Three species of birds are found mainly along rivers during the breeding season in British Columbia. These are the Harlequin Duck (Histrionicus histrionicus), the Belted Kingfisher (Ceryle alcyon), and the American Dipper (Cinclus mexicanus). They have been collectively grouped as riverine birds for purposes of this manual.
Riverine birds comprise a distinctive component of the avifauna of British Columbia. They are familiar to anyone who spends time along our mountain streams or valley-bottom rivers. Populations are widespread in the province because of its vast area of mountainous regions with their abundant river systems.
The Harlequin Duck (hereafter harlequin) is a small "sea duck" that occurs on rivers only during the breeding season. At other times it occurs on the coast where it frequents rocky islets and reefs. Populations in British Columbia are relatively large, but may be declining (I. Goudie pers. comm.), and there are considerable potential threats from oil spills, logging of riparian habitat, and disturbance from commercial river rafting (I. Goudie pers. comm.; Cassirer et al. 1993; Hunt 1993).
The Belted Kingfisher (hereafter kingfisher) is widespread along rivers from spring through autumn, but many interior birds move to marine coasts or coastal rivers for the winter. Some populations also breed along marine coasts or along lake shores, so it is not strictly a riverine species. There are no significant management or conservation concerns for kingfisher at present in British Columbia.
The American Dipper (hereafter dipper) is truly a riverine species, found almost exclusively along fast-flowing rivers and streams during all seasons. Populations are limited mainly by stream productivity and nesting site availability (Price and Bock 1983). The few threats to habitat include the down slope effects (e.g., siltation) from logging of watersheds and general pollution of waterways. Because of their sensitivity to stream pollution, dippers are good indicators of stream quality (Tyler and Ormerod 1994).
The purpose of this manual is to recommend methodologies and provide protocols for the inventory of riverine birds at three levels of survey intensity - presence/not detected (possible), relative abundance, and absolute abundance.
This section summarizes the distribution and ecology of riverine birds. This background information is important to consider when developing inventory programs. Excellent summaries of the biology, distribution and location of major populations of riverine birds in British Columbia are contained in Campbell et al. (1990a, 1990b, 1997). Other major references include Cannings et al. (1987), Palmer (1976), Cramp and Simmons (1977) for harlequin; Price and Bock (1983), Kingery (1996) for dipper; and Hamas (1994) for kingfisher.
A medium-sized duck weighing about 450-750 g with sexually dimorphic plumage. Females are brownish with a bright white spot behind the eye, and white below the eye and between the eye and forehead. Males in breeding plumage are brightly coloured with chestnut sides and white streaks scattered over a slate blue background. Males do not reach their full breeding plumage until their third year, and have distinctive juvenile (1st year) and subadult (2nd year) plumages. Moulting males look similar to females when in full eclipse plumage.
Harlequins have a disjunct holarctic distribution (Bengtson 1972; Palmer 1976). Breeding occurs in eastern Siberia, northwestern North America, eastern Canada, Greenland, and Iceland. Wintering distribution is mainly confined to coastal areas. Harlequins in British Columbia have a widespread breeding range despite the paucity of breeding records (Campbell et al. 1990a). Although their breeding range is confined to regions with fast-flowing rivers and streams; in British Columbia this includes the Rocky Mountains, Cassiar Mountains, Coast Mountains, Vancouver and Queen Charlotte Islands. Harlequins may also occasionally breed on coastal islets with dense cover. Breeding densities vary markedly according to habitat quality and presence of spring staging areas. The Queen Charlotte Islands probably support a resident, insular population (I. Goudie pers. comm.).
The harlequin is a short-distance migrant that moves to breeding streams from Pacific coastal areas. Arrival on breeding streams is dependent on timing of spring break-up, which varies with latitude and altitude. Males spend only 4-10 weeks on breeding streams, depart during the onset of incubation and fly to coastal moulting sites, where they join nonbreeders (Palmer 1976). Breeding females move to the coast later depending on breeding success and whether or not females abandon young. Nonbreeding females also remain on rivers through the incubation period. Successful females and juveniles arrive on the coast in mid to late September. Some coastal breeding populations are probably nonmigratory.
Very large aggregations of harlequins have been reported during early spring associated with Pacific herring spawn (Campbell et al. 1990a). For example, up to 4,500 birds were reported to be off Hornby Island in March, 1995 (Goudie and Wright in prep.).
