7.2.4 Birds

Nearshore waters are used periodically by a variety of waterfowl species from late summer until migratory flights the following spring are complete. Groups of dabbling ducks begin to use areas adjacent to coastal wetlands as resting and refuge sites in August and September. Sites with open water in the winter can become important to wintering flocks of mallards as resting areas (Reed 1971).

Major use of nearshore waters for feeding and resting is done by five species of diving ducks (lesser scaup, canvasback, redhead, ring­necked duck, and greater scaup, listed in order of importance) and by six species of sea ducks (common goldeneye, bufflehead, oldsquaw, hooded merganser, red­breasted merganser, and common merganser). Seeds, tubers, rootstocks, and vegetative parts of submersed plants, benthic organisms, and fish are eaten in accordance with availability and with each duck species' food preferences. Diving ducks are most abundant group of waterfowl: flocks of hundreds and even thousands of birds are associated with the 15 major waterfowl habitat complexes in the Great Lakes that have been identified by Prince et al. (1992).

Documented responses of migrating ducks, especially lesser scaup, to abundant supplies of zebra mussels are beginning to appear in the literature. If this trend continues, an increased use of nearshore waters during the October-November and March-April periods can be expected. Evaluation of the dynamics of waterfowl use of zebra mussels should be monitored. Diving ducks (common goldeneye and common merganser) are often attracted for feeding and resting to ice­free nearshore waters kept open by heated water discharges or by mechanical means in the winter (Padding 1993). Each new ice­free area resulting from expanded human activity needs an ecological evaluation in this context.

7.2.4.1 The Importance of the Nearshore Aquatic Zone for Wildlife on the Canadian Great Lakes

The Canadian Nearshore Aquatic Zone (NAZ) does not provide a great variety of habitat to non-fish wildlife species. Birds are the main wildlife species in this area, but amphibians and reptiles, as well as selected species of mammals, do make heavy use of wetlands.

This section poses three questions to guide the reader through a consideration of the NAZ's importance. Each question is discussed in the light of colonial waterbirds, aquatic raptors, and waterfowl. All references to the Great Lakes in this section refer to the Canadian Great Lakes (unless otherwise stated); no attempt is made here to evaluate the NAZ's importance for wildlife in the U.S. waters of the Great Lakes.

Why Is the Nearshore Aquatic Zone So Important for Wildlife? What Are We Trying to Protect beyond Wetlands?

Importance for nesting and feeding during the breeding season: In addition to wetlands, the other habitat that is exceedingly important to wildlife in the NAZ is islands. Most of the islands in the Great Lakes occur in the NAZ-i.e., in water that is less than 30 m deep. On the Canadian Great Lakes, islands provide nesting habitat for more than 105 species of aquatic birds-including colonially nesting gulls, terns, herons, cormorants, etc.; waterfowl; and aquatic raptors-as well as several species of reptiles and amphibians.

The colonial waterbirds that breed on the Great Lakes include the following: ring-billed gulls, herring gulls, great black-backed gulls, and little gulls (see Appendix A for Latin names); common terns, caspian terns, black terns, and forster's terns; double-crested cormorants; black-crowned night-herons; great blue herons; and great egrets.

The first three gull species are generalists when it comes to nesting habitat. They will nest on barren, rocky, grassy, or treed islands that are either close to shore (less than 100 m) or at much greater distances offshore (12 km to 60 km). In Southern Ontario, they will also nest at mainland sites where access is restricted-e.g., Toronto's Tommy Thompson Park, Hamilton's Eastport facility, or Port Colborne's Canada Furnace property. Common and caspian terns often nest in association with herring and ring-billed gulls but usually in areas of specific microhabitat-e.g., places with gravel of a specific size, etc. Their breeding areas are therefore often unique to specific sites. Great blue herons and great egrets require tall trees and often nest at the same site. The night-herons nest at low elevations in mature trees or in shrubs and bushes of various species. Cormorants nests in trees at mainland sites and in trees or on the ground on insular sites. Little gulls, black terns, and forster's terns are marsh or wetland nesters; they will nest in wetlands that are located on islands. Of the above-mentioned species, great egrets, little gulls, black terns, and forster's terns are quite restricted in their nesting range on the Great Lakes: forster's terns are known to nest at only one site, and little gulls are not known to have nested since the late 1980s or early 1990s.

