Just spotted the first bats of the year, there are two of them flying past the east side of my flat as I write. This is not the earliest sighting I have had, that was 26th March 2012, although in recent years they have tended to be later, usually in the first week of April.
All of these sightings are probably Pipistrellus pipistrellus or Pipistrellus pygmaeus (based on previous identifications), it is impossible to tell the two species apart without specialist equipment. I take the bat sighting as a sign of the coming summer, and so am always on the lookout for them at this time of year. The next thing to look and listen out for is the first swifts returning to nest in Edinburgh.