The female weighed 1200 grams. The largest ovum was eight mm in diameter; others were smaller and the smallest were in clusters. On leaving the nest we placed mosses and grasses over it to protect the single egg from the parasitic jaegers. We wished to learn whether the male returned and incubated the egg. On our approach on July 8 he was on the nest but left and swam approximately 200 feet under water before surfacing. On the afternoon of the same day the single egg was cold and unattended. The male was swimming on a nearby lake some 300 yards distant. Two pairs of the Arctic loon were observed swimming on adjacent lakes. On July 9, the male was again incubating the egg. The Arctic loon calls frequently when flying overhead. The Eskimos were adept at imitating the loon's call and were successful in having the birds respond. At Kaolak River (July 12-18, 1951), pairs of the Arctic loon used the course of the stream as a flight lane. On an airflight from east to west between the mouth of the Canning River Canyon and Umiat (July 18, 1952) I noted an increase in the numbers of this loon, especially over the lakes near the Colville River. Seven pairs and two singles of this species were observed between the mouth of the Avalik River and a point 23.3 miles from the Arctic Ocean when I flew directly from Kaolak to Point Barrow. In the above 33 miles of coastal plain, the greatest interval between loons was 9.7 miles, the shortest 1.9 miles, the average 5.9 miles. The last 23.3 miles before reaching the Arctic Ocean, produced no records of the loon. On a lake near the Arctic Ocean, 3.8 miles southwest from Barrow Village, a single pair was observed. Upon our arrival at Barrier Lake, northeast of Teshekpuk Lake (July 29, 1951), there were two adult and two young Arctic loons at the south end of the lake at a point approximately 300 feet from where we camped. During our stay at the lake, the loons nearly all of the time remained on approximately 1-1/2 acres of water in spite of being disturbed and having their territory periodically invaded by us. Adjacent to the area of the lake used by this family of loons were three small lakes connected by wide channels to Barrier Lake. Other small lakes to the east were connected by smaller channels. The loons preferred to feed in the lakes having larger connecting channels.