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SuAsCo Focal Species Purpose of Using Focal Species Method for Choosing Focal Species Table 1: "SuAsCo Focal Species by Group"
Focal Species are used to indicate what animals and plants are important to protect in the watershed. They also serve as ambassadors to connect citizens to what lives in the SuAsCo Biodiversity Sites and other habitats throughout the watershed.
Definition
Focal Species are species that warrant special protection and stewardship. As such, they help determine sites for protection and stewardship actions to sustain and improve populations or at least to protect regularly documented occurrences. Focal Species fit one or more of the categories below: • Keystone species: Species which have significant effect on the diversity of a natural community. Example: Beaver • Umbrella species: Species which are wide ranging so that the protection of their various habitats preserves numerous other species. Example: Fisher • Flagship species: Species with public appeal and therefore broad political support. Example: Otter, great blue heron. • Habitat specialists or indicators: Species which indicate the quality of a natural community. Example: The Bog copper butterfly resides only in bogs, the bobolink requires large fields that are managed to maximize breeding success; the northern waterthrush nests only in well-protected wooded swamps. • Vulnerable species: Species listed by the Massachusetts Natural heritage and Endangered Species Program (NHESP) as “rare” and “endangered,” “special concern,” or “watch-listed” species and other species that may be in decline on a more localized scale. Example: spotted turtle; whip-poor-will. An additional caveat is added once the other criteria are met: • Species that can be inventoried relatively easily in that they are readily identifiable by biologists in the region and are relatively easy to find in their habitats. Fowler’s toad is excellent indicator species and are relatively common; however, they are very difficult to inventory as they require listening for their calls under very specific conditions (thunderstorms) and, therefore, are not included.
Note: Not all state-listed rare species are included as Focal Species because of their extreme rarity in the area, lack of specific habitat requirements, or inability of people to inventory them. Even so, all of our endangered species need protection, and are protected under the state’s Endangered Species Act..
On the other hand, common indicator species such as red-winged black birds that indicate good marshes are not Focal Species because they are so common. They have been included as associated species under the natural community descriptions. Purpose of Using Focal Species
1. To help determine the quality of habitats and the overall ecological system in the watershed. 2. To help monitor the quality of habitats and the overall ecological system over time in the watershed. 3. To help foster public interest in protecting habitat. Knowing that a species lives in a certain place increases people’s connection to it.
Natural communities with a suite of Focal Species as opposed to just one or two would indicate especially important Biodiversity Sites. A combination of Focal Species indicates that there are a variety of habitat features supporting a diversity of species, and therefore, indicates a more complex and intact natural system. Method for Choosing Focal Species
There are various methods for determining which are appropriate Focal Species for a given area. One approach involves in-depth research of the list of species in an area, their habitat needs, available habitat, their population sizes, and then determination of which species should be of conservation concern. Another method, devised by Dr. Karen Beazley in Canada, is having scientists review lists of species and providing their best professional judgment based on information already known, and ranking the species relative to the categories listed above. This method has been used to good effect in Nova Scotia and in Maine.
For this report, Focal Species were selected by consulting 10 respected local and state naturalists and scientists. Each reviewer was sent an abbreviated matrix to determine the relative frequency of the species, whether or not it was a good indicator species, and if it was a good Focal Species. Reviewers ranged in their responses, with some being more exclusive and others generally inclusive. Some had very different opinions, based on their experience with different species and the weight they attributed to the different categories. For instance, one reviewer weighted the flagship status as particularly important even if the species was relatively common. Another chose only rare species. Even so, by tallying up the responses, a general consensus as to which species to include became apparent. While not always the simplest process, a great deal of useful information was captured. The author is responsible for the final list. The list of Focal Species is a good first step and is subject to refinement.
Focal Species were selected based on the matrix which was circulated to over 15 expert naturalists. They are listed in Table 1. The following comments serve to illustrate the how different species’ use the watershed and their particular needs. The information also serves to encourage public support for these vulnerable animals and plants. Additional information on the species can be found in field guides (See references).
Most medium- and large-sized mammals in the SuAsCo Watershed are wide-ranging and surprisingly adaptable, but still they are subject to the effects of habitat loss, fragmentation, and degradation as well as harassment. At a minimum, individual animals need food, resting places, and corridors to pass through safely. In addition, localized species require safe places to breed and rear young.
The following mammals have all been seen in the SuAsCo Watershed. Local hunters and trackers have been particularly helpful in documenting sites. More information on these species’ habits and habitats, particularly in such a fragmented region, is essential to their protection.
