Portobello Creek National Wildlife Area Management Plan: chapter 2

2 Ecological resources

2.1 Terrestrial and aquatic habitats

The flora of Portobello Creek National Wildlife Area (NWA) reflects the area’s low-lying topography combined with a warm microclimate. The area contains a wide range of wetlands, including floodplain forest, shrub swamp, sedge meadow, wooded swale, open marsh and open water with dense submergent vegetation (figures 8 and 9). The extensive forested area within Portobello Creek NWA is dominated by Silver Maple (Acer saccharinum), White Birch (Betula papyrifera), Red Oak (Quercsus rubra), American Elm (Ulmus american), Yellow Birch (Betula lutes), Red Spruce (Picea rubra), Black Spruce (Picea mariana) and Balsam Fir (Abies balsamea). The ground cover under the floodplain forest is generally sparse as a result of delayed development caused by the spring freshet. Ostrich Fern (Pteretis penslyvanica)--the iconic "fiddlehead"--and Sensitive Fern (Onoclea sensibilis) cover broad areas within this habitat (Figure 10).

The majority of the ground cover within the shrub swamps consists of Leatherleaf (Chamaedaphne calyculata), Meadow Sweet (Spirea latifolia), Sweet Gale (Myrica gale) and Speckled Alder (Alnus rugosa). Buckbean (Menyanthes trifoliata), Water Arum (Calla palustris), and a variety of sedges and grasses can be found in standing water within these swamps. The wooded swales are confined to margins and islands of the Portobello and Noonan streams. These open wetland areas are characterized by dense grass and sedge mats supporting a sparse cover of alder and willow (Hinds 1983; Blaney 2003; Deichmann 2004).

Within the marsh areas, emergent vegetation is dominated by sedges (Carex spp.), bulrush (Scirpus spp.), Wild Rice (Zizania aquatica), Pickerelweed (Pontederia cordata) and Buckbean. Blue-joint (Calamagrostis canadensis) and Fresh-water Cord Grass (Spartina pectinata) are also dominant in some areas. The dominant submergents in the marsh areas are Coontail (Ceratophyllum demersum) and Water Milfoil (Myriophyllum spp.). Other common floating-leaved and submergent vegetation include Duckweeds (Lemna minor) and (Spirodella polyrhiza), Bladderwort (Utricularia spp.), pondweeds (Potomageton spp.), Fragrant Water Lily (Nymphea odorata), Yellow Water Lily (Nuphar spp.) and Waterweed (Elodea canadensis).

Not surprisingly within such a diversity of wetlands, this area supports a large diversity of dragonflies and damselflies, with 61 species recorded (Brunelle 2011).

2.2 Wildlife species

2.2.1 Birds

The wetlands of Portobello Creek provide quality breeding habitat for waterfowl (Carter 1952; Prince 1965; Wright 1967; Whitman 1968). The American Black Duck (Anas rubripes) is the most common breeding species, although other waterfowl such as Mallard (Anas platyrhynchos), Blue-winged Teal (Anas discors), American Wigeon (Anas americana), Wood Duck (Aix sponsa), Ring-necked Duck (Aythya collaris) and Common Goldeneye (Bucephala clangula) are common breeders. Other species of ducks frequent the area on a regular basis, such as Green-winged Teal (Anas carolinensis), Northern Shoveler (Anas clypeata), Northern Pintail (Anus acuta), Hooded Merganser (Lophodytes cucullatus) and Common Merganser (Mergus merganser). Canada Geese (Branta canadensis) use the area as a stopover during spring migration.

The composition of waterfowl species fluctuates as migrant populations pass through the area. Black Duck and Common Goldeneye are the first migrants to arrive in the spring. The number of waterfowl peaks in mid-April, and only breeding birds remain by the first week of May. Wood Duck, Ring-necked Duck and Blue-winged Teal arrive during the first week of April but do not reach maximum numbers until late in the month. These species generally do not nest until May, after the spring freshet has subsided. During fall migration in September, large numbers of Wood Duck, Blue-winged Teal, Black Duck and Ring-necked Duck occur. Wood Duck and Blue-winged Teal usually depart by mid-September, while other species do not leave until October and November.

The large and older-growth hardwood trees within the floodplain, such as Silver Maple and American Elm, are essential to cavity-nesting waterfowl such as Wood Duck, Hooded Merganser and Common Goldeneye. The loss of many of the old elm trees to Dutch Elm Disease has severely limited the availability of cavities for these birds (Johnsen 1992).

Many other waterbirds use the area, primarily during the breeding season. There is one active Bald Eagle (Haliaeetus leucocephalus) nest on French Island and several Osprey (Pandion haliaetus) nests within the Portobello Creek system. Other frequently encountered wetland birds include Pied-billed Grebe (Podilymbus podiceps), Common Loon (Gavia immer), Sora Rail (Porzana Carolina), American Bittern (Botaurus lentiginosus), Spotted Sandpiper (Actitis macularius) and Belted Kingfisher (Megaceryle alcyon). Great Blue Heron (Ardea herodius), Black Tern (Chlidonias niger) and Common Tern (Sterna hirundo) are frequently seen foraging in the open marshes.

