Challenges and benefits of using unstructured citizen science data to estimate seasonal timing of bird migration across large scales

Millions of bird observations have been entered on online portals in the past 20 years either as checklists or arbitrary individual entries. While several hundred publications have been written on a variety of topics based on bird checklists worldwide, unstructured non-checklist observations have received little attention and praise by academia. In the present study we tested the suitability of non-checklist data to estimate key figures of large-scale migration phenology in four zones covering the whole of Finland. For that purpose, we analysed 10 years of ornithological non-checklist data including over 400 million. individuals of 115 bird species. We discuss bird- and human-induced effects to be considered in handling non-checklist data in this context and describe applied methodologies to address these effects. We calculated 5%, 50% and 95% percentile dates of spring and autumn migration period for all species in all four zones. For validation purposes we compared the temporal distributions of 43 bird species with migration phenology from standardized long-term ringing data in autumn of which 24 species (56%) showed similar medians. In a model approach, non-checklist data successfully revealed latitudinal migration progression in spring and autumn. Overall, non-checklist data proved to be well suited to determine descriptors of migration phenology in Northern Europe which are challenging to attain by any other currently available means. The effort-to-yield ratio of data processing was commensurate to the outcomes. The unprecedented spatiotemporal coverage makes non-checklist data a valuable complement to current migration databases from bird observatories. The basic concept of the present methodology is applicable to data from other bird portals, if combined with local field ornithological knowledge and literature. Species-specific descriptors of migration phenology can be potentially used in climate change studies and to support echo interpretation in radar ornithology.

Estimation of the Autumn Migration Pattern of Passerines within the SE European Flyway by Orientation Cage Tests

The general migration pattern of passerines can be estimated using a variety of methods. A number of partial analyses based on ringing data, usually limited to a few species, have been published. A very few continent-scale presentations have been offered, as extremely long periods of ringing activity are necessary for passerines. This is especially true for areas where the recovery rate is very low, including vast areas of north-eastern and eastern Europe and the Middle East/Africa. Similarly, radar and moon-watching studies are of limited value for drawing migration patterns within wider areas. Radar studies require good coverage by the radar systems, while weather radar distribution density and the level of evaluation are very uneven. Modern logger and satellite tracking are more applicable to non-passerines, and as yet enable detailed study only of limited numbers of individuals, and not population studies. At the end of the 20th century, a very simple tool was introduced for field studies on the preferred headings of individual birds caught for ringing, i.e. the use of flat orientation cages. This method was introduced as a standard within the SEEN (SE European Bird Migration Network) in 1995. This study presents a preliminary large-scale evaluation of the data collected within this project. The database used contains more than 43,000 orientation tests performed at 45 ringing sites. The area covered stretches from the northern part of western Russia to southern Egypt and from Italy and Poland to Siberia and Armenia. Eight streams of migration are identified within this area, creating a fairly complicated pattern of avian movements.

Using large-scale citizen science ringing data as a means of calculating maximum longevity in birds

This article calculates estimates of avian longevity for southern African Passeriformes and demonstrates the impact citizen scientists have on data volumes curated by the South African Bird Ringing Unit (SAFRING). We calculated taxon-specific longevity records for 341 species from 33 families using ringing data collected between 1948 and 2017. An increase in active ringer participation over time correlated positively with an increase in retrap and recovery data, allowing for more reliable longevity calculations. These results highlight the significant contribution citizen scientists have made to bird ringing in southern Africa and identify data-deficient taxa to which future ringing activities should be targeted.

Sarcocystis rileyi emerging in Hungary: is rice breast disease underreported in the region?

Reports of Sarcocystis rileyi-like protozoa (‘rice breast disease’) from anseriform birds had been rare in Europe until the last two decades, when S. rileyi was identified in northern Europe and the UK. However, despite the economic losses resulting from S. rileyi infection, no recent accounts are available on its presence (which can be suspected) in most parts of central, western, southern and eastern Europe. Between 2014 and 2019, twelve mallards (Anas platyrhynchos) were observed to have rice breast disease in Hungary, and the last one of these 12 cases allowed molecular identification of S. rileyi, as reported here. In addition, S. rileyi was molecularly identified in the faeces of one red fox (Vulpes vulpes). The hunting season for mallards in Hungary lasts from mid-August to January, which in Europe coincides with the wintering migration of anseriform birds towards the south. Based on this, as well as bird ringing data, it is reasonable to suppose that the first S. rileyi-infected mallards arrived in Hungary from the north. on the other hand, red foxes (Vulpes vulpes), which are final hosts of S. rileyi, are ubiquitous in Hungary, and our molecular finding confirms an already established autochthonous life cycle of S. rileyi in the region. Taken together, this is the first evidence for the occurrence of S. rileyi in Hungary and its region.

Hitchhikers’ guide to analysing bird ringing data

This paper is the third part of our bird ringing data analysis series (Harnos et al. 2015a, 2016a) in which we continue to focus on exploring data using the R statistical environment. Here, we give a short description of missing data patterns, then handling and visualization techniques that help simultaneously explore the data and the structure of missing values. We try to emphasize that missing data can seriously distort the results of the analyses, therefore the conclusions drawn.