Western Grebe
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Western Grebe Low breeding numbers and threats to their nesting colonies put these birds at risk. Ministry of Environment, Lands and Parks – in Salmon Arm Bay on Shuswap Lake, early 1940s, no nesting has occurred and in the north arm of Okanagan Lake since about 1964. At Swan Lake, where – are located in areas where recreational about 40 pairs nested between 1950 activity is already high and development and 1966, there has been no evidence of Why are Western Grebes could potentially increase. The Salmon nesting since 1992. Breeding colonies of at risk? Arm colony is also at risk from the up to 90 pairs at Shuswap Lake, 40 pairs he Western Grebe, a large waterbird impacts of cattle grazing along the lake at Okanagan Lake and 55 pairs at that breeds in the interior of British shore. The third remaining colony, at CVWMA have persisted in recent years. Columbia and winters on the coast, is the Creston Valley Wildlife Management Scattered occurrences of one or two nests T at risk in this province because its spe- Area (CVWMA), is less susceptible to at other locations have also been report- cialized habitat requirements limit it to human disturbance. Nevertheless, this ed. Although a few small colonies may only a few nesting locations and because of colony is vulnerable to storms and to have gone undetected, it is unlikely that human disturbance at these sites. water-level changes associated with the province supports many more than British Columbia has many lakes, but downstream flood control. 200 nesting pairs. only a few meet the Western Grebe’s Threats on the wintering grounds In fall and winter, the provincial nesting requirements. These include: may include death or injury from oil population is swelled by migrants from warm water temperatures and a long spills, gill nets and pesticides, and breeding colonies as far east as Manito- ice-free period to allow the growth of decrease in prey availability due to over- ba, and possibly from the northern appropriate aquatic vegetation for nest- fishing by humans and degradation United States. Christmas counts on B.C.’s building; the presence of significant of estuaries. coastal waters have averaged about 20 000 populations of small, schooling fish; sta- in recent years. ble water levels; protection from wind What is their status? Because of its low breeding num- and waves; and deep water near the ased on Christmas bird counts along bers in British Columbia and the threats nesting area for feeding. The scarcity of the Pacific coast, biologists estimate to its nesting colonies, the Western suitable breeding habitat in B.C. is com- that the total population of the West- Grebe has been assigned to the provin- pounded by the fact that nesting is easi- B ern Grebe is over 100 000. They cial Red List of species being consid- ly disrupted by humans. The floating have been unable to determine whether ered for legal designation as Endan- nests are located in shallows along the the population is increasing, decreasing gered or Threatened. The Western edges of lakes and are easily tipped or or remaining stable. Nesting habitat Grebe is protected from killing or col- flooded by the wakes of passing has been lost in lecting by the British Columbia Wildlife boats. Excessive noise, human Although some areas, while Act and by the federal Migratory Bird activity and shoreline development alterations to the Convention Act. can also cause the grebes to aban- British landscape, such as don their nests. The best nesting Columbia reservoir construc- What do they look like? sites are medium to large lakes tion, have provid- rebes are highly specialized for swim- in the warm Southern Interior – has many ed new habitat ming and diving. They are seldom exactly the kinds of places favoured lakes, only in others. seen out of the water except when on by people for summer recreation. The number of G their nests. Their legs and feet are well Although nesting has been a few meet Western Grebes designed for providing strong propulsion recorded at about 14 locations in the Western that nest in British underwater – the legs are set far back on the province, some were not suit- Columbia is small. the body and the feet are lobed rather than able for maintaining colonies. Grebe’s nesting Our colonies have fully webbed like a duck’s. Colonies of five or more pairs are requirements. not been surveyed Six species of grebes are found in known to have existed at only five regularly, so we do British Columbia. The Western Grebe locations in B.C. and are now found not have accurate (Aechmophorus occidentalis) is our larg- at only three of those. The loss of former information about the trend in provincial est species, measuring about 64 centime- colonies at Swan Lake near Vernon and at abundance. We know that two former tres in length and weighing up to 1.8 Williams Lake is mainly attributed to the nesting colonies have been abandoned. kilograms. The Western Grebe is best dis- effects of human disturbance. At Williams Lake, where a colony of 5 to tinguished by its long, curved neck. It Two of the surviving nesting colonies 35 pairs was present in the 1930s and is the only one of our grebes that sports strongly contrasting black and white grebes. It is found in large groups at begins soon after the grebes reach their plumage year-round. Both sexes have the breeding colonies, on lakes during migra- nesting colonies in late April or early May. same colouring, but males are slightly tion and on the ocean in winter. They are readily observed at accessible larger than females. Clark’s Grebe, a closely related colonies like the one at Salmon Arm. The top of the head, It is species that was formerly thought The two main rituals are the “rush- the back of the neck to be a colour phase of the Western ing ceremony” and the “weed ceremo- and the upper parts unlikely Grebe, is an occasional visitor to ny.” During the rushing ceremony, two of the body are that the southern B.C.; nesting is extremely grebes engage in advertising calls and black to slatey-grey rare. The most obvious difference various head movements, then lunge in colour, while the province between these two similar species forward and run rapidly across the throat, the front and supports is that the dark head feathers of the surface of the water, side-by-side, for sides of the neck, and Western Grebe extend down below up to 20 metres. They do not call dur- the belly are white. many more its eyes, whereas the eyes of Clark’s ing the rush, but the pattering of their During the breed- than Grebe are surrounded by white feet on the water can be heard for some ing season, the black feathers. Their bills are also differ- distance. At the end of the rush they feathers on top of the nesting ent colours: Clark’s is orange-yel- dive. The rushing ceremony is believed head form a slight pairs. low, while the Western Grebe’s is to be important for attracting mates. crest. At close range, yellowish-green. The weed ceremony, which occurs this graceful grebe’s bright red eyes are later in pair formation, starts with vari- also discernible. What makes them unique? ous postures such as “neck-stretching” Even when not visible, the presence of he Western Grebe’s unique courtship and “bob-shaking,” after which both the Western Grebe is often revealed by its ceremonies have been studied exten- members of the pair dive and bring far-carrying call, a plaintive, high-pitched sively and are among the most complex up weeds in their bills. They then face “creek-creek” that is easily recognizable. T known among birds. The elaborate one another, feet churning to hold This grebe is more gregarious than other and energetic series of ritualized displays their bodies vertical, and move slowly forward or spiral with their weed-laden chicks riding on their parents’ backs. Present range of the bills held close together. This “weed They may travel several kilometres to Western Grebe dance” ends when one bird drops its where food is most available. Some- in Canada and the United States weeds, but the ceremony continues times the last egg is left behind. with further posturing. Newly hatched young spend only brief periods off their parents’ backs. How do they reproduce? Back-brooding lasts two to four weeks, ollowing several days of courtship, although the young still ride occasional- both members of the pair set to work ly until they are almost fully grown. building their nest. In B.C. this usual- Usually, one parent carries the brood F ly happens in May. The floating nests while the other dives for their food. At measure about 50 cm across and have a the end of a session of brooding, the soggy depression in the middle which carrying adult rises up in the water, holds the eggs. These small rafts flaps its wings and are made of aquatic vegetation The Western dumps the chicks in and anchored to plants like rushes the water. They then or pondweed. It takes about three Grebe’s climb onto the other days to build a nest big enough to unique parent’s back. The support a grebe, but the pair con- adults provide a tinues to add nest material during courtship foothold for the the laying and incubation period. ceremonies young by holding The eggs are laid one day one foot stiffly out apart.