When you arrive on Scilly get yourself one of the island maps from the Tourist Information Board, they're about 50p I think and it shows pretty much all the paths and roads that can be used, with exception of the seasonal permitted paths set aside for October birders.
You certainly won't see all of the islands in 5 days, I've been going for 25 years and I'm still finding nooks and crannies I've never been to.
There are less birders going each year, one reason for this is due to the fact it can be easily twitched when news breaks and one can be on the islands sometimes the same day, still there's no substitute for being there when a major bird is found there is a 'run' on. Arriving red faced, out of breath, sweating buckets and near collapse with a sloppy ear to ear grin on your face because that you just nailed the bird. I still pick up pace for birds I've seen dozens of times, its all part of experience and fun.
If you don't have a pager or form of instant bird news being away from other birders may be a problem as others will always pass on important bird news, 2way radios though can be bought at the birdlog in the Scillonian Club for about £40.
There have been many threads on Scilly and that its had its day, especially after last October. Although last October was especially quiet on Scilly it still had more half decent birds than probably the rest of the whole of southern England put together at the time, Brown Shrike excluded. There have been very quiet years on the islands, the second half of October 1988, 1992 and 1994 were quiet and I remember the same conversations then, Scillies has had it but then came along 1999 and blew everyone away. Its just one of those places you just never right off.
Enjoy the islands as much as the birds, hope you don't get i'll on the Sicklonian and have fun.
