House Martins in October??

Observation - House Martins in October??. Description: sitting in the car park on Selsey Bill beach at around 2.30 on Saturday afternoon (low tide, hot sunny spells and low winds 8/10/11) we saw about a dozen birds which looked like house martins flying low over the beached seaweed and around the cars in the

sitting in the car park on Selsey Bill beach at around 2.30 on Saturday afternoon (low tide, hot sunny spells and low winds 8/10/11) we saw about a dozen birds which looked like house martins flying low over the beached seaweed and around the cars in the car park, presumably collecting the flies that were around the weed and warm vehicles. They were around for about 15 mins, then disappeared. It seems very late for such birds to still be around, were we seeing delayed migrants still hanging around to take advantage of the recent hot weather taking their last fill before hopping over the Channel, or were we seeing something else?