Spring is on its way Grahams recent post of Platycheirus albimanus got me thinking about when we might realistically start to expect a regular flow of hovers. We know that several species occur throughout the winter as various previous analyses have shown. BUT, when does the spring really start in various parts of the country? Platycheirus albimanus is quite a nice species to look at because it is one of the first flush of hoverflies that often occur vast numbers (with Melanostoma scalare). What I had initially intended to show was the relative timings of spring, but the graph that resulted was rather more interesting. It not only showed how northern England and Scotland was about a month behind the south, but also showed how there are much more pronounced generations the further one goes north. In essence it is almost continuously brooded in southern England but in the north there are clear spring and summer generations. This is not wholly unexpected as we know that several butterfly species have only a single generation in the north. What IS nice to see is that even with relatively low numbers of records from photography we can pick up very strong differences. This helps to show just how important it is to record all species as thoroughly as possible - I wonder what else we will pick up over time? Maybe three weeks to go in the south before we start to see hovers regularly. I fear that members in the north will be champing at the bit by mid-March when the spring finally stirs.
Posted on: Sun, 25 Jan 2015 11:56:03 +0000
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