Time series are a critical component of ecological analysis, used to track changes in biotic and abiotic variables. Information can be extracted from the properties of time series for tasks such as ...classification (e.g., assigning species to individual bird calls); clustering (e.g., clustering similar responses in population dynamics to abrupt changes in the environment or management interventions); prediction (e.g., accuracy of model predictions to original time series data); and anomaly detection (e.g., detecting possible catastrophic events from population time series). These common tasks in ecological research all rely on the notion of (dis-) similarity, which can be determined using distance measures. A plethora of distance measures have been described, predominantly in the computer and information sciences, but many have not been introduced to ecologists. Furthermore, little is known about how to select appropriate distance measures for time-series-related tasks. Therefore, many potential applications remain unexplored. Here, we describe 16 properties of distance measures that are likely to be of importance to a variety of ecological questions involving time series. We then test 42 distance measures for each property and use the results to develop an objective method to select appropriate distance measures for any task and ecological dataset. We demonstrate our selection method by applying it to a set of real-world data on breeding bird populations in the UK and discuss other potential applications for distance measures, along with associated technical issues common in ecology. Our real-world population trends exhibit a common challenge for time series comparisons: a high level of stochasticity. We demonstrate two different ways of overcoming this challenge, first by selecting distance measures with properties that make them well suited to comparing noisy time series and second by applying a smoothing algorithm before selecting appropriate distance measures. In both cases, the distance measures chosen through our selection method are not only fit-for-purpose but are consistent in their rankings of the population trends. The results of our study should lead to an improved understanding of, and greater scope for, the use of distance measures for comparing ecological time series and help us answer new ecological questions.
Wet grassland populations of wading birds in the United Kingdom have declined severely since 1990. To help mitigate these declines, the Royal Society for the Protection of Birds has restored and ...managed lowland wet grassland nature reserves to benefit these and other species. However, the impact of these reserves on bird population trends has not been evaluated experimentally due to a lack of control populations. We compared population trends from 1994 to 2018 among 5 bird species of conservation concern that breed on these nature reserves with counterfactual trends created from matched breeding bird survey observations. We compared reserve trends with 3 different counterfactuals based on different scenarios of how reserve populations could have developed in the absence of conservation. Effects of conservation interventions were positive for all 4 targeted wading bird species: Lapwing (Vanellus vanellus), Redshank (Tringa totanus), Curlew (Numenius arquata), and Snipe (Gallinago gallinago). There was no positive effect of conservation interventions on reserves for the passerine, Yellow Wagtail (Motacilla flava). Our approach using monitoring data to produce valid counterfactual controls is a broadly applicable method allowing large‐scale evaluation of conservation impact.
Un Enfoque Hipotético para Medir el Impacto de la Conservación de Pastizales Húmedos sobre Poblaciones Reproductoras de Aves en el Reino Unido
Resumen
Las poblaciones de aves zancudas en los pastizales húmedos del Reino Unido han declinado gravemente desde 1990. Para ayudar con la mitigación de estas declinaciones, la Real Sociedad para la Protección de las Aves ha restaurado y manejado las reservas naturales en pastizales húmedos de tierras bajas para beneficiar a estas y otras especies. Sin embargo, el impacto de estas reservas sobre las tendencias poblacionales de las aves no ha sido evaluado experimentalmente debido a la falta de poblaciones control. Comparamos las tendencias poblacionales entre 1994 y 2018 de cinco especies de aves de importancia para la conservación, que se reproducen dentro de estas reservas naturales, mediante tendencias hipotéticas creadas a partir de los censos de observación de aves reproductoras emparejadas. Comparamos las tendencias de las reservas con tres casos hipotéticos diferentes basados en diferentes escenarios de cómo las poblaciones de la reserva podrían haberse desarrollado en ausencia de la conservación. Los efectos de las intervenciones de conservación fueron positivos para las cuatro especies focales de aves zancudas: Vanellus vanellus, Tringa totanus, Numenius arquata y Gallinago gallinago. No hubo un efecto positivo de las intervenciones de conservación para la especie paserina Motacilla flava. Nuestra estrategia utilizando datos de monitoreos para producir controles hipotéticos válidos es un método ampliamente aplicable que permite ka evaluación del impacto de la conservación a gran escala
摘要
自1990 年以来, 英国湿草地涉禽的数量急剧下降。为了缓解这些鸟类种群丧失, 英国皇家鸟类保护协会通过恢复和管理低地湿草地自然保护区来帮助保护这些鸟类及其它物种。然而, 由于缺乏对照种群, 保护区对鸟类种群动态的影响还没有得到实验评估。本研究将在这些保护区繁殖的五种受保护鸟类 1994–2018 年的种群动态与配对的鸟类繁殖调查获得的反事实动态进行了比较。我们比较了保护区鸟类种群动态与三种反事实动态, 这些反事实动态是基于保护区种群在没有保护的情况下如何发展的不同情景假设。结果表明, 研究关注的四种涉禽:凤头麦鸡 (Vanellus vanellus) 、红脚鹬 (Tringa totanus) 、白腰杓鹬 (Numenius arquata) 和扇尾沙锥 (Gallinago gallinago) 的保护措施均取得了积极成效, 而对保护区中雀形目鸟类黄鹡鸰 (Motacilla flava) 的保护干预没有积极作用。我们的方法利用监测数据产生了可靠的反事实对照, 是一种可用于大规模评估保护影响的广适性方法。【翻译: 胡怡思; 审校: 聂永刚】
Article impact statement: Post hoc quasi‐experimental analysis shows that wet grassland conservation has positively affected targeted breeding bird populations.
