Conservation and Management

Shooting

Overhunting was common at the turn of the 18-19th centuries (Phillips 1925). Today, this species is important game for late-season hunters when other species have already moved south. Annual hunting kill estimates for the period 1971–1980 suggest that 188,300 Common Goldeneyes were shot in North America: 56% in Canada and 44% in U.S., representing 3.6% and 0.6% of total annual Canadian and U.S. waterfowl harvest, respectively (Carney et al. 1983, Canadian National Harvest Survey data, H. Levesque unpubl. data). More recent (1988–1991) Canadian harvest numbers are lower (average estimate 68,200; Levesque et al. 1993), but these numbers may underestimate actual kill. In North America, most birds are shot in Ontario or Quebec (64% of annual Canadian harvest, 36% of annual Common Goldeneye total harvest). In U.S., most birds are shot in Mississippi Flyway (18% of annual total Common Goldeneye harvest), with approximately equivalent proportions shot in Atlantic and Pacific flyways (11%). Only 3% of annual harvest occurs in Central Flyway.

The pattern of migration in fall results in differential sex and age ratios in the harvest in Canada, northern and most of Atlantic Coast states, and s. U.S. (calculated from Canadian and U.S. fall harvest data; HGL). Adult males are taken significantly more often than females in e. Canada and northern states than in Atlantic Coast states and the south. However, more immature females are taken than immature males throughout. Age ratios are similarly distorted by timing of migration and winter distribution. In e. Canada, 5 times as many immatures are harvested as adult females. This ratio declines significantly in the northern states and still further in the Atlantic Coast states and the south where the ratio is a little over 2 immatures per adult female. Because adult females leave the breeding grounds on molt migration much later than males and subadults, they complete the molt later and migrate south later. This results in fewer adult females in the harvest than adult males in Canada and the northern states. In the Atlantic Coast and southern states where seasons close later, however, adult females outnumber adult males in the bag (HGL).

Pesticides And Other Contaminants

PCBs, DDE, and mercury (Hg) have been detected in Common Goldeneye eggs collected in n. and w. U.S. (Zicus et al. 1988), although levels are generally considered low. Levels of various organochlorine pollutants increase in Common Goldeneyes wintering in Michigan and New York (Smith et al. 1985, Foley and Batcheller 1988) and tend to be higher in adults, suggesting retention of contaminants. Concentrations are sufficiently high to warrant concern for hunters consuming high numbers of contaminated birds.

For individuals breeding in areas affected by acid deposition, tissue concentrations of trace metals may be elevated (Eriksson et al. 1989, Scheuhammer 1991) but usually do not reach levels of toxicological risk.

Degradation Of Habitat

Declines in habitat quality have occurred on both breeding and wintering grounds. In breeding areas, availability of suitable cavity-producing trees has been reduced by forestry practices (Phillips 1925). Acid precipitation has affected large portions of the eastern breeding zone (e.g., 50% of Common Goldeneyes in Ontario breed in areas considered moderate to high risk from acid rain; McNicol et al. 1990). Because this species prefer fishless lakes for feeding, nesting, and rearing broods (Mallory et al. 1993, Wayland and McNicol 1994), lake acidification has caused shifts in their patterns of habitat use and diet in some regions (McNicol et al. 1987a). This is the only duck in North America known to derive short-term benefits from lake acidification (Mallory et al. 1994; see also Eriksson 1984, Gilyazov 1993 for similar results in Europe); in some areas, populations may decline as lakes recover from acid rain (Blancher et al. 1992, McNicol et al. 1995).

On wintering grounds, habitat quality may decline because of river channelization, increased sediment loads from agricultural and industrial practices, loss of coastal and interior wetlands, and increased pollutant exposure near industrial effluent discharge sites (Foley and Batcheller 1988, Stewart et al. 1988).

Sensitivity To Disturbance At Nest

Nesting females may desert their clutch if scared off the nest or handled by observers during first 2 wk of incubation (this probably depends on the degree of conditioning of local Common Goldeneyes to humans), but they usually return if handled only during the last 2 wk (JME, MLM).

Females generally do not breed until their second year, are highly philopatric to their natal area, and usually do not renest in the event of nest loss. These factors make potential recovery of local populations slow if numbers of local adults are severely reduced. Hunting on wintering grounds must be monitored carefully to ensure that overharvesting of local “populations” does not occur. In recent years, Common Goldeneyes have shifted some traditional wintering sites to take advantage of warm, productive, open-water sites immediately downstream of industrial effluent discharges (see Sayler and Afton 1981); care and monitoring of water quality and contaminant levels must be taken on the wintering grounds to minimize exposure of flocks to hazardous pollutants (oil or chemical spills, industrial effluent).

During breeding season, require unaltered, natural rivers and lakes surrounded by forests with large trees suitable for nesting. The loss of many of these habitats due to forestry, agriculture, and urban expansion is a cause for concern. However, species readily use human-made nest boxes and show high breeding site fidelity, which could prove useful in re-establishing populations in areas where nesting trees have been reduced (e.g., by fires, clearcut logging, fumigations) or in monitoring local population size (Zicus and Hennes 1987). In Scotland, a local breeding population of Common Goldeneyes was established by providing nest boxes in a region where they were spending the summer. It took 14 yr for the boxes to be used, after which box use and population size followed an exponential growth pattern (Dennis and Dow 1984). In Maine, females and broods were relocated to a site where nest boxes were available, and a local breeding population was established, although population growth has been slow (Coulter 1979; also see Breeding: nest site).