A census in 1980 of all nesting sites of five predominant species of colonial waterbirds estimated that more than 300,000 pairs of birds (600,000 individual birds) were nesting on the Canadian Great Lakes at that time. Approximately 40 percent of these birds occurred on the lower Great Lakes, where all islands are within the NAZ; most of the remaining birds occurred in Lake Huron (where most, though not all, islands occur in the NAZ). Hence, the Nearshore Aquatic Zone-and particularly its islands-serves as home to nearly all the colonial waterbirds that occur on the Great Lakes.

The waterfowl species that breed regularly on the Great Lakes and that would use the NAZ include the following: mute swan; Canada goose; wood duck; green-winged teal; American black duck; mallard; northern pintail; blue-winged teal; northern shoveller; gadwall; American wigeon; canvasback; redhead; ring-necked duck; lesser scaup; goldeneye; hooded merganser, common

merganser, and red-breasted merganser; and ruddy duck. Common loons also breed on the Great Lakes and are included here, but are not considered a waterfowl species.

The shoreline and NAZ of the Great Lakes are not great areas for breeding waterfowl. There are no large concentrated breeding areas; water-level fluctuations may cause problems for breeding waterfowl; and isolated pairs of most of the above species can be found on some islands or near wetlands. Red-breasted mergansers breed on some, and maybe most, of the islands in the northern lakes, and their total numbers may be considerable. Loons and diving ducks breed in specific and well-known areas, but their overall populations are probably small.

Ospreys and bald eagles are the two aquatic raptors that breed on the Great Lakes. Historically, both these species nested along the shoreline of the Great Lakes and on offshore islands. On Lake Erie, only the eagle has recolonized the shoreline (mainland) sites. Neither species has returned to nest on islands there, nor are any eagles or ospreys nesting on Lake Ontario, though suitable habitat exists on both the mainland and the islands. In Lakes Huron and Superior, eagles are making a slow recovery, primarily on island sites, while ospreys have responded very well to artificial nesting platforms and other human-made structures. There are good numbers of ospreys in Lake Huron's Georgian Bay and in the St. Marys River.

Importance for feeding and resting during migrational staging: The migrational staging areas of most colonial waterbirds on the Great Lakes are not very well known. Western Lake Erie is a known area for common terns (Courtney and Blokpoel 1983) and cormorants (D.V. Weseloh, personal observation) in autumn. Cormorants also gather on islands in eastern Lake Ontario at that time of year. Long Point Bay, on Lake Erie's north shore, may be an important staging area for little gulls: more than 300 have been observed at one time there. The Long Point peninsula is certainly an important area for summering immature gulls and may also be important for migrational staging. The Niagara River is an important area for gulls from late autumn through the winter, when there are huge daily movements up and down the river (D.V. Weseloh, personal observation), and may also be important for migrant gulls. The St. Clair River (at Sarnia) is known to be a migrational route for several species of resident and transient colonial waterbirds, but they do not appear to do any staging in the area. Except for this information on specific sites, however, very little species-specific information is known on a Great Lakes-wide basis. For example, nothing is known about staging areas for the other three species of terns, for any herons, or for night-herons. There is virtually no information on staging during spring migration for colonial nesters. Presumably, the Great Lakes are important areas for these birds as they move north, waiting for those areas to "open up" (i.e., thaw).

The Great Lakes, particularly the NAZ, are an extremely important area for migrating and staging waterfowl, especially the diving and sea ducks. In spring and autumn, sites such as Lake St. Clair, Long Point (Lake Erie), Presqu'Ile Provincial Park (Lake Ontario), and Prince Edward County and Wolfe Island (at Lake Ontario's eastern end) are of international importance for tundra swans, canvasbacks, redheads, greater scaups, lesser scaups, common goldeneyes, common mergansers, and red-breasted mergansers. Use of the NAZ, which is greatest in the autumn, is more concentrated in the spring because of the limited amount of open water that is available. These sites, where ice thaws first and, presumably, food is first available, may be more critical or limiting in the spring.

