Red-whiskered Bulbuls recorded per party hr on the
Honolulu Christmas Count, 1944-2014 (see Count
Page), indicating increasing trends following
introduction in the mid-1960s, followed by fluctuating populations in
the 1990-2010s. See also van Riper et al. (1979), Williams (1983a, 1987),
Moulton and Scioli (1986), and Ralph (1990). 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/