Wednesday, 2 September 2009

Additional stuff

Hi Cliff,

Some additional info that I sent on earlier to Rich.

"It was certainly unusual, both the Common and the Risso's were seen jumping clear of the water occasionally, there was obviously a bit of a feeding frenzy going on - with lots of Gannets etc getting in on the action. The Commons were in three large groups - all visible simultaneously across the horizon - and the Risso's were loosely attached to one of these (which was useful for comparison purposes). I remember seeing Risso's occasionally from Port Eynon when I seawatched from there (and in the Bristol Channel from the Swansea-Cork ferry) so I guess they must get around. Perhaps the sightings reflect the distribution of observers? I haven't seen anybody else seawatching from the south coast this summer - whereas at Strumble......"



Hi Clive,
Thanks for the more complete version. The bit that was not clear was that the Risso’s were associating/feeding? with the commons. As you say, it also does sound like you probably had a lot more Commons than your conservative estimate. Interestingly Janet Baxter (see June reports ) had a similar instance of Risso’s and Commons feeding together back in June which opens up a couple of interesting questions, such as what were they feeding on, were they both feeding on the same thing?

I have seen literally thousands of groups of Commons in recent years , and also pods of Risso’s but never seen them associating. The generally accepted principle is that Risso’s feed on squid and squid is not generally that common here, although we do see Risso’s regularly. Maybe there is more squid about than we used to think was the case, maybe the they were all feeding on squid or maybe Risso’s have a much more catholic taste than previously thought. Perhaps food shortages/gluts brought on by climate change or fishing practice is making animals adapt their diet.

Another interesting phenomena is that I never see birds with Risso’s, or in my limited experience with Sperm Whales as if the birds recognise that as bottom feeders that they are unlikely to derive benefit from following them...

Hmm so much to know, so little in the way of resources to find out with. Thank god for the unsung army of reliable observers out there watching.
Allthingsgood, cliff