Averages of the three highest counts per decade for selected birds in Plum Island Sound.

Averages of the three highest counts per decade (1930's, 1040's, 1950's and 1990's) for a variety of birds including: four shorebirds (black-bellied plover, greater yellowlegs, semipalmated plover, and semipalmated sandpiper), six waterfowl (American black duck, common loon, green-winged teal, mallard, red-breasted merganser, and white-winged scoter), one gull (Bonaparte's gull), and one tern (common tern) in Plum Island Sound., Massachusetts.本数据集统计了美国马萨诸塞州普拉姆岛湾（Plum Island Sound）内多种鸟类在四个年代（1930年代、1940年代、1950年代及1990年代）的单年代最高三项计数的平均值。涵盖的鸟类类群及具体物种包括：四类滨鸟（shorebirds）：黑腹斑鸻（black-bellied plover）、大黄腿鹬（greater yellowlegs）、半蹼斑鸻（semipalmated plover）以及半蹼滨鹬（semipalmated sandpiper）；六种水禽（waterfowl）：美洲黑鸭（American black duck）、普通潜鸟（common loon）、绿翅鸭（green-winged teal）、绿头鸭（mallard）、红胸秋沙鸭（red-breasted merganser）以及白翅海番鸭（white-winged scoter）；一种鸥类（gull）：博纳帕特氏鸥（Bonaparte's gull）；一种燕鸥（tern）：普通燕鸥（common tern）。