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Monday, 11 January 2016

Wilson Journal of Ornithology, December 2015: Volume 127, Issue 4

The Wilson Journal of Ornithology
Published by: The Wilson Ornithological Society

Table of Contents
Dec 2015 : Volume , 127 Issue 4 



Avifaunal Surveys of the Upper Apurímac River Valley, Ayacucho and Cuzco Departments, Peru: New Distributional Records and Biogeographic, Taxonomic, and Conservation Implications 
Peter A. Hosner, Michael J. Andersen, Mark B. Robbins, Abraham Urbay-Tello, Luis Cueto-Aparicio, Karen Verde-Guerra, Luis A. Sánchez-González, Adolfo G. Navarro-Sigüenza, Roger L. Boyd, Jano Núñez, Jorge Tiravanti, Mariela Combe, Hannah L. Owens and A. Townsend Peterson

The sliver of humid tropical and montane forest on the east slope of the Andes in Ayacucho Department ranks among the least surveyed sectors of the Peruvian Andes. This mountainous region, along with adjacent Apurímac Department and western Cuzco Department, comprise the Apurímac River Valley, a putative biogeographic barrier. Hence, understanding avian distributions in the vicinity of the Apurímac River Valley is fundamental to understanding faunal turnover across it. Here, we report results of recent avifaunal surveys (2008–2012) from five sites in the Apurímac Valley region. We report 35 bird species previously undocumented in Ayacucho, six of which represent range extensions, including records of the endemic Black-spectacled Brush-Finch (Atlapetes melanopsis), Marcapata Spinetail (Cranioleuca marcapatae), and Chestnut-breasted Mountain-Finch (Poospiza caesar); the remaining records filled perceived range gaps. Specimen evidence suggests little phenotypic introgression between differentiated forms across the region, except for apparent introgression zones in Superciliaried Hemispingus (Hemispingus superciliaris) and Mountain Cacique (Cacicus chrysonotus); these observations uphold the idea that the Apurímac River Valley functions to isolate bird populations. Specimens of two Grallaria sp. and one Scytalopus sp. may represent new taxa, two of which appear to be endemic to Ayacucho (the third extends into adjacent Junín Department). More generally, montane forest bird species richness and avian endemism in eastern Ayacucho are similar to those of Cuzco and Pasco departments; previous assessments that considered Ayacucho as an area of reduced diversity were misled by sparse sampling effort.

Warmer Summers and Drier Winters Correlate with More Winter Vagrant Purple Gallinules (Porphyrio martinicus) in the North Atlantic Region 
Andrew Farnsworth, Frank A. La Sorte and Marshall J. Iliff

Individuals from a diverse array of bird species sometimes occur well outside of their historic distributions. These vagrants, and their patterns of occurrence, may yield valuable insights regarding how birds respond to environmental change. Among the Rallidae, which are champion dispersers, the Purple Gallinule (Porphyrio martinicus) disperses exceptionally long distances. Whereas most Purple Gallinule vagrants occur from April to October, a much smaller number of records represent a more enigmatic vagrancy pattern that occurs from November to February. Using eBird, a global bird-monitoring project, we compiled 77 occurrences of vagrant Purple Gallinules from 1957–2014 during this seasonal window and examined how those occurrences correlated with environmental conditions and population trends. Average temperature anomalies showed significant correlations with patterns of records, with warmer late summer temperatures in particular in Florida and Puerto Rico correlating with more vagrants. Drier conditions in eastern Mexico, especially during winter, showed similar significant relationships. Our results indicate the potential utility of studying vagrants to understand relationships between bird populations and environmental changes, and more importantly highlight the potential for understanding how vagrancy may relate to changes in this species’ distribution under new climate regimes.

