Mystery Bird: Bank swallow, Riparia riparia

Bank swallow, Riparia riparia , also known as the collared sand martin, photographed during the Smith Point Hawk Watch at Gulf Coast Bird Observatory , Texas, USA. Image: Joseph Kennedy , 16 September 2010. [ larger view ]. Nikon D200, Kowa 883 telescope with TSN-PZ camera eyepiece 1/640s f/8.0 at 1000.0mm iso400 Question: These small migratory birds have a nearly world-wide distribution, primarily limited by one factor. Can you name this species and tell me what is the main factor that limits its distribution? Response: As its scientific name implies, the bank swallow or collared sand martin, Riparia riparia , is strongly dependent upon riparian areas, where it lives and breeds. The occurrence of riparian areas is the primary limit to where you will find this small bird within its nearly cosmopolitan range. If you have bird images, video or mp3 files that you'd like to share with a large and appreciate audience, feel free to email them to me for consideration.