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Wednesday, 15 July 2015

Avian Conservation and Ecology, Volume 10, Issue 1. July 2015: Abstracts

AVIAN CONSERVATION AND ECOLOGY





Table of Contents: Volume 10, Issue 1

LINK

Guest Editorial 

Migratory bird protection, a crack in the armor: the case of the Double-crested Cormorant

Linda R. Wires
Abstract
The year 2016 marks the centennial of the convention between the United States and Great Britain (for Canada) for the Protection of Migratory Birds. Signed on 16 August 1916, this historic convention originated out of the need to protect birds from a long tradition of overuse and destruction. In Canada the Migratory Birds Convention Act, 1994 (MBCA) was passed in 1917, while in the United States the Migratory Bird Treaty Act (MBTA) was passed in 1918. These acts resulted in the implementation of the convention in each country and provided protection under the law to migratory birds, their nests, and eggs. This protection represents a milestone in bird conservation efforts. To celebrate the centennial, increase awareness of migratory birds, and prepare for the next century of migratory bird conservation, the U.S. Fish and Wildlife Service (USFWS) is planning multiple activities that will occur throughout 2015-2016 (http://www.fws.gov/birds/MBTreaty100/). Environment Canada has not yet announced plans for centennial celebrations, but presumably will also undertake activities to celebrate this event.


Research Paper 

Density dependence and phenological mismatch: consequences for growth and survival of sub-arctic nesting Canada Geese

Rodney W. Brook, James O. Leafloor, Kenneth F. Abraham, and David C. Douglas
Abstract
The extent to which species are plastic in the timing of their reproductive events relative to phenology suggests how climate change might affect their demography. An ecological mismatch between the timing of hatch for avian species and the peak availability in quality and quantity of forage for rapidly growing offspring might ultimately affect recruitment to the breeding population unless individuals can adjust the timing of breeding to adapt to changing phenology. We evaluated effects of goose density, hatch timing relative to forage plant phenology, and weather indices on annual growth of pre-fledging Canada geese (Branta canadensis) from 1993-2010 at Akimiski Island, Nunavut. We found effects of both density and hatch timing relative to forage plant phenology; the earlier that eggs hatched relative to forage plant phenology, the larger the mean gosling size near fledging. Goslings were smallest in years when hatch was latest relative to forage plant phenology, and when local abundance of breeding adults was highest. We found no evidence for a trend in relative hatch timing, but it was apparent that in early springs, Canada geese tended to hatch later relative to vegetation phenology, suggesting that geese were not always able to adjust the timing of nesting as rapidly as vegetation phenology was advanced. Analyses using forage biomass information revealed a positive relationship between gosling size and per capita biomass availability, suggesting a causal mechanism for the density effect. The effects of weather parameters explained additional variation in mean annual gosling size, although total June and July rainfall had a small additive effect on gosling size. Modelling of annual first-year survival probability using mean annual gosling size as an annual covariate revealed a positive relationship, suggesting that reduced gosling growth negatively impacts recruitment.


Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation

Keith A. Hobson, Steve L. Van Wilgenburg, Erica H. Dunn, David J. T. Hussell, Philip D. Taylor, and Douglas M. Collister
Abstract
The Canadian Migration Monitoring Network (CMMN) consists of standardized observation and migration count stations located largely along Canada’s southern border. A major purpose of CMMN is to detect population trends of migratory passerines that breed primarily in the boreal forest and are otherwise poorly monitored by the North American Breeding Bird Survey (BBS). A primary limitation of this approach to monitoring is that it is currently not clear which geographic regions of the boreal forest are represented by the trends generated for each bird species at each station or group of stations. Such information on “catchment areas” for CMMN will greatly enhance their value in contributing to understanding causes of population trends, as well as facilitating joint trend analysis for stations with similar catchments. It is now well established that naturally occurring concentrations of deuterium in feathers grown in North America can provide information on their approximate geographic origins, especially latitude. We used stable hydrogen isotope analyses of feathers (δ²Hf) from 15 species intercepted at 22 CMMN stations to assign approximate origins to populations moving through stations or groups of stations. We further constrained the potential catchment areas using prior information on potential longitudinal origins based upon bird migration trajectories predicted from band recovery data and known breeding distributions. We detected several cases of differences in catchment area of species passing through sites, and between seasons within species. We discuss the importance of our findings, and future directions for using this approach to assist conservation of migratory birds at continental scales.


Bald eagle (Haliaeetus leucocephalus) population increases in Placentia Bay, Newfoundland: evidence for habitat saturation?

Karla R. Letto, Yolanda F Wiersma, Joe Brazil, and Bruce Rodrigues
Abstract
Across North America, Bald Eagle (Haliaeetus leucocephalus) populations appear to be recovering following bans of DDT. A limited number of studies from across North America have recorded a surplus of nonbreeding adult Bald Eagles in dense populations when optimal habitat and food become limited. Placentia Bay, Newfoundland is one of these. The area has one of the highest densities of Bald Eagles in eastern North America, and has recently experienced an increase in the proportion of nonbreeding adults within the population. We tested whether the observed Bald Eagle population trends in Placentia Bay, Newfoundland during the breeding seasons 1990-2009 are due to habitat saturation. We found no significant differences in habitat or food resource characteristics between occupied territories and pseudo-absence data or between nest sites with high vs. low nest activity/occupancy rates. Therefore there is no evidence for habitat saturation for Bald Eagles in Placentia Bay and alternative hypotheses for the high proportion of nonbreeding adults should be considered. The Newfoundland population provides an interesting case for examination because it did not historically appear to be affected by pollution. An understanding of Bald Eagle population dynamics in a relatively pristine area with a high density can be informative for restoration and conservation of Bald Eagle populations elsewhere.


