4.1 Definition

At certain times of the year, some species of wildlife are highly concentrated within relatively small areas. In spring and autumn, migratory species of birds and butterflies concentrate in critical stopover areas where they can rest and feed. Other examples of such habitat include winter deer yards, bird breeding colonies, and hibernation sites for bats or snakes. See the Significant Wildlife Habitat Decision Support System for a detailed description of significant seasonal concentration habitats.

4.2 Ecological functions/effects of loss

Areas of seasonal concentrations of animals provide important cover and protection from inclement weather conditions and predators. They may also provide access to abundant food sources or nesting and breeding sites. This habitat may be limited and directly influence populations numbers of a species. Loss of these seasonal concentration habitats results in a disproportionate loss of associated wildlife. To maintain the biodiversity of the planning area and Ontario, these critical wildlife habitats should be identified and protected.

4.3 Identification of potentially significant seasonal concentration areas

One approach to the identification of potentially significant seasonal concentration areas is outlined below. Emphasis is on first identifying known important sites and then looking for additional habitats. Appendix C provides sources of information about seasonal concentration of animals. The habitat matrices in Appendix G describe the habitat requirements of species that concentrate seasonally.

4.3.1 Mapping and verifying known seasonal concentration areas

  • First, narrow the search for species that may concentrate seasonally. Use the habitat matrices in Appendix G plus the various atlases for the province (butterflies, amphibians and reptiles, breeding birds, mammals [see Appendix I]) to determine which species are likely to occur in the planning area. There is no point in looking for late winter moose habitat or tern breeding colonies if these species are known not to occur in the study area.
  • Ask the OMNR ecologist and biologist, and staff at the Canadian Wildlife Service, Ontario Region Office in Ottawa (for birds) to identify known significant seasonal concentrations of animals within the planning area. Appendix C provides information sources for identifying seasonal concentration areas and Appendix G identified habitat requirement for these species. Several provincially and regionally significant seasonal concentration areas have already been recognised and mapped by the OMNR (winter deer yards, some waterfowl stopover areas, and some heronries) and by the Canadian Wildlife Service (some colonial bird nesting sites, some waterfowl breeding and staging habitat, and some shorebird and landbird migratory stopover areas). Sometimes a specific concentration habitat may not be mapped, but knowledgeable staff may be able to identify potential sites (wild turkey and raptor winter roosting areas, amphibian breeding ponds, and migration stopover sites).
  • Map (preferably at 1:10,000 scale) all of the important concentration areas that are known to occur in the municipality.

4.3.2 Finding animal concentration areas that have not been previously identified

  • Begin to identify seasonal concentration habitats most likely to exist within the planning area that have not been identified and described. Examples may include potentially significant waterfowl breeding and staging habitats, heronries, and migratory bird stopover areas; winter feeding and roosting areas for hawks, owls, and wild turkeys; turkey vulture summer roosting areas; reptile and bat hibernacula; and butterfly migratory stopover areas. Some of these habitats may not exist in the planning area or the species may not occur even if there appears to be suitable habitat. It must be realised that seasonal concentration areas are difficult to find. For example, snakes often overwinter underground. In spring, a large number of snakes may emerge from a small opening within a few days and unless someone is present at the right time and place, these sites can easily be overlooked.
  • Appendix C provides a list of information sources for the identification of seasonal concentrations of animals. OMNR site district and inventory reports, wetland evaluations, sensitive area reports, ANSI inventory reports, and consultant reports are the most easily obtained materials and contain the most site-specific information.
  • A Conservation Advisory Committee (CAC) might be very helpful in finding seasonal concentration habitats. They are also an excellent liaison with other groups within the planning area. Landowners with potentially significant wildlife habitats on their property might be able to provide more information. Hunters, anglers, trappers, members of cottage associations, fish and game, and naturalist clubs, as well as people working in the outdoor recreation sector (outfitters and resort operators) are often aware of seasonal wildlife concentrations.
  • Encourage knowledgeable people to help the planning authority to identify potentially significant habitats, particularly those habitats that are hard to find.

4.4 How to find some specific seasonal concentration areas

A number of habitats of species that concentrate seasonally are described below and steps to find them are presented. Emphasis is on use of existing information sources to find potentially significant sites. The information sources outlined in Table 3-1 and discussed in Section 3.2 will be very useful to find potentially significant wildlife habitats. Key elements of the habitat are listed. Field investigations may be necessary to confirm the use of the habitat by the species. Specific information about how to conduct field investigations is discussed in Appendix D.

