The parable of the sheep and the goats

On Tuesday evening, at 630pm, I am speaking at an event at The Royal Society on priorities for saving species from extinction - the other speakers are all very good!  Details of the event can be found here http://royalsociety.org/event.asp?id=8362 including details of a webcast. How would you choose which species to save?  And I can never remember - is it better to be a sheep or a goat?