Red-whiskered Bulbuls recorded per party hr on the Waipi'o Christmas Count, O'ahu, 1977-2014 (see Count
Page), showing increasing but
fluctuating populations since first detected on the count in 1993. Graphs of Christmas Count data developed as part
of The Birds of the Hawaiian Islands: Occurrence, History, Distribution, and
Status by Robert L. Pyle and Peter Pyle http://hbs.bishopmuseum.org/birds/rlp-monograph/