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1. Methods papers play a crucial role in advancing applied ecology. Counting organisms, in particular, has a rich history of methods development with many key advances both in field sampling and the treatment of resulting data. 2. Most counts, however, have associated errors due to portions of the population of interest being unavailable for detection (e.g. target population not fully sampled; individuals present but not detectable), detection mistakes (e.g. detectable individuals missed; non-existent individuals recorded), or erroneous counts (e.g. large groups miscounted; individuals misidentified). 3. Developments in field methods focus on reducing biases in the actual counts. Simultaneously, statisticians have developed many methods for improving inference by quantifying and correcting for biases retrospectively. Prominent examples of methods used to account for detection errors include distance sampling and multiple-observer methods. 4. Simulations, in which population characteristics are set by the investigator, provide an efficient means of testing methods. With good estimates of sampling biases, computer simulations can be used to evaluate how much a given counting problem affects estimates of parameters such as population size and decline, thereby allowing applied ecologists to test the efficacy of sampling designs. Combined with cost estimates for each field method, such models would allow the cost-effectiveness of alternative protocols to be assessed. 5. Synthesis and applications. Major advances are likely to come from research that looks for systematic patterns, across studies, in the effects of different types of bias and assumption violation on the ecological conclusions drawn. Specifically, determining how often, and under what circumstances, errors contribute to poor management and policy would greatly enhance future application of ecological knowledge.

Aim Citizen science data are increasingly used for modelling species distributions because they offer broad spatiotemporal coverage of local observations. However, such data are often collected without experimental design or set survey methods, raising the risk that bias and noise will compromise modelled predictions. We tested the ability of species distribution models (SDMs) built from these low‐structure citizen science data to match the quality of SDMs from systematically collected data and tested whether stringent data filtering improved predictions. Location Northeastern USA. Methods We evaluated models built from a rapidly growing dataset of avian occurrences reported by birders—eBird—against models built from four independent, systematically collected datasets. We developed SDMs for 96 species using both data sources and compared their predictive abilities. We also tested whether culling eBird data by applying stringent data filters on survey effort or observer expertise improved predictions. Results We found that SDMs built from low‐structure citizen science data matched or exceeded performance of SDMs from systematically collected datasets for 12%–31% of species (x¯ = 22%), depending on the dataset. At least one culling option produced equivalent or better performance for 40%–70% of species (x¯ = 49%). Data culling by restricting survey effort improved predictions more than restricting by observer expertise. The optimal effort restriction differed by dataset, and for three of the datasets was further informed by species traits. Main conclusions Species distribution models developed using low‐structure citizen science data sometimes performed as well as those from systematic data. Culling generally improved models, but results were heterogeneous, prohibiting clear recommendations for how to cull. Our results indicate that the growing availability of citizen science data holds potential for creating high‐quality spatial predictions, but that time should be invested in determining how best to cull datasets and that one‐size‐fits‐all solutions beyond basic outlier filtering may be hard to find.

The human aspects of conservation are often overlooked but will be critical for identifying strategies for biological conservation in the face of climate change. We surveyed the behavioral intentions of coastal landowners with respect to various conservation strategies aimed at facilitating ecosystem migration for tidal marshes. We found that several popular strategies, including conservation easements and increasing awareness of ecosystem services, may not interest enough landowners to allow marsh migration at the spatial scales needed to mitigate losses from sea-level rise. We identified less common conservation strategies that have more support but that are unproven in practice and may be more expensive. Our results show that failure to incorporate human dimensions into ecosystem modeling and conservation planning could lead to the use of ineffective strategies and an overly optimistic view of the potential for ecosystem migration into human dominated areas.

The interdisciplinary nature of conservation problems is increasingly being incorporated into research, raising fundamental questions about the relative importance of the different types of knowledge and data. Although there has been extensive research on the development of methods and tools for conservation planning, especially spatial planning, comparatively little is known about the relative importance of ecological versus non-ecological data for prioritization, or the likely return on investment of incorporating better data. We demonstrate a simple approach for (1) quantifying the sensitivity of spatial planning results to different ecological and non-ecological data layers, and (2) estimating the potential gains in efficiency from incorporating additional data. Our case study involves spatial planning for coastal squeeze, a process by which development blocks coastal ecosystems from moving landward in response to sea-level rise. We show that incorporating spatial data on landowners' likelihood of selling had little effect on identifying relative priorities but drastically changed the outlook for whether conservation goals could be achieved. Better data on the costs of conservation actions had the greatest potential to improve the efficiency of spatial planning, in some cases generating more than an order of magnitude greater cost savings compared to ecological data. Our framework could be applied to other systems to guide the development of spatial planning and to identify general rules of thumb for the importance of alternative data sources for conservation problems in different socio-ecological contexts.