Planning authorities are advised to rely on OMNR advice for locations and significance of deer and moose seasonal concentration areas. However, if they wish to examine these habitats in more detail, a suggested approach is outlined below.

4.4.1 Winter deer yards

White-tailed deer do not move well in deep snow. As snow begins to accumulate, deer start to move to sheltered areas and remain in the general vicinity until early April. In areas with little snow accumulation, such as in much of southwestern Ontario, deer may not yard in the traditional sense, but often still congregate in large numbers in suitable forested areas.

Deer yards consist of a core area of mainly coniferous trees (pines, hemlock, cedar, spruce) with a canopy cover of more than 60%. In severe winters, deer are confined to the core part of the yard. In mild winters, they may be found in loose aggregations in and around the core of the yard. This core area provides primarily shelter, ease of movement, and protection from predators. The land surrounding the core area is usually mixed or deciduous forest. Understorey shrubs and small trees, especially white cedar, provide winter food. When snow accumulation is light, deer move to nearby agricultural land if it provides food such as leftover corn and grains. Deer tend to use the same yards year after year and are not highly adaptable in moving to a new yard. Animals will often move long distances to some deer yards. Generally, deer yards make up about 10% of the summer deer range.

How to find

  • OMNR biologists, foresters, conservation officers, and local hunters know the location of some deer yards.
  • Use FRI maps in conjunction with aerial photographs to help to find other potential areas. Locate areas consisting of preferred tree species such as hemlock, white cedar, pines, and white spruce. Use aerial photographs to verify existence of potential sites and to assess the apparent canopy closure and features of the surrounding landscape.
  • Conduct field investigations during mid to late winter to confirm use (can be done from a vehicle or aircraft).

4.4.2 Moose late winter habitat

As snow accumulates, moose move to dense stands of coniferous trees that permit easier movement and provide protection from cold winds and predators. This usually occurs in mid to late winter. Canopy closure within the conifer stand should be at least 60% and most trees should be at least 6 metres tall. Moose are not as dependent on late winter habitat in the southern part of their range as they are in the north because snow is generally not as deep and temperatures not as cold as in northern areas. When moose congregate farther south, they generally use the association of hemlock, balsam fir, and white spruce because of its superior snow interception qualities.

How to find

  • OMNR biologists, foresters, conservation officers, and some local hunters and trappers may know the location of some late-winter habitat.
  • Use FRI maps in conjunction with aerial photographs to help to locate potential habitats. Identify contiguous forest stands consisting of mainly older (> 40 years) conifer trees. FRI maps indicate species composition and age of forest stands.
  • Use aerial photographs to verify existence of potential habitats, assess the apparent canopy closure and features of the surrounding landscape, and determine the approximate size of these habitats. Suitable habitat should be greater than 4 ha.
  • Conduct field investigation in late winter to confirm use by moose. Since many areas are difficult to reach, flying over potential areas is recommended.

4.4.3 Colonial bird nesting sites

Colonial birds are a diverse group including several species of herons, gulls, terns, and swallows. Sometimes an entire local population can depend on the survival of just one or two colonies. Under favourable conditions, some species are capable of rapid population growth. In some planning areas, species with expanding populations such as ring-billed gulls and double-crested cormorants may be unpopular and considered pests. Planning authorities will have to decide on the level of protection offered to these species. However, these birds are protected by the Convention of Migratory Birds and these laws must be abided. The habitat matrices in Appendix G provide a list of all of the colonial nesting birds and describe their habitats.

Generally, herons nest in trees in swamps and along large bodies of water. Gulls and terns prefer to nest on the ground, and colonies are frequently found on islands in the Great Lakes and large rivers such as the St. Lawrence River and Ottawa River. Birds often show considerable nesting site fidelity, returning year after year. Different species of swallows congregate on specific habitat types such as cliffs, banks, and artificial structures. Certain grassland birds are also colonial.

