Most of our birds are migrators, passing their breeding season in summer with us and then leaving for warmer climes. In addition to the climatic reasons for this migration, the question of food supply is doubtless an important factor, for while they might stand the severity of our winters the insectivorous birds could not get any food when our ground was covered with snow and ice, and, in proof of this, as a rule the omnivorous migratory birds are the first to come in the spring and the last to leave in the fall. In 1877 I began making notes of the arrival of the robin, bluebird, and swallow; these notes have been made every spring, mostly by myself, but during my absence by some member of my family, and were all taken at Au Sable Forks. The earliest date for the robin is March 10th; for the bluebird, March 7th; and for the swallow, April 4th. The latest date for the robin is April 7th; for the bluebird, April 7th; and for the swallow, April 25th. The average date is for the robin, March 28th; bluebird, March 26th; and the swallow, April 15th. In every year the first robins that came were males, and this was true with the bluebird excepting two years when I saw both male and female birds on the same day. The sex of the swallow is not as easily determined, and I am not sure about them, but my general observation has been that the males come first, and are followed in a few days by the females, and that the courtship and mating are all arranged after their arrival. My observations have been quite careful, and I think they are full enough to go far toward establishing this fact. Of course, there will be exceptions and our observations are necessarily imperfect, for it is not probable that we happen to see the very first bird that comes.