This report contains: an introduction; summer census; observations; and a protection section. Trumpeter swan (Cygnus buccinator) observations were carried on by the Yellowstone staff during the 1937 season, and a census of adults and cygnets was taken in July by the ranger force. The counting of 29 cygnets was significant and most encouraging as far as the status of the trumpeter is concerned, since this is more than twice the number of young birds counted in either 1935 or 1936. Yellowstone was not the only area where there were unusually large numbers of cygnets, as 51 were reported from the Biological Survey Refuge at Red Rock Lakes where Junior Refuge Manager Archie V. Hull very willingly cooperated with us in making a swan count. The increase in cygnets this year over last year amounts to 50 0.000000or the Yellowstone and Red Rock areas; and if a reasonable number of the 80 juvenile trumpeters survive in these protected areas, the precarious status of the species will be greatly improved.