Uncommon Levels of Relatedness and Parentage in a Cooperatively Breeding Bird, the Brown-Headed Nuthatch (Sitta pusilla)
Kin-Lan Han, James A. Cox and Rebecca T. Kimball

Cooperatively breeding birds employ a variety of mating strategies, and we do not fully understand breeding group structure and the range of reproductive strategies used by group members. We examined group structure and parentage in a population of Brown-headed Nuthatches (Sitta pusilla). We genotyped 346 adults and nestlings banded at 59 nests using nine microsatellite loci to determine parentage and relatedness and compared the results to field observations of marked individuals from 282 nests monitored from 2006–2010. Based on field observations, 23% of nests were cooperative, and only 13% of the cooperative groups had more than one helper. Consistent with field observations, genetic analyses indicated that 83% of helpers were related to at least one parent at the nest, and that most helpers were male. Extra-group paternity appeared to be common at nests of both pairs (45%) and cooperative groups (32%, but did not differ in frequency between the two nest types. Although male helpers unrelated to the breeding female might be expected to sire offspring in cooperative groups, we did not observe this phenomenon. Instead, we found one, and possibly two, cases of incestuous breeding involving related helpers.

High-Latitude Passerine Migrants Overlap Energetically Demanding Events in Autumn
Anna-Marie Benson and Kevin Winker

Temporal constraints on migratory birds to molt, store fat, and migrate in autumn are probably most severe in populations breeding at high latitudes. We examined whether high-latitude time constraints were related to the overlap of these energetically demanding events in migratory passerine species. We also examined how much overlap of molt and fattening occurs within individuals. Data were collected on molt intensity and subcutaneous fat during autumn migration from 1992 to 2004 in Fairbanks, Alaska, (64° 50′ N 147° 50′ W). Among 17 migrant species, we found a negative relationship between length of breeding ground occupancy (number of days between median spring and autumn passage, our measure of time constraints) and the amounts of molt-migration overlap. There was also a positive relationship between molt-fat overlap and distance to wintering range among these 17 species. No individual completely overlapped the peak levels of both molt intensity and fat storage observed within a species, but several individuals approached this theoretical maximum in four species. Molt-fat overlap was highest in an individual Yellow Warbler (Setophaga petechia) that achieved 70% of the maximum possible overlap of peak fat storage and peak molt intensity for that species. These findings indicate that high-latitude passerines can overlap energetically demanding events during the annual cycle but that there is considerable variation among species in how they juggle time and energy constraints. Our data provide strong support for a conceptual model that passerine migrants breeding at high latitudes use strategies that reduce the time required to complete breeding season activities. In doing so, many of these birds appear to push energetic limits by overlapping molt, migration, and fattening to a degree not previously documented.

Rapid Evolution of Bright Monochromatism in the Domestic Atlantic Canary (Serinus canaria)
Rebecca E. Koch and Geoffrey E. Hill

Males exhibit more colorful plumage than females in many bird species. Phylogenetic reconstructions indicate that transitions from dichromatism to monochromatism are not uncommon and that monochromatism can result from the evolution of brighter plumage in females. To better understand the time scale over which such changes in dichromatism can evolve, we used a reflectance spectrophotometer to quantify feather coloration in the Atlantic Canary (Serinus canaria), a species that is sexually dichromatic in the wild but that has been under strong artificial selection for color in both sexes for several centuries. We measured the plumage coloration of males and females in the wild progener population of canaries, in captive canaries bred for bright yellow or red plumage coloration, and in Black-hooded Red Siskins (Carduelis cucullata), which were hybridized with yellow canaries to produce red canaries. We show that domestic canaries evolved from dichromatism to monochromatism under strong selection for increased female coloration in <500 years and that red canaries, the hybrid lineage resulting from canary-siskin crosses, evolved from dichromatic to monochromatic in <75 years. These observations show that bright monochromatic plumage can rapidly evolve from a dichromatic ancestral state.

