The Red Admiral in Dorset

The red admiral must be one of the most instantly recognisable of British butterflies; it is a familiar sight in gardens, parks and open countryside. It is so familiar that one would think this was a resident species but it is not, it is a migrant arriving in May and June having travelled from north Africa. These early arrivals lay eggs once they arrive and these hatch in to adults later in the summer but numbers are also continually boosted by new arrivals, especially in late summer, and it is from late August through until October that they seem to be most numerous. There is some evidence to suggest that some return back across the channel to mainland Europe as the autumn turns to winter, other succumb to the severe winter conditions and some find sheltered places to hibernate. These hibernating insects will often awake on warmer days in winter and that accounts for why you can actually see them in even January and February.

The red admiral is one of the most regularly reported butterflies in the Nature of Dorset database with ninety five reports in 2017 and 2018 combined. What is remarkable perhaps is that there are records every month from February 2017 through until December 2018 without a break. This demonstrates that some successfully over winter here on the south coast especially as the last two winters have been relatively mild. For much of the year there are just odd reports in most weeks but in September and October the number of reports surges to reflect the combination of more incoming migrants as well as emerging new adults from the eggs laid by the early arrivals.

You can encounter red admiral just about anywhere in Dorset with nearly 120 sites reporting them but if you look at the sites where the most are recorded you will see they are all coastal which shows they are most frequently seen arriving or preparing to leave, often in autumn.