We compared trends in the number of Hawaiian Petrels (Pterodroma sandwichensis; formerly Dark-rumped Petrels [P. phaeopygia sandwichensis]) and Newell's Shearwaters (Puffinus auricularis newelli) seen visiting Kauai, Hawaii, on ornithological radar in June 1993 and 1999–2001 and summarized and evaluated trends in the number of young Newell's Shearwaters recovered in the “Save Our Shearwaters” (SOS) Program on Kauai, 1979–2001. After pairing sampling dates at each site to remove temporal effects, radar data indicated that the number of Newell's Shearwaters visiting Kauai declined significantly between 1993 and 1999–2001. The mean change from 1993 numbers of radar targets across 13 sites was −59.8 ± 7.2% (SE) in 1999, −62.1 ± 5.5% in 2000, and −61.5 ± 5.4% in 2001, with all sites except one showing decreases of 38–93% in 1999 and all sites showing decreases of 31–96% in 2000 and 37–92% in 2001. Our data suggest that the decline is concentrated in Newell's Shearwaters, whereas the Hawaiian Petrel population actually appears to have increased. The SOS fallout data exhibited a consistent 72% overall decline in Newell's Shearwater recoveries from 1993 to 2001. Although we believe that the SOS data only generally reflect population size and productivity of shear-waters on Kauai, we conclude from the radar data that there has been a significant decrease in the number of Newell's Shearwaters visiting Kauai since 1993.