Flight Feather Molt in Yellow-Headed Blackbirds (Xanthocephalus xanthocephalus) in North Dakota
Daniel J. Twedt and George M. Linz

Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) in central North Dakota undergo prebasic molt or prejuvenile molt during late summer. Nestling Yellow-headed Blackbirds initiate a complete prejuvenile molt, grow their primary and secondary regimes in about 40 days, completing molt after they leave the nest by the first week in August. Remiges are not replaced during the subsequent preformative molt, being retained until the second prebasic molt. Nonlinear (logistic) regression of primary remex growth during definitive prebasic molts of Yellow-headed Blackbirds indicated 38 days were required to complete the linear phase of growth (between 10% and 90% of total primary length). Males added 19.5 mm/d and females added 15.7 mm/d to the total length of all primaries during this linear growth phase; an average of 4–5 mm per primary remex per day. Definitive prebasic molting of primary remiges in males and females was initiated in late June, after nesting and brood rearing were completed. Molts of Yellow-headed Blackbirds were completed by early September, before birds emigrated from North Dakota during mid-September. Because of their comparatively early completion of molt and emigration from the state, as well as their more diverse diet, agricultural depredation caused by Yellow-headed Blackbirds in North Dakota is likely less than that of Red-winged Blackbirds and Common Grackles.

Seasonal Dynamics of Mourning Dove (Zenaida macroura) Body Mass and Primary Molt 
Clait E. Braun, Roy E. Tomlinson and Gregory T. Wann

Mourning Doves (Zenaida macroura) are common throughout much of North America and have been extensively studied. Seasonal changes in body mass are largely unreported and have not been examined in relation to replacement of primary flight feathers. We studied changes in body mass in relation to primary molt of doves captured in southeastern Arizona during 2000 through 2012. Body mass for adult males and females averaged 116.3 g (SE = 0.16) and 109.0 g (SE = 0.18), respectively. The distribution of body mass was similar for all months and was normally distributed. Body mass of adult males was lowest in August and September, and highest in November through January. Body mass of adult females was lowest in June through October and increased from October through March. Changes in body mass of adults generally tracked breeding and nesting activities and to a lesser extent timing of primary feather replacement. Body mass of juvenile doves increased linearly with replacement of juvenal primaries from prior to molt through replacement of P 8-10, while body mass of adult doves decreased from prior to molt through replacement of P 8-10. Adult primary feather replacement started in April and was mostly completed by October with some doves still replacing adult primaries well into December. Primary feather molt of hatch-year doves started in April, depending upon when hatching occurred and was mostly completed by December. The relationship between declines in body mass and progress of primary molt in adults is believed to be due primarily to energetic demands of breeding activities, although primary molt may also have a role.

Low Fecundity of Red-Headed Woodpeckers (Melanerpes erythrocephalus) at the Northern Edge of the Range
Barbara Frei, James W. Fyles, Jacob L. Berl, John W. Edwards and Joseph J. Nocera

The Red-headed Woodpecker (Melanerpes erythrocephalus) is a threatened bird species undergoing continued population declines across most of its range. Despite the conservation concern, there are few published studies on the species’ fecundity. We examined the nesting phenology, clutch size, and fledging success of Red-headed Woodpecker nests in southern Ontario and northern New York, where population declines are especially pronounced. We calculated the fecundity of the Red-headed Woodpecker populations from fledgling numbers and nest survival estimates. We found that nest phenology and clutch sizes were similar to those reported in other studies for the species. Red-headed Woodpecker nests monitored using video inspection had an unusually low fledging success (39%), and an average fecundity of 0.43 female fledglings per female per year. The fledgling success and fecundity for the monitored Red-headed Woodpecker population was lower than that reported by other published studies on Melanerpes spp., as well as for other genera of woodpeckers. The fecundity was also below the minimum threshold needed to offset mortality for the species, when compared to a majority of minimum fecundity values estimated from the literature. We suggest low fecundity for Red-headed Woodpeckers at the northern edge of their range may be the chronic condition of sink populations, or a more recent phenomenon for small populations approaching local extinction.

The Nest-Concealment Hypothesis: New Insights from a Comparative Analysis
Kathi L. Borgmann and Courtney J. Conway