The global biodiversity crisis has sparked a rise in conservation actions. However, the impact of conservation actions on species' populations is often not evaluated. In particular, studies of the ...impact of large-scale conservation, such as area protection or national legislation aimed at safeguarding biodiversity, on population trends remain poorly represented in the scientific literature. The resulting limited knowledge of conservation effectiveness potentially hinders effective evidence-based decision making and leads to suboptimal conservation outcomes. Here, I collate longitudinal records of vertebrate abundance, conservation interventions and ancillary information to measure the impact of conservation on species' populations across different spatial and temporal scales. Specifically, I estimate the impact of lowland wet grassland reserves on breeding trends of wading birds in the United Kingdom by creating counterfactual reserve trends from national monitoring records collected by volunteers. This demonstrates that lowland wet grassland reserves have a positive impact on targeted species of wading birds. To understand the drivers of breeding abundance within these reserves, I combine local management records with climatic variables and breeding counts and use a Bayesian mixed modelling framework to estimate the association between conservation actions, site-specific conditions and annual breeding abundance for four wading bird species. The resulting estimates show that breeding abundance associates with different factors for the four species and provides new information on conservation effectiveness that can be used to inform local reserve management. Last, I explore the impact of conservation actions on trends in vertebrate populations worldwide. I categorize conservation actions for more than 26,000 populations, create counterfactual population indices representing how populations may have developed in the absence of conservation, calculate the impact of conservation on a global population index, and estimate how specific conservation actions relate to population changes. I show that conservation benefits targeted vertebrate populations, that in the absence of conservation, a global index of vertebrate abundance could have declined in addition to what is currently observed and that, in particular, conservation through species and land & water management has a positive impact on targeted populations. The methods developed and applied in this thesis demonstrate how to estimate the impact of conservation actions on species' populations. This work also highlights the potential of longitudinal abundance records for evaluating conservation impact and emphasizes the importance of large-scale monitoring programmes.
Breeding populations of many wading birds have declined globally, primarily caused by habitat degradation and loss. In the UK, population declines have been particularly notable on lowland wet ...grasslands. In response, some areas of lowland wet grassland have been restored and are under ongoing management to improve the breeding conditions of target species. Here, we assess the efficacy of management measures using a Bayesian framework and controlling for confounding factors. We focus on four wader species, Northern Lapwing Vanellus vanellus, Eurasian Curlew Numenius arquata, Common Snipe Gallinago gallinago and Common Redshank Tringa totanus, that breed in numbers on wet grassland reserve sites in the UK. We collated annual site‐specific climate variables, management information (e.g. the creation of wet features and predator control measures) and bird counts between 1994 and 2018. We found the effects of conservation actions varied between intervention types and species. For Lapwing and Redshank, excluding predators by predator‐exclusion fencing, especially in combination with fox control, was generally associated with higher breeding counts. For all study species, sites with longer histories of management were associated with higher breeding numbers, with the effect of site age being particularly notable for management on former arable land. Our findings support the effectiveness of targeted conservation actions to achieve high numbers of breeding waders on lowland wet grassland reserves, and also highlight the value of consistent and reliable monitoring data.
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