bird curlew nature pole spring european hidden nest pebble rest rock sand stone beak bill call feathers flight fly flying Lofoten Islands natural norway norwegian Numenius arquata sky tail wader wading wings azure beach birding birds blue coast curlews curved bill estuary feed forage gregarious hunt migratory Migratory Bird Numenius phaeopus ornithology Scolopacidae sea search shore Shore Bird water Whimbrel winter Wintering