Cattle Egrets recorded per party hr on the Waipi'o Christmas Count, 1977-2014 (see Count
Page). As on the Honolulu Christmas Count, the data
indicate initial island-wide expansion in population and abundance beginning
with release in 1959 and peaking in the early 1970-1980s, followed by a decline
but, unlike other counts in Hawaii, populations rebounded again during the 2000-2010s. 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/