Reduced ecological specialization is an emerging, general pattern of ecological networks in fragmented landscapes. In plant–herbivore interactions, reductions in dietary specialization of herbivore communities are consistently associated with fragmented landscapes, but the causes remain poorly understood. We propose several hypothetical bottom–up and top–down mechanisms that may reduce the specificity of plant–herbivore interactions. These include empirically plausible applications and extensions of theory based on reduced habitat patch size and isolation (considered jointly), and habitat edge effects. Bottom–up effects in small, isolated habitat patches may limit availability of suitable hostplants, a constraint that increases with dietary specialization. Poor hostplant quality due to inbreeding in such fragments may especially disadvantage dietary specialist herbivores even when their hostplants are present. Size and isolation of habitat patches may change patterns of predation of herbivores, but whether such putative changes are associated with herbivore dietary specialization should depend on the mobility, size, and diet breadth of predators. Bottom–up edge effects may favor dietary generalist herbivores, yet top–down edge effects may favor dietary specialists owing to reduced predation. An increasingly supported edge effect is trophic ricochets generated by large grazers/browsers, which remove key hostplant species of specialist herbivores. We present empirical evidence that greater deer browsing in small forest fragments disproportionately reduces specialist abundances in lepidopteran assemblages in northeastern USA. Despite indirect evidence for these mechanisms, they have received scant direct testing with experimental approaches at a landscape scale. Identifying their relative contributions to reduced specificity of plant–herbivore interactions in fragmented landscapes is an important research goal.

Climate change and sea-level rise pose an imminent threat to the survival of coastal ecosystems, but the mechanisms by which animals inhabiting these areas may be affected by these changes are not well studied. During 2007–2009, we quantified the frequency of nest-flooding events at two salt marshes located in the northeastern United States that are of global importance to Saltmarsh Sparrow (Ammodramus caudacutus) conservation. Although nest flooding is a major cause of nest failure in this species, we lack a detailed understanding of exactly how flooding affects success, so it is difficult to determine the magnitude of the threat posed by sea-level rise. We tested whether variables associated with the timing of nest initiation, tide height, and flooding frequency can be used to estimate three aspects of nest fate: the probability of nest success, the probability of nest failure due to flooding, and the number of offspring lost to flooding. Of the 191 nests that we monitored, only 15% were never flooded and 18% were successful; the mean (± SD) number of flooding events observed per nest was 2.8 ± 2.1 (range: 0–10). The top-performing model for each measure of nest fate included variables related to tidal metrics, but model composition for the three measures differed in the importance of particular tide variables. Both tide height and flooding frequency emerged as important drivers of nest fate in this system. Saltmarsh Sparrow nests appear to be extremely vulnerable to even slight increases in sea level.

