Midflight collisions with power lines impact 12 of the world's 15 crane species, including 1 critically endangered species, 3 endangered species, and 5 vulnerable species. Power lines can be fitted with line markers to increase the visibility of wires to reduce collisions, but collisions can persist on marked power lines. For example, hundreds of Sandhill Cranes (Antigone canadensis) die annually in collisions with marked power lines at the Iain Nicolson Audubon Center at Rowe Sanctuary (Rowe), a major migratory stopover location near Gibbon, Nebraska. Mitigation success has been limited because most collisions occur nocturnally when line markers are least visible, even though roughly half the line markers present include glow-in-the-dark stickers. To evaluate an alternative mitigation strategy at Rowe, we used a randomized design to test collision mitigation effects of a pole-mounted near-ultraviolet light (UV-A; 380–395 nm) Avian Collision Avoidance System (ACAS) to illuminate a 258-m power line span crossing the Central Platte River. We observed 48 Sandhill Crane collisions and 217 dangerous flights of Sandhill Crane flocks during 19 nights when the ACAS was off, but just 1 collision and 39 dangerous flights during 19 nights when the ACAS was on. Thus, we documented a 98% decrease in collisions and an 82% decrease in dangerous flights when the ACAS was on. We also found a 32% decrease in the number of evasive maneuvers initiated within 25 m of the power line along the river, and a 71% increase in the number of evasive maneuvers initiated beyond 25 m when the ACAS was on. Sandhill Cranes reacted sooner and with more control, and experienced substantially fewer collisions, when the ACAS was on. Installation of the ACAS on other high-risk spans, and perhaps on other anthropogenic obstacles where birds collide, may offer a new solution to a long-running conservation dilemma.

A detailed understanding of species' responses to global climate change provides an informative baseline for designing conservation strategies to optimize protection of biodiversity. However, such information is either limited or not available for many tropical species, making it difficult to incorporate climate change into conservation planning for most tropical species. Here, we used correlative ecological niche models to assess potential distributional responses of 3 range-restricted West African birds, Timneh Parrot (Pscittacus erithracus timneh), Ballman's Malimbe (Malimbus ballmanni), and White-necked Rockfowl (Picathartes gymnocephalus), to global climate change. We used primary biodiversity occurrence records for each species obtained from the Global Biodiversity Information Facility, eBird, and VertNet; for environmental data, we used climatic variables for the present and future, the latter characterized by 2 IPCC representative concentration pathways (4.5, 8.5) future emissions scenarios and 27 general circulation models for a 2050 time horizon. We found broad present–day potential distributions with respect to climate for all 3 species. Future potential distributions for Ballman's Malimbe and White-necked Rockfowl tended to be stable and closely similar to their present-day distributions; by contrast, we found marked climate change–driven potential range loss across the range of Timneh Parrot. Our results suggest that impacts of climate change on the present distributions of West African birds will in some cases be minimal, but that individual species may respond differently to future conditions. Thus, to optimize conservation of these species, and of bird diversity in general, we recommend that regional-to-national species conservation action plans incorporate climate change adaptation strategies for individual species; ecological niche models could provide an informative baseline information for this planning and prioritization.

Human activities in marine coastal areas may coincide with protected areas for birds. Some of these anthropogenic activities may pose threats, such as gillnet fisheries, which can significantly affect populations of diving birds, especially gregarious species that gather in huge flocks in small areas such as Greater Scaup (Aythya marila). The Odra Estuary (Baltic Sea, Poland) is known for its importance as a wintering site for scaup; it is also used by fishermen using gillnets. Precise tools to determine the distribution and abundance of birds allow evaluation of risks faced by large aggregations. We used kernel density interpolation to estimate the spatial density of scaup in the Odra Estuary in spring 2011. At that time, an extraordinarily high number of scaup (95,400) was recorded, ∼73% (63.0–94.5%) of the entire northwest European flyway population. Three variables are particularly important for conserving highly mobile long-distance migrating species: spatial distribution, abundance, and time (season of the year). This event concentrated most of the scaup flyway population in a small space, making the population vulnerable to mass mortality. We also show aggregated data of the spatial distribution of scaup during the 2015–2016 and 2016–2017 seasons to highlight differences in the spatial use of the area between seasons. Vast areas occupied by scaup in 2011 were not used during 2 other studied seasons; this spatial variation may be crucial in conservation planning of this species. Our results are a first step in documenting the spatial distribution of scaup in the Odra Estuary and identifying the potential area of overlap with fishing activity.

