Wallace Bay National Wildlife Area Management Plan: chapter 2


2 Ecological resources

2.1 Terrestrial and aquatic habitats

The uplands and low-lying wetlands of Wallace Bay National Wildlife Area (NWA) support unusually high plant diversity for a site of this size in the region (Blaney et al. 2011). Wallace Bay NWA contains 472 vascular plant species, including 373 native and 99 non-native species. Surprisingly, there are relatively few rare plants: only eight species are provincially listed.

When lands for the National Wildlife Area were acquired by the Canadian Wildlife Service between 1971 and 1973, most of the marshlands reclaimed for farming were a composite of ponds, marsh and swamp, with little evidence of the site’s former agricultural importance. The vegetation is comprised of several species, including Meadowsweet (Spiraea latifolia), Broad-leaf (Spartina pectinata), Blue-joint (Calamagrostis canadensis), Round-stem Bulrush (Scirpus validus), Woolgrass (Scirpus cyperinus), Wild Rose (Rosa virginiana), and Speckled Alder (Alnus rugosa) (Whitman 1966).

Following construction of controlled water level impoundments (in collaboration with Ducks Unlimited Canada), these shallowly-flooded freshwater wetlands provide an interspersion of open water and emergent vegetative cover. The emergent vegetation in these habitats consists largely of cattail (Typha spp.) and Burreed (Sparganium eurycarpum), while submerged and floating aquatics include duckweed (Lemna minor) and pondweeds (Potamogeton pusillus and P. epihydrus).

The extensive salt marsh extending along both sides of the tidal channel east of the Aboiteau Road is primarily a “high” salt marsh that is not typically flooded daily by the tides and was the area once targeted for dyking by early settlers. The principal plant species in this habitat is salt-marsh hay (Spartina patens). Lower sections throughout the marsh, and along tidal creeks, support cord grass (Spartina alterniflora). Salt marsh pools that provide habitat for small fish are located throughout the tidal wetlands.

Forest habitat in the NWA consists of 100 ha of a mixture of deciduous and coniferous species, including Trembling Aspen (Populus tremuloides), Red Maple (Acer rubrum), White Birch (Betula papyrifera), Wire Birch (Betula populifolia), Balsam Fir (Abies balsamea), and Spruce (Picea spp.). A 5 ha island located within the salt marsh has a forest cover consisting of mature Red Oak (Quercus borealis), Large-toothed Aspen (Populus grandidentata), and White Pine (Pinus strobus). This small island is a remnant of what was probably a more common forest type along the coast.

The NWA includes 10 ha of agricultural upland that is used by local farmers under a permit. An additional 14 ha of old field is in the early stages of succession and consists of several species of grasses, herbaceous plants, shrubs and young trees.

For a complete list of plants found within Wallace Bay NWA, see Malone 1978, Spicer and MacKinnon 1998, and Blaney et al. 2011.

2.2 Wildlife

2.2.1 Birds

Nine species of waterfowl regularly breed at Wallace Bay NWA, including Green-winged Teal (Anas crecca), Black Duck (Anas rubripes), Mallard (Anas platyrynchos), Northern Pintail (Anas acuta), Blue-winged Teal (Anas discors), Northern Shoveler (Anas clypeata), American Wigeon (Anas americana), Ring-necked Duck (Aythya collaris), and Hooded Merganser (Lophodytes cucullatus). Broods of Wood Duck (Aix sponsa) as well as the less common Redhead (Aythya americana) have also been recorded. Of interest, the first Redhead brood was reported in 1979, and during three of the next five years broods were observed in the NWA.

The present importance of Wallace Bay NWA to breeding waterfowl is largely the result of the wetland development and habitat improvements undertaken since 1972 by Ducks Unlimited Canada in cooperation with the Canadian Wildlife Service. These wetlands currently support 70-80 duck broods per year. Wetlands in the NWA also provide important staging and migration habitat for waterfowl. Numbers of waterfowl steadily increase after about the middle of July with the arrival of post-breeding adults and young of the year. Peak numbers of over 1,000 birds occur around the middle of September. The principal migrant and staging waterfowl at Wallace Bay NWA are Canada Goose (Branta canadensis), Green-winged Teal, Black Duck, and Blue-winged Teal. Other species, including American Wigeon, Ring-necked Duck, Hooded Merganser and Common Merganser (Mergus merganser) also commonly occur in smaller numbers. Small numbers of Greater Scaup (Aythya marila) occur in late fall (Table 4).