Selection of a breeding site is critical for many animals, especially for birds whose offspring are stationary during development. Thus, birds are often assumed to prefer concealed nest sites. However, 74% of studies (n = 106) that have evaluated this relationship for open-cup nesting songbirds in North America failed to support the nest-concealment hypothesis. We conducted a comparative analysis to identify factors that contribute to variation in the ability of researchers to find support for the nest-concealment hypothesis. We found that some of the discrepancy among studies can be explained by interspecific differences in morphological and extrinsic factors that affect nest predation. Moreover, methods that investigators used to estimate concealment affected whether studies found support for the nest-concealment hypothesis; 33% of the studies that used quantitative estimates found support for the nest-concealment hypothesis whereas only 10% of the studies that used qualitative estimates found support. The timing of measurements also explained some of the ambiguity; studies that provided little information regarding the timing of their foliage density estimates were less likely to support the nest-concealment hypothesis. Species with more conspicuous male plumage were less likely to support the nest-concealment hypothesis when we analyzed studies that used visual estimates. Whereas species with more conspicuous female plumage were more likely to support the nest-concealment hypothesis when we analyzed studies that used quantitative measures. Our results demonstrate that support for the nest-concealment hypothesis has been equivocal, but that some of the ambiguity can be explained by morphological traits and methods used to measure concealment.

Phylogeography of the Military Macaw (Ara militaris) and the Great Green Macaw (A. Ambiguus) Based on MTDNA Sequence Data
Jessica R. Eberhard, Eduardo E. IñIgo-Elias, Ernesto Enkerlin-Hoeflich and E. Paùl Cun

The Military Macaw (Ara militaris) and the Great Green Macaw (A. ambiguus) are species whose close relationship is reflected in their morphological similarity as well as their geographic ranges. Military Macaws have a disjunct distribution, found in Mexico as well as several areas in South America, while Great Green Macaws have two or more disjunct populations from Honduras to eastern Ecuador. We used mitochondrial sequence data to examine the phylogenetic relationships between these two species, and also among representative samples across their ranges. Our data clearly support recognition of the two species as being distinct evolutionary lineages, and while we found significant phylogeographic structure within A. militaris (between samples collected in eastern and western Mexico), we did not find any evidence of lineage divergence between A. ambiguus from Costa Rica and Ecuador.

Breeding Season Home Range and Habitat Use of Mexican Spotted Owls (Strix occidentalis lucida) Below the South Rim of Grand Canyon National Park
Tim S. Bowden, Jake M. Ferguson, Rolla V. Ward, Mark L. Taper and David W. Willey

We studied breeding season home range characteristics and habitat of paired male Mexican Spotted Owls (Strix occidentalis lucida) below the south rim of Grand Canyon National Park from 2004–2005. Adult male owls (n = 5) were captured and radio-tracked using tail-mounted VHF transmitters. We used minimum convex polygons and 90% fixed kernels to estimate breeding season home range size (mean = 355 ha and 372 ha, respectively). We also generated adaptive kernel home range estimates to describe areas of concentrated use within home ranges. Home ranges were located in the upper reaches of relatively narrow rocky canyons, and Spotted Owls showed limited use of adjacent forested plateaus. We conducted an analysis of habitat use and selection at two scales and found that owls selected (i.e., used disproportionate to availability) limestone cliffs present in their home ranges. Home ranges were approximately centered on nest and associated roost sites located on limestone cliffs within canyons. Our results contrasted with observations in Utah where spotted owls nested primarily on sandstone cliffs. In Grand Canyon, both sandstone and limestone cliffs were present in the home range, but limestone appeared to be the preferred substrate. At the landscape level, owls placed home ranges in areas dominated by piñon-juniper (Pinus edulis – Juniperus monosperma) woodland. We delineated 40 ha use-areas around nest sites and found that these conservation zones closely approximated adaptive kernel 30% isopleths, thus supporting core area designation of the Mexican Spotted Owl Recovery Plan.

Density, Abundance, and Habitat Associations of the Inland Swamp Sparrow (Melospiza georgiana georgiana) in Iowa
Tyler M. Harms and Stephen J. Dinsmore

