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Great blues select unconventional home
By Frances Wood
Before I make an important decision, I sit on it for 24 hours to be sure I'm convinced it's a good decision. Apparently some great blue herons don't. Usually these tall, long-legged, gray-blue birds nests in colonies in large stands of trees well away from people and human activity. But one pair on Whidbey Island has chosen the top of a wing wall -- those large walls on either side of the ferry loading ramp -- of the Keystone ferry dock to make its nest.
After discovering the nest earlier this spring, I questioned the herons' decision, since Washington state ferries arrive and depart every 45 minutes. Engines roar as the boats dock tight to the wing walls. Cars rumble up the ramp, workers clang chains, tourists call to each other. No matter how good the nearby fishing may be, I thought all the commotion would detract from raising a heron family.
Each time I boarded the ferry, I quickly jumped from my car and headed upstairs and outside for a bird's-eye view of the nest before the ferry departed. The nest, a loosely-woven platform of twigs and branches, is perched atop the wing wall no more than 10 feet from the ferry railing. Earlier this spring while incubating the eggs, the parents hunkered down low, trying to hide, but ferry riders still managed excellent views.
I wondered why a pair of herons would choose such a busy, exposed nesting perch. Great blue herons typically nest in colonies of from five to 200 nests in tall stands of conifer or deciduous trees. Two nearby examples are the colony in Bellefield Park and a newly-established one in Medina Park. Both parents participate in the 27-day incubation period. When the chicks hatch they are covered in pale gray down. The young stay in the nest for about two months before taking their first flights.
By nesting close to each other -- often several nests are crowded into one tree -- the herons can jointly ward off predators. One such predator is the bald eagle. As these eagles have increased in numbers the collateral impact on heron rookeries has also increased. In 1991 two of the five heron colonies in King County were abandoned in late spring due to bald eagle disturbances.
Over the years, herons have been on the lookout for places to nest safe from the eagles. One such place is within the nesting territory of osprey, another large bird of prey that scare off intruding eagles to protect their own young. The herons benefit from this protection as well. And since ospreys eat only fish, they aren't a threat to heron eggs or young.
I'm not aware of any osprey nesting near the Keystone ferry. Perhaps the pair of great blue heron that nest on the ferry wing wall is protected by all the human commotion.
Last week while waiting for the ferry, I watched one of the adult herons stalking the shores of the harbor within 25 yards of the ferry dock. After catching and swallowing a fish, the bird flew up to the nest. The two young birds -- now about three-quarters the size of the adults -- begged loudly for food. The parent opened its mouth wide and one young jammed its beak deep into the parent's throat to trigger regurgitation of the food. Just before the ferry arrived the parent flew off leaving the young standing in the nest.
After boarding, I darted upstairs to check on the nest. In it the two large juvenile herons stood side by side. Their plumage was similar to the adults', except brown feathers were mixed into the gray body feathers and the black and white head markings seen on adults were fuzzy and indistinct. When I asked a ferry worker about the nest, he mistakenly thought they were adults.
The young had already learned some defensive tactics. They raised the feathers on top of their heads to look larger and flapped their wings to appear threatening. They were obviously alarmed by the ferry and human commotion.
These large healthy young look ready to fledge in the next few weeks. So perhaps their great blue heron parents did sit on their decision for 24 hours. Perhaps their unusual choice of nesting location wasn't as impulsively made as I had assumed.
Frances Wood is author of ``Brushed by Feathers: A Year of Bird-watching in the West'' available at local bookstores. She can be reached at firstname.lastname@example.org.