Table 4: Maximum Daily Number of Waterfowl Observed in Wallace Bay National Wildlife Area (ECCC/CWS file records)
Waterfowl species Maximum Number Observed
Black Duck 600
Canada Goose 500
Green-winged Teal 250
Blue-winged Teal 200
Ring-necked Duck 100
American Wigeon 50
Common Merganser 100
Hooded Merganser 75
Greater Scaup 50

The wetlands within Wallace Bay NWA are of importance to a diversity of other marsh birds. Common Snipe (Gallinago delicata), Sora (Porzana carolina), and Pied-billed grebe (Podilymbus podiceps) are frequently seen in the freshwater wetlands. American Bittern (Botaurus lentiginosus) and Long-billed Marsh Wren (Cistothourus palustris) are present but less often observed (Cash et al. 1981). The COSEWIC designated as “threatened” Least Bittern (Ixobrychus exilis) was recorded within impoundment No. 1 in 1981 (Cash et al. 1981; Erskine 1992).

2.2.2 Mammals

Most of the land mammals commonly found in Nova Scotia are expected to occur at Wallace Bay NWA (Banfield 1974; Gilhen and Scott 1981; Dawe 2004). Nearly all of the typical larger mammals are present. Muskrat (Ondatra zibethicus) is probably the most abundant and noticeably visible species within the wetlands. Five species of small mammals have been recorded: Masked Shrew (Sorex cinereus), Maritime Shrew (Sorex maritimensis), Short-tailed Shrew (Blarina brevicauda), Deer Mouse (Peromyscus maniculatus), and Meadow Vole (Microtus pennsylvanicus). An additional five small mammal species are expected to occur based on the available habitat (Dawe 2004).

2.2.3 Reptiles and amphibians

The amphibian and reptile fauna likely comprise most of the species that commonly occur in the region. Although a detailed inventory has not been conducted, the following six species are frequently encountered: Green Frog (Rana clamitans), Northern Spring Peeper (Hyla crucifer), Yellow Spotted Salamander (Ambystoma maculatum), Bullfrog (Rana catesbeiana), Mink Frog (Rana septentrionalis), andMaritime Garter Snake (Thamnophis sirtalis pallidulus). An additional nine species may potentially occur within the NWA (Brannen 2001).

2.2.4 Fish

Nine fish species are documented for Wallace Bay NWA, but other marine fish undoubtedly occur. Gaspereau (Alewife - Alosa pseudoharengus) and American Eel (Anguilla rostrata) are harvested commercially with nets set in the tidal channel near the aboiteau. The numerous tidal creeks and salt marsh pools support typical brackish and salt water species such as Banded Killifish (Fundulus majalis), Ninespine Stickleback (Pungitius pungitius), and Fourspine Stickleback (Apeltes quadracus), all important food fish for a variety of wildlife.

2.3 Species at risk

There are seven COSEWIC-listed “threatened” species and one listed as “endangered” (Red Knot) that potentially could be observed in Wallace Bay NWA. An additional 39 species have, or have previously had, some level of provincial concern.

Few species at risk as listed under the Species at Risk Act (SARA) have been recorded within the Wallace Bay NWA. Some, like the Peregrine Falcon, likely visit the area on occasion; others, such as the threatened Least Bittern, which prefers dense stands of cattail, may find suitable habitat within the NWA (Table 5).

Table 5: Species at Risk in Wallace Bay National Wildlife Area
Species type Common and Scientific Names of Species Status
Canada
SARA c
Status
Canada
COSEWIC d
Status
Nova Scotia
Provincial Ranking e
Presence or Potential of Presence f
Birds Barn Swallow
Hirundo rustica
No Status Threatened Endangered (2013) probable
Birds Bobolink
Dolichonyx oryzivorus
No Status Threatened No Status probable
Birds Chimney Swift
Chaetura pelagica
Threatened Threatened Endangered (2007) probable
Birds Common Nighthawk
Chordeiles minor
Threatened Threatened Threatened (2007) probable
Birds Least Bittern
Ixobrychus exilis
Threatened Threatened No Status confirmed
Birds Peregrine Falcon
Falco peregrinus anatum
Special Concern Special Concern Vulnerable (2007) confirmed
Birds Short-eared Owl
Asio flammeus
Special Concern Special Concern No Status potential

c Species at Risk Act: Extinct, extirpated, endangered, threatened, special concern, not at risk (assessed and deemed not at risk of extinction) or no status (not rated)

d Committee on the Status of Endangered Wildlife in Canada: the same names as the SARA status

e Provincial Ranking using provincial codes, if applicable

f List as ‘confirmed’, ‘probable’, or ‘potential’

2.4 Invasive species

Some scattered Norway maple (Acer platanoides) near some old house sites in the NWA may present a problem, as they have the potential to competitively exclude native plant species. Periodic botanical surveys assist in monitoring expansion of species such as Norway Maple and identifying new potential species of concern. The other 97 species of non-native plants are not considered invasive.

Although not recorded within the immediate waters of the NWA, the invasive European Green Crab (Carcinus maenas) was reported in the nearby harbour of Wallace Bay in 2001. This species competes with existing fauna and is detrimental to the shellfish industry, eelgrass and native fauna (Seymour et al. 2002, Klassen and Locke 2007).

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