Wetlands continue to decline throughout North America and the Prairie Pothole Region, thus emphasizing the importance of understanding population trends and habitat associations of wetland species to ensure effective conservation and habitat management of those species. We estimated density and abundance and evaluated habitat associations of the Inland Swamp Sparrow (Melospiza georgiana georgiana) in Iowa. We conducted standardized distance sampling surveys for Swamp Sparrows and measured habitat characteristics at 307 wetlands in two regions of Iowa in 2009 and 2010. We used Program Distance to model detection probability and estimate region-specific breeding densities of Swamp Sparrows at Iowa wetlands. We then extrapolated density estimates to the total area of wetlands in each region to obtain estimates of breeding abundance. We correlated Swamp Sparrow counts to nine habitat variables using Poisson regression in Program R. Swamp Sparrow counts were positively correlated with percent cover of cattail (Typha spp.) and water depth (cm) and negatively correlated with percent cover of woody vegetation, vegetation size (m), and wetland size (ha). We estimated breeding densities of Swamp Sparrows to be 1.488 birds/ha (95% CI = 1.308 − 1.692) in region 1 (Des Moines Lobe landform) and 0.041 birds/ha (95% CI = 0.006 − 0.275) in region 2 (remainder of the state). Our results, in comparison to those of other studies, indicate that Swamp Sparrows associate with a variety of wetland characteristics depending upon what is available. Swamp Sparrows are relatively uncommon breeders in Iowa, and our work confirms that most occur in the Des Moines Lobe landform in north-central and northwestern Iowa. Biologists and land managers should incorporate our findings on this species’ habitat associations into management activities to ensure that Swamp Sparrow populations persist into the future.

Roost Habitat of Mexican Spotted Owls (Strix occidentalis lucida) in the Canyonlands of Utah
David W. Willey and Charles Van Riper III

In large portions of their geographic range, Mexican Spotted Owls (Strix occidentalis lucida) roost in forest-dominated environments, but in some areas the owls use relatively arid rocky canyonlands. We measured habitat characteristics at 133 male roosts (n = 20 males) during 1992–95, and 56 female roosts (n = 13 females) during 1994–95 in canyon environments of southern Utah. Across all years, 44% of Mexican Spotted Owls’ roosts were located in small stands of mixed-conifer forest, 30% in desert scrub vegetation, 16% in pinyon-juniper woodlands, and 10% of roosts were in riparian habitat. Roost sites were located in canyons composed of cliff-forming geologic formations. The width of canyons measured at roosts averaged 68.6 m (8.2 SE), and ranged from 1–500 m. The mean height of cliffs at roost sites was 77 m (10.9 SE) and ranged from 6–411 m. Roosts were located at caves and ledges (46% of all roosts) or in various tree species (54%). Roost height above ground averaged 9.5 m overall (1.1 SE), with mean tree roost height of 3.7 m (0.2 SE), and cliff roost height equal to 17.2 m (2.2 SE). For both males and females, coniferous trees species were used most frequently (64%), primarily Douglas-fir (Pseudotsuga menziesii), white fir (Abies concolor), and Utah juniper; and 36% of roosts occurred in deciduous trees, including big-tooth maple (Acer grandidentatum), boxelder (A. negundo), and Utah serviceberry (Amelanchier uthaensis). Canopy cover of tress at roosts ranged from 44–71%, mean tree height of trees present was 9.5 m and mean diameter of trees was 25.4 cm. Upland habitats that were not used for roosting were warmer, not as steep, possessed fewer caves and ledges, and trees present were of smaller stature than trees present in roost habitat.

Vocal Responses of Adult Eastern Bluebirds (Sialia sialis) to Potential Nest Predators and the Behavioral Responses of Nestlings 
Erin E. Grabarczyk and Gary Ritchison

The alarm calls of some birds are functionally referential and may provide nestlings with information about the threat posed by potential predators. However, few investigators have examined the responses of nestlings in cavity nests to the anti-predator vocalizations of adults. Our objectives were to examine (1) the vocal responses of cavity-nesting adult Eastern Bluebirds (Sialia sialis) to different predators, and (2) the behavioral responses of nestlings to those vocalizations. From April–July 2013, pairs of Eastern Bluebirds were exposed to mounts or models of four potential nest predators, including a raccoon (Procyon lotor), eastern chipmunk (Tamias striatus), American Kestrel (Falco sparverius), and black rat snake (Pantherophis obsoletus), plus a control (Mourning Dove, Zenaida macroura). During 3-min trials, mounts or models were placed adjacent to nest boxes with 12–19-day-old nestlings. Adult vocalizations were recorded and the behavior of nestlings simultaneously recorded with a camcorder. Adult bluebirds (n = 27 pairs) uttered longer-duration alarm and chatter calls at significantly higher rates in response to the raccoon, and nestlings responded more often (23 of 39 trials [59%], excluding nine control trials) when adult bluebirds uttered chatter and alarm calls at higher rates. Nestling responses included crouching (21 trials), climbing the walls of the nest box (one trial), and fledging (one trial). Crouching may reduce the risk of predation by large predators unable to enter a nest cavity, but able to reach into it. In contrast, premature fledging when a predator is nearby would likely increase the risk of mortality. Adult Eastern Bluebirds do not produce predator-specific vocalizations, but call characteristics and call rates appear to provide nestlings with information about the presence of potential predators.