Invasive predators have caused widespread loss of biodiversity in island ecosystems, yet certain species are able to tolerate the presence of generalist invaders. For example, the invasive brown treesnake (BTS; Boigairregularis) caused the extirpation of 10 of 12 native forest bird species on the island of Guam, but a remnant population of the Micronesian Starling (Aplonis opaca), or Såli, has managed to persist on a military installation in northern Guam. Understanding how Micronesian Starlings are coping with the presence of BTS can inform conservation efforts for island bird populations facing invasive predators and provide insight into strategies for expanding the starling population. We monitored the survival, movements, and habitat use of 43 radio-tagged starling fledglings during this vulnerable life-history stage. Invasive predators accounted for 75% of fledgling mortality (56% from BTS; 19% from feral cats) and contributed to one of the lowest post-fledging survival rates (38% through day 21 post-fledging) recorded for passerine birds. Predation by BTS persisted at elevated rates following natal dispersal, further reducing cumulative survival to 26% through 53 days post-fledging. Nest location was an important predictor of survival: fledglings from nest boxes closer to the forest edge were more likely to use forest habitat at younger ages and more likely to be depredated by BTS. Overall, our findings indicate that BTS continue to severely impact Guam's starling population, even more so than invasive predators affect native birds in other island systems. We recommend deploying nest boxes farther from the forest to improve fledgling survival and implementing urban predator control to promote growth of the Micronesian Starling population on Guam and facilitate future reintroductions of other species.

In Hawaii and other oceanic islands with few native land mammals, black rats (Rattus rattus) are among the most damaging invasive vertebrate species to native forest bird populations and habitats, due to their arboreal behavior and generalist foraging habits and habitat use. We evaluated the nesting response of Hawaii Elepaio (Chasiempis sandwichensis; Monarchidae), a generalist insectivore, to the removal of black rats using rodenticide in a before-after-control-impact study in high- and low-elevation mesic montane habitat recovering from long-term damage from introduced ungulates and weeds. We monitored nesting success and rat abundance during 2015–2016 before applying rodenticide bait in 2017 to remove rats from two 700 × 700 m treatment plots that were paired with 2 nontreatment plots of the same size. Rat abundance was reduced by 90% during treatment, with combined variables treatment and elevation best explaining the change using GLM methods and AIC model selection. The daily survival rate (DSR) of nests (n = 191) was greater on treated plots after rodenticide application (mean ± SE = 0.980 ± 0.004 treatment; 0.964 ± 0.004 nontreatment), modeled nest success increased from 29% to 50%, and apparent nest success (number of successful nests per total nests) increased from 37% to 52%. The most informative model for predicting DSR included the effect of treatment. Predation by rats was documented at 3 of 16 nests using video surveillance, and we observed additional evidence of rat predation during in-person nest monitoring. Rats targeted adults on the nest and sometimes removed intact eggs, leaving little trace of their activity. Our results demonstrate that reducing rat predation can immediately improve the nesting success of even a common bird species in habitat with a long history of forest restoration. Sustained predator control may be critical to accelerating the recovery of native forest bird communities.

Analysis of North American Breeding Bird Survey (BBS) data requires controls for factors that influence detectability of birds along survey routes. Identifying factors that influence the counting process and incorporating them into analyses is a primary means of limiting bias in estimates of population change. Twedt (2015) implemented an alternative counting protocol on operational and nonrandom BBS survey routes in the southeastern United States. Observers on selected routes employed a time–distance protocol in which they recorded birds in 1–min intervals and in 2 distance categories. We hypothesized that processing and recording observations using this time–distance protocol could cause observers to count fewer birds relative to observers using the standard protocol. We used a hierarchical log–linear model with a categorical covariate associated with protocol (standard vs. time–distance) to assess whether use of the time–distance protocol had a measurable effect on counting birds along BBS routes. We applied this model to BBS data from portions of 8 states in which the time–distance protocol was implemented and estimated a protocol effect for 167 bird species. We documented a significant overall effect of the time–distance protocol on observers'counts of birds. On average, the effect of the time–distance protocol was a 10% decline in counted birds; 80% of species had lower counts when the time–distance protocol was used on a survey route. However, because the time–distance protocol was only used on a small portion of the operational BBS routes and for a limited time, including the covariate for the time–distance protocol data had insignificant effects on analysis of population change. Although the covariate controlled for the effects of the time–distance protocol in BBS data, the results emphasize the importance of standardization as well as a need to track and, if necessary, control in analyses for changes in counting procedures along BBS routes.

