One of the most important geographical bottlenecks for migrating raptors in the east African-Palearctic migration system is situated between the easternmost tip of the Black Sea and the Lesser Caucasus, just north of Batumi, in the Republic of Georgia (Verhelst et al. 2011).
Since 2008 citizen scientists of the Batumi Raptor Count(BRC) monitor the autumn raptor passage daily from mid August till mid October, collecting also detailed information about the age and sex of focal species. These data are included in the BRC dataset. This dataset offers a unique baseline for monitoring the state of migrant raptor populations in the east African-Palearctic flyway in the 21st century.
Each season a large number of raptors are counted during the autumn migration count. The numbers fluctuate around the million individuals in each season. This dataset represent the data during the 2008-2017 seasons. A detailed description of the BRC migration count protocol, data management strategy, and the open access BRC dataset in GBIF are provided by Wehrmann et al. (2019). This dataset has been used to analyse changes in the abundance and demography of eight abundant raptor species at BRC between 2011-2017. The resulting research paper is currently in 2nd review and will be shared through this webpage immediately upon publication.
此資源sampling event的資料已發佈為達爾文核心集檔案（DwC-A），其以一或多組資料表構成分享生物多樣性資料的標準格式。 核心資料表包含 725 筆紀錄。
亦存在 2 筆延伸集的資料表。延伸集中的紀錄補充核心集中紀錄的額外資訊。 每個延伸集資料表中資料筆數顯示如下。
Wehrmann J, de Boer F, Benjumea R, Cavaillès S, Engelen D, Jansen J, Verhelst B, Creuwels JCS, Vansteelant WMG (2018): Batumi Raptor Count (BRC) - Autumn migration data. v1.2. Batumi Raptor Count. Dataset/Samplingevent. http://ipt.nlbif.nl/resource?r=brc-autumn_migration_counts&v=1.2
此資料的發布者及權利單位為 Batumi Raptor Count。 To the extent possible under law, the publisher has waived all rights to these data and has dedicated them to the Public Domain (CC0 1.0). Users may copy, modify, distribute and use the work, including for commercial purposes, without restriction.
Occurrence; Autumn migration; raptor; African-Palearctic flyway; monitoring
- 出處 ●
The bottleneck is situated at the narrowest point between the eastern coast of the Black Sea and the foothills of the Lesser Caucasus, just to the north of the city of Batumi, in the Republic of Georgia.
|緯度南界 經度西界 [41.684, 41.699], 緯度北界 經度東界 [41.688, 41.802]
Soaring birds and few others such as Roller
|Coracias garrulus (European Roller), Streptopelia turtur (European turtle dove), Ciconia ciconia (White Stork), Ciconia nigra (Black Stork)
|mid Aug to mid Oct annually from 2008 till present.
Since 2008 citizen scientists of the Batumi Raptor Count(BRC) monitor the autumn raptor passage daily from mid August till mid October, collecting also detailed information about the age and sex of focal species. Counts are focused on high-quality data for monitoring of target species, and for which species we can provide high-quality data useful for trend analyses.
|Batumi Raptor Counts - Autumn migration data
|NLBIF partly funded publication and processing of the BRC dataset to GBIF
|The two count stations are located on hilltops with unobstructed view facing north into the landscape, and within visible range from each other. Locations are the villages Sakhalvasho and Shuamta, North of Batumi, in the Republic of Georgia, between the easternmost tip of the Black Sea and the Lesser Caucasus.
|Migration counts are performed simultaneously from two count stations to cover the approximately 12km long transect line.
Daily counts from 17st August till 16st October. The daily count period starts at one hour after sunrise and ends two hours before sunset. Counts consisted of continuous monitoring during the count period and recording all occurrences.
|The villages Sakhalvasho and Shuamta, North of Batumi, in the Republic of Georgia.
|Counts are conducted by experienced and less experienced bird-watchers that volunteer to count at least two weeks. Count-coordinators screen, select and schedule volunteers such that each station can be staffed by a team consisting of one coordinator and 6 to 12 counters, depending on migration intensity, diversity and also counter availability. We try to enter records always immediately to enable the double count detection in later phase. Digital photography has become an important tool to aid identification of easily confused species.
- At the end of each day count-coordinators go through the records to check for major errors (using simple criteria such as large flocks of rare birds, or specific age and sex combinations), and where possible correct them by discussing these observations with their daily count team. Observations that are suspect due to insufficient information (for example, a large eagle cannot be identified without being aged) are degraded to a less specific level (large eagle spec.).
- At the end of each season the data is verified with an automated script in the open source R software (R Core Team 2017) that validates each single record, ensures count protocol integrity and changes the identification of the species-level of those records with insufficient information.
- An important final step in the production of the NLBIF data product is to detect all double counts in the overlapping count zones between the two stations. An automated procedure written in R detects potential double counts in different spatial and temporal windows for different species.
- Wehrmann J, de Boer F, Benjumea R, Cavaillès S, Engelen D, Jansen J, Verhelst B, Vansteelant WMG (2019) Batumi Raptor Count: autumn raptor migration count data from the Batumi bottleneck, Republic of Georgia. ZooKeys 836: 135-157. https://doi.org/10.3897/zookeys.836.29252
- Verhelst B, Jansen J, Vansteelant WMG (2011) South West Georgia: an important bottleneck for raptor migration during autumn. Ardea 99: 137–146. https://doi.org/10.5253/078.099.0203
Information about killed and injured birds during the Autumn raptor monitoring is given in the extension ExtendedMeasurementOrFact. Due to a technical error (which is under review at GBIF) this extension does not automatically link data in this extension with the occurrence dataset. Therefore these data will not be shown at the GBIF portal. However, these data can be retrieved from DwCA in the file "extendedmeasurementorfact.txt".
|Monitoring the abundance, demography and timing of migrant raptors and selected threatened species in the East African-Palearctic flyway. In addition the data collected may be useful for studying the influence of weather on diel and seasonal migration dynamics of soaring birds.
|Dataset is annually maintained.