Determination of Sex Using Morphometrics in the Northern Waterthrush (Parkesia noveboracensis) and Swainson’s Thrush (Catharus ustulatus) 
Kristen M. Covino

Many species of passerines are sexually monochromatic and thus sex cannot be determined based on plumage characteristics. Northern Waterthrushes (Parkesia noveboracensis) and Swainson’s Thrushes (Catharus ustulatus) are two such species. The objective of this study is to examine morphological differences between males and females of both species and determine whether this information may be used to determine sex. With genetically sexed birds, I indicate wing chord values can be used to determine sex with 95% confidence. This information would allow field researchers to determine sex of 58% of Northern Waterthrushes and 33% of Swainson’s Thrushes with 95% confidence of correct assignment. If age is taken into account, the proportion of individuals for which sex can be determined increases to 62% and 38%, respectively. This information may be used by avian ecologists in future studies of behavioral ecology, conservation biology, or evolutionary biology these species.

Comparisons Between Autonomous Acoustic Recordings and Avian Point Counts in Open Woodland Savanna
Renata D. Alquezar and Ricardo B. Machado

In order to evaluate the possibility of using this method in the Brazilian Cerrado or other open vegetation areas, we compared the performance of point counts and autonomous recording units (ARU) for avian monitoring. From September to November 2012, we surveyed birds in 13 points established in six localities in central Brazil by using simultaneously ARU and point counts for species presence only comparisons. We identified a total of 84 species and found no significant differences between the number of species obtained by each method. Differing from what we initially expected, few records in point counts were obtained only by visual detection. The number of species registered by ARU corresponded to 90.4% of all observed species. About 92% of the recorded species sang at least once during point counts. Of all species recorded, 17% were not recorded by point counts and 10% were missed by ARU. Jaccard’s index of similarity was 68%. Our results indicate that the ARU can be an effective method to sample bird assemblages in open vegetation areas, such as the Brazilian Cerrado, being as efficient as the point count proceeding is. The disadvantages of ARU have already been highlighted in the literature (huge data volume to process, high costs to acquire the equipment, malfunctioning and loss, among others), but we must add that missing visual contacts with species must be considered depending of the study’s scope and the type of bird species in question. Nevertheless, the use of ARU can be a cost-effective method for long-term monitoring programs and also helps to quickly obtain the necessary data to characterize species assemblages associated with highly threatened ecosystems, such as the Brazilian Cerrado.


Vocal and Molecular Phylogenetic Evidence for Recognition of a Thistletail Species (Furnariidae: Asthenes) Endemic to the Elfin Forests of Ayacucho, Peru
Peter A. Hosner, Luis Cueto-Aparicio, Gregorio Ferro-Meza, Darwin Miranda and Mark B. Robbins

