What a great summer

13th October 2009, Tuesday

Looking through the results of a number of timed bumblebee walks this summer it is interesting to compare different sites.  The most productive in terms of numbers of bumblebees were the walks on fields sown with agricultural red clovers.  These monocultures produced very high counts of bumblebees, with an average of three bumblebees encountered per minute in the best fields.  This compared with only 0.8 bumblebees per minute on the best natural grasslands, at the Dungeness RSPB reserve.

Although these fields might be expected to favour the long-tongued bumblebees it was notable that the most common bee in these fields was the short-tongued buff-tailed bumblebee Bombus terrestris.  They did seem to be very good for the bees that burrow underground to nest, including the long-tongued garden bumblebee Bombus hortorum

So if these fields are so good, why bother to enhance wild-flower meadows if they support only one eighth of the numbers of bees?  Well from a practical point of view agricultural red clover leys need resowing every 2-3 years, unlike a wild meadow. Furthermore meadows, such as the one below, contain a much wider range of plants and are therefore likely to appeal to more species of invertebrates.  The scarcer ground nesting carder bbes, which nest above ground in grassy tussocks also seem to do better in these habitats.

In reality a mix of both habitats is probably the ideal.

One memory that comes back looking at these photos are the large numbers of insects flying around the fields this year.  It really was a good summer!