How to find

  • Colonial bird nesting sites are often found by speaking with knowledgeable landowners whose property provides suitable habitat. Local naturalists may be especially helpful in finding these sites.
  • Check Appendix G to see which of the colonial bird species was documented in the relevant site district(s). Also, check the Atlas of the Breeding Birds of Ontario to determine which atlas squares they were sighted in. This will greatly narrow the search. In addition, the habitat information provided in this appendix and the Significant Wildlife Habitat Decision Support System will help planning authorities to key in on areas that may support colonial- nesting birds.
  • OMNR offices have some information about local heronries but it may be out-dated and require verification. Bird Studies Canada has information on the Ontario Heronry Inventory, which was completed in the early 1990s.
  • Check all OMNR Wetland Evaluations because these indicate the presence of colonial nesting species.
  • Bird Studies Canada coordinates the Ontario Birds at Risk program and several colonial-nesting birds are on the list of Ontario Birds at Risk. Volunteers report nesting sites.
  • Local conservation authorities may also have wetland or watershed studies that identify these areas.
  • Sometimes aerial photographs can help to identify large heronries. They are most easily seen by using a stereoscope or magnifying glass to search lightly wooded swamps consisting of mostly dead trees. Great blue herons tend to use wooded swamps. Aerial photographs can also be used to identify specific habitat types. For example, black terns generally use sedge or cattail marshes that are about 50% water and 50% vegetation. Many of these can be identified on aerial photographs.
  • Sometimes black tern and heron colonies can be identified from the air. The flight should cover potential areas identified from aerial photographs and care should be taken not to disturb nesting birds.
  • Check potential sites and verify reports of colonies by field investigation.
colonial nesting species such as gulls, will seek islands to nest and return to the same location annually.
Figure 4-1. Colonial nesting species such as gulls, will seek islands to nest and return to the same location annually.

4.4.4 Waterfowl stopover and staging areas

During spring and fall migration, waterfowl require habitat that supplies adequate food to replenish energy reserves, resting areas, and cover from predators and adverse weather conditions. Migrating waterfowl usually prefer larger wetlands, especially those adjacent to large bodies of water, and relatively undisturbed shorelines with vegetation.

Many waterfowl congregate in relatively large flocks before fall migration. They raise broods in small areas (ponds, marshes, drainage ditches, and creeks). Then they set up a pattern of pre-migration staging, whereby 30 to a few hundred ducks move between feeding ponds and a large night roosting pond. Often these roosting ponds are used until they freeze over and many of them are used year after year. These ponds may be considered locally significant. Appendix K outlines an approach on how to determine significant waterfowl habitat.

How to find

  • OMNR staff such as local conservation officers may be aware of important fall staging areas within the planning area, such as areas that traditionally receive heavy hunting pressure. Often local duck hunters and fish and game club members know the most important areas.
  • CWS staff know the larger, most significant sites. They also commonly fly to find “baited” ponds and often observe local staging areas.
  • Check OMNR wetland evaluations and ANSI inventory reports because these indicate presence of locally and regionally significant waterfowl staging habitat. Conservation authorities may also have wetland or watershed studies that identify locally significant sites.
  • Use aerial photographs to find large beaver ponds and small lakes. In early September, observations of flights of ducks in the evening can also help to locate these ponds.
  • Conduct field investigation of the most likely areas identified from aerial photographs, preferably in the early evening just before dark.

4.4.5 Waterfowl nesting

The most significant waterfowl nesting sites are usually relatively large, undisturbed upland areas with abundant ponds and wetlands. The upland areas provide nesting cover. Most species nest in grassy or shrubby fields adjacent to wetlands and most nests occur in relatively dense vegetation that is about 50 cm tall. Wood duck, bufflehead, common goldeneye, and hooded merganser nest in cavities in trees located in swamps or on the shorelines of water bodies, and sometimes in adjacent upland woods. Species such as mallard and teal commonly nest near small ponds surrounded by grassy cover. Sites with an aggregation of several small ponds may be significant for waterfowl nesting. Upland areas should be at least 100 m wide so that predators such as racoons, skunk, and fox have difficulty finding nests. The area should also provide plenty of food and cover for young and adult birds.

One of the best approaches for the conservation of waterfowl is to protect relatively large areas with a high density of small and medium-sized ponds. If single wetlands are being examined, large, diverse wetlands are most likely to contain the best nesting habitat for waterfowl (Appendix I).

In 1996, a group of waterfowl experts was assembled to examine criteria for determining significant waterfowl habitat. The group prepared a report that outlined a number of factors that should be considered when identifying significant waterfowl habitat. This report is included as Appendix K.

