Many bird species utilize the presence of conspecifics to gauge habitat quality and guide territory selection. When individuals preferentially settle in areas where conspecifics are perceived, this process is referred to as conspecific attraction. Substantial attention has been given to how natural and simulated social signals can recruit species to protected habitats, particularly as a conservation tool for migratory songbirds. While there is strong experimental evidence that broadcasting territorial song is a feasible strategy to recruit male songbirds, most experiments carried out to date have been in high-density populations and at a local scale. Because many species of conservation concern persist at low densities across heterogeneous landscapes, and because conspecific attraction as a management strategy has the most potential to benefit these species, it is important to test its efficacy in low-density populations. We tested the response to conspecific attraction in a low-density population of the declining Golden-winged Warbler (Vermivora chrysoptera) across private lands in a 500 km² study area. We observed a modest (0.276 ± 0.135 males) increase in estimated male abundance at points within 250 m of experimentally broadcast social cues (“treatment points”), with estimated abundance generally decreasing at untreated control points across the study area in that year. Male recruitment at treatment points was greater than at control points, but when control points were split into high- and low-density points, male recruitment was the same at treatment and low-density control points. The number of males recruited to conspecific playback was lower in our study than what has been observed in previous studies of conspecific attraction in high-density systems. Our results suggest that expectations for and applications of conspecific attraction need to be tailored to the density and distribution of the target population.

Shifts in the distribution of benthivorous predators provide an indication of underlying environmental changes in benthic-mediated ecosystems. Spectacled Eiders (Somateria fischeri) are benthivorous sea ducks that spend the nonbreeding portion of their annual cycle in the Bering, Chukchi, Beaufort, and East Siberian seas. Sea ducks generally molt in biologically productive areas with abundant prey. If the distribution of eiders at molting areas matches prey abundance, spatial shifts may indicate changes in environmental conditions in the Arctic. We used a randomization procedure to test for shifts in the distribution of satellite telemetry locations received from Spectacled Eiders in the 1990s and 2008–2011 within 4 late-summer, ice-free molting areas: Indigirka–Kolyma, northern Russia; Ledyard Bay, eastern Chukchi Sea; Norton Sound, northeastern Bering Sea; and Mechigmenskiy Gulf, northwestern Bering Sea. We also tested for interannual and interdecadal changes in dive depth required to reach prey, which might affect the energetic costs of foraging during the molting period. Transmitter-marked birds used each molting area in each year, although the distribution of Spectacled Eiders shifted within each area. Interdecadal shifts in Ledyard Bay and Norton Sound decreased dive depth in recent years, although minor differences in depth were biologically negligible in relation to the energetic expense of feather growth. Shifts in Mechigmenskiy Gulf and Indigirka–Kolyma did not occur consistently within or among decades, which suggests greater interannual variability among environmental factors that influence distribution in these areas. Shifts in each molting area suggest dynamic ecosystem processes, with implications for Spectacled Eiders if changes result in novel competition or predation, or in shifting prey regimes.

Recruitment of juveniles is an important vital rate that influences population growth and is fundamental to understanding trends in population size. Estimates of recruitment are often focused on the period just after hatching (prefledgling stage), which is typically the lowest survival period and often the most variable. Few studies examine true recruitment—survival from hatching to entering the breeding population—although this information is more relevant to understanding population trends. We studied the recruitment of Gunnison Sage-Grouse (Centrocercus minimus), a federally threatened species in the U.S., to examine the relative importance of chick and juvenile survival to recruitment patterns. We evaluated recruitment from 2005 to 2010 by combining separate estimates of chick survival (hatching to 30 days of age) and juvenile survival (31 days of age to the start of the first breeding season). To explain variation in these survival rates, we examined the effects of population, individual (i.e. age), and temporal (within-year and among-year differences) factors associated with recruitment of Gunnison Sage-Grouse. The factors that most explained juvenile survival rates were temporal (among-year trends and within-year seasonal effects). Chick survival rates varied by population, and daily chick survival increased with chick age. We found a slight negative trend in chick survival and a strong negative trend in juvenile survival from 2005 to 2010. The overall recruitment rate declined from 0.32 (± 0.09 SE) in 2005 to 0.04 (± 0.03 SE) in 2010. This decline coincided with a decline observed in population index data, which was not reflected in other demographic data. If survival had not been monitored past 30 days of age, estimates of recruitment would have remained relatively stable. This work highlights the importance of monitoring juvenile survival, as it may influence population dynamics.

