Sooty Storm Petrel On 22 April one bird of this species was observed in the grid area. This species appears to occur uncommonly but possibly regularly in the grid area. Bulwer's Petrel Concurrent with the arrival of this species on its northern breeding grounds, an increase in numbers of 367% from six in March to 28 in April was experienced. This species was distributed in the southern and western portions of the grid and adjacent to Oahu where it breeds in fair numbers. Red-tailed Tropicbird Numbers of this species diminished to seven, only one-third of the March total of twenty, due possibly to increased domestic responsibilities at this time. White-tailed Tropicbird Four individuals of this species were seen in the grid area, a slight increase over the two seen in March. This species appears to occur regularly but in low numbers throughout the grid area in spring. Blue-faced Booby Four immature Blue-faced Boobies were observed in the southern portion of the grid in April, indicating a small but regular springtime population in that area. Brown Booby Four individuals of this species were seen within ten miles of Oahu on 4 May.