard biochemical validations (e.g., parallelism, recovery of exogenous testosterone) demonstrated that the assay accurately and precisely measured testosterone in avian plasma. We compared plasma testosterone levels in males and females of all four species and Indigo Buntings in various reproductive stages to physiologically validate the assay's ability to determine biologically important changes in testosterone levels. Plasma testosterone levels were higher in males compared to females in three of four species. Prebreeding and breeding male Indigo Buntings had higher circulating testosterone levels than postbreeding males. Testosterone levels in our study were similar to reported values for other passerine species using radioimmunoassay procedures. Our results suggest that this EIA procedure is very effective for determining testosterone levels in small-volume avian plasma samples and is sensitive enough to detect biologically important changes in the gonadal activity of birds. Thus, this assay has considerable utility for measuring testosterone in small birds (<15 g), from which only small volumes of plasma (20 µL) can be collected.