Passage: Aulavik National Park of Canada, a fly-in park, protects about 12,274 km2 (4,739 sq mi) of Arctic lowlands at the northern end of the island. The park has the highest concentration of muskoxen on earth, and is home to the endangered Peary caribou. The Thomsen River runs through the park, and is the northernmost navigable river (by canoe) in North America. Ptarmigan and ravens are considered the only year-round birds in the park, although 43 species make seasonal use of the area. In Inuvialuktun Aulavik means "place where people travel" and the "wildlife and land have supported aboriginal peoples for more than 3,400 years, from Pre-Dorset cultures to contemporary Inuvialuit."The first confirmed grizzly–polar bear hybrid found in the wild was shot on Banks Island in April 2006, near Sachs Harbour.

Question: The Thomsen River sees what birds as permanent residents?
Ptarmigan and ravens