The Northern Mockingbird (Mimus polyglottos) is a successful urban adaptor known to display flexibility in foraging, nesting, and anti-predator behavior. Its vocal behavior is also complex, with a breeding song composed of a wide variety of non-mimetic and mimetic elements, or “syllable types.” We tested the hypothesis that Northern Mockingbird adaptation to urban settings includes changes in its vocal behavior in noisy urban environments. We studied an urban/suburban mockingbird population to test the effect of urban background noise on breeding song frequency and syllable-type composition. Given that urban noise overlaps most strongly with low-frequency vocalizations, a phenomenon known as “signal masking,” we predicted a positive association between noise levels and mockingbird average peak frequency (a measure of vocalization power). We further predicted a positive effect of noise levels on the peak frequency of the lowest-pitched syllable type in a mockingbird's song, no effect on the peak frequency of the highest-pitched syllable type, and thus a negative effect on mockingbird peak frequency range. Lastly, we predicted a negative effect of background noise on the use of syllable types experiencing heavy signal masking and, conversely, a positive effect on the use of syllable types experiencing minimal signal masking. We found a significant positive effect of noise levels on both average peak frequency and peak frequency of the lowest-pitched syllable type, but no effect on the peak frequency of the highest-pitched syllable type and peak frequency range. In addition, as background noise levels increased, we found significant declines in the percentages of heavily masked syllable types (1–3 kHz) and significant increases in the percentages of syllable types in the 3–5 kHz range; percentages of syllable types >5 kHz were, however, unaffected by background noise. These results were consistent with the hypothesis that Northern Mockingbird breeding songs change in pitch and syllable-type composition in noisy settings, providing further evidence that songs of urban-adapting species differ in noisy environments.

Early-successional forest birds, which depend on disturbance events within forested landscapes, have received increased conservation concern because of long-term population declines. Herbicides are often used to control vegetation within early-successional forests, with unknown effects on avian vital rates. We used a large–scale experiment to test how nest and post–fledging survival were influenced by herbicide intensity within managed conifer plantations across 2 breeding seasons. We created a gradient of 4 stand–scale herbicide treatments (light, moderate, and intensive, and no–spray control) and evaluated the reproductive response of the White–crowned Sparrow (Zonotrichia leucophrys), a declining songbird in managed forest landscapes of the Pacific Northwest. Against initial predictions, we found no evidence that either daily nest survival (n > 760 nests across all treatments) or post–fledging survival (n = 70 individuals reared in control and moderate treatments) were influenced by herbicide application intensity. Increased herbicide intensity resulted in an extensive reduction in vegetation cover at both stand and nest–patch scales; in contrast, vegetative cover at nest sites did not differ across herbicide treatments, nor was nest survival related to vegetation concealment measures. As the largest experimental investigation to assess forest herbicide effects on songbird demography, our study indicates that components of sparrow reproductive success were not influenced by experimental vegetation control measures, although additional work on other early-successional species will be useful to evaluate the generalities of our findings.

Great Salt Lake (GSL) is the largest hypersaline lake in North America and is the fall staging area for a high proportion of North America's Wilson's Phalaropes (Phalaropus tricolor) and Red-necked Phalaropes (Phalaropus lobatus). Unfortunately, diversion of freshwater for agriculture and development has decreased the size of GSL by 48%. To assess the potential impact of a smaller GSL on phalaropes, we collected data from 2013 to 2015 from sites where large, dense flocks of phalaropes congregated and sites where there were no phalaropes. At each site, we measured the densities of invertebrates that were preyed upon by phalaropes, including larval and adult brine flies (Ephydridae), adult brine shrimp (Artemia franciscana), chironomid larvae (Chironomidae), and corixid adults (Corixidae). Abiotic characteristics measured included water depth, water salinity, water temperature, wind speed, and benthic substrate. We analyzed high-salinity sites separately from low-salinity sites because they contained different invertebrates. High-salinity sites were in Carrington and Gilbert bays and were relatively deep (mostly <2 m). At the high-salinity sites, phalaropes exhibited a preference for sites with an abundance of adult brine flies and for microbialite substrates. The low-salinity sites were in Ogden and Farmington bays and were shallow (<1 m). At low-salinity sites, large phalarope flocks were more likely to occur at sites that were shallower, less saline, and had a high biomass of benthic macroinvertebrates. Our results indicate that physical features and prey availability are both important in determining phalarope habitat use at GSL. Phalaropes prefer to use shallower parts of GSL and brackish waters. These areas will be especially impacted by decreased freshwater inflow into GSL.