Coastal marshes are one of the world's most productive ecosystems. Consequently, they have been heavily used by humans for centuries, resulting in ecosystem loss. Direct human modifications such as road crossings and ditches and climatic Stressors such as sea-level rise and extreme storm events have the potential to further degrade the quantity and quality of marsh along coastlines. We used an 18-year marsh-bird database to generate population trends for 5 avian species (Rallus crepitans, Tringa semipalmata semipalmata, Ammodramus nelsonii subvirgatus, Ammodramus caudacutus, and Ammodramus maritimus) that breed almost exclusively in tidal marshes, and are potentially vulnerable to marsh degradation and loss as a result of anthropogenic change. We generated community and species trends across 3 spatial scales and explored possible drivers of the changes we observed, including marsh ditching, tidal restriction through road crossings, local rates of sea-level rise, and potential for extreme flooding events. The specialist community showed negative trends in tidally restricted marshes (-2.4% annually from 1998 to 2012) but was stable in unrestricted marshes across the same period. At the species level, we found negative population trends in 3 of the 5 specialist species, ranging from -4.2% to 9.0% annually. We suggest that tidal restriction may accelerate degradation of tidal marsh resilience to sea-level rise by limiting sediment supply necessary for marsh accretion, resulting in specialist habitat loss in tidally restricted marshes. Based on our findings, we predict a collapse of the global population of Saltmarsh Sparrows (A. caudacutus) within the next 50 years and suggest that immediate conservation action is needed to prevent extinction of this species. We also suggest mitigation actions to restore sediment supply to coastal marshes to help sustain this ecosystem into the future. Los humedales costeros son uno de los ecosistemas más productivos en el mundo. Consecuentemente, han sido utilizados intensivamente por los humanos durante siglos, resultando en la pérdida del ecosistema. Modificaciones humanas directas como caminos y zanjas, así como agentes climáticos estresantes como el incremento del nivel del mar y eventos de tormentas extremas tienen el potencial de degradar aun más la cantidad y calidad de humedales a lo largo de las costas. Utilizamos una base de datos de 18 años de aves de humedal para generar tendencias poblaciones de especies de aves (Rallus crepitans, Tringa semipalmata semipalmata, Ammodramus nelsonii subvirgatus, A. caudacutus, y A. maritimus) que se reproducen casi exclusivamente en marismas y que son potencialmente vulnerables a la degradación y pérdida de humedales como resultado de cambios antropogénicos. Generamos tendencias de la comunidad y de especies en 3 escalas espaciales y exploramos los posibles factores de los cambios observados, incluyendo la construcción de canales, la restricción de mareas por medio de caminos, tasas locales de incremento del nivel del el potencial de eventos de inundación extremos. La comunidad de especialistas mostró tendencias negativas en humedales restringidos por las mareas (-2.4% anualmente de 1998 a 2012), pero fue estable en humedales no restringidos. A nivel de especies, encontramos tendencias poblacionales negativas en 3 de las 5 especies especialistas que variaron entre -4.2% a 9% anualmente. Sugerimos que la restricción de mareas puede acelerar la degradación de la resiliencia de marismas al incremento del nivel del mar al limitar el aporte de los sedimentos necesarios para la acreción de marismas, lo cual resulta en la pérdida de habitat en marismas restringidas por las mareas. Con base en nuestros resultados, pronosticamos un colapso de la población global de A. caudacutus en los próximos 50 años y sugerimos que se requieren acciones de conservación inmediatas para prevenir la extinción de esta especie. También sugerimos acciones de mitigación para restaurar el aporte de sedimentos en los humedales costeros para ayudar a sostener este ecosistema en el futuro.

Rice (Oryza sativa) is one of the world's most important crops. The crop is grown in at least 114 countries, occupies over 156 million ha of land annually, is a primary source of nutrition for over half the world's human population and constitutes over a fifth of the global grain supply. Rice is generally grown under flooded conditions and, if managed appropriately, can provide important habitat for wetland species. Waterfowl, wading birds, shorebirds and other waterbirds use rice fields, foraging on a variety of prey, nesting in the crop and in fringing vegetation, and staging during migration. Conflicts also exist, with some cropping practices harmful to birds and some bird activity detrimental to yield production. Much early research on waterbirds in rice fields was conducted in Mediterranean Europe with only scattered work elsewhere. More recently, there has been a growing focus on the conservation value of rice fields, with studies from most of the major regions where rice is grown. The body of research has included: community studies of the range of birds that use rice fields, detailed studies of endangered species, behavioral studies of reproductive success, foraging ecology and movement, and applied studies of cropping techniques. As the world's natural wetlands diminish, researchers studying waterbirds in rice fields are working to globalize interactions with each other. Also, some researchers are working closely with conservation groups and rice growers to identify ways to maximize the benefits of agricultural wetlands while minimizing the agronomic costs.

In eastern North America, the invasive hemlock woolly adelgid ( Adelges tsugae Annand), has expanded northward at a pace that exceeds predictions from mechanistic models, suggesting successful long-distance dispersal despite the only viable dispersive phase being a flightless nymph, or “crawler.” We hypothesize that migrating birds may contribute to long-distance dispersal of crawlers by passively transporting them in their plumage during northward migration. We collected hemlock woolly adelgid crawlers from the plumage of wild birds in Connecticut hemlock forests in spring and summer 2016–2017 and evaluated the factors that influence crawler loads on wild birds. Of 456 birds examined, 40 individuals of 22 species carried adelgid crawlers. Crawler loads varied strongly over time, showing a mid-spring peak that mirrored the phenological pattern in crawler abundance. However, crawler load was not affected by either local crawler abundance at capture sites or the degree of bird species association with hemlock forests. To test whether dispersed crawlers could start new invasions, we experimentally simulated avian-assisted dispersal of adelgids onto uninfested nursery hemlocks. Although rare, crawlers placed on birds did settle successfully on experimental branches during the adelgid’s summer generation. Our study confirms that birds carry hemlock woolly adelgid crawlers most often during the period of peak spring songbird migration, and that crawlers can move off bird plumage to settle on hemlock foliage. Bird-mediated, long-distance dispersal of crawlers likely has played a key role in hemlock woolly adelgid spread, and with warming temperatures, this mechanism may continue to be important for future range expansion.