How to find

  • Ask OMNR biologists and local hunters and naturalists for locations of habitats of greatest use. This is often determined by the number of broods on the wetland, although different ponds or wetlands may be used for nesting and brood habitat.
  • Check OMNR Wetland Evaluations for indication of significant waterfowl nesting habitat.
  • Check with Ducks Unlimited. Staff may know the locations of particularly productive sites.
  • Use topographical maps to find areas with a large number of wetlands.
  • Use aerial photographs to examine wetlands and determine density, and general nature of surrounding vegetation. Photographs can also help to determine the approximate configuration of the adjacent upland nesting habitat, as well as aggregations of small ponds and potential disturbances to the habitat.

4.4.6 Shorebird migratory stopover areas

Migrating shorebirds often follow shorelines of the Great Lakes in their movements between winter and summer ranges. Traditionally used areas provide safe places to rest and feed to replenish energy reserves needed to continue migration. Large numbers of shorebirds may accumulate in stopover areas during poor flying weather. Important areas must provide relatively undisturbed shorelines that produce abundant food (insects, clams, snails, and worms) for many birds of a variety of species. Great Lakes shorelines provide some of the best shorebird migratory stopover habitat because of their location along migration routes and because wave action maintains large and productive beaches. Southern James Bay is a critical shorebird staging area, particularly in autumn. Almost the entire world population of certain shorebird species may congregate here each year. The shorebird migration period may last one to three months in late summer and fall.

How to find

  • Staff at the CWS and OMNR may be aware of the most significant sites. Participants in a recently initiated shorebird monitoring program coordinated by CWS staff may also be aware of locally important sites.
  • Ask knowledgeable people such as local birders. These people will probably know the locations of most of the important seasonal concentrations of shorebirds.

4.4.7 Landbird migratory stopover areas

Since flying across large water bodies such as the Great Lakes is potentially exhausting and dangerous for landbirds, many choose to cross at narrow spots (Point Pelee, Wolfe Island). During migration, large numbers of birds move along Great Lakes shorelines and stop at traditionally-used sites to feed, rest, and/or wait out periods of bad flying weather.

These stopover areas must provide a variety of different habitat types ranging from open fields to large woodlands, to provide abundant food and cover for the diversity of different species during migration. In addition, raptors will use updrafts along cliff faces to assist in migration during spring and fall.

How to find

  • Ask local birders for the location of important migratory stopover areas. Many of the best sites are found within 2 km of Lake Ontario and Lake Erie.
  • Topographical maps and aerial photographs may be used to find natural habitats close to the Great Lakes that may be used by migratory landbirds.

4.4.8 Raptor winter feeding and roosting areas

Open fields, including hayfields, pastures, and meadows that support large and productive small mammal populations (mice, voles) are important to the winter survival of many birds of prey. Such fields usually have a diversity of herbaceous vegetation that provides food for mammals. Scattered trees and fence posts provide perches for hunting birds. Windswept fields in more open areas that are not covered by deep snow are preferred by raptors because hunting prey is easier. The best roosting sites will likely be found in relatively mature mixed or coniferous woodlands that abut these windswept fields. Some species, such as northern harriers and short-eared owls, roost in large grassy fields. Some feeding and roosting sites support many birds, especially in years when northern species are numerous. In areas with few remaining forested areas, woodlots with dense conifer cover may support numerous roosting birds, especially long-eared owls. Highway corridors appear to attract many hunting raptors throughout the year, because these areas are open, and the vegetation is relatively low, making hunting easier. As with waterfowl nesting habitat, protection of large areas of potentially suitable habitat will increase the probability of including significant raptor winter feeding and roosting areas within a Natural Heritage System.

How to find

  • Residents are most likely to know where these habitats are found. Local naturalists may know the locations of winter concentrations of raptors.
  • If a Christmas bird count (CBC) is conducted in the planning area, the compiler of the CBC data should be contacted to see if there are significant concentrations of wintering raptors.
  • Farmers in areas of potential habitat often know when and where concentrations of raptors are found on their property.
  • Use aerial photographs to locate open field areas next to woodlands comprised of at least some large trees. Prime areas would be hayfields, old fields, and pastures.
  • Field investigations in potential areas should be conducted after first accumulation of snow. Usually, raptors are easily seen from roads.

