Sussex Branch

There is always something rather special about first sightings, whether the first Primroses, the first Swallows, and for our Sussex BC members we can also include the first butterfly sightings of the season. This is especially so for spring species such as Orange-tip, as it gives us hope that the cold winter months are now firmly behind us. But are the winter months “cold”, anymore? With climate change there is a firm expectation of mild, wet winters and (hopefully) warm, sunny springs and summers. As regards sunshine and warmth, the year 2025 has exceeded all expectations, and is probably “the best year” for butterfly-watching we have had, so far, in this 21st century.

The spring of 2025 was the sunniest and driest since weather records began, and also the fifth warmest, ever. This exceptional weather resulted in many butterfly species emerging 2-3 weeks earlier than the median-average for the years 2007-2025.

Why 2007-2025, when we have previously used 2006-2024 as our reference? We do have data for 2006 (the original website was created, that year) but looking back at the records it is apparent that there were very few posts in the early part of that year, and therefore large gaps in the data. The same problems apply to the Covid year of 2020 and therefore the records for 2006 and 2020 have been omitted from any analysis.

The following graphs show the “first-ever sighting date”, followed by the “median-average sighting date”, and then finally the “latest, first-sighting date”. The red circle tells us when we recorded our first sighting in 2025. With few exceptions they were very early!