Implanted biologging devices, such as satellite-linked platform transmitter terminals (PTTs), have been used widely to delineate populations and identify movement patterns of sea ducks. Although in some cases these ecological studies could reveal transmitter effects on behavior and mortality, experiments conducted under controlled conditions can provide valuable information to understand the influence of implanted tags on health and physiology. We report the clinical, mass, biochemical, and histological responses of captive Common Eiders (Somateria mollissima) implanted with PTTs with percutaneous antennas. We trained 6 individuals to dive 4.9 m for their food, allowed them to acclimate to this dive depth, and implanted them with PTTs. We collected data before surgery to establish baselines, and for 3.5 mo after surgery. The first feeding dive took place 22 hr after surgery, with 5 of 6 birds diving to the bottom within 35 hr of surgery. Plumage waterproofing around surgical sites was reduced ≤21 days after surgery. Mass; albumin; albumin:globulin ratio; aspartate aminotransferase; β₁-, β₂-, and γ-globulins; creatine kinase; fecal glucocorticoid metabolites; heterophil:lymphocyte ratio; and packed cell volume changed from baseline on one or more of the postsurgery sampling dates, and some changes were still evident 3.5 mo after surgery. Our findings show that Common Eiders physiologically responded for up to 3.5 mo after surgical implantation of a PTT, with the greatest response occurring within the first few weeks of implantation. These responses support the need for postsurgery censor periods for satellite telemetry data and should be considered when designing studies and analyzing information from PTTs in sea ducks.

Avian populations can respond dramatically to extreme weather such as droughts and heat waves, yet patterns of response to weather at broad scales remain largely unknown. Our goal was to evaluate annual variation in abundance of 14 grassland bird species breeding in the northern mixed-grass prairie in relation to annual variation in precipitation and temperature. We modeled avian abundance during the breeding season using North American Breeding Bird Survey (BBS) data for the U.S. Badlands and Prairies Bird Conservation Region (BCR 17) from 1980 to 2012. We used hierarchical Bayesian methods to fit models and estimate the candidate weather parameters standardized precipitation index (SPI) and standardized temperature index (STI) for the same year and the previous year. Upland Sandpiper (Bartramia longicauda) responded positively to within-year STI (β = 0.101), and Baird's Sparrow (Ammodramus bairdii) responded negatively to within-year STI (β = −0.161) and positively to within-year SPI (β = 0.195). The parameter estimates were superficially similar (STI β = −0.075, SPI β = 0.11) for Grasshopper Sparrow (Ammodramus savannarum), but the best-selected model included an interaction between SPI and STI. The best model for both Eastern Kingbird (Tyrannus tyrannus) and Vesper Sparrow (Pooecetes gramineus) included the additive effects of within-year SPI (β = −0.032 and β = −0.054, respectively) and the previous-year's SPI (β = −0.057 and −0.02, respectively), although for Vesper Sparrow the lag effect was insignificant. With projected warmer, drier weather during summer in the Badlands and Prairies BCR, Baird's and Grasshopper sparrows may be especially threatened by future climate change.

The Canada Warbler (Cardellina canadensis) is a species of high conservation importance because of its low overall density and long-term widespread population declines on the breeding grounds. Results of previous research on the species suggest that its breeding habitat preferences vary across its range. However, the underlying processes associated with habitat use are unknown. Using a 20 yr dataset, we developed occupancy models for Canada Warblers to determine the influence of habitat characteristics (e.g., understory vegetation, canopy cover), landscape context (e.g., edge, forest patch size), and species co-occurrence on occupancy, colonization, and local extinction parameters. Our results show that multiple habitats are used by Canada Warblers on the breeding grounds; common variables associated with large-scale, long-term occupancy dynamics are forest age, landscape composition at the 100 m and 500 m scales, and mean patch size. Overall, Canada Warblers were nearly twice as persistent in mature forest stands (>80 yr) and large, mixed forest stands. Further, models indicated that species co-occurrence was an important predictor of Canada Warbler occupancy in some cover types. The results of this study increase our understanding of population processes over large, dynamic landscapes and provide essential conservation information to improve habitat and landscape management for the Canada Warbler.