Common Snipe (Gallinago gallinago) nest in the marshes, and Woodcock (Scolopax minor) and Ruffed Grouse (Bonasa umbellus) breed in the wooded areas. Other land birds using the area during migration or nesting include Kestrel (Falco sparverius), Northern Harrier (Circus cyaneus), Broad-winged Hawk (Buteo platypterus), Great Horned Owl (Bubo virginianus), Barred Owl (Strix varia), Common Nighthawk (Chordeiles minor) and various woodpeckers, most notably the Pileated Woodpecker (Dryocopus pileatus). Many species of songbirds, such as Tree Swallow (Tachycineta bicolor), Veery (Catharus fuscescens), Yellow Warbler (Setophaga petechia) and Common Yellowthroat (Geothlypis trichas), breed and forage in the varied habitats.

2.2.2 Mammals

Thirty-five species of mammals have been recorded within the Portobello Creek NWA. Moose (Alces alces) and White-tailed Deer (Odocoileus virginianus) are common summer inhabitants of the Portobello Creek complex (figures 11 and 12). Moose use shrub hummocks close to water during spring calving and are often forced onto high land while the wetland areas are flooded. Deer are present in the hardwood stands and regenerating areas within the NWA. All provincially common furbearers, including Beaver (Castor canadensis), Muskrat (Ondatra zibethicus), Raccoon (Procyon lotor) and Eastern Coyote (Canis latrans) are known to frequent the area (Dilworth 1966). Also present are Mink (Mustela erminea), River Otter (Lutra canadensis), Red Fox (Vulpes vulpes), Fisher (Martes pennanti), Snowshoe Hare (Lepus americanus) and Porcupine (Erethizon dorsatum). Common small mammals in the area include Eastern Chipmunk (Tamias striatus), Red Squirrel (Tamiasciurus hudsonicus), Grey Squirrel (Sciurus carolinensis) and Deer Mouse (Peromyscus maniculatus). Habitat is present in the hardwood areas for Little Brown Bat (Myotis lucifugus) and Eastern Pipistrelle (Perimyotis subflavus) (Banfield 1974).

2.2.3 Reptiles and amphibians

The entire area provides excellent habitat for reptiles and amphibians. At least nine species of reptiles and amphibians, such as Green Frog (Rana clamitans), Northern Spring Peeper (Hyla crucifer), American Toad (Bufo americanus) and Northern Leopard Frog (Rana pipiens), are found within Portobello Creek NWA. Additional species that would be expected to be present are Blue-spotted Salamander (Ambystoma laterale), Red-Spotted Newt (Notophthalmus viridescens), Redback Salamander (Plethodon cinereus), Mink Frog (Rana septentrionalis), Wood Turtle (Clemmys insculpta), Maritime Garter Snake (Thamnophis sirtalis), Ringneck Snake (Diadophis punctatus), Smooth Green Snake (Opheodrys vernalis) and Redbelly Snake (Storeria occipitomaculata). Eastern Painted Tutle (Chrysemys picta) are quite common, while there is a small possibility that the Grey Tree Frog (Hyla versicolor) could be present, as a number of the latter have been identified in the Fredericton area (Brannen 2004).

2.2.4 Fish

Chain Pickerel (Esox niger), White Perch (Morone Americana) and Yellow Perch (Perca flavescens) spawn in the flooded marshes in the spring. These species are commonly caught by anglers throughout the year and particularly during the ice fishing season. Economically or recreationally important fish species present in waters adjacent to the marsh areas include Gaspereau, American Eel (Anguilla rostrata) and Smallmouth Bass (Micropterus dolomieu). There are commercial fisheries for Gaspereau (used as lobster bait) and American Eel within the Portobello Creek system.

2.3 Species at risk

Butternut (Juglans cinerea), a species of special concern listed under the Species at Risk Act , occurs within the Portobello Creek NWA. This species is found sporadically throughout the lower Saint John River floodplain. The closest notable assemblage of Butternut occurs on nearby Gilbert’s Island (Table 3).

A single adult of the endangered Skillet Clubtail (Gomphus ventricosus), listed as Endangered by the Committee on the Status of Endangered Wildlife in Canada, was found within the NWA in 2004, but the species was not observed in more recent surveys in 2009.

2.4 Invasive species

Invasive fish such as Muskellunge (Esox masquinongy) and Smallmouth Bass (Micropterus dolomieu) are present within the Portobello Creek system, and further release and/or expansion of illegal or exotic fish are a concern because of the potential impacts on native fish poulations and food web dynamics. The invasive Purple Loosestrife is present but has not, as yet, occupied large areas of wetlands.