Scanning through flocks of common species is a well-established and effective method for finding vagrant birds. When vagrants associate with common birds, the common bird is sometimes referred to as the 'carrier species'. For example, White-rumped Sandpiper is frequently found among flocks of Dunlin so, in this instance, Dunlin is the carrier species. In fact, some vagrants are almost always found among carrier species, and are rarely seen alone. Often, the carrier species is closely related to the vagrant and there are often similarities in appearance, behaviour and habitat preferences. In some cases, the vagrant may have travelled to the UK from its normal range with the carrier, but in others it may latch onto the carrier after its arrival in the UK.CLICK ON LINK
