Status of the Heerman’s Gull

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Arbutus overhanging Roberts Bay, Shoal Harbour Sanctuary, provide a valuable berry mast for Mallards, and Kingfisher perch.

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Part of large flock of 101 Common Mergansers fishing beneath Arbutus in Roberts Bay, October 7th, 2014

Heerman's Gull

Heerman’s Gull in full breeding plumage (white head).

Status of the Heerman’s Gull in Shoal Harbour Migratory Bird Sanctuary, 2014

Heerman’s Gulls, looking like tanned cousins of their boreal cousins, the Mew Gull, share a common roost on Sidney’s Surfside Islets, overlooking Sidney Channel Important Bird Area (below, Sept 27th). They share these roosts with a diverse community of migratory shorebirds and seabirds in September and October. With Mount Baker in the hazy background, it is a spectacular vista ( photo below).

Virtually the entire population of this handsome Mexican gull nests on a small island (142 acres), Isla Rasa, in the Gulf of California. It is entirely dependent on shoals of “forage fishes”, anchovies, sardines and sandlance, and is often found in large mixed feeding aggregations with marine mammals and seabirds. In Canadian waters, they make their furthest north migrations in late summer and fall, and the largest aggregations occur around southeast Vancouver Island.

A video of Isla Rasa, an Important Bird Area, is shown here http://www.youtube.com/watch?v=FUBX_tlHySc

Some of the largest aggregations (400-600) of this species used to occur in Sidney Channel, more particularly over the large underwater dune field between Sidney and James Island, that formed the habitat for large Sandlance populations. Its no accident that the once thriving Chinook Salmon fishery coincided with this feature, and that knowledgeable fishermen followed the seabird frenzies.

Heerman's (Sea of Cortez) Gulls roosting on Surfside islet, Sidney, an Important Bird Area.

Heerman’s (Sea of Cortez) Gulls roosting on Surfside islet, Sidney, an Important Bird Area.

Although the Heerman’s Gull is not considered endangered, its extremely confined breeding habitat and its dependence on oceanographic conditions favouring small foraging fishes, make it highly vulnerable to fisheries practices and climatic / oceanographic patterns. Its abundance is a reasonable reflection of the state of the marine environment, and their northern most extension into Canadian waters is an indication of particular ecological conditions unique to this country. It is no accident that exotic elements of the Coastal Douglas Fir ecosystem, such as the iconic Arbutus, coincide with the view below. Just as the endangered Sage Grouse finds its northernmost extension on the Canadian prairies, Canada has international responsibilities to protect the habitat of this migrant.

Last year, after inquiring about the status of the Heerman’s Gull, I made contact with several Mexican and American biologists, concerning the apparent decline over the last decade or so, in Sidney Channel IBA. Regrettably I didn’t keep records of this species over this time, but as part of my volunteer counts for the BC Coastal Waterbird Count, I have kept regular daily counts of their roosting islets ( Site 39). Their numbers have been very consistent at 80 – 100 through September. I have also conducted a few boat surveys of Sidney Channel and have seen very few; and practically none on their former sandspit roosts (James Island). It is apparent that they show strong preference for certain islets at the mouth of Shoal Harbour Sanctuary and the IBA. These essential roosting sites and migratory stop-over places for many other species have no protective status.

This is the very first place in Canada, where, when visitors step off the ferry at Schwartz Bay, or the international Anacortes ferry, or the Victoria airport, they can see a real Heerman’s Gull and an Arbutus, hand in hand, and get a sniff of the Salish Sea, and a taste of our Spanish heritage in Quadra, Galiano and Lopez.

James K. Finley
volunteer caretaker Shoal Harbour Sanctuary-Sidney Channel IBA
volunteer monitor, BC Coastal Waterbird Survey
Friends of Shoal Harbour

 

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