The Andean Cordillera is notable for numerous centers of avian endemism along its great length. Yet, the narrow band of humid montane forest in eastern Ayacucho in south-central Peru is not known to harbor endemic bird species despite its position between two putative biogeographic barriers: the arid Apurímac and Mantaro river valleys. We report the first documented records of the endemic Ayacucho subspecies of Vilcabamba Thistletail, Asthenes vilcabambae ayacuchensis since its initial discovery and collection in 1968–1970. Unexpectedly, the previously unknown song of A. v. ayacuchensis is more similar to Eye-ringed Thistletail Asthenes palpebralis of Junín Department than to nominate A. v. vilcabambae of western Cuzco Department. Phylogenetic analyses of DNA sequences reinforce vocal evidence, and support that A. v. ayacuchensis is more closely related to A. palpebralis and the Rusty-fronted Canastero A. ottonis than to A. v. vilcabambae. Based on distinct vocalizations, phylogeny, and diagnosable plumage characters, ayacuchensis merits species recognition. The “Ayacucho Thistletail” is documented certainly from elfin forest localities in three small valleys in the Apurímac drainage in eastern Ayacucho. There are no protected areas or reserves that overlap A. ayacuchensis’ limited distribution and we suspect that it, like many elfin-forest specialists in the Andes, is threatened by anthropogenic habitat modification.

Sharing the Load: Role Equity in the Incubation of a Monomorphic Shorebird, the Masked Lapwing (Vanellus miles)
Adam P. A. Cardilini, Michael A. Weston, Peter Dann and Craig D. H. Sherman

Sex roles during incubation vary dramatically in socially monogamous shorebirds. The “incubator conspicuousness” hypothesis posits that, for biparentally incubating and sexually dimorphic birds, the more conspicuous sex should incubate when visually foraging predators are inactive, and in many ecosystems this is at night. Therefore, sexually monomorphic species should share incubation equitably throughout the day and night. We examined incubation patterns in Masked Lapwings Vanellus miles and found that the contribution of the sexes to incubation was equitable. Another measure of incubation behavior, bout duration, was similar between the sexes; male bout durations were slightly shorter than for females. This finding is consistent with the predictions of the incubator conspicuousness hypothesis, although other processes may also explain equitable care.

Parasitism of the Black-crowned Waxbill (Estrilda nonnula) by the Pin-tailed Whydah (Vidua macroura): Implications for Host-specific Adaptation by a Generalist Brood-parasite
Allison L. Lansverk, Jean-Bernard Dogmo, Justin G. Schuetz and Christopher N. Balakrishnan

In the African brood parasitic finches (Viduidae), complex nestling mouth markings have evolved to mimic those of their estrildid finch hosts, reducing the chances of detection or discrimination by host parents. Most Vidua species are highly host-specific whereas the Pin-tailed Whydah Vidua macroura is less so, potentially limiting its evolutionary potential for mimicry. Here we document parasitism of a novel host, the Black-crowned Waxbill (Estrilda nonnula), by the Pin-tailed Whydah. Of the 28 active Black-crowned Waxbill nests that we located in central Cameroon, six were parasitized by Pin-tailed Whydahs. Unlike the remarkable similarity of Pin-tailed Whydah nestling mouth markings to those of a previously described host in southern and central Africa, the Common Waxbill (Estrilda astrild), Pin-tailed Whydahs have mouth patterns that differ conspicuously from their Black-crowned Waxbill hosts in central Africa. Across its range, the Pin-tailed Whydah appears to be a generalist brood parasite of hosts in the genus Estrilda, but precise nestling mimicry is limited to particular species. The behavioral, ecological, and evolutionary mechanisms that allow different degrees of similarity to persist between Vidua and their hosts require further study. 

The Influence of Environmental Cues and Anthropogenic Activity on Roost Departure Times in the Northwestern Crow (Corvus caurinus) 
Mehdi Khadraoui and David P. L. Toews

While communal roosting is fairly common in animals, the costs, benefits, and proximal factors influencing this behavior are poorly understood. Moreover, many species with communal roosting that have been studied to date have a strong association with humans; however, there have been few formal tests of how human activity might influence roosting behaviors. We studied roosting activity in the Northwestern Crow (Corvus caurinus) within a highly urbanized setting. Specifically, we were interested in whether variation in anthropogenic noise influenced departure times of crows from their roosts. We tested this by comparing roosting activity between days that differed in the extent and timing of automobile noise. We also tested whether other environmental factors (i.e., sunrise time and precipitation) might also influence roost departure times. We found that morning departure was later on rainy mornings and was largely correlated with sunrise time, consistent with previous studies of other species. We also found departure times accelerated over the season, to the point where the first groups of crows were waking well before any perceptible light (i.e., prior to astronomical dawn). We found no evidence that variation in anthropogenic activity, particularly from automobile noise, had any effect on crows’ roost departure time. These results suggest that, although many corvids are closely associated with urbanized landscapes, these crows appear to maintain natural circadian rhythms at least for roosting departures, likely by means of detecting cues from natural light and other environmental factors.