Fisher: A large member of the weasel family, fishers are a solitary, wide-ranging animal which appear to prefer dense, closed canopy forests in both uplands and wetlands. They typically roam over an area 8-15 miles in diameter. They eat almost anything, including gray squirrels and small rodents, acorns, birds, and carrion. They appear to have a preference for porcupines. There have been frequent sightings of this species throughout the watershed in recent years. Fishers are likely the sources of reports of “cougars” as fishers have long tails, appear cat-like, and are surprisingly large. Many places including Estabrook Woods Site in Concord and the Desert Area Site in Sudbury and Marlborough have breeding fisher.
Gray fox: Red fox is a common species of agricultural landscapes; however gray fox is a shy, rarely seen animal of dense forests with rocky terrain. Gray fox climb trees. Tracks and other sign have been observed in the western part of the watershed as well as in Concord. Preservation of large forested tracts on the Shrewsbury Ridge, minimal trails, and linkage to habitat to the west are important to ensure the ongoing presence of gray fox in the SuAsCo Watershed.
Bobcat: Rarely documented in the watershed, this secretive feline requires large areas with dense cover and uses rocky ledges and crevices to raise young. Bobcat tracks have been seen in some of the larger swamps and forests in the western part of the watershed and along the Concord River. Where bobcat have been found, habitat should be protected from people and especially from dogs.
Porcupine: These prickly creatures are denizens of hemlock stands with rock outcrops for dens. Porcupines are uncommon in the watershed due to the limited number and size of hemlock stands, their preferred food, and to the high risk of road-crossing mortality. They extend their range slowly. The introduced woolly adelgid insect threatens porcupines by killing hemlock trees. Porcupines are eaten by fishers, their main predators. Porcupines are found in Estabrook Woods Site in Concord, Nobscot Mountain Site in Framingham, and western portions of the watershed.
River otter: Playful members of the weasel family, otters are seen frequently along the lower Sudbury and Assabet Rivers and Concord River as well as along Nashoba Brook and many other tributaries. They have been observed in ponds near these rivers in Lincoln and in Concord. Otter are primarily fish and amphibian eaters and appear to be fairly adaptable, having been seen in areas close to highways. They have also been seen as road kill. Accumulations of toxins and dog harassment are risks to their longevity. Otter are perhaps the pre-eminent flagship species of the SuAsCo Watershed.
Mink: These small members of the weasel family are indicators of good stream habitat as they depend on water dependent organisms such as fish, crayfish, and amphibians for food. They travel extensively along waterways. They also eat muskrats, especially the young.
Southern bog lemming: These rodents burrow into the grasses and sphagnum hummocks of bogs and fens, which are rare natural communities in SuAsCo.
Water shrew: This species of “special-concern” is found in wetlands around ponds and lakes and along streams, especially beaver controlled wetlands. They are indicative of the many small mammals, such as shrews and voles, that can be habitat specific and thus affected by habitat fragmentation.
Beaver: Beaver is perhaps the most important species in the watershed as it contributes to the overall biodiversity of the region through its dam building. As such, it is called a keystone species. Beavers create impoundments which foster frogs, turtles, snakes, and fish. The trees killed by the high water provide nesting habitat for great blue herons, wood ducks, and hooded mergansers. River otters are often found near beaver dams as they feed on the fish, turtles, and snakes that flourish in these wetland habitats. After abandonment of the dam by beavers, the resulting beaver meadows provide habitat for an unusual succession of plants, although some of these meadows are becoming dominated by purple loosestrife. Large conservation areas that allow for this natural disturbance dynamic to continue are critical. A beaver control policy among municipal and state departments of public works (DPW) and Division of Fisheries and Wildlife (DFW) that balance the values of natural diversity along with human needs of functioning septic systems and roadways is essential. Without beavers, the SuAsCo Watershed would not support many of our Focal Species.
Bear and Moose: These two large animals have been sighted in Concord, Carlisle, Stow, Boxborough, Northborough, and other SuAsCo towns. Although these large mammals were given consideration, ultimately they were not included as Focal Species. Encounters of bear or moose with people are generally not healthy for either party. It is unlikely that moose and bear will be able to pass safely through the SuAsCo Watershed.
