Phillips took various short journeys throughout the West of the United States and Canada. In 1900 he published the first two short article about his hunting experiences at Wenham Lake, as well as bighorn sheep (Ovis canadensis) in Wyoming. The area of the Glacier National Park fascinated him even before the time it was put under protection. Many of the geographical features today bear the name which he had assigned to them. In 1896 he accompanied Robert Edwin Peary (1856-1920) on his Greenland expeditions. Ten years later, he and his friend Theodore Lyman (1874-1954) visited Japan and its colony Chōsen with a foray into the south of China to hunt tigers. Further excursions, which he undertook together with Glover Morrill Allen (1879-1942), were in the valley of the Blue Nile and the border of Ethiopia between 1912 and 1913, as well as the Sinai Peninsula and Palestine in 1914. He brought important bird and mammal collections back from both, which were handed over to the Louis Agassiz Museum of Comparative Zoology. In 1938, he visited Cuba and Florida with Thomas Barbour (1884-1946). His last long journey took him to Kenya via Uganda and the east of the Belgian Congo with his wife and son John in the years 1923-1924 to hunt African game in its natural habitat.