The impact of data quality filtering of opportunistic citizen science data on species distribution model performance

Opportunistically collected species occurrence data are often used for species distribution models (SDMs) when high-quality data collected through standardized recording protocols are unavailable. While opportunistic data are abundant, uncertainty is usually high, e.g. due to observer effects or a lack of metadata. To increase data quality and improve model performance, we filtered species records based on record attributes that provide information on the observation process or post-entry data validation. Data filtering does not only increase the quality of species records, it simultaneously reduces sample size, a trade-off that remains relatively unexplored. By controlling for sample size in a dataset of 255 species, we were able to explore the combined impact of data quality and sample size on model performance. We applied three data quality filters based on observers' activity, the validation status of a record in the database and the detail of a submitted record, and analyzed changes in AUC, Sensitivity and Specificity using Maxent with and without filtering. The impact of stringent filtering on model performance depended on (1) the quality of the filtered data: records validated as correct and more detailed records lead to higher model performance, (2) the proportional reduction in sample size caused by filtering and the remaining absolute sample size: filters causing small reductions that lead to sample sizes of more than 100 presences generally benefitted model performance and (3) the taxonomic group: plant and dragonfly models benefitted more from data quality filtering compared to bird and butterfly models. Our results also indicate that recommendations for quality filtering depend on the goal of the study, e.g. increasing Sensitivity and/or Specificity. Further research must identify what drives species' sensitivity to data quality. Nonetheless, our study confirms that large quantities of volunteer generated and opportunistically collected data can make a valuable contribution to ecological research and species conservation

Poperinge, Sint-Janscollege (W.-Vl.): een eeuwenlange pottenbakkerijsite. Eindverslag van een toevalsvondst oude regelgeving

De uitbreiding van het gebouwenbestand van het Sint-Janscollege aan het Burgemeester Bertenplein in Poperinge noopte in 2015 gedurende een maand tot een uitgebreid toevalsvondstonderzoek. Dit terrein bevond zich op het achtererf van pottenbakkerij Dupont die tot in 1975 actief bleef. De vroegste vermelding van de potterie dateert uit 1543. De onderzochte zone, de achterzijde van het perceel, kreeg pas in de loop van de 19de eeuw permanente bewoning. De oudste aangetroffen muren zijn wellicht de restanten van de kleiwerkplaats die hier rond 1850 werd opgericht. Vóór 1850 was dit een open zone vol kuilen en depressies waar afval van de pottenbakkerijsite werd gestort. De vele kuilen, depressies en lagen leverden een enorme hoeveelheid vondstmateriaal op, vooral aardewerk. Het betreft zowel huishoudelijk gebruiksaardewerk, bouwkeramiek als productiematerieel. De bestudeerde contexten vertegenwoordigen drie tijdsblokken: 14de vroege 15de eeuw, tweede helft 15de vroege 16de eeuw, en 18de eeuw. De gedetailleerde aardewerkstudie leverde niet alleen inzichten op over deze Poperingse pottenbakkerijsite, haar evolutie en de pottenbakkersactiviteiten zelf. Minstens even belangrijk is de bijdrage over de evolutie van de aardewerkproductie in de regio, over verschillende periodes van de 14de eeuw tot in de 18de eeuw heen

The 3-D reconstruction of medieval wetland reclamation through electromagnetic induction survey

Studies of past human-landscape interactions rely upon the integration of archaeological, biological and geological information within their geographical context. However, detecting the often ephemeral traces of human activities at a landscape scale remains difficult with conventional archaeological field survey. Geophysical methods offer a solution by bridging the gap between point finds and the surrounding landscape, but these surveys often solely target archaeological features. Here we show how simultaneous mapping of multiple physical soil properties with a high resolution multi-receiver electromagnetic induction (EMI) survey permits a reconstruction of the three-dimensional layout and pedological setting of a medieval reclaimed landscape in Flanders (Belgium). Combined with limited and directed excavations, the results offer a unique insight into the way such marginal landscapes were reclaimed and occupied during the Middle Ages. This approach provides a robust foundation for unravelling complex historical landscapes and will enhance our understanding of past human-landscape interactions

Waarnemingen.be : non-native plant and animal occurrences in Flanders and the Brussels Capital Region, Belgium

Citizen scientists make important contributions to the collection of occurrence data of non-native species. We present two datasets comprising more than 520,000 records of 1,771 non-native species from Flanders and the Brussels Capital Region in Belgium, Western Europe, collected through the website http://www.waamemingen.be hosted by Stichting Natuurinformatie and managed by the nature conservation NGO Natuurpunt. Most records were collected by citizen scientists, mainly since 2008. Waarnemingen.be aims at recording all species, native and non-native, and it is shown here that this kind of biodiversity portals are also particularly well suited to collect large amounts of data on non-native species. Both datasets presented here are also discoverable through the Global Biodiversity Information Facility (GBIF)