Birds are excellent Focal Species because they fly (vs. burrow or creep), usually move around during the daylight hours, and are appealing to watch. Many people are avid bird watchers so there are extensive records of bird locations and numbers. Also, many birds are excellent habitat indicators, especially when suites of species are found in a given natural community. A forest or field with several Focal Species can be a high-quality example of that community type. Finally, many of the Focal Species are neotropical, migratory songbirds which are in sharp decline due to losses of habitat here and in their over wintering areas in Central and South America. These have been listed by Partners in Flight (PIF), an international conservation coalition. Conservation efforts in the SuAsCo Watershed contribute to the survival of these birds worldwide. Due to the large number and similar characteristics, Focal Species of birds are grouped below by habitat.
Marshland birds: American and least bittern, pied-billed grebe, sora, Virginia and king rails are part of a group of secretive and rare wetland birds found in the watershed. Many prefer marshes larger than 40 acres which have thick cattails or grasses mixed with weedy open water. These birds have declined over the years due to the draining of wetlands, the edge effect of development, poor water quality, and the degradation of habitat by purple loosestrife and other exotics. Frequent disruptions by canoeists and jet skiers reduce the amount of secluded habitat as well. Great Meadows, Wash Brook, and Delaney Sites are historical and current locations for many of these species. Locally common species, such as marsh wren and swamp sparrow, are Focal Species because they are regionally unusual. They are easily seen in the Great Meadows National Wildlife Refuge (NWR) impoundments.
Grassland birds: Bobolinks, eastern meadowlarks, savannah sparrows, and American kestrels require large fields that are not mowed until late in the season to allow for nesting success. Once more common when more land was in agricultural use, these birds are now declining. To sustain this “watchable wildlife” species in the watershed, conservationists need to protect clusters of fields greater than 10-15 acres and manage them for grassland birds, understanding that each species may have slightly different habitat requirements.
Currently, there are several Biodiversity Sites which nurture grassland birds throughout the SuAsCo Watershed: Assabet National Wildlife Refuge in Stow and Maynard; Heard Farm in Wayland; Callahan State Forest in Framingham; and Wataquadock Fields in Bolton. The Minute Man National Historical Park in Lexington and Concord is clearing successional growth to restore the 18th Century landscape and will be managing these areas for grassland birds. There are other locally important fields, particularly in Lincoln, Southborough and Westborough, and Grafton. Of note also is the importance of Hanscom Field, just over the watershed line in Lexington and Bedford, for upland sandpipers and grasshopper sparrows, which require much larger areas of short-grass fields.
Successional/field-edge birds: Indigo buntings, prairie warblers, blue-winged and chestnut-sided warblers, brown thrashers, towhees, and field sparrows are not rare, but they are becoming less common. Because many fields have either been developed or allowed to grow back into forest, Massachusetts Division of Fisheries and Wildlife has initiated an upland wildlife management program. Nearly 50 acres of 15- to 30-year old successional fields in the Westborough Wildlife Management Area (WMA) have recently been cut to eliminate exotics and to restore early successional stages of up to 15 years old. Powerline rights-of-way also have some of the same characteristics. The state-listed golden-winged warbler is the best indicator of excellent shrub habitat but is difficult to find.
Interior forest birds: Our forests do not support viable populations of interior sensitive birds that research indicates require up to one square mile of territory, but several birds are regular breeders in the SuAsCo Watershed. Scarlet tanagers, wood peewees, hermit and wood thrushes, ovenbirds, and black-throated green warblers were regularly heard or seen during the review of Biodiversity Sites that are greater than 500 acres. Brown creepers, barred owls, pileated woodpeckers, and red-eyed vireos are relatively common as well. Collectively, these species indicate good interior, usually mature forest habitat. Winter wrens and Louisiana and northern waterthrushes are found only in the largest tracts, such as Estabrook Woods, with wooded wetlands and streams. Mt. Pisgah in Northborough and Berlin, Spring Hill in Acton, and Greater Walden in Lincoln and Concord have a variety of interior forest birds.
Raptors: Several of these birds of prey require specific habitats with particular structural features such as large trees to nest in, as well as plenty of small rodents and birds for prey. As top predators, they indicate a healthy ecosystem. (see Focal Species list and Natural Community descriptions for more information).
Other species considered:
Many birds, such as warblers, depend on forests and thickets during migration. Migrating waterfowl, such as gadwall, pintails, green-wing and blue-winged teals; American widgeon, canvas-back, ruddy, and ring-necked ducks, rest and feed in quiet corners of ponds, lakes, and reservoirs, particularly where there is open water early in spring. As documented by the records of the National Audubon Society Christmas Bird Counts, many birds regularly use habitats in the SuAsCo Watershed during the winter months. Winter is a particularly vulnerable time for birds (and other animals) due to the need to have shelter from the weather, to find food, and to minimize energy expenditure. Large fields are important to snow buntings, water