This bird, next to the western sandpiper, was by far the most abundant of all the shore birds. It was noted in immense flocks the day of my arrival, May 3, and was very common when I left, May 24. Mixed flocks of this species and western sandpipers must have contained 6,000 or 7,000 birds. Herbert W. Brandt in his manuscript notes says: The red-backed sandpiper is one of the most abundant shore birds inhabiting the Hooper Bay region, confining itself almost entirely to the low-lying flats. The Eskimos first reported this hardy species on May 10 and two days later we collected our first specimen at Point Dall. They were common in loose flocks by May 15 and abundant by May 20. At that time they were often associated with the Aleutian sandpiper, to which, in the field, they bear a marked resemblance. Soon after the later date the flocks disintegrated into mated couples and they then repaired to their lowland breeding haunts. _Courtship._--Dr. E. W. Nelson (1887) gives an attractive account of the courtship of this species, as follows: Soon after they arrive in spring they are engaged in pairing, and the males may be seen upon quivering wings flying after the female and uttering a musical, trilling note, which falls upon the ear like the mellow tinkle of large water drops falling rapidly into a partly filled vessel. Imagine the sounds thus produced by the water run together into a steady and rapid trill some 5 to 10 seconds in length, and the note of this sandpiper is represented. It is not loud but has a rich full tone, difficult to describe, but pleasant to hear among the discordant notes of the various waterfowl whose hoarse cries arise on all sides. As the lover's suit approaches its end the handsome suitor becomes exalted, and in his moments of excitement he rises 15 or 20 yards, and, hovering on tremulous wings over the object of his passion, pours forth a perfect gush of music, until he glides back to earth exhausted, but ready to repeat the effort a few minutes later. The female coyly retreats before the advances of the male, but after various mishaps each bird finds its partner for the summer and they start off house hunting in all the ardor of a rising honeymoon. Mr. Brandt in his manuscript notes describes it a little differently, thus: