Hampshire and Isle of Wight Butterfly and Moth Society
Hampshire and Isle of Wight Butterfly and Moth Society
| Family: | Pieridae |
| Subfamily: | Coliadinae |
| Genus: | Colias |
| Species: | croceus |
| Authority: | (Geoffroy, 1785) |
The Clouded Yellow is primarily an immigrant to the UK, originating from north Africa and southern Europe, with numbers varying greatly from year to year - an estimated 36,000 butterflies appearing in one of the infrequent "Clouded Yellow" years in 1947. In more recent years, it has been shown that this species has successfully overwintered in the south of England. However, it is believed that the majority of individuals perish, since both larva and pupa of this continuously-brooded species are easily killed by damp and frost. In good years this species can produce up to 3 generations in the UK. In flight, this species is often mistaken for one of the commoner "whites", but the orange-yellow colour is quite distinctive, even in flight, and unlike any other species. The Clouded Yellow has a distribution befitting a highly-migratory species, and can be found anywhere in the British Isles. Many immigrants remain near the coast where they feed, mate, and lay eggs. Others disperse inland and this species is found in both Scotland and Ireland in good years.
| #Individuals | #Tetrads | 2022 | 2023 | Abundance Trend | 2022 | 2023 | Distribution Trend |
|---|---|---|---|---|---|
| 8788 | 202 | -97% | 206 | 85 | -58% |
| #Records | #Individuals | Earliest Record | Latest Record | |
|---|---|---|---|---|
| All Records | 6,990 | 20,704 | 08/05/2005 | 30/12/2007 |
| 2023 | 158 | 202 | 23/3/2023 | 24/10/2023 |
| Location | Date | Quantity | |
|---|---|---|---|
| Earliest Record | Boscombe | 23/3/2023 | 1 |
| Latest Record | Hook with Warsash | 24/10/2023 | 1 |
| Highest Count | Revetment, Ventnor | 2/9/2023 | 6 |
One of the issues with 'raw' trend data is that there is inherent bias based on the number of recorders. For example, the number of individuals and populated tetrads recorded are likely to increase if there is an increase in the number of recorders. In order to remove this bias, the normalised trends use data that has been recalculated using the average number of recorders over the trend period. This normalisation gives a much better picture of the true trends.
Average #Recorders: 84.8
Average #Recorders: 84.8