Raptors do not generally migrate over large or even moderately sized expanses of water; in fact, they avoid them. Migration of raptors, including aquatic raptors, in Ontario is very structured so that they can avoid travelling over open water. The main avenue of migration in the spring is westward along the Niagara Escarpment between Lakes Erie and Ontario, and then northward. In the autumn, raptors migrate southwestward along the north shores of Lakes Ontario and Erie, crossing into the United States over the very narrow Detroit River. In the north, raptors move westward along the north shore of Lake Superior, passing south at the lake's west end, at Duluth, Minnesota.

Importance for feeding while overwintering: Most species of colonial waterbirds are absent from the Great Lakes during winter, having migrated in September and October. Adult herring gulls remain in the Great Lakes: they do not migrate. Great black-backed gulls migrate into the Great Lakes from the Atlantic; several species of Arctic nesting gulls migrate to the Great Lakes in small numbers; most ring-billed gulls also migrate out of the Great Lakes. For those gulls that occur on the Great Lakes in winter, the Niagara River is the major staging and congregating area. Observations suggest that the large number of fish that go through the hydro turbines and then back into the River and the abundant shallow water above the Falls provide excellent feeding habitat for gulls in this area.

Gulls need open water to feed in the winter, so any such areas have the potential to attract them. Gaps between otherwise frozen expanses of water in Lake Erie and ice edges in Lake Ontario are known to attract gulls (D.V. Weseloh, personal observation); the same may be true for the upper lakes. These areas may usually be outside the NAZ.

Among waterfowl, there are overwintering populations of canvasback, scaup, common goldeneye, and common merganser in the Detroit, St. Clair, Niagara, and St. Lawrence Rivers. Lake Ontario and Lake Erie provide overwintering habitat for sea-ducks such as white-winged scoters and oldsquaw; for example, as many as 40,000 oldsquaw ducks have been recorded in the Kingston basin on a single survey. Recently, the invasion of zebra mussels has affected the migratory and wintering distribution of scaup and other molluscivorous ducks in Lake Erie (Wormington and Leach 1992) and Lake Ontario.

The only known overwintering population of aquatic raptors occurs along the St. Lawrence River, from Gananoque to Mallorytown, Ontario. This portion of the river is mostly open all winter; the bald eagles feed on ducks and deer carcasses, most of the latter being intentionally provided by humans (Ewins and Andress 1995).

What needs protection: For colonial waterbirds, the most critical factor is breeding habitat. Preservation of traditional sites that have large and varied nesting populations is a must if the diversity is to be protected, especially in the lower lakes, where demand for developmental lands is high. Preservation of such sites as Pigeon Island, the islands of Presqu'Ile Provincial Park (Gull and High Bluff Islands), Tommy Thompson Park, and Eastport and its associated islands in Lake Ontario, and of Middle, East Sister, and Middle Sister Islands and Port Colborne in Lake Erie, is essential. In the upper lakes, where there are many more islands and nesting colonies, specific sites may not be as critical; however, the Limestone Islands, the Cousin Islands, the Watcher Islands in Lake Huron ,and other islands with Caspian Terns on them (these islands always have other colonials nesting on them) are good candidates for protection.

For colonial waterbirds, an adequate population of small to medium-sized fish as a food supply is also essential, but at present that does not seem to be a problem.

For waterfowl, it is more a question of protected sites for unique feeding opportunities during migration that is critical. Large underwater beds of vegetation, such as those found at Long Point Bay, are essential for Canvasbacks and Redheads. Areas with high densities of snails are crucial for several waterfowl species (e.g., scaup at Wolfe Island and in Prince Edward County). The recent introduction of zebra mussels may have provided a gala winter boost for the duck species that feed on molluscs.

Aquatic raptors require the maintenance (or creation) of nesting sites (super-canopy trees and artificial platforms) and accessible open water in winter at nearshore situations. For example, if the St. Lawrence River froze over at Gananoque-Mallorytown, the overwintering eagles there would almost certainly leave.