Small-scale disturbance and trash associated with campgrounds may provide opportunities for generalist species in areas important for conservation. We examined the influence of campgrounds on the space use and behavior of Steller's Jays (Cyanocitta stelleri) in Redwood National and State Parks, California, USA. In 2010 and 2011, we used radiotelemetry to monitor the movements of adult male Steller's Jays. We found that home range size of campground jays (16.4 ± 2.6 ha, n = 20) did not differ from non-campground jays (15.0 ± 2.0 ha, n = 10). However, we observed extensive home range overlap among campground jays, possibly contributing to the high density of Steller's Jays previously observed at these sites. Jays roosted alone, primarily in old-growth forest stands away from campgrounds and other human recreation areas. Campground jays regularly commuted between campgrounds and nocturnal roosts. Commuting distance was positively associated with home range size. Campground jays were more frequently observed <1 m from the ground, and were more frequently observed perching than non-campground jays, likely in response to the location and predictability of anthropogenic food. Our findings suggest that campgrounds directly influenced space use and behavior of Steller's Jays in Redwood National and State Parks. Steller's Jays are opportunistic nest predators, leading to concern that their elevated abundance near campgrounds could increase nest predation on federally threatened Marbled Murrelets (Brachyramphus marmoratus) or other birds nesting in redwood forests.

Both of the 2 passerines endemic to Nihoa Island, Hawai‘i, USA—the Nihoa Millerbird (Acrocephalus familiaris kingi) and Nihoa Finch (Telespiza ultima)—are listed as endangered by federal and state agencies. Their abundances have been estimated by irregularly implemented fixed-width strip-transect sampling from 1967 to 2012, from which area-based extrapolation of the raw counts produced highly variable abundance estimates for both species. To evaluate an alternative survey method and improve abundance estimates, we conducted variable-distance point-transect sampling between 2010 and 2014. We compared our results to those obtained from strip-transect samples. In addition, we applied state-space models to derive improved estimates of population size and trends from the legacy time series of strip-transect counts. Both species were fairly evenly distributed across Nihoa and occurred in all or nearly all available habitat. Population trends for Nihoa Millerbird were inconclusive because of high within-year variance. Trends for Nihoa Finch were positive, particularly since the early 1990s. Distance-based analysis of point-transect counts produced mean estimates of abundance similar to those from strip-transects but was generally more precise. However, both survey methods produced biologically unrealistic variability between years. State-space modeling of the long-term time series of abundances obtained from strip-transect counts effectively reduced uncertainty in both within- and between-year estimates of population size, and allowed short-term changes in abundance trajectories to be smoothed into a long-term trend.

Local populations that fluctuate synchronously are at a greater risk of extinction than those that do not. The closer the geographic proximity of populations, the more prone they are to synchronizing. Shorebird species select habitat broadly, and many breed across regions with diverse nesting habitat types. Under these conditions, nearby populations may experience conditions sufficiently different to prevent population synchrony, despite dispersal. In the U.S. Northern Great Plains, the Piping Plover (Charadrius melodus), federally listed as Threatened, is a migratory shorebird species that nests on the shorelines of rivers, reservoirs, and alkaline lakes. We assessed the degree to which local plover breeding population abundances were correlated (population synchrony), changed over time (population stability), and were influenced by environmental factors such as available habitat, precipitation, and within-season reservoir level rise. We found that the abundances of breeding populations nesting in riverine and reservoir habitats were the most synchronous, while populations nesting in alkaline lake habitats exhibited the greatest stability. Changes in local breeding population abundances were not explained by a single factor across habitat types. However, the abundances of local populations nesting in alkaline lake and river shoreline habitats were positively correlated with changes in nesting habitat availability. Our results suggest that dispersal among populations nesting in either river or reservoir and alkaline lake shoreline habitat may have an overall stabilizing effect on the persistence of the Great Plains Piping Plover metapopulation.

Mercury contamination has become a major concern in the Arctic, where elevated mercury deposition has led to large increases in mercury exposure for some Arctic wildlife over the past century. Chronic mercury exposure in birds is known to reduce reproductive success, which may ultimately result in population declines. Many species of Arctic-breeding shorebirds are declining, and exposure to environmental contaminants, such as mercury, may be an important factor. We quantified mercury exposure in 10 shorebird species breeding and staging in Alaska. We analyzed 229 blood and 73 feather samples collected in 2008–2009 for total mercury concentrations. Mercury in blood represents local exposure, whereas mercury in feathers reflects exposure during feather development. Concentrations of mercury ranged from 0.03 to 2.20 μg g⁻¹ in shorebird blood and from 0.16 to 3.66 μg g⁻¹ in shorebird feathers. Most shorebirds sampled during staging had relatively low blood mercury, but some breeding species had sufficiently high concentrations for potential adverse effects. Overall, blood mercury concentrations of breeding shorebirds differed by moisture content of their predominant foraging habitat, with the highest concentrations found in species using wet to aquatic habitats. We also found variation in mercury concentrations by age class and sex for some species, with females showing lower concentrations than males, but we found no relationship between the amount of mercury in feathers and in blood. The degree of mercury exposure seen in Arctic-breeding shorebirds may be of particular concern when combined with other ecological stressors, such as habitat loss, predation, disturbance, and climate change.

