Red-whiskered Bulbuls recorded per party hr on the
Honolulu Christmas Count, 1944-2007 (see Count
Page), indicating increasing trends following
introduction in the mid-1960s, followed by a
general decline in the 1990-2000s (but with some fluctuation. 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/2009/