Large amounts of money are spent each year to control overabundant species that imperil biodiversity and ecosystem functioning across the globe. Lesser Snow Geese (Anser caerulescens caerulescens) are emblematic of this issue, as their overabundance has affected a whole suite of plant, insect, and bird communities via a trophic cascade that managers have attempted to stop before it spreads further across the North American (sub)Arctic. To achieve this goal, liberalized harvest measures designed to decrease Lesser Snow Goose survival and abundance were implemented almost 2 decades ago. Our previous quantitative assessment of management effectiveness indicated that the growing Lesser Snow Goose population quickly overwhelmed a satiated hunter population despite liberalized harvest regulations, eventually reducing the fraction of Lesser Snow Geese being harvested each year. Consistent with the philosophy of adaptive resource management, we apply improved methods to additional years of monitoring data to evaluate the ongoing impact of harvest conservation efforts on Lesser Snow Goose harvest rates. Our previous results suggested little effect of liberalized harvest regulations on harvest rates, but our new findings suggest even less of an impact. Harvest rates have recently stabilized at ∼3%, the lowest levels observed over the last 48 yr of our study. Barring adverse effects of environmental change on natural mortality or reproductive success, additional measures will need to be taken to reduce Lesser Snow Goose overabundance and their ecosystem damage.

Aerial insectivores (birds that forage on aerial insects) have experienced significant population declines in North America. Numerous hypotheses have been proposed for these declines, but current evidence suggests multiple factors could be operating in combination during their annual migratory cycles between breeding and nonbreeding areas. Potential drivers include decreased prey abundance, direct or indirect impacts of environmental contaminants, habitat loss, phenological changes due to warming climate, and conditions on migratory stopover or wintering grounds. While no single threat appears to be the cause of aerial insectivore declines, existing evidence suggests that several of these factors could be contributing to the declines at different times in the annual lifecycle. Breeding productivity for most of these species does not appear to be limited by overall prey abundance, contaminants, or habitat loss, which suggests that similar issues on nonbreeding grounds or carryover effects could play important roles. However, a better understanding of the importance of prey quality throughout the lifecycle is critically needed. Based on current evidence, we propose that changes in availability of high-quality prey, with variability across breeding and nonbreeding grounds, reduce various combinations of fledging success, post-fledging survival, and nonbreeding season body condition of aerial insectivores, resulting in species and geographic differences in population trends. We encourage others to use this hypothesis as a starting point to test specific mechanisms by which availability of high-quality prey influences demographic parameters. We suggest that future research focus on defining prey quality, monitoring insect abundance in conjunction with birds, comparing demographic models across local populations experiencing different population growth rates, and using tracking technology to document important migratory and nonbreeding areas. Considerable research progress already has been made, but additional research is needed to better understand the complex web of potential causes driving aerial insectivore declines.

One of the greatest challenges to informed conservation of migratory animals is elucidating spatiotemporal variation in distributions. Without such information, it is impossible to understand full-annual-cycle ecology and effectively implement conservation actions that address where and when populations are most limited. We deployed and recovered light-level geolocators (n = 34) at 6 breeding sites in North America across the breeding range of a declining long-distance migratory bird, the Prothonotary Warbler (Protonotaria citrea). We sought to determine migratory routes, stopover location and duration, and the location of overwintering grounds. We found that the species exhibits a large-scale, east—west split in migratory routes and weak migratory connectivity across its range. Specifically, almost all individuals, regardless of breeding origin, overlapped in their estimated wintering location in northern Colombia, in an area 20% the size of the breeding range. Additionally, most of the individuals across all breeding locations concentrated in well-defined stopover locations in Central America while en route to Colombia. Although error inherent in light-level geolocation cannot be fully ruled out, surprisingly much of the estimated wintering area included inland areas even though the Prothonotary Warbler is considered a specialist on coastal mangroves in winter. Based on these results, conservation efforts directed at very specific nonbreeding geographical areas will potentially have benefits across most of the breeding population. Our findings highlight the importance of using modern technologies to validate assumptions about little-studied portions of a species' annual cycle, and the need to distribute sampling across its range.