What Is the Population Status of Wildlife in the Nearshore Aquatic Zone? (Bad and increasing? Bad and getting worse? Stable?)

Colonial waterbirds can be grouped into four categories for the purpose of evaluating their status. The categories and the species that occur in each category are listed below.

Common to abundant, populations stable or increasing

• Ring-billed and herring gulls
• Double-crested cormorant
• Caspian tern
• Great blue heron

Uncommon, populations stable or increasing, species at edge of range

• Great egret
• Great black-backed gull

Common but populations under some pressure from various sources

• Common tern
• Black-crowned night-heron
  

Uncommon, populations declining (or, where marked by an asterisk, at edge of range)

• Black tern
• Forster's tern
• Little gull*

Waterfowl are more easily grouped according to species and then evaluated. They are listed by species group below.

Dabblers and geese: Stable

Bay ducks (scaup, redhead, canvasback, ring-necked duck): Numbers are stable but variable; availability of zebra mussels may cause redistribution of bay duck numbers in some areas.

Mergansers and goldeneye: Reasonably stable.

Sea ducks: Increased numbers overwintering because of zebra mussels.

Aquatic raptors are dealt with on a species-by-species basis below:

Osprey: Relatively common in eastern Georgian Bay and the St. Marys River; slowly returning and increasing in other areas because of the placement of artificial nesting platforms.

Bald eagle: Well-established and reasonably numerous breeding population present on western Lake Erie; smaller numbers in northern Lake Huron and Lake Superior. Not yet breeding on the shores of Lake Ontario, but did breed within that lake's basin in 1996.

What Are the Problems for the Various Species and What Management Actions Are Needed?

Colonials:

• Double-crested cormorant: No problems other than perhaps excessive numbers. Controls may be needed now or in the near future to safeguard rare trees and to reduce competition with black-crowned night-herons.

• Black-crowned night-heron: Competition for nest sites with and fouling by cormorants; protection of colonies of more than 100 nests is required.
  

• Herring gull, great black-backed gull, and great blue heron: No problems; no management actions required.
  

• Ring-billed gull: Excessive numbers in some areas. Control needed to help common terns (e.g., in Port Colborne).
  

• Great egret: Few nesting sites; protection of the few existing colonies is required.
  

• Black tern and forster's tern: Deterioration of nesting habitat due to disturbance and unknown other factors; surveys are needed to determine trends. If populations are declining, ecological studies are needed to find out why and to arrive at conservation options. Meanwhile, protection of all important colonies (for black terns, colonies of more than 50 nests; for forster's terns, all nesting sites) is required.
  

• Little gull: Marginal nesting habitat; protect any colony if found nesting again.
  

• Caspian tern: Few problems (perhaps disturbance); protect all long-standing colonies of more than 100 nests.
  

• Common tern: Competition and predation from ring-billed and herring gulls, as well as disturbance from humans; protect all colonies of more than 100 nests.
  

Waterfowl:

• Dabblers and geese: Disturbance at roosting sites; protection at and/or of roosting sites.
  

• Divers-Bay Ducks: Quiet shallow water is needed for feeding; bay ducks are more susceptible to disturbance than are other ducks; protected areas are needed.
  

• Divers-Sea Ducks: Few problems, because they use more offshore waters than do other ducks.
  

Aquatic Raptors:

• Osprey: Lack of suitable natural nesting habitat and absence of local nesting population; erect nesting platforms.
  

• Bald eagles: Lack of suitable natural nesting habitat; contaminants may be a problem in some areas (e.g., Lake Ontario); disturbance by humans. Erect platforms in specific areas for specific pairs; continue current restrictions (and impose new ones) on contaminants; and restrict access to all nest sites, especially any new ones.
  
  

7.2.5 Mammals

Few species of mammals use the nearshore waters. River otters, minks, beavers, muskrats, and raccoons occur in sheltered parts of the system, including embayments, tributaries, and the connecting channels. Larger mammals, including deer and moose, and carnivores, including wolves and coyotes, use the ice bridges in nearshore waters as migration routes.