Sunday, 25 May 2014

The first bioblitz of the year!

Last weekend was a busy one.  Saturday was the first ever Shotover Conference, celebrating almost 200 years of biological recording at Shotover Country Park, a fantastic SSSI to the northeast of Oxford (and the setting for a previous blog post!).  Then it was over to south Northamptonshire for my first BioBlitz of the year, an invitation-only event at Halse Copse, run by the Northamptonshire Biological Records Centre.  For those who haven't yet encountered a BioBlitz, the best way to think of it is like Time Team for wildlife - the aim is to find as many species as possible in (roughly) 24 hours, and generally showing the general public just what natural riches can be found on their doorstep.

There was a reason we were at Halse Copse in particular: the two patches of ancient woodland and associated meadows are right in the path of the projected route of HS2.  Historically under-studied, the record centre held records for just 171 species in the Local Wildlife Sites, making them (apparently) much less biodiverse than my garden - which just goes to show the value of surveying thoroughly!  The BioBlitz was an attempt to get a better picture of the diversity in line to be destroyed.
Hard at work adding to the insect numbers...
Once we got to the site, it was immediately clear that the 171 species so far were a massive understatement.  A couple of hours (before lunch!) surveying the first meadow generated 105 species records in my notebook, plus a good number of beetles and bugs as yet unidentified.  Being slightly biased, my favourite was the inconspicuous ladybird Scymnus haemorhoidalis, swept from the grassland by my girlfriend Kate. We also found a rather pretty wood-boring beetle (Hedobia imperialis) in the woodworm family, and the first Small Copper butterfly (Lycaena phlaeas) ever recorded on site!
Scymnus haemorhoidalis, a 2mm hairy ladybird (pic Jo Bogaert)
The first Small Copper ever recorded at Halse Copse!
After a quick lunch consisting mainly of cake and tea (the essential food groups for any naturalist in the field!), we decided to try our luck in the more southerly of the two woodlands (which had contributed just 68 species to the grand total pre-BioBlitz, and just 3 insects).  The woodland was definitely less diverse (or at least the wildlife more elusive) than the meadow, but in a few hours surveying we had a list of 71 species identified there and then, with another series of beetles and bugs that needed checking under the microscope.  The afternoon highlights included several Brown Hares (Lepus europaeus) lounging around just outside the wood, and a beautiful orange-striped millipede, Ommatoiulus sabulosus, which were the first of their respective groups to be found at the site.  Also present in large numbers was another new species to me, the stripy brown click beetle Agriotes linearis, present in big numbers on hazel leaves.  This group of beetles has an impressive trick: when threatened, they first tuck in all their legs and appendages to look like a seed; then, if that doesn't work, they use a special joint between the thorax and abdomen to fire themselves skywards and out of reach.  The effect, particularly on a hard surface, can be quite impressive!
Ommatoiulus sabulosus, beaten from gorse
The click beetle Agriotes linearis, here in walking mode rather than catapulting itself through the air
 As we stopped off in the meadow for one last look, a rather special hoverfly presented itself.  Recognisable from the dark abdominal stripe and the huge snout, this was the hoverfly Rhingia campestris (also known as the Heineken fly, because it can reach the parts other flies can't reach (if you don't remember beer adverts from days gone by, that probably won't make any sense...)).  This species, by virtue of mounting its tongue on the end of a very elongated face, can reach deeper into flowers than most other fly species and consequently can feed on complex flowers that are otherwise mostly reliant on long-tongued bumblebee species for pollination,
The Heineken Fly, busy reaching further
 Waiting for me to finish poking around in the heap of dead wood, Kate had wandered off to photograph areas containing fewer spiders, when photography of a vetch flower was interrupted by the red ants (Myrmeca sp.) running up and down the stems. On closer inspection the ants were raiding the extra-floral nectaries (glands on non-flower bits of the plant which secrete nectar) and passing the nectar to each other.  Most plants produce nectar as a sweet treat to entice pollinating insects to visit their flowers: these extra-floral nectaries, by contrast, are nothing to do with pollination, but are instead a sneaky way for the plant to avoid being eaten - they ensure a good supply of ants across the plant, ready to evict or eat any small herbivores like caterpillars, while even big herbivores like rabbits aren't keen on a faceful of biting, stinging ants at every mouthful!
A red ant nose-deep in an extra-floral nectary
In a single afternoon, we at least doubled, if not trebled, the number of species known to occur in Halse Coppice: with a variety of other excellent naturalists also present, the site should be well on its way to 1000 species. Just goes to show the value of recording!