Phenology
| Year | Migration site | First | Migration site | Last | |||||
|---|---|---|---|---|---|---|---|---|---|
| 2021 | Maasvlakte II | 12 January | Maasvlakte II | 12 January | |||||
| 2019 | Maasvlakte II | 20 January | Maasvlakte II | 20 January | |||||
| 2018 | Maasvlakte II | 16 December | Maasvlakte II | 16 December | |||||
| 2016 | Maasvlakte II | 2 November | Maasvlakte II | 27 November | |||||
| 2015 | Maasvlakte II | 21 November | Maasvlakte II | 21 November | |||||
| 2013 | Maasvlakte II | 17 March | Maasvlakte II | 6 September | |||||
| 2012 | Maasvlakte II | 28 October | Maasvlakte II | 28 October |