4.4.9 Wild turkey winter range

Since most of its feeding is on the ground, the wild turkey’s ability to move and forage freely is critical to its winter survival. Wild turkey will use fields and pastures, feeding on weed seeds and waste grain if the snow is not too deep. The birds do not stray too far from dense conifer cover. Dense coniferous forests provide the best winter habitat because they minimise snow accumulation on the ground and provide protection from the cold and predators. Coniferous stands used by turkeys are usually on valley floors or lower slopes. Hemlock stands appear to provide the best thermal protection and are often used during severe weather.

Wild turkey always roost at night for protection from predators. They prefer to use the largest conifers for roosts. Favoured roosts are normally found close to winter food supplies, which often includes agricultural fields where they can scratch for seeds left over from harvesting. Acorns are another favoured food. Wild turkeys readily move to new food sources and may change roosting sites from year to year. However, most significant winter roost sites will be used year after year.

The presence of groundwater seeps in the forest enhances wild turkey winter habitat because they melt the snow and expose food in the form of foliage and invertebrates. The best seeps are found on slopes with southern aspects that have increased exposure to sunlight, resulting in reduced snow depth and increased food availability. Turkeys also drink water regularly, so the presence of seeps or open watercourses is essential.

Wild turkey do not use winter range areas consistently over time. Use appears to depend on food supply conditions and availability of coniferous cover. Where coniferous cover is limited, they may use the same roosts more frequently. The most consistently used areas have stable, abundant, and high quality food sources located nearby (cornfields, oak trees). Those sites that have consistent use year after year would be considered significant.

How to find

  • Ask the OMNR biologist for the location of important winter turkey habitat. Many OMNR offices have been conducting post card surveys to determine the distribution of birds. Farmers may have observed wild turkey feeding in their fields and be aware of potential habitat in adjacent areas. Landowners may also know where groundwater seeps occur.
  • Use FRI maps in conjunction with aerial photographs to identify older coniferous or mixed woods with a good proportion of conifers and/or oaks. Stands of large conifers can often be identified from aerial photographs, these are areas are most likely to be used. In some areas, there is a shortage of coniferous forest and these pockets of conifers may be used. Birds may be forced to roost in hardwoods when conifers are rare.
  • Conduct field investigations of most likely areas during winter. Flocks of feeding birds may be observed and winter roosts will usually be in the near vicinity.

4.4.10 Turkey vulture summer roosting areas

Turkey vultures like to roost on rocky cliff ledges and large, dead or partially dead trees, preferably in undisturbed areas, and often near water. Preferred day roosting areas appear to be open areas where the birds can easily take flight or sunbathe. Cliff ledges have excellent rising air currents that are conducive for flight and soaring. Significant sites are those that are used consistently year after year.

How to find

  • Ask OMNR staff, local naturalists, and cottage owners for help in locating these areas.
  • Use topographical maps in conjunction with aerial photographs to find areas with steep relief. Further examination of aerial photographs might reveal cliff areas with trees on the summit.
  • Conduct field investigations on warm summer days after rainy periods, when birds frequently perch at roosts with outstretched wings. Copious amounts of whitewash (excrement) may be present at popular roosts.

4.4.11 Reptile hibernacula

Some species of snakes and turtles overwinter in sizeable concentrations in sites known as hibernacula. These sites are often in animal burrows, rock crevices, and other areas that enable the animals to hibernate below the frost line and often in association with water to prevent desiccation. Frequently hibernacula are found among broken rocks at the base of cliffs or in karst areas because these landforms provide an abundance of suitable subterranean crevices. In fall, snakes and turtles usually make a gradual movement toward their hibernacula and may be observed basking in groups close to the hibernacula. In spring, many snakes may emerge together and usually remain close to the hibernacula for a few days before dispersing.

Few hibernacula are known and they are normally very difficult to find. Radiotelemetry studies may be required to locate them. Since hibernacula have ideal microclimate conditions, they are very important to long-term sustainability of local populations; therefore, a reasonable amount of effort should be made to find these sites. Searches can be focused near sites where snakes or turtles have been observed. The assistance of groups of volunteers might be enlisted to search the most likely locations at the best times of the year.

