Saturday, June 16, 2007

Vomit news

Renata's PhD project focuses on the diet of storm petrels during their long-distance migrations, and we have managed to collect some excellent samples of vomit (which mist-netted storm petrels occasionally produce) and faeces. You may particularly enjoy this fine sample, featuring various bits of fish and (just above the centre of the paper disk) three tiny isopods.

Vomit samples are quite rare from migrating stormies, and each one is received with great rejoicing from Rob. Perhaps he should get out more...

Quite how storm petrels manage to feed on isopods at night is a bit of a mystery -see our recent paper:
Thomas, R.J., Pollard, A.L. & Medeiros, R. Evidence for intertidal foraging by European Storm Setrels Hydrobates pelagicus during migration. Atlantic Seabirds, in press.

New light was shed on this mystery last night, when Earthwatchers Sherri and Karen discovered that isopods can find and attach themselves to dead fish floating in the surf zone -so perhaps stormies eat isopods by "accident" when eating bits of fish, rather than by actively hunting isopods in the dark.


RAFASAIZ said...

Hello, Rob.

When diving in the sea, here in Basque Country, is quite normal to watch parasitic isopods attached to small fishes' head, so it could be not so unusuall what you suggest.

Rob T said...

Yes, it seems quite possible that storm petrels would eat these parasitic species too -though we have not (yet) found any parasitic species in the storm petrel vomit. The isopod species we have found so far in stormies vomit are a range of intertidal, inshore and pelagic predators/carrion feeders rather than parasites.