Abstract
Opportunistic reporting of species observations to online platforms provide one of the most extensive sources of information about the distribution and status of organisms in the wild. The lack of a clear sampling design, and changes in reporting over time, leads to challenges when analysing these data for temporal change in organisms. To better understand temporal changes in reporting, we use records submitted to an online platform in Sweden (Artportalen), currently containing 80 million records. Focussing on five taxonomic groups, fungi, plants, beetles, butterflies and birds, we decompose change in reporting into long-term and seasonal trends, and effects of weekdays, holidays and weather variables. The large surge in number of records since the launch of the, initially taxa-specific, portals is accompanied by non-trivial long-term and seasonal changes that differ between the taxonomic groups and are likely due to changes in, and differences between, the user communities and observer behaviour.
Highlights
MethodsThe Swedish Species Observation System (Artportalen; https://www.artportalen.se/) is a web portal and database to which the public can submit reports of species observations across taxa from plants to animals, covering all multicellular taxa, currently holding 80 million records
Online portals through which volunteers submit reports of observations of wildlife gather large amounts of data worldwide. The majority of such species occurrence data are collected opportunistically with little or no underlying sampling design, but often with much higher temporal and spatial resolution compared to designed studies
To improve biological inference about temporal change from opportunistic data, we argue that several steps will be necessary
Summary
The Swedish Species Observation System (Artportalen; https://www.artportalen.se/) is a web portal and database to which the public can submit reports of species observations across taxa from plants to animals, covering all multicellular taxa, currently holding 80 million records. There is no requirement on adhering to any specific sampling design: observers choose which species to report, where to observe them, when, and what amount of time and effort to devote. These aspects of the data imply that the vast majority of data can be called ‘opportunistic’. Some data from systematic surveys, with varying degrees of standardisation, are submitted
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