Red-vented Bulbuls recorded per party hr on the Honolulu
Christmas Count, 1944- 2014 (see Count
Page), indicating significantly increasing
trends in the 1970s-mid 1990s, after introduction in 1965-1966, followed by a
declining trend through the 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/