Pictured: clouded yellow, Colias croceus
200-year trend in Cambridgeshire: Little change.
Modern records
Jenyns’ notes show that as with today, this species was visiting Cambridgeshire nearly 200 years ago. The clouded yellow is a regular migrant from Europe but as with all of our migrant butterflies, numbers can vary by a large amount year on year. Occasionally, huge ‘bumper years’ are recorded, where hundreds or even thousands of individual butterflies make the journey across the channel. In former times fields of leguminous plants such as clover and lucerne would have supported temporary breeding populations, but this species did not survive British winters until a few very recent examples were discovered on the south coast, indicative of climate-change related range expansion.
National records map
Clouded yellow national records map: https://species.nbnatlas.org/species/NHMSYS0000501953
Pale clouded yellow, Colias hyale
200-year trend in Cambridgeshire: Little change, possible slight decline.
Modern records
This migratory species is much rarer than the closely related clouded yellow, Colias croceus. It is also very hard to distinguish from a pale ‘helice’ form of Colias croceus, as well as another very closely related species, the Berger’s clouded yellow, which was only recognised in 1945. Therefore, some historical records are likely misidentifications, and could potentially represent any of these three species. Taking ‘many’ specimens, as recorded in Jenyns’ notes, was probably not a common occurrence and as today, pale and Berger’s clouded yellow butterflies were likely very rare in most years.
National records map
Pale clouded yellow national records map: https://species.nbnatlas.org/species/NHMSYS0000501954
Berger’s clouded yellow national records map: https://species.nbnatlas.org/species/NHMSYS0021143487
