Northern Mockingbirds recorded per party hr on the
Honolulu Christmas Count, 1944-2007 (see Count
Page), showing peak numbers during an
expansion phase in the 1960s followed by a steady
decline in numbers during a withdrawal phase through the 2000s. 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/2009/