| 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 |
---|---|---|---|---|---|---|---|---|
Northward migration | 2800 | 1001 | 153 | 3000 | 3000 | 7730 | 22,432 | 21,745 |
12 May | 10 Apr | 3 May | 7 May | 13 May | 7 May | 13 May | 12 May | |
Southward migration | 800 | 700 | 500 | 10 | 1000 | 511 | 3640 | 6537 |
22 Jul | 1 Aug | 25 Jul | 19 Aug | 17 Jul | 11 Aug | 18 Aug | 4 Aug |