Trends and tactics of mouse predation on Tristan Albatross Diomedea dabbenena chicks at Gough Island, South Atlantic Ocean

Delia Davies, Ben J. Dilley, Alexander L. Bond, Richard J. Cuthbert, and Peter G. Ryan
Abstract
The critically endangered Tristan Albatross Diomedea dabbenena breeds almost exclusively on Gough Island, in the central South Atlantic, where breeding success is much lower than other great albatrosses (Diomedea spp.) worldwide. Most breeding failures occur during the chick-rearing stage, when other great albatrosses suffer few failures. This unusual pattern of breeding failure is assumed to be largely due to predation by introduced house mice Mus musculus, but there have been few direct observations of mouse attacks. We closely monitored the fates of 20 chicks in the Gonydale study colony (123 chicks in 2014) using motion-activated cameras to determine the causes of chick mortality. Only 5 of 20 chicks survived to fledge, and of the 15 failures, 14 (93%) were due to mouse predation. One mouse-wounded chick was killed by a Southern Giant Petrel Macronectes giganteus; the rest died outright from their wounds within 3.9 ± 1.2 days of the first attack. Despite this high impact, most chicks were attacked by only 1-2 mice at once (maximum 9). The remaining 103 chicks in the study colony were checked less frequently, but the timing of failures was broadly similar to the 20 closely monitored nests, and the presence of mouse wounds on other chicks strongly suggests that mice were responsible for most chick deaths. Breeding success in the Gonydale study colony averages 28% from 2001 to 2014; far lower than the normal range of breeding success of Diomedea species occurring on islands free from introduced predators. Island-wide breeding success fell below 10% for the first time in 2014, making it even more urgent to eradicate mice from Gough Island.


Variables associated with nest survival of Golden-winged Warblers (Vermivora chrysoptera) among vegetation communities commonly used for nesting

Kyle R. Aldinger, Theron M. Terhune II, Petra B. Wood, David A. Buehler, Marja H. Bakermans, John L. Confer, David J. Flaspohler, Jeffrey L. Larkin, John P. Loegering, Katie L. Percy, Amber M. Roth, and Curtis G. Smalling
Abstract
Among shrubland- and young forest-nesting bird species in North America, Golden-winged Warblers (Vermivora chrysoptera) are one of the most rapidly declining partly because of limited nesting habitat. Creation and management of high quality vegetation communities used for nesting are needed to reduce declines. Thus, we examined whether common characteristics could be managed across much of the Golden-winged Warbler’s breeding range to increase daily survival rate (DSR) of nests. We monitored 388 nests on 62 sites throughout Minnesota, Wisconsin, New York, North Carolina, Pennsylvania, Tennessee, and West Virginia. We evaluated competing DSR models in spatial-temporal (dominant vegetation type, population segment, state, and year), intraseasonal (nest stage and time-within-season), and vegetation model suites. The best-supported DSR models among the three model suites suggested potential associations between daily survival rate of nests and state, time-within-season, percent grass and Rubus cover within 1 m of the nest, and distance to later successional forest edge. Overall, grass cover (negative association with DSR above 50%) and Rubus cover (DSR lowest at about 30%) within 1 m of the nest and distance to later successional forest edge (negative association with DSR) may represent common management targets across our states for increasing Golden-winged Warbler DSR, particularly in the Appalachian Mountains population segment. Context-specific adjustments to management strategies, such as in wetlands or areas of overlap with Blue-winged Warblers (Vermivora cyanoptera), may be necessary to increase DSR for Golden-winged Warblers.


Changes in heron and egret populations on the Laurentian Great Lakes and connecting channels, 1977-2009

Scott A Rush, Cynthia Pekarik, D.V. Weseloh, Francesca Cuthbert, David Moore, and Linda Wires
Abstract
Canadian and U.S. federal wildlife agencies completed four decadal surveys, spanning the years 1977 to 2009, to census colonial waterbirds breeding on the Great Lakes and adjoining bodies of water. In this paper, we reports abundance, distribution, and general population trends of three species: Black-crowned Night-Heron (Nycticorax nycticorax), Great Egret (Ardea alba), and Great Blue Heron (Ardea herodias). Estimates of nest numbers ranged from approximately 4000-6100 for the Black-crowned Night-Heron, 250-1900 for the Great Egret, and 3800-6400 for the Great Blue Heron. Average annual rates of change in nest numbers between the first (1977) and fourth (2008) census were −1% for the Black-crowned Night-Heron, +23% for the Great Egret, and −0.27% for the Great Blue Heron. Across the 30-year census, Black-crowned Night-Heron estimates decreased in U.S. (−57%) but increased (+18%) in Canadian waters, Great Egret nests increased 1381% in Canadian waters with a smaller, but still substantial increase in the number of nests at U.S. colonies (+613%), and Great Blue Heron numbers increased 148% in Canadian waters and 713% in U.S. waters. Although a single factor cannot be clearly linked to changes observed in each species’ distribution, hydrological variation, habitat succession, nest competition with Double-crested Cormorants (Phalacrocorax auritus), and land use changes likely all contributed. Management activities should support both breeding and foraging conditions including restoration of early successional habitats and anticipate continued northward expansions in the distributions of these waterbirds.


Suburban immigrants to wildlands disrupt honest signaling in ultra-violet plumage

Angela Tringali and Reed Bowman
Abstract
Urbanization changes habitat in a multitude of ways, including altering food availability. Access to human-provided food can change the relationship between body condition and honest advertisements of fitness, which may result in changes to behavior, demography, and metapopulation dynamics. We compared plumage color, its relationship with body condition and feather growth, and use as signal of dominance between a suburban and a wildland population of Florida Scrub-Jay (Aphelocoma coerulescens). Although plumage color was not related to body condition at either site, suburban birds had plumage with a greater proportion of total reflectance in the ultra-violet (UV) and peak reflectance at shorter wavelengths. Despite the use of plumage reflectance as a signal of dominance among individuals in the wildlands, we found no evidence of status signaling at the suburban site. However, birds emigrating from the suburban site to the wildland site tended to be more successful at acquiring breeder status but less successful at reproducing than were immigrants from an adjacent wildland site, suggesting that signaled and realized quality differ. These differences in signaling content among populations could have demographic effects at metapopulation scales and may represent an evolutionary trap whereby suburban immigrants are preferred as mates even though their reproductive success relative to effort is lower.


