According to the Wikipedia article on American White Pelican, “In the breeding
season, there is a laterally flattened "horn" on the upper bill, located about
one-third the bill's length behind the tip. This is the only one of the eight
species of pelican to have a bill "horn". The horn is shed after the birds have
mated and laid their eggs. “
Logic dictates that if the knob is shed after breeding, at some point it grows
back. The bare parts also get more brightly colored during breeding season.
So, who knows? This is the the time of year when birds start moving around and
putting on their breeding finery. Part of what makes birding fun.
Sent slowly from Phillip Kite's iPhone