What does John Reid and a seagull have in common?

Good letter in the guardian today - The commercial world calls somebody who had nine jobs in 10 years (Reid's shock resignation, May 7) a "corporate seagull" - one who flies in for a short period, defecates and flutters off. (John Heelan Bembridge, Isle of Wight) Actually many regard seagulls as rats with wings! They can be very agressive too.