Stand and within-stand factors influencing Golden-winged Warbler use of regenerating stands in the central Appalachian Mountains

Marja H Bakermans, Brian W Smith, Benjamin C Jones, and Jeffery L Larkin
Abstract
The Golden-winged Warbler (Vermivora chrysoptera) is currently being considered for protected status under the U.S. Endangered Species Act. The creation of breeding habitat in the Appalachian Mountains is considered a conservation priority for this songbird, which is dependent on extensively forested landscapes with adequate availability of young forest. We modeled abundance of Golden-winged Warbler males in regenerating harvested forest stands that were 0-17 years postharvest at both mid-Appalachian and northeast Pennsylvania regional scales using stand and within-stand characteristics of 222 regenerating stands, 2010-2011. Variables that were most influential at the mid-Appalachian scale were different than those in the northeast region. Across the mid-Appalachian ecoregion, the proportion of young forest cover, i.e., shrub/scrub cover, within 1 km of regenerating stands best explained abundance of Golden-winged Warblers. Golden-winged Warbler response was best explained by a concave quadratic relationship in which abundance was highest with 5-15% land in young forest cover. We also found evidence that the amount of herbaceous cover, i.e., the amount of grasses and forbs, within a regenerating stand positively influenced abundance of Golden-winged Warblers. In northeastern Pennsylvania, where young forest cover is found in high proportions, the distance to the nearest regenerating stand best explained variation in abundance of Golden-winged Warblers. Abundance of Golden-winged Warblers was <1 male per survey when another regenerating stand was >1500 m away. When modeling within-stand features in the northeast region, many of the models were closely ranked, indicating that multiple variables likely explained Golden-winged Warbler response to within-stand conditions. Based on our findings, we have proposed several management guidelines for land managers interested in creating breeding habitat for Golden-winged Warblers using commercial timber operations. For example, we recommend when managing for Golden-winged Warblers in the central Appalachian Mountains that managers should strive for 15% young forest in a heavily forested landscape (>70% forest cover) and cluster stands within 1-2 km of other young forest habitats.


Assessing the use of forest islands by parrot species in a neotropical savanna

Igor Berkunsky, María V Simoy, Rosana E. Cepeda, Claudia Marinelli, Federico P. Kacoliris, Gonzalo Daniele, Agustina Cortelezzi, José A. Díaz-Luque, Juan Mateo Friedman, and Rosana M. Aramburú
Abstract
Understanding the effect of habitat fragmentation is a fundamental yet complicated aim of many ecological studies. Beni savanna is a naturally fragmented forest habitat, where forest islands exhibit variation in resources and threats. To understand how the availability of resources and threats affect the use of forest islands by parrots, we applied occupancy modeling to quantify use and detection probabilities for 12 parrot species on 60 forest islands. The presence of urucuri (Attalea phalerata) and macaw (Acrocomia aculeata) palms, the number of tree cavities on the islands, and the presence of selective logging,and fire were included as covariates associated with availability of resources and threats. The model-selection analysis indicated that both resources and threats variables explained the use of forest islands by parrots. For most species, the best models confirmed predictions. The number of cavities was positively associated with use of forest islands by 11 species. The area of the island and the presence of macaw palm showed a positive association with the probability of use by seven and five species, respectively, while selective logging and fire showed a negative association with five and six species, respectively. The Blue-throated Macaw (Ara glaucogularis), the critically endangered parrot species endemic to our study area, was the only species that showed a negative association with both threats. Monitoring continues to be essential to evaluate conservation and management actions of parrot populations. Understanding of how species are using this natural fragmented habitat will help determine which fragments should be preserved and which conservation actions are needed.


Piping Plover response to coastal storms occurring during the nonbreeding season

Nadine R Bourque, Marc-André Villard, Marc J. Mazerolle, Diane Amirault-Langlais, Eric Tremblay, and Serge Jolicoeur
Abstract
The increase in coastal storm frequency and intensity expected under most climate change scenarios is likely to substantially modify beach configuration and associated habitats. This study aimed to analyze the impact of coastal storms on a nesting population of the endangered Piping Plover (Charadrius melodus melodus) in southeastern New Brunswick, Canada. Previous studies have shown that numbers of nesting Piping Plovers may increase following storms that create new nesting habitat at individual beaches. However, to our knowledge, no test of this pattern has been conducted over a regional scale. We hypothesized that Piping Plover abundance would increase after large coastal storms occurring during the nonbreeding season. However, we expected a delay in the colonization of newly created habitat owing to low-density populations, combined with high site fidelity of adults and high variability in survival rate of subadults. We tested this hypothesis using a 27-year (1986-2012) data set of Piping Plover abundance and productivity (nesting pairs and fledged young) collected at five sites in eastern New Brunswick. We identified 11 major storms that could potentially have modified Piping Plover habitat over the study period. The number of fledged young increased three years after a major storm, but the relationship was much weaker for the number of nesting pairs. These findings are consistent with the hypothesized increase in suitable habitat after coastal storms. Including storm occurrence with other factors influencing habitat quality will enhance Piping Plover conservation strategies.

Essay 

Threshold detection: matching statistical methodology to ecological questions and conservation planning objectives

Judith D. Toms and Marc-André Villard
Abstract
Two types of ecological thresholds are now being widely used to develop conservation targets: breakpoint-based thresholds represent tipping points where system properties change dramatically, whereas classification thresholds identify groups of data points with contrasting properties. Both breakpoint-based and classification thresholds are useful tools in evidence-based conservation. However, it is critical that the type of threshold to be estimated corresponds with the question of interest and that appropriate statistical procedures are used to determine its location. On the basis of their statistical properties, we recommend using piecewise regression methods to identify breakpoint-based thresholds and discriminant analysis or classification and regression trees to identify classification thresholds.


