Northern Mockingbirds recorded per party hr on the
Honolulu Christmas Count, 1944-2014 (see Count
Page), showing peak numbers during an
expansion phase in the 1960s followed by a steady decline in numbers through
the 2010s. See also 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/