This is the latest instalment in our series of articles on the remarkable diversity of birds that visit Mayne Island’s shores in winter.
Grebes
Grebes are similar to loons, superficially, but are smaller, have lobed toes (as opposed to webbed) set far back on their bodies, and have longer, thinner necks. Grebe tails look almost non-existent from a distance so this gives them a stunted body appearance on the water. Most have sharp, pointed bills and short wings. In winter grebes are generally dark brown to black above and paler below.
The larger grebes are primarily fish eaters on the wintering grounds while smaller ones may consume small invertebrates and fish. Capture is by pursuit. Like loons, grebes have hydrodynamic bodies and dense bones for diving. Their eyes allow for both aerial and underwater vision. While most of their foraging is near or at the surface of water, grebes are capable of dives up to 27m. Large grebes dive by starting with an upward leap, which is easily observed from the surface. It is estimated that larger grebes can consume about 0.5 kg of fish in a day.
Grebes are also known to consume a large number of their own feathers. The purpose of this behaviour is thought to protect their stomach from puncture by indigestible parts of prey or other hard items. The feathers and these indigestible components are then regurgitated.
For the Mayne Island region, we have five species of the grebe family recorded: The Pied-bill Grebe in which we have only three records in winter, all on fresh water ponds; the Eared Grebe, which we only have a few records; the Horned Grebe, the Red-necked Grebe and the Western Grebe which are all usually present yearly, albeit in low numbers. Two are described in more detail below.
Horned Grebe
The striking combination of rusty neck, dark head and golden plumes or “horns” makes the Horned Grebe perhaps the most visually attractive of all the grebes in breeding plumage. We can see this wonderful display sometimes in the late winter. The winter plumage is a gray-brown back mottled at the waterline with a dark nape and whitish front. The cheek area is white and its head has a black cap that is in line with its red eyes. The short sharp bill is yellowish with a white tip. This species is consistently found in Horton Bay and off Reef Bay in winter. In other areas it is less common but can be found almost anywhere in nearshore waters of bays. It is rarely in flocks. It can remain submerged for up to 3 minutes and travel underwater for up to 150 m.
Western Grebe
This is the largest grebe in the province and is found only in North America. The Western Grebe winters along the coast from southwestern British Columbia to Baja California. This grebe, besides its large size, is also very slender with a long neck. Its bill is also long and thin and a dull yellow in colour. Its plumage is a clean dark gray with a white breast and throat. The eyes are red and the black cap of the head surrounds the eyes. Historically there were large flocks of Westerns in Saanich Inlet in late winter – perhaps tied to the winter flight feather molt. In the early 2000’s, a flock up to 100 was observed annually in late winter in Plumper Sound off of St. John Point. Our recent Christmas Bird Counts have tallied 1-5 Westerns in Horton Bay and in the waters between Mayne and Saturna Islands.
In the early 20thCentury, grebe species were commercially hunted for their plumes for hats and coats. The populations at that time were decimated. The species has been red-listed in British Columbia since 1992. It was assessed as a Special Concern nationally by COSEWIC (the Committee On The Status of Endangered Wildlife in Canada) in 2014, and is listed as such under the federal Species at Risk Act. Reductions of 50-90% have been reported for populations wintering in the Salish Sea region. Western Grebes are susceptible to oiling and turn up in beached bird surveys in our region.
0 Comments