A review of olivaceous warbler records commenced in 1986, and continued through the 1990s. The results of this review were published in 1999: six of the previously accepted records were rejected as not meeting modern identification standards. In 2003, following the split of olivaceous warbler into two species, the accepted records were all reviewed again to ascertain which of the two they were—all nine proved to be eastern olivaceous warblers. Following the split of Bonelli's warbler into two species, the committee reviewed all the 121 accepted records, and concluded that 51 were western and two were eastern; for the remainder, not enough evidence was available to make a firm decision. The committee had previously stated that it would regard as western Bonelli's warbler all except proven eastern Bonelli's warblers, however, this announcement rescinded that decision. In 2003–04, all desert warbler records were reviewed, and it was concluded that all were referable to the newly split Asian desert warbler, rather than African desert warbler.