Hampshire and Isle of Wight Butterfly and Moth Society
Hampshire and Isle of Wight Butterfly and Moth Society
| Family: | Lycaenidae |
| Subfamily: | Theclinae |
| Genus: | Thecla |
| Species: | betulae |
| Authority: | (Linnaeus, 1758) |
This is the largest hairstreak found in the British Isles. It is a local species that lives in self-contained colonies that breed in the same area year after year. This species can also prove elusive, since it spends much of its time resting and basking high up in tall shrubs and trees. The female is particularly beautiful, with forewings that contain large orange patches, and was once considered to be a separate species known as the "Golden Hairstreak". This species is found in the southern half of England and Wales, and also around the Burren in Ireland. In England its strongholds are in West Sussex, Surrey, Oxfordshire, Buckinghamshire, North Devon and South Devon. Strongholds in Wales are in Cardiganshire and Carmarthenshire. In Ireland it is primarily found in the Burren limestones of Clare and South-east Galway. The northernmost sites are found in North Lincolnshire.
| #Individuals | #Tetrads | 2023 | 2024 | Abundance Trend | 2023 | 2024 | Distribution Trend |
|---|---|---|---|---|---|
| 922 | 98 | -89% | 42 | 69 | +64% |
| #Records | #Individuals | Earliest Record | Latest Record | |
|---|---|---|---|---|
| All Records | 1,611 | 5,444 | 18/07/2017 & 2018 | 16/10/1986 |
| 2024 | 198 | 98 | 29/7/2024 | 20/9/2024 |
| Location | Date | Quantity | |
|---|---|---|---|
| Earliest Record | Portsdown Hill | 29/7/2024 | 1 |
| Latest Record | Noar Hill | 20/9/2024 | 1 |
| Highest Count | Noar Hill | 20/8/2024 | 34 |
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: 23.6
Average #Recorders: 23.6