Hawaiian Hawks recorded per party hr on the Volcano
Christmas Count, Hawai'i, 1972-2014 (see Count
Page), showing fluctuations
during this period. 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/