How to find

  • Ask the OMNR ecologist for the location of potential reptile hibernacula. Local naturalists and experts, as well as university herpetologists may also know where to find some of these sites.
  • The Herpetofaunal Atlas should be referred to. The records are mostly from observations during the summer. However, the records may reveal what species are most likely to inhabit the area, and Appendix G can be referred to for their preferred habitat.
  • In spring, search any place where numerous snakes or turtles are encountered within a small area in less than a couple of hours. For snakes, prime spots to check are around slabs of broken or fissured bedrock, talus slopes, abandoned houses, and other places that provide access to subterranean areas. For turtles, prime areas are bogs and oxbows of rivers.
  • Naturalists may provide assistance, especially for the more uncommon species.
  • Consider conducting a public survey among residents and animal control professionals. In spring, some people observe the emergence of snakes from hibernacula on their property.

4.4.12 Bat hibernacula

Many species of bats overwinter in caves or abandoned mines. These winter hibernacula must have interior air temperatures slightly above freezing, relative humidity levels above 90%, and sufficient space for roosting. Preferred hibernacula are usually deep caves or abandoned mines, with remote and restricted openings with sufficient space for entry by flight. Flowing water helps moderate temperature and maintain sufficient humidity inside the cave. Largely because of their intolerance of disturbance, large, open caves and crevices are rarely used by bats in winter.

Hibernacula are relatively scarce and therefore large numbers of bats from several thousand square kilometres converge on certain sites every year. These populations are extremely vulnerable if these main hibernacula are altered, destroyed, or disturbed during critical periods. Research has shown that disturbances in winter hibernacula are a major mortality factor. Bats must wake periodically during hibernation. This requires a considerable amount of energy obtained from the conversion of fat reserves. Any unnecessary disturbance further stresses the animals. Even minor disturbances can have a lethal impact. Aroused individuals produce an alarm response and a chain reaction, triggering the arousal of many others.

How to find

  • Natural caves are scarce in Ontario. Large caves are usually found in limestone areas where underground water dissolves the rock and produces chambers (karst topography). Geological maps indicate the presence of limestone formations and the potential for caves. In southern Ontario, most caves and karst topography are found in the upper Ottawa Valley and along the Niagara Escarpment, including the Bruce Peninsula. Ask OMNR ecologists in these districts for locations of known hibernacula or for potential candidate sites.
  • Contact the Ontario Ministry of Northern Development and Mines to obtain locations of abandoned mines in the planning area. They can be checked to determine if they are still open or have been sealed off.
  • Some faculty members in university biology departments may know locations of hibernating bats. Contact the OMNR ecologist for names.
  • Some recreationists explore caves and may know caves with hibernating bats. Contact the Sierra Club.

4.4.13 Bullfrog concentration areas

Bullfrogs are primarily aquatic and found in marsh habitat. They require permanent waterbodies for survival. Bullfrog tadpoles may take up to several years before undergoing metamorphosis. Numbers of bullfrogs in a wetland can vary drastically depending upon geographical location. Populations on the Canadian Shield tend to be smaller than those in located off the shield.

Bullfrogs will congregate in the early summer and males will chorus for breeding purposes. Populations have declined in Ontario due to habitat destruction and exploitation.

How to find

  • Consult the Ontario Herpetofaunal Summary for distribution of bullfrogs. In addition, the CWS (Burlington) may have documentation of bullfrog populations through Amphibian Road Surveys, Backyard Amphibian Call Count.
  • Ask the local OMNR ecologist, biologist for known populations.
  • Use 1:50,000 NTS maps or aerial photography to locate marsh habitat
  • Consult wetland evaluations for documented populations.
  • Surveys could be conducted from mid-May to late June to locate chorusing population.

4.4.14 Migratory butterfly stopover areas

In fall, during the southward migration, some species of butterflies (monarchs) stop to feed, rest, or wait for inclement weather conditions to pass before they attempt to cross Lake Ontario, Lake Erie, and Lake Huron. Preferred stopover areas provide an abundance of preferred nectar plants, as well places for shelter and sunning.

How to find

  • Ask the local OMNR ecologist, local naturalists, and butterfly experts for help in locating these areas. Agriculture Canada (Ottawa) has entomologists on staff with expertise in butterflies.
  • Use aerial photographs to find fields and other open areas within 5 km of Lake
  • Ontario, Lake Erie, or Lake Huron shorelines.
  • Conduct field investigations of selected areas in mid September, preferably just after rainy periods