Thursday, 9 July 2015

The Wilson Journal of Ornithology June 2015 Volume 127 Issue 2: Abstracts

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




June 2015 : Volume 127 Issue 2 

LINK

MARGARET MORSE NICE MEDAL ESSAY

From passion to science 
Edward H. Burtt, Jr.

Abstract
We began our ornithological careers out of passion, for watching birds, for identifying them, for sharing our excitement and knowledge with our friends. At some point our desire to know and understand birds led us into science. We joined Christmas Bird Counts and wondered why the species and numbers varied annually. We wondered what characterized good sparrow habitat. We found that special patch and saw more sparrows than any other participant. Then, we discovered that people wrote about and published their observations of birds. We read some of those papers, at first the short ones, those that focused on natural history, on what we could observe. Then we tried to imitate the authors, by watching birds, asking questions and collecting data. We were unaware that the child hobbyist had become the adolescent scientist. I joined the Wilson Ornithological Society and began to prepare my observations for publication. One day I screwed up my courage and submitted a short paper on Tree Swallows (Tachycineta bicolor). It was rejected. But by then I was an undergraduate. I had just received a small research grant. The die was cast. Graduate school followed. I wrote more short papers. Some were published. I synthesized some of these into longer papers with substantive conclusions that were cited by real ornithologists. Imperceptibly, I became a scientist. I began to formulate hypotheses, deduce predictions, collect data, and create new explanations about the evolution of avian color, an aspect of birds that had fascinated me almost since I became aware of birds and painted a papier-mâché duck brilliant white with scarlet feet and bill, and large, blue eyes.
This observation-based entry into a scientific career is very different from a course-based entry in which the future scientist learns a paradigm, is excited and decides to devote her or his career to that scientific discipline. The importance of one’s introduction to science is explored with respect to different disciplines and the way different scientists think about science. Finally, the importance of the observation-based entry into science is explored with respect to the Wilson Ornithological Society, The Wilson Journal of Ornithology, ornithology, and the field sciences generally.


MAJOR ARTICLES

Social behavior and organization of a native chukar (Alectoris Chukar Cypriotes) population
Philip U. Alkon

Abstract
A 2-year field study of a free-ranging population of Chukar (Alectoris chukar cypriotes), occupying Mediterranean habitat in Israel’s Lower Galilee, yielded unique insights on (1) the array and context of specific behaviors of wild birds, (2) the complex dynamics of their social processes, and (3) the interaction of behavioral and population dynamics. Systematic observations of individually marked wild birds clarified the function of several prominent displays (e.g., waltzing as a male courtship display) and vocalizations (e.g., the chuk-ar call as an individual announcement that varied widely in form and function). Behavioral relationships among birds were complex, and Chukars demonstrated individual differences in demeanor and status. Strong social bonds among adult males and brood mates were significant cohesive forces, and adult males exhibited strong site affinities from year to year. Chukars spent autumn and winter in coveys of 10–20 birds having heterogeneous gender and age compositions, and occupied separate but overlapping ranges of 4–8 ha. Adult males displayed and threatened conspecifics more than did females during most seasons, but broody hens were aggressive towards other birds. Overt social interactions were most intense while coveys disbanded in early spring, during breeding, and in post-breeding covey formation. Paired males closely accompanied females within restricted nesting territories, but most left their mates during incubation. Large late-summer aggregations of Chukars occurred at open water and in fallow fields where intense social interactions preceded the establishment of permanent covey ranges. The study population underwent an inverse, density-dependent fluctuation that was mediated by behavioral processes. A low overwintering population in Year 1 exhibited little social strife and no population change preceded an orderly and productive breeding season. The subsequent dense population in Year 2 exhibited heightened social strife in winter, a large decline in numbers with the onset of pairing, considerable disturbance of nesting pairs, and lowered reproductive success.


Habitat preference and survival for western meadowlark (Sturnella Neglecta) fledglings in a contiguous prairie system
Matthew D. Giovanni, Larkin A. Powell, and Walter H. Schacht

Abstract
Grassland bird populations in North America continue to decline according to count and vital-rate data, highlighting the importance of remaining grasslands. Conservation efforts may be enhanced by understanding fledgling habitat preference and survival in relation to age and ambient temperature. We radio-tracked 46 Western Meadowlark (Sturnella neglecta) fledglings in 2006 and 2007 to evaluate variation in habitat preference and survival in subirrigated meadows of the Nebraska Sandhills, one of North America’s largest contiguous grassland systems. Our research indicates that habitat preference varied with fledgling age and ambient temperature: at higher ambient temperatures, fledglings tended to select sites with deeper litter and shorter vegetation, while younger, mostly flightless fledglings tended to select sites with shallower litter and taller vegetation. We confirmed 23 fatalities, including 8 (35%) from predators, 2 (9%) from haying operations, and 13 (56%) from unknown causes. Seven of the eight (88%) depredated fledglings were tracked to live snakes, including six bullsnakes (Pituophis catenifer sayi). The probability of daily survival (0.981) was high compared to estimates for passerine fledglings in other grassland systems. Survival increased with age and ambient temperature but decreased with litter depth. Prior research indicates prescribed burning can decrease litter depth and associated abundance of snakes in grasslands, but neither are likely conservation strategies in subirrigated meadows of the Nebraska Sandhills, because hay production provides winter feed for cattle. We recommend maintaining mid to late summer hay harvest so first cohorts of nestlings can fledge, attain flight, and evade machinery.