Shiny Cowbird (Molothrus bonariensis) Parasitism Records for Three Globally Threatened Species from the South American Pampas 
Adrián B. Azpiroz

The Shiny Cowbird (Molothrus bonariensis) is a generalist brood parasite known to have parasitized more than 200 species, many of which are able to rear cowbird young. Here I provide new records of Shiny Cowbird parasitism on three globally threatened birds from the Pampas of South America: Black-and-white Monjita (Xolmis dominicanus; vulnerable), Pampas Meadowlark (Sturnella defilippii; vulnerable), and Yellow Cardinal (Gubernatrix cristata; endangered). Cowbirds parasitized 24 out of 32 monjita nests, four out of 17 cardinal nests and three out of 169 meadowlark nests. These are the largest nest samples reported for the monjita and for the meadowlark, documented detailed parasitism records were lacking until now. In the case of the cardinal, data reported here complement information recently obtained in northeastern Argentina. Although habitat loss and illegal trapping may represent more important threats than brood parasitism, more studies are needed in order to establish the impact of brood parasitism on the fragmented and declining populations of these threatened Pampas passerines.

First Description of the Nest of Whitehead's Spiderhunter (Arachnothera juliae, Aves: Nectariniidae)
Matthew L. Brady and Ryan C. Burner

We describe the nest of the endemic Whitehead's Spiderhunter (Arachnothera juliae) from Mt. Mulu National Park, Sarawak, Malaysian Borneo, and compare it to those of the most closely related species, the Yellow-eared Spiderhunter (A. chrysogenys) and the Naked-faced Spiderhunter (A. clarae). The nest was found on 3 August 2014 in lower montane forest at 1,400 m elevation along the summit trail on the western slopes of Mt. Mulu. It consisted of a bowl lined with fine bark material inside a naturally occurring hanging ball of moss 19 m above the ground in a large tree. It contained no eggs, but the pair was observed carrying in nest materials on several occasions.

First Record of an Aberrantly Colored Pin-tailed Sandgrouse (Pterocles alchata)
Ana Benítez-López and Iván García-Egea

The distribution and frequency of color aberrations in wild birds is relatively poorly known. Here we report, for the first time, the observation of an aberrantly colored Pin-tailed Sandgrouse (Pterocles alchata), a threatened steppe bird with cryptic plumage and behavior. The bird displayed a continuous white patch on its back that was not bilaterally symmetrical (i.e., not far from the neural crest), thus discarding leucism as an explanation. Plausible explanations are progressive graying and, most likely, an injury that damaged feather follicles affecting the pigment cells in that area. This very rare observation (0.02%, n = 5,720) contributes to future studies exploring the frequency of color aberrations in wild birds depending on their ecological and behavioral characteristics.

Egg Carrying by a Male Wood Duck (Aix sponsa) 
Larry J. Handyman

Egg carrying by female ducks has been reported for several species around the world. The first record of a male Wood Duck (Aix sponsa) carrying an egg herein is reported. This is only the second documented account of a male of any waterfowl species carrying an egg or eggshell.

Behavior, Reproduction, and Development in Little Tinamou (Crypturellus soui)

Two captive pairs of Little Tinamou (Crypturellus soui) were studied to describe reproduction, development, and associated behaviors of this extremely cryptic forest dwelling species. Pairs were strongly territorial. Precopulatory courtship behaviors were performed by the female. Male tinamous showed strong nest attendance during incubation and sat without leaving the nest from day 14 until the eggs hatched. Nest abandonment and false abandonment occurred due to environmental stress, flushing by humans, eggs being laid in a poor location, and if clutch size was too large. Renewed reproductive efforts began shortly following loss of a previous clutch, with calling activity and inter-clutch duration being a minimum of 3 and 5 days, respectively.

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