Spring migrants arrive to swiftly-flowing breeding streams, with relatively little insect prey available, shortly after ice-out although snow is usually still on the ground. Their arrival, in the southern Canadian Rocky Mountains at least, coincides with the spawning of the Long-nosed Sucker (Catostomus catostomus), which provide pre-nesting birds with an important food source (Van Tighem 1994). Later, they feed on insect larvae and crustaceans. Elsewhere, harlequins feed primarily on aquatic insect larvae during the breeding season (Cassirer and Groves 1994) while on the coast they eats mainly molluscs and crustaceans.
Harlequins nest on the ground, under roots along banks, on cliffs among boulders, and in large tree cavities. Clutch and brood sizes range from 3-10 eggs or young. The incubation period is about one month and young fledge after about two months (Bengtson 1972; Campbell et al. 1990a).
During nonbreeding seasons, harlequins are gregarious, almost always occurring in conspecific flocks. In British Columbia, they do not usually associate with other duck species. On breeding streams, pairs tend to avoid other pairs but are not considered territorial (Palmer 1976).
The kingfisher is a familiar bird to most people in British Columbia. Its bluish and white plumage, raucous call, crested head, and habit of plunging into water to catch prey, are distinctive. The females differs from the male in the chestnut band across her chest, just below the blue band which both sexes share. Juveniles tend to look like males.
The kingfisher is one of the most widely distributed "landbirds" in North America (American Ornithologists' Union 1983). In British Columbia, it breeds throughout the province wherever fish-bearing streams or lakes and banks suitable for burrowing exist. It winters mainly along the coast, but small numbers winter in southern interior valleys (Campbell et al. 1990b).
Spring migration occurs in March and April, and into May in the north. Migrants follow river valleys and lake shores. Autumn migrants leave the northern interior in August and early September, and the southern interior in October (Campbell et al. 1990b). Winter populations occur most frequently along coastal rivers with plentiful small fish populations, in estuaries and harbours, and in the vicinity of fish hatcheries.
Kingfishers excavate burrows in soft, sedimentary material in vertical banks along rivers, lake shores, gravel pits, or roads. They occasionally nest in piles of sawdust or buildings (Campbell et al. 1990b). Clutches of 5-8 eggs are laid mainly in late May. The incubation period is about three weeks while fledging requires about four weeks. Young stay with parents about three weeks after leaving the nest. The kingfisher is solitary outside the breeding season (Hamas 1994).
Kingfishers feed mainly on small fish and require clear waters for visual detection of prey and a supply of perches (dead branches, sticks, snags) along the water's edge.
The dipper is a plump, thrush-sized bird, with longish legs. Its plumage is a dark slate grey all over, except for thin white marks on the upper and lower eyelids. Both sexes appear similar. Dippers are usually seen perched on a rock at the water's edge where they can be seen bobbing up and down in a distinctive manner. Males have a melodious song, mainly heard in late winter and spring, that beautifully compliments the sounds of their riverine habitat.
The dipper is resident in western North America from Alaska south through British Columbia, Alberta and Montana to Mexico (American Ornithologists' Union 1983). In British Columbia, it breeds throughout most of the province along fast-flowing rivers with exposed cobble beaches, boulder-strewn rapids and riffles, and canyons. In winter, it leaves frozen rivers and migrates to river reaches near the coast or to milder climates in the interior. Some birds will remain as far north as open water allows (Campbell et al. 1997).
Spring migration occurs in February and March and migrants follow coastlines and major river valleys. After breeding, birds disperse along breeding rivers. Autumn migrants leave as waters begin to freeze up. Large numbers move to coastal streams to take advantage of salmon spawn in the autumn and hatching fry in late winter.
The dipper builds a large domed nest out of moss and mud, with an opening on the side. The nest is usually tucked away in a rock crevice in a cliff, behind a waterfall, under a bridge, or in a cutbank. A clutch of 4 to 6 eggs is laid. Incubation lasts about 15 days and young fledge after about three weeks. Young are vulnerable to disturbance and may leave the nest prematurely (Kingery 1996; Campbell et al. 1997).
Dippers feed mainly on aquatic insects, crustaceans, fish spawn and fish fry. They are unique among "songbirds" in that they walk and swim underwater to capture prey. Dippers are essentially restricted to rivers, occurring occasionally along lake shores during migration, and along marine shorelines when nesting on streams that cascade down steep mountainsides to the sea.