Habitat use by grassland birds in natural areas and soybean fields in southern Brazil and Uruguay
Thaiane Weinert Da Silva, Graziela Dotta, Daniel Tourem Gressler, and Carla Suertegaray Fontana

Abstract
Livestock production and the replacement of semi-natural grasslands by crops result in land use changes and as consequence some habitat is no longer suitable for all species of grassland birds. Although some generalist species could benefit from such changes, habitat alteration is detrimental to the populations of most sensitive species. In this study, we investigated the patterns of habitat use by breeding grassland birds through the assessment of their presence/absence and abundance in a landscape composed of semi-natural grasslands and croplands in southern Brazil and Uruguay. We sampled grassland birds in 160 100-m radius point counts: 80 in a semi-natural grassland dominated landscape and 80 in soybean fields with grassland patches. We classified vegetation cover on a 100-m radius buffer following three classes of land use: semi-natural grasslands, wet grasslands, and soybean fields. We used GLMM to analyze presence/absence and abundance of grassland birds found in the region. Nine species showed a positive response to the semi-natural grasslands and/or wet grassland vegetation cover categories. Five species recorded are of conservation concern. Most of the grassland bird species preferred sites with high semi-natural grassland cover and only one species used primarily soybean fields. Grassland birds required around 80% of semi-natural grassland cover to maintain larger abundances. Research across landscapes and a better understanding of the responses of grassland birds to habitat modification are still needed to establish conservation practices of natural grasslands and their avifauna in southern Brazil and Uruguay.


Reproductive success of Field Sparrows (Spizella Pusilla) in response to invasive Morrow’s Honeysuckle: does Morrow’s Honeysuckle promote population sinks?
Holly M. Mcchesney and James T. Anderson

Abstract
The bush honeysuckle genus (Lonicera) comprises a suite of invasive shrubs that are naturalized in early successional landscapes throughout many parts of central and eastern United States. Although several studies have connected the use of bush honeysuckle as a nesting substrate to decreased nesting success, few have examined its potential effects on the growth or decline of songbird populations. From 2007–2009, we examined the nesting success of Field Sparrows (Spizella pusilla) in southwestern Pennsylvania old-fields to assess reproductive success based on nesting substrate and the density of Morrow’s honeysuckle (Lonicera morrowii) surrounding the nest site. We used the information-theoretic approach to model nesting success as a response to nest substrate, cover of Morrow’s honeysuckle, midpoint of nesting attempt, and clutch size. Our model indicated that Morrow’s honeysuckle, as a substrate and when found in dense patches surrounding the nests of Field Sparrows, had a negative impact on nesting success. We developed a population model to determine if the measured reproductive success (17% ± 5) could maintain a stable population. Results of the population model yielded 1.21 female offspring/adult female. This was not sufficient to maintain a stable population and resulted in a population sink. A sensitivity analysis indicated that adult survivorship was the most influential parameter in the population model, indicating that although breeding success was important, it was not the primary driver of population stability.


Breeding origins of Northern Shovelers (Anas Clypeata) wintering on the Great Salt Lake, Utah
Anthony J. Roberts and Michael R. Conover

Abstract
The breeding origin and migratory connectivity of wintering birds are important to address how population changes on wintering areas are impacted by changes elsewhere in the birds’ annual cycle. In addition, identifying important point sources of nutrients used throughout the annual cycle can assist managers in identifying sources of toxins or pathogens. We used stable hydrogen isotope ratios to identify breeding locations of Northern Shovelers (Anas clypeata; henceforth shoveler) wintering at the Great Salt Lake (GSL), Utah. Stable-isotope likelihood-based assignment placed the largest number of shovelers collected during winter on the GSL as breeding in the western US and southern Canada, similar to a small sample size of banding records. Shovelers wintering on the GSL generally did not breed locally or at the northern extent of their breeding range, rather wintering shovelers came from across their nesting range.


Food habits and resource partitioning in a guild of Neotropical swifts
Charles T. Collins

Abstract
The Coastal Cordillera of Venezuela has a rich avifauna including swifts. The aerial arthropod prey of three species found there, Gray-rumped Swift (Chaetura cinereiventris), Vaux’s Swift (Chaetura vauxi), and White-tipped Swift (Aeronautes montivagus), included spiders plus nine orders and 110 families of insects. Diptera and Hymenoptera were the most numerous prey taxa (>60%) taken by all three swifts. Prey size ranged from 0.5–17.9 mm body length, and averaged 2.69 mm for Gray-rumped Swifts, 2.91 mm for Vaux’s Swifts, and 5.52 mm for White-tipped Swifts. Niche breadth was similar in Gray-rumped and Vaux’s Swifts (2.4 and 3.13), and niche overlap was also high (0.98). Niche breadth was higher in White-tipped Swifts (8.49) and niche overlap was <60 with both Gray-rumped and Vaux’s swifts. Observed elevational differences in foraging habitat and altitudinal foraging zones are proposed as resource partitioning mechanisms for this guild of sympatric aerial insectivores.


Nesting biology of the Red-crested Cardinal (Paroaria Coronata) in south temperate forests of central Argentina
Luciano N. Segura, Bettina Mahler, Igor Berkunsky, and Juan C. Reboreda

Abstract
Studies on breeding biology in Neotropical birds are crucial for understanding different aspects of their life histories and also for their conservation. We describe the nesting biology of the Red-crested Cardinal (Paroaria coronata) in central Argentina, a common suboscine that inhabits south temperate forests. We monitored 367 nests from October to February 2005–2008. Nest initiation followed a unimodal distribution with a peak in November. Within the forest, no nests were built on exotic tree species. Mean clutch size was 3.05 ± 0.05 eggs and decreased with time within the breeding season; egg size did not vary across the breeding season. Nesting cycles lasted, on average, 25.8 ± 0.1 days (nest construction: 6.1 ± 0.4 days; incubation period: 11.9 ± 0.1 days; nestling period: 13.8 ± 0.1 days). At least one young fledged in 26% of nests, 62% were depredated, and 11% were abandoned. Egg survival rate was 0.95 ± 0.02, hatching success rate was 0.84 ± 0.02, and nestling survival rate was 0.81 ± 0.03. Partial nestling losses were detected in 45% of the nests, of which 52% were because of brood reduction. Each breeding pair had on average 4.4 ± 0.2 nesting attempts over the breeding season. Our results support the prediction that small clutch sizes are associated with extensive breeding seasons and several nesting attempts within a season. Except for the short incubation period, all other breeding features reported in this study differ from those of most north temperate birds and are consistent with the life history traits of Neotropical birds.