We can improve our ability to assess population viability and forecast population growth under different scenarios by understanding factors that limit population parameters in each stage of the annual cycle. Postfledging mortality rates may be as variable as nest survival across regions and fragmentation gradients, although factors that negatively impact nest survival may affect postfledging individuals in different ways. We examined nest and postfledging survival of Ovenbirds (Seiurus aurocapilla) and Acadian Flycatchers (Empidonax virescens) in mature forest fragments in central Missouri. We used an information-theoretic approach to determine support for effects of factors intrinsic to the individual or nest site, temporal factors, local vegetation characteristics, and distance to edge on survival in both stages. We also examined the effect of incorporating the resulting survival estimates on population growth. In both species, survival increased from nest to postfledging stages (Ovenbirds: 0.27 ± 0.06 to 0.50 ± 0.09; Acadian Flycatcher 0.30 ± 0.03 to 0.89 ± 0.11). Age was by far the best predictor of survival in postfledging birds, with the majority of mortalities occurring in the first week out of the nest. We did not find support for survival tradeoffs of habitat used by nesting or postfledging birds. Acadian Flycatcher nest and postfledging survival were both related to variables associated with mature forest. Ovenbird nest survival was most affected by habitat characteristics associated with core mature forest, although postfledging survival may have improved near non-forest edges. We replaced an arbitrary estimate of juvenile survival (half of adult survival) with an estimate incorporating empirical postfledging survival estimates. With these revised parameters, Acadian Flycatcher population growth was more affected (13–26% increase in lambda) than Ovenbird population growth (3–6% change). Our results illustrate that species occupying similar nesting habitat do not necessarily face the same risks during the postfledging period.

The range-wide monitoring program for the Lesser Prairie-Chicken (Tympanuchus pallidicinctus) plays an important role in landscape conservation initiatives for the recovery of this species. Methodologies to evaluate the species' responses to habitat conditions and conservation practices are necessary to evaluate the success of these initiatives. We adapted the design of the range-wide monitoring program and applied a multiscale occupancy model. The objectives were to (1) estimate occupancy at multiple spatial scales and (2) conduct an exploratory evaluation of responses to habitat condition and conservation practices at multiple spatial scales. The application of the model to a single year of data from the range-wide monitoring program yielded a coefficient of variation (CV) of large-scale occupancy of 17%. The CVs of small-scale occupancy for the 4 ecoregions ranged between 21% and 52% and were acceptable for detecting differences between strata. We used the method of multiple working hypotheses and predictions from fitted models to evaluate a priori how a subset of habitat configuration and anthropogenic practices potentially affect site occupancy at multiple spatial scales. We derived a subset of habitat configuration and anthropogenic conservation covariates based on the 15 × 15 km grid cells and 7.5 × 7.5 km quadrants. Our results show that Lesser Prairie-Chicken occupancy was positively affected by increased mean patch size of native land cover in the landscape, and by the percentage of land enrolled in prescribed grazing at the large scale (225 km²) and in the Conservation Reserve Program at the small scale (56 km²).

Remotely sensed land cover data enable characterization of avian habitat over large spatial scales, which can be applied to regional conservation planning. Black Terns (Chlidonias niger) have been declining in the U.S. Great Lakes region for decades. Although causes of the decline are not well understood, habitat loss and degradation are viewed as major barriers to recovery. The Upper Mississippi River and Great Lakes Region Joint Venture, a partnership for bird conservation in the Upper Midwest, developed a landscape suitability index for the wetland-breeding Black Tern based on remotely sensed land cover to choose habitat to enhance or restore. We tested the validity of this index and compared it to an alternative index we constructed from results of field surveys. Over 2 breeding seasons, we surveyed for presence of Black Tern breeding colonies in 158 wetlands across the Great Lakes region and compared our findings with predictions of the existing index. We used our first season of surveys, numerous remotely sensed landscape variables, and random forest classification to build our alternative index. Key predictors of Black Tern colony presence in the alternative index were wetland area, wetland type (emergent vegetation, open water, or combination), and area of wetlands available for foraging within 2 km. The 2 indices performed similarly well, correctly identifying categories of sites most likely to host Black Terns, but even high-suitability sites had <20% predicted occupancy probability. The best use of these and similar indices is in prioritizing restoration projects at a regional scale by identifying sites with potential for use.

