Missing: 600 Great Blue Herons. Reward offered.

By Meg Olson

It was once thought to be the largest heronry on the west coast, and now it's empty. This June the few herons that had chosen to nest in the Point Roberts heron colony this year abandoned their nests and their young. Biologist Ann Eissinger, who has been monitoring the colony for years says she doesn't know why.

Right off the top we were missing 600 birds, Eissinger said. The herons were slow to return and out of the expected 400 or more nesting pairs expected, only 100 returned.

In fall, herons move out of their colonies and disperse around what Eissinger calls the Salish Sea, the inland marine waters of Washington and British Columbia wintering in fields, wetlands, along stream banks and the marine shoreline. In spring they congregate in staging areas near the colony they use year after year for nesting. Before the golf course the heron staged right there in those ponds and along the bluff, Eissinger said. During construction of the Point Roberts Golf and Country Club Eissinger worked with the developer to try to minimize impact on the colony, which is adjacent to the golf course. However, while some birds have continued staging along the bluff most have been congregating in the salt flats between the two causeways in Tsawwassen and on tribal lands there.

This year Eissinger said staging was scattered in March. There was no coalescing and it wasn't until sometime in April they settled into nesting, she said. While the 100 nesting pairs that returned to Point Roberts did incubate eggs and hatch young, Eissinger said they were jumpy, skittish, not like they usually are.

The first week in June local colony monitor Renee Coe reported to Eissinger the usually chattering colony seemed very quiet. “I got up there and the herons were gone, Eissinger said. It was completely silent, extremely eerie.

Regarding the reasons for the abandonment, all Eissinger has are theories. This is a highly unusual situation and hard to explain, she said. Other than a catastrophe what affects colonies of birds is usually a combination of effects. Food shortage, human disturbance or bald eagle predation may all have contributed. The eagles were in there consistently, Eissinger said, referring specifically to the juvenile bald eagles that grab eggs and fledglings from the nest.

In an apparent contradiction, the new Tsawwassen colony has sprung up around an active eagle nest, with a heron even building a nest further down on the same tree. The more successful colonies seem to have established themselves in a bald eagle territory, Eissinger said, explaining that an adult nesting pair might occasionally steal eggs and baby herons, but would also chase away marauding juvenile eagles from their territory. In Point Roberts an eagle nest next to the golf course's ninth hole probably played that role but is not active this year, Eissinger said. The success of that colony seems to perhaps depend on the success of that nest, she said.

While Eissinger doesn't know why the herons abandoned Point Roberts, she has an idea where some of them went. On the bluff behind the condominiums at the foot of the ferry causeway a new colony has formed this year. We can assume some of the birds likely went to the Tsawwassen bluff.

There is a chance the herons will come back to the Point Roberts colony, just as they did in Birch Bay where 700 adults abandoned their nests in June 1999 but returned to the colony the following year. That colony continues to be successful. The Point Roberts colony itself had a history of moving around before settling at its current location in 1973. The Trillium Corporation and state department of fish and wildlife subsequently purchased the colony and adjacent lands to protect it from human disturbance.

Eissinger said the loss of the Point Roberts colony could diminish the number of herons throughout the Salish Sea and, while she hoped the herons would be back, she said it underscored the importance of long term monitoring of heron colonies. The state does periodic monitoring but we need long-term, consistent monitoring, she said. This may be part of a natural process a colony grows, stabilizes, then fragments.

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