| Observationsplats | C.V. (recr.)% | Recruitment series | |
|---|---|---|---|
| Begin | End | ||
| Black Brows Beck | 34.8 | 1967 | 1991 |
| Black Brows Beck | 53.7 | 1967 | 1991 |
| Black Brows Beck | 38.2 | 1967 | 1989 |
| Black Brows Beck | 75.4 | 1967 | 1991 |
| Black Brows Beck | 92.9 | 1967 | 1991 |
| Wilfin Beck, Aug/Sept | 36.8 | 1966 | 1972 |
| Wilfin Beck, Aug/Sept | 37.1 | 1966 | 1972 |
| Wilfin Beck, May/June | 25.5 | 1966 | 1972 |
| Wilfin Beck, May/June | 24.4 | 1966 | 1972 |