Photo Mug. Black-tailed Godwit (Limosa limosa melanuroides), Great Knot (Calidris teniurostris), Curlew Sandpiper (Calidris ferruginea) & Eurasian Avocet (Recurvirostra avocetta) mixed flock, in flight & standing in water, Mai Po Marshes Reserve, Deep Bay, New Territories, Hong Kong, China, April