Saturday, March 13 2010 @ 08:17 PM EST
Contributed by: terrytvgal
At Colony Farm in Coquitlam, great blue herons roost on swallow boxes near the wetland as they gather in large groups in preparation for nesting.
Hilary Maguire photo
Published: March 12, 2010 6:00 AM
Great blue herons are truly one of our most elegant birds.Seeing them while out on a stroll can be a breathtaking sight. Approximately one metre tall, with long and graceful necks, herons can often be seen in shallow water as they search for small fish on which to feed.
Reliable locations to observe herons along the water’s edge include Port Moody’s Shoreline Park, DeBoville Slough in Coquitlam or Colony Farm Regional Park, where public nature walks focused on herons will be offered this Sunday, March 14 as well as March 27.
Because herons are not an uncommon sight locally, it is can be hard to understand why they are one of our species at-risk. Our herons belong to a unique sub-population that, unlike great blue herons across Canada, does not migrate south in winter. It is this coastal subspecies, thought to number about 4,000 pairs, that is considered to be at-risk.
Our coastal areas provide herons with sufficient food to make it through the winter without having to risk a long journey south. Oddly enough, although the herons feed mainly on fish throughout the rest of the year, fish often do not form a main part of their diet in winter.
The fields at Colony Farm Regional Park are one of the best places to view herons in winter because herons use these fields to catch voles, meadow mice and frogs to augment their diet. During the winter, our coastal waters are not as abundant with small fish such as smelt and young salmon as at other times of the year so herons turn to more terrestrial sites in their constant search for food. In addition, juvenile herons, in their first winter, often lack the skills to catch fish. To survive, they must rely on slower moving prey.
As spring approaches, herons prepare for the nesting season by gathering in large aggregations in which they size up one another and form breeding pairs. The bills and feet of breeding herons turn an attractive orange during the breeding season. Adult herons, ready to breed, can also be distinguished from younger ones by the presence of long plumes on their neck and a cap of white feathers on their head set off by black ones immediately below. This year, the herons appear to be aggregating near the wetlands on the Port Coquitlam side of Colony Farm Regional Park.
Great blue herons in the Lower Mainland often form large nesting colonies in which to rear their young. They require stands of tall trees close to feeding areas and, as a consequence of development, not many suitable areas are left. Herons are typically quite skittish in their nesting colonies and have been known to abandon an area if disturbed.
The one exception to this appears to the nesting herons at Stanley Park. There, herons choose a nesting site that was already busy below with people. As the people were there first, it seems the herons have decided these humans and their activities do not pose a threat to the colony. In general, it is never a good idea to walk close to a heron colony as it can cause the herons to abandon the site even if there are young herons in the nests.
The herons at Colony Farm Regional Park are thought to nest in a large colony located at the mouth of the Coquitlam River in an area protected as a provincial Wildlife Management Area. This heronry, unlike many in the Lower Mainland, has been steadily growing in size since it was established in the early 1990s. It is now believed to number more than a hundred nests.
The success of this colony is thought, in large part, to be due to the fields at Colony Farm, where herons, especially young ones, find sufficient food. Scientists estimate that, under normal conditions, only one quarter of juvenile herons that leave the nest in summer will survive their first year on their own.
The free public heron walks at Colony Farm, approximately two hours in length, will depart from the parking lot at the end of Colony Farm Road (off Lougheed Highway) at 9:30 a.m. on Sunday, March 14 and Saturday, March 27. These walks, led by volunteers from the Colony Farm Park Association and Burke Mountain Naturalists, will provide an opportunity to enjoy all the wildlife found at Colony Farm.
Elaine Golds is a Port Moody environmentalist who is vice-president of Burke Mountain Naturalists, chair of the Colony Farm Park Association and president of the PoMo Ecological Society.
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