Wintering bird communities are tracking climate change faster than breeding communities

Global climate change is driving species' distributions towards the poles and mountain tops during both non-breeding and breeding seasons, leading to changes in the composition of natural communities. However, the degree of season differences in climate-driven community shifts has not been thoroughly investigated at large spatial scales. We compared the rates of change in the community composition during both winter (non-breeding season) and summer (breeding) and their relation to temperature changes. Based on continental-scale data from Europe and North America, we examined changes in bird community composition using the community temperature index (CTI) approach and compared the changes with observed regional temperature changes during 1980-2016. CTI increased faster in winter than in summer. This seasonal discrepancy is probably because individuals are less site-faithful in winter, and can more readily shift their wintering sites in response to weather in comparison to the breeding season. Regional long-term changes in community composition were positively associated with regional temperature changes during both seasons, but the pattern was only significant during summer due to high annual variability in winter communities. Annual changes in community composition were positively associated with the annual temperature changes during both seasons. Our results were broadly consistent across continents, suggesting some climate-driven restructuring in both European and North American avian communities. Because community composition has changed much faster during the winter than during the breeding season, it is important to increase our knowledge about climate-driven impacts during the less-studied non-breeding season.Peer reviewe

African savanna raptors show evidence of widespread population collapse and a growing dependence on protected areas

The conversion of natural habitats to farmland is a major cause of biodiversity loss and poses the greatest extinction risk to birds worldwide. Tropical raptors are of particular concern, being relatively slow-breeding apex predators and scavengers, whose disappearance can trigger extensive cascading effects. Many of Africa’s raptors are at considerable risk from habitat conversion, prey-base depletion and persecution, driven principally by human population expansion. Here we describe multiregional trends among 42 African raptor species, 88% of which have declined over a ca. 20–40-yr period, with 69% exceeding the International Union for Conservation of Nature criteria classifying species at risk of extinction. Large raptors had experienced significantly steeper declines than smaller species, and this disparity was more pronounced on unprotected land. Declines were greater in West Africa than elsewhere, and more than twice as severe outside of protected areas (PAs) than within. Worryingly, species suffering the steepest declines had become significantly more dependent on PAs, demonstrating the importance of expanding conservation areas to cover 30% of land by 2030—a key target agreed at the UN Convention on Biological Diversity COP15. Our findings also highlight the significance of a recent African-led proposal to strengthen PA management—initiatives considered fundamental to safeguarding global biodiversity, ecosystem functioning and climate resilience

Effects of drought on birds in the Kalahari, Botswana

Results are presented from point-counts at six sites in the Kalahari in Botswana. Counts were repeated three times: during a dry season following good rains (1991), during the next wet season when rains were far below average, and the following dry season (1992) when the area became drought-stricken. Compared to the wet season, bird numbers decreased during the drought by 37–81% and species by 8–52%; compared to the previous dry season, birds decreased by 5–71% and species by 2–47%. Bird diversity (relative to numbers) tended to increase during the wet season but was little affected by drought, except in the northern Kalahari, where a greater proportion of birds moved out in response to drought. This gave the northern Kalahari the most distinct bird community during a wet cycle, but it became again typically Kalahari during the drought. Thus, the typical Kalahari bird communities expanded their range during drought into the moister periphery. Changes in numbers, most probably resulting from (local) movements were found in many species. Most confirmed earlier reports on their nomadic nature but some, like Red-crested Lophotis ruficrista and Northern Black Afrotis afraoides Korhaan, Chestnut-vented Tit-Babbler Parisoma subcaeruleum, Ant-eating ChatMyrmecocichla formicivora, Tinkling Cisticola Cisticola rufilatus, Black-chested Prinia Prinia flavicans, Marico Flycatcher Bradornis mariquensis and Brown-crowned Tchagra Tchagra australis have not been or are not widely recognised as mobile species. Ostrich 2004, 75(4): 217–22

Major concentrations of river warbler Locustella fluviatilis wintering in northern Botswana

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Citizen science and smartphones take roadkill monitoring to the next level

Road networks, even in industrialized countries, become denser year after year and traffic volumes continue to increase at a steady pace. It is imperative that we monitor the impact of this trend on wildlife, but monitoring roads for flattened fauna is a time consuming effort and roadkill monitoring projects conducted up till now have been relatively small scale both in terms of time and space. This hampers the progress of road ecology analyses at the population level and at larger landscape extents. We demonstrate that citizen science projects in combination with smartphones and other new technologies allow analysis at this level and extent, and simultaneously offer more complete data for safer transportation and mitigation of roadkill hotspots. Monitoring roadkill with citizen scientists poses certain challenges regarding data quality and people management, but we show that these challenges can be addressed, which allows researchers to benefit from the many other advantages and possible applications of monitoring roadkill with citizen scientists, including raising public awareness on the matter