Cat Island lies in the southwest waters of the Penghu Archipelago, consisting of the Big and Small Cat Islets. Viewed from afar, it resembles a crouching cats floating on the sea, and thus named accordingly. The islands are surrounded by lofty wonder of cliffs. The Pig Cat Islets is the highest summit of the Penghu Archipelago. Due to abundant fishery resources influenced by the Japan Current in summer, most summer migrating birds breed on the Cat Island, especially terns. After the appeals of conservation groups and the on-the-spot evaluation of experts, "Cat Island Seabird Reservation Area" was announced as the first wildlife reservation area in Taiwan on May 22, 1991.Until now, there are 75 types of birds belonging to 28 families found on Cat Island. Among them, red swallow gulls and white brow swallow gulls are most abundant in numbers. Some rare birds also appeared here, such as short-tailed albatrosses, black-footed albatrosses, big-jacanas, gray-jacanas and white belly boobies.