Female Red-Breasted Flycatchers (Ficedula Parva) mated with older males produce male-biased broods
Joanna Mitrus, Cezary Mitrus, and Robert Rutkowski

Abstract
Recent avian studies suggest that offspring sex ratios can vary with environmental or parental characteristics. One example is that females may adjust brood sex ratio of fledglings in response to the sexual attractiveness of their mate and are expected to produce more sons when mated with older or more ornamented males. We determined offspring sex ratios at fledging (158 nestlings from 33 broods) in a population of migratory bird species, Red-breasted Flycatchers (Ficedula parva) that were breeding on the western edge of their geographic range, in the strictly protected part of the Białowieża Forest (north-eastern Poland). The ratio of individual broods ranged from all male to all female, but the average offspring sex ratio at the population level did not deviate significantly from the expected 50:50 sex ratio. Moreover, we found no evidence that sex ratio varied significantly with year, with the incidence of extra-pair paternity, with partial brood losses, or with brood size. However, females mated to older males (older males are also more ornamented) were significantly more likely to produce male-biased broods. Our data suggest that female Red-breasted Flycatchers manipulate sex ratio in response to their mate’s age.

SHORT COMMUNICATIONS

Population Variation in Mobbing Ospreys (Pandion haliaetus) by American Crows (Corvus brachyrhynchos)
John M. Marzluff, Jack H. DeLap, and Kristina Haycock

Abstract
American Crows (Corvus brachyrhynchos) aggressively mob a variety of natural predators and learn to recognize unique threats. Because mobbing is a costly and risky behavior, we hypothesized that crows would selectively ignore benign heterospecifics that look similar to predators, perhaps even learning to do so. Through a series of natural observations and experiments we found that American Crows were more likely to mob Red-tailed Hawks (Buteo jamaciensis) and Bald Eagles (Haliaeetus leucocephalus) than Ospreys (Pandeon haliaetus). Mobbing intensity was higher to a taxidermic mount of a Red-tailed Hawk than to a mount of an Osprey, indicating that mobbing increases with the risk posed by the predator. However, we also found that Ospreys were more likely to be mobbed in locations where they rarely occur, suggesting that crow populations that frequently encounter Ospreys habituate to this benign raptor. The extensive distribution of Ospreys and resulting co-occurrence with many mobbing species suggests our findings may have wide application.


Song Repertoire of Carolina Chickadees (Poecile carolinensis) in Southeastern Pennsylvania
Evan P. Kelemen, Karen E. Zusi, and Robert L. Curry

Abstract
Songs of the Carolina Chickadee (Poecile carolinensis) vary throughout the species' geographic range. The aim of this study was to investigate quantitatively the repertoires of individual Carolina Chickadees in southeastern Pennsylvania. Previous qualitative work in the same region identified two song types produced with different degrees of consistency. We recorded locally breeding males during 2 years to assess song types at the population level and to characterize repertoires of individuals. Most males included the same two common song types (A and B) in their repertoires; cluster analysis also identified a third song type (B′) resulting from deletion of an initial note. The amount of variation within the song types differed, with the more stereotyped A song produced more frequently (averaging 79% of songs by individual males) than the more variable B (21%) and B′ (<1%) song types. Differences in the degree of song fidelity and repertoire composition may reflect variation in function between song types, but this hypothesis remains to be tested.


Probable Interspecific Song Learning in a Florida Grasshopper Sparrow (Ammodramus savannarum floridanus)
Erin L. Hewett Ragheb, Cody Mezebish, and Bernard Lohr

Abstract
We report a case of probable interspecific song learning in a male Florida Grasshopper Sparrow (Ammodramus savannarum floridanus), a critically endangered grassland bird. This individual was observed to sing a distinctive song where the second phrase of the song accurately resembled a typical song of a Bachman’s Sparrow (Peucaea aestivalis), and the introductory phrase was intermediate between the songs of Bachman’s and Grasshopper sparrows. The exact mechanism of development of this unusual song is unknown, but scarcity of species-typical tutors as a result of rapid population decline may have resulted in interspecific song development. The atypical individual exhibited a strong response to recordings of conspecific song and successfully defended a territory in high-quality habitat but nevertheless appeared to be unpaired. Improper song learning may inhibit mate attraction and qualify as an Allee effect contributing to the extirpation of small populations.


Observation of Sandhill Cranes’ (Grus canadensis) Flight Behavior in Heavy Fog
Eileen M. Kirsch, Michael J. Wellik, Manuel Suarez, Robert H. Diehl, Jim Lutes, Wendy Woyczik, Jon Krapfl, and Richard Sojda

Abstract
The behaviors of birds flying in low visibility conditions remain poorly understood. We had the opportunity to monitor Sandhill Cranes (Grus canadensis) flying in heavy fog with very low visibility during a comprehensive landscape use study of refuging cranes in the Horicon Marsh in southeastern Wisconsin. As part of the study, we recorded flight patterns of cranes with a portable marine radar at various locations and times of day, and visually counted cranes as they departed the roost in the morning. We compared flight patterns during a fog event with those recorded during clear conditions. In good visibility, cranes usually departed the night roost shortly after sunrise and flew in relatively straight paths toward foraging areas. In fog, cranes departed the roost later in the day, did not venture far from the roost, engaged in significantly more circling flight, and returned to the roost site rather than proceeding to foraging areas. We also noted that compared to mornings with good visibility, cranes flying in fog called more frequently than usual. The only time in this 2-year study that observers heard young of the year calling was during the fog event. The observed behavior of cranes circling and lingering in an area while flying in poor visibility conditions suggests that such situations may increase chances of colliding with natural or anthropogenic obstacles in the vicinity.