Bird–window collisions at houses have been identified as a significant source of mortality for North American birds, but which types of houses and windows are most problematic remains poorly understood. We assessed how neighborhood type, yard conditions, house attributes, and window type influenced collision rates. Data were collected from citizen scientists across Alberta, Canada, who surveyed their houses daily. In relation to the best-fitting model, the yard model explained 58.1% of the explained deviance, the neighborhood model 45.6%, and the house model 42.6%. The factors that had the largest effect for predicting collision risk included season and whether the house was in a rural or an urban area (rural areas in the fall had a 6.0× higher collision risk than urban areas in the winter), the height of vegetation in the front yard of the house (trees >2 stories high increased collision risk by 3.6× compared to houses with no trees), and the presence of a bird feeder (which increased collision risk by 1.7×). This suggests that multiple factors affect collision rates and that the suitability of a yard as bird habitat is likely a key driver. Given that few homeowners are likely to take an approach that reduces the number of birds in their yards, future focus needs to be given to bird-friendly urban design and developing the most effective window deterrents so that collisions can be reduced and birds enjoyed in urban environments.

Due to climate change, extreme weather events are becoming more frequent and severe. These extreme events have been documented to affect avian predators in stream ecosystems. To better understand the mechanisms behind this effect, we used a decade-long dataset from a mountain stream in Taiwan to assess the effects of extreme flooding caused by typhoons on invertebrate abundance in different periods of the year and the resulting effects on reproductive output of an avian predator of these invertebrates, the Brown Dipper (Cinclus pallasii). In this study stream, all extreme floods occurred between June and October, and these floods negatively affected invertebrate density. Consequently, average invertebrate density was lowest in October at the end of the typhoon season, and highest 4 mo later. Because invertebrate density increases over time after a flood, the length of the recovery period between floods that occurred between June and October was more important than each flood's magnitude in determining invertebrate density in October. October invertebrate density then positively correlated with invertebrate density, the number of dipper breeding pairs, and the proportion of breeding individuals in the following breeding season, which lasted from January to early April. The effects of lower invertebrate densities in October and then February percolated all the way through the system, affecting laying date, fledgling population, and the next winter's population. Given our results, an increase in the frequency of typhoons, especially late-season typhoons, will have a negative effect on Brown Dipper reproductive output through bottom-up effects in stream ecosystems.

Cryptic species are often difficult to count and thus protect. Audubon's Shearwater (Puffinus lherminieri) is a cryptic seabird that has disappeared from many colonies, but knowledge of the population's status is incomplete. This paper reviews the survey methods in detail and assesses the status. This species nests or once nested on at least 154 islands in the Caribbean and remains on 137 today, with most habitat just above sea level. Remaining colonies represent 1% of the former breeding area and are remote, with 98 sites lacking any estimate of density. In 16 plots searched on multiple nights using playback, the probability of detection of defended nests was 79 ± 5% (57 of 72 defended nests) in a single night of searching. Pairs were attempting to breed in 54 ± 6% (39 of 72) of defended nests. Average densities, adjusted for missed detections, ranged from 0.6 to 246 defended nests ha⁻¹ (n = 21 colonies, median = 18.5 ha⁻¹, area-weighted mean = 104 ha⁻¹). Using the best data from every colony, at least 13,600 defended nests (7,400 breeding pairs) remain. If conservative densities from surveyed colonies occur on unsurveyed colonies, then about 37,900 defended nests (20,500 breeding pairs) should exist. Assuming shearwaters nested on the known extirpated sites in lower densities compared to surveyed colonies, populations were at least 446,000 and potentially >2,000,000 defended nests. Uncertainty in current population estimates could be reduced by surveying the largest unsurveyed colonies first. Audubon's Shearwater could be used as an indicator of island and marine ecosystem health with the caveat that the population is a small fraction of its former size. Conservation recommendations include continuing standardized monitoring, surveying large unsurveyed sites, limiting the rise of sea level, and removing invasive species from colonies.

A recent article published in The Condor: Ornithological Applications by Hale et al. (2014) is entitled, “No evidence of displacement due to wind turbines in breeding grassland songbirds.” The conclusion stated in that title, unfortunately, is based on inappropriate statistical analysis of data collected by the authors. In fact, their data provide evidence of potential displacement by wind turbines in 2 of the 3 species considered.

Johnson (2016) criticized our 3-year study investigating displacement in breeding grassland birds at an operational wind facility in the southern Great Plains. Although Johnson characterized our statistical methods as inappropriate and our study as intentionally misleading, his claims are based on his own view of the appropriate analysis and interpretation. Although we failed to reject the null hypothesis of no displacement in breeding grassland birds at our study site, the main message of our manuscript was a cautionary tale—that is, that at many wind facilities it will be difficult to isolate the effect of distance to turbine from other factors that covary with distance.