‘Ōhi'a lehua (Metrosideros polymorpha) is the principle tree species in forests across the Hawaiian Islands and provides critical foraging and nesting habitat for native passerines. Rapid Ohia Death (ROD), caused by the vascular wilt fungus Ceratocystis lukuohia and the canker pathogen C. huliohia, was first detected in the Puna District of Hawaii Island in 2010. It affects all life stages of ‘ōhi'a and as of July 2018 had spread to an estimated 40,469 ha across Hawaii Island. To determine the impact of ROD on the forest bird community we conducted point counts in lowland ‘ōhi'a forest in 2016 and compared them to counts from 2003 to 2004, before the appearance of ROD. We found an increase in species diversity and a significant decrease in the densities of a native Hawaiian honeycreeper, the Hawaii Amakihi (Chlorodrepanus virens), and the nonnative Japanese White-eye (Zosterops japonicus). Yellow-fronted Canary (Crithagra mozambica) and Saffron Finch (Sicalis flaveola), 2 nonnative passerines associated with the shrub layer and more open habitats, were only detected in 2016. Proportion of survey points occupied were comparable between survey periods, but relative abundances were generally lower. Hawaii Amakihi densities declined by 79% and Japanese White-eye densities declined by 33%. Our findings suggest that the loss of ‘ōhi'a canopy due primarily to ROD has adversely affected populations of native Hawaii Amakihi and nonnative Japanese White-eye, 2 of the most abundant species of lowland Hawaiian forests.

Limited data on harvest and population parameters are impediments to assessing shorebird harvest sustainability. Because of sharp declines in shorebird populations, timely conservation efforts require approaches that account for uncertainty in harvest sustainability. We combined harvest assessment and ethnographic research to better understand shorebird conservation concerns related to subsistence harvest in Alaska and to support culturally sensible conservation actions. Our objectives were to (1) estimate the Alaska-wide shorebird subsistence harvest and (2) document shorebird indigenous knowledge on the Yukon-Kuskokwim Delta. Harvest estimates were based on surveys conducted in 1990–2015 (n = 775 community-years). Key respondent interviews conducted in 2017 (n = 72) documented shorebird ethnotaxonomy and ethnography. The Alaska-wide shorebird harvest was 2,783 birds per year, including 1,115 godwits per year—mostly Bar-tailed Godwits (Limosa lapponica baueri), whose population has low harvest potential. The egg harvest was 4,678 eggs per year, mostly small shorebird eggs. We documented 24 Yup'ik shorebird names and 10 main ethnotaxonomic categories. Children learning harvesting skills focused on small birds and adults also occasionally harvested shorebirds, but shorebirds were not primary food or cultural resources. Older generations associated shorebirds with a time when people were closer to nature and their cultural roots. Shorebirds connected people with the environment as well as with Yup'ik traditions and language. Our results can inform improvements to harvest assessment and management, as well as outreach and communication efforts to engage subsistence users in shorebird conservation.

Comparing impacts of co-occurring anthropogenic features is necessary for regional planning and can help identify mechanisms of negative impacts of development on wildlife. Because of the vast abundance of anthropogenic features in the Northern Great Plains, their combined negative impacts on songbird habitat use (e.g., abundance) and productivity (e.g., nesting success and clutch size) could exacerbate the decline of songbird populations. We compared the cumulative effects of energy-related infrastructure (oil wells, shallow gas wells, and roads) on habitat use and productivity of songbirds across a 120 × 180 km region in southern Alberta, Canada. We examined effects on Chestnut-collared Longspur (Calcarius ornatus) and Sprague's Pipit (Anthus spragueii), both of which are listed as Threatened in Canada, and Savannah Sparrow (Passerculus sandwichensis), Vesper Sparrow (Pooecetes gramineus), and Western Meadowlark (Sturnella neglecta). Using piecewise regressions and generalized linear models, we estimated effects of distance from infrastructure and shallow gas well density on the habitat use and productivity of each species. We then used these analyses to quantify the availability of habitat suitable for settlement and breeding throughout our study region. Shallow gas wells, which are more abundant, affected a larger geographic area than oil wells, but oil wells were associated with the added impacts of roads. Our analyses suggest that impacts of wells on songbirds are not caused by industrial noise because individual shallow gas wells, which produce no mechanical noise, had similar impacts to noisy oil wells. Our results highlight the importance of regional plans that consider the impacts of multiple co-occurring anthropogenic features in working landscapes.