Incidence of Cartwheeling Flights in Raptors of South-Central Chile 
Victor Raimilla, Tomás Rivas-Fuenzalida, Alejandro Kusch, José Díaz, Jorge Toledo, Álvaro García, and Jaime E. Jiménez

Abstract
Cartwheeling flight is a behavior that involves aerial locking of talons by raptors followed by a descending mutual rotation around a central axis, like a cartwheel. We provide information on 32 recorded cartwheeling events from south-central Chile involving 12 raptor species; 26 were by dyads of the same species, of which 61.5% were associated with aggressive events. Only one case was considered a courtship behavior and two as play. Milvago chimango was the most frequently involved in intraspecific cartwheeling (38.5%), whereas Geranoaetus polyosoma had the highest frequency of allospecific encounters (67%). This is the first account on the occurrence of cartwheeling flights in South American raptors, and we suspect that this behavior is more prevalent than has been reported previously.


On a Tightrope: Use of Open Sky Urban Telephone Wires by Azure-crowned Hummingbirds (Amazilia cyanocephala) for Nesting
Juan F. Escobar-Ibáñez and Ian MacGregor-Fors

Abstract
Birds are considered excellent bioindicators in urban areas. Some of the ecological processes behind bird ecological patterns in urban areas have been related to birds’ capacities to shift their behaviors. In this brief communication, we report a nest of Azure-crowned Hummingbird (Amazilia cyanocephala) built on a metallic structure that connects telephone wires, surrounded by other electricity and cable wires. After visiting the nest for 19 days, we did not have any evidence of predation, and because of the size and behavior of the chicks during the last two visits, we assume that the nest was successful. Previous studies have suggested that urban systems lay open to colonization by species that can reach them, use their resources, and survive their hazards. We recorded a nest of Azure-crowned Hummingbirds that was built on an open sky telephone. Our observation was a notable example of the degree of venture that some individual birds can exhibit in response to urbanization, suggesting a certain degree of ecological plasticity. Thus, future detailed studies are needed to untangle the advantages and disadvantages of nesting on open sky urban wires, to assess if it is profitable to nest on such structures.


A Radio-telemetry Study of Home Range and Habitat Use of the Endangered Yellow-billed Cotinga (Carpodectes antoniae) in Costa Rica
Karen M. Leavelle, Luke L. Powell, George V. N. Powell, and Adrian Forsyth

Abstract
The Yellow-billed Cotinga (Carpodectes antoniae) is one of Central America’s rarest and most endangered species. A regional endemic to Panama and Costa Rica, between 250 and 999 individuals appear to now survive mainly within Pacific coastal mangroves and adjacent lowland forest within the Térraba-Sierpe National Wetlands and the Osa Peninsula of Costa Rica, an Alliance for Zero Extinction Site. We used radio telemetry to determine seasonal movements and habitat use and requirements of three Yellow-billed Cotingas at the Rincón River and mangrove estuary on the Osa Peninsula. During the breeding months from approximately December to June, radio-tagged cotingas used mangroves primarily for courtship display, insect feeding, protection from inclement weather, and night roosts. They used lowland forest for feeding on fruit and insects and for infrequent courtship display. Birds fed on fruits from 23 lowland forest tree species throughout the year. Although the female ranged farther than the males during the non-breeding season, no bird showed evidence of migratory behavior. They did not wander from the Rincón mangroves during the non-breeding months from July to November, and they roosted in the same mangrove plot each night. The juxtaposition of mangroves and lowland forest rich in fruit trees may be critical to the survival of the species.


Brood Habitat Selection of Chinese Grouse (Tetrastes sewerzowi) at Lianhuashan, Gansu, China
Zhao Jin-Ming, Fang Yun, Lou Ying-Qiang, and Sun Yue-Hua

Abstract
We studied habitat selection in Chinese Grouse (Tetrastes sewerzowi) hens with dependent broods at Lianhuashan, Gansu, China in 2010–2012. We divided the dependent brood period into four stages (weeks 1–2, 3–4, 5–8, and beyond 8 weeks post hatching) and compared used with available habitat, and found that hens with broods chose sites with significantly less canopy cover (0.28 ± 0.01 vs 0.49 ± 0.02), greater willow cover (0.31 ± 0.02 vs 0.14 ± 0.01), and greater herb height (21.36 ± 1.05 vs 14.43 ± 0.59). Broods used a variety of vegetation types at different stages of chick development. They used more early successional deciduous forests and shrubs during stages 2 and 3 (weeks 3–8, Kruskal-Wallis Test: χ2  =  13.918, df  =  3, P  =  0.003). Sites with more invertebrates were used in Stage 1 compared to available sites (54.5 ± 7.2 vs 36.4 ± 4.4), but not in Stage 2. Compared to sites used during stage 4, chicks in stage 2–3 used sites of earlier successional stages, greater herbaceous vegetation height, and closer proximity to forest edges, whereas sites utilized during stage 1–3 showed visits in lower willow cover.


