Hawaiian Ducks (Koloa) recorded per party hr on the Honolulu Christmas

Count, 1944-2007 (see Count Page), showing a peak in observations during the

1970s-1990s, due to re-propogation programs, followed by a decline through the

2000s. Most observations of these ducks after the 1990s were identified as hybrids

with Mallard.

Species account.

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/