Nest, Eggs, and Nestlings of the Atlantic Forest Endemic Star-throated Antwren (Rhopias gularis)
Daniel F. Perrella, Carlos H. Biagolini-Júnior, Lais Ribeiro-Silva, Paulo V. Q. Zima, Galetti, Pedro M. Jr, and Mercival R. Francisco

Abstract
Here, we describe nests, eggs, and nestlings of the monotypic Star-throated Antwren, Rhopias gularis (formerly Myrmotherula gularis), found at Carlos Botelho State Park, in Atlantic Forest in the state of São Paulo, Brazil. Nests were pensile cups of dark rootlets and black fungal hyphae, found near forest streams, 34–70 cm high, over ground or water. A leaf appeared to form a roof over two nests. Clutch size was always two eggs, white with reddish and dark brown spots and blotches. Hatchlings were naked with pinkish skin. Nest architecture, eggs, and nestlings were similar to other Myrmotherula and Epinecrophylla, suggesting that nesting characteristics may not be informative to reconstruct recent DNA-based phylogenies that resolved the monotypic genus of this Brazilian Atlantic Forest endemic species.


Cooperative Breeding at a Nest of Slaty-backed Nightingale-Thrushes (Catharus fuscater)
Harold F. Greeney, Andrzej Dyrcz, Romuald Mikusek, and Jeff Port

Abstract
Our observations on the reproductive habits of the Slaty-backed Nightingale-Thrush (Catharus fuscater) were made at a single nest between 2–12 November 2009 at an elevation of 2,050 m, in the vicinity of the Yanyacu Biological Station and Center of Creative Studies (00o 36′ S, 77o 53′ W), 5 km west of Cosanga (Napo Province, northeastern Ecuador). During the first 3 days following hatching, the only adult which provisioned nestlings was a color-banded female. Beginning with day 4, however, we observed five other individuals bringing food to the nest, including three color-banded males, one unmarked male, and one unmarked individual presumed to be female. The last two birds and one of the banded males were sexed using morphological differences, the remaining banded individuals were sexed molecularly. Most (72%) of provisioning visits to 4–9 day old nestlings were made by the color-banded female which also incubated the eggs. Our observations suggest the existence of a potentially complex cooperative breeding system in Slaty-backed Nightingale-Thrush.


First Nesting Records in Southwestern Louisiana for American Oystercatchers (Haematopus palliatus) and Reddish Egrets (Egretta rufescens), with Implications for Dredge Spoil Island Restoration 
Will Selman and Bruce E. Davis

Abstract
American Oystercatchers (Haematopus palliatus) and Reddish Egrets (Egretta rufescens) are coastal species of conservation concern known to nest along most of the Gulf of Mexico’s coastline. However, there is a distributional gap in breeding records for both species between southeastern Louisiana and eastern Texas. Herein, we report on the first breeding records for each species from southwestern Louisiana at Rabbit Island (Cameron Parish, Louisiana), a small, marsh island in Calcasieu Lake. Suitable nesting habitat for American Oystercatchers (1 nesting pair) was present on the island via shell rake and for Reddish Egrets (6–12 pairs, min) in clumps of Juncus roemerianus; this is the first report of Reddish Egrets utilizing this plant species for nesting. A large scale island restoration project is slated for Rabbit Island and therefore, we provide restoration recommendations for conservation planners to improve habitat suitability for multiple bird guilds at this and other potential dredge spoil island projects.


Observations on Fecal Sac Consumption and Near-ground Foraging Behavior in the Olive-sided Flycatcher (Contopus cooperi) 
Julie C. Hagelin, Shannon Busby, April Harding-Scurr, and Aleya R. Brinkman

Abstract
We present details on parental care and foraging behavior of Olive-sided Flycatchers (Contopus cooperi) in central Alaska. We document the first evidence of fecal sac consumption in this species. Both sexes exhibited this behavior while tending chicks less than one week old. Adults with older nestlings (1.5–2 weeks) removed fecal sacs only. The general pattern of reduced fecal sac consumption with chick age is consistent with other passerines and may supplement parental nutrition. Near-ground foraging behavior in C. cooperi is rarely reported, as birds typically sally for aerial insects near or above the canopy. Two breeding females fed multiple times from 1–3 m perches, hovering over, flying directly above or disappearing into low vegetation (<0.5 m) for up to 15 secs. Low stumps and saplings in a wood cutting area and in undisturbed forest provided access to patches of flowering vegetation that appeared to concentrate pollinator prey during cool or inclement weather. Given the conservation concerns for this species, its low productivity, dietary specialization, and hypothesized early-season reliance on insect prey, flowering vegetation presents a testable visual stimulus that may govern settlement behavior of breeding adults.


Common Ravens (Corvus corax) Prey on Rhinoceros Auklet (Cerorhinca monocerata) Eggs, Chicks, and Possibly Adults
James L. Hayward, Gordon J. Atkins, Ashley A. Reichert, and Shandelle M. Henson

Abstract
We observed Common Ravens (Corvus corax) on Protection Island, Washington that used their bills to dig into the nesting burrows of Rhinoceros Auklets (Cerorhinca monocerata) and prey on auklet eggs. In addition, we observed a raven fly away from a burrow with an auklet chick, a raven attack and unsuccessfully attempt to capture an adult auklet, and a raven fly with and feed on a freshly killed adult auklet. Although Common Ravens have been reported to prey on Rhinoceros Auklets’ eggs, to our knowledge this is the first report of a raven preying on a chick and the first report of an attempt by a raven to capture an adult auklet.


A Modified Leg-noose Trap for Crab-plovers (Dromas ardeola) at Burrow Nests
Giorgio Chiozzi, Giuseppe De Marchi, and Mauro Fasola

Abstract
Being trapped is a potentially stressful experience, especially for breeding birds, so capture should be limited to target individuals and be as least harmful as possible. We describe here a modified leg-noose trap that we developed for the burrow nesting Crab-plover (Dromas ardeola). Similar to other commonly used devices, it consists of monofilament fishing line nooses secured to a heavy metal base. We modified this traditional device by positioning the nooses perpendicular to the bird movement and by adding shock-absorbing elastic bands. This last addition proved effective in protecting the captured bird's legs from superficial wounds and abrasions; it did not affect capture success relative to a version of the same trap lacking these improvements. Such improvements could be applied to similar noose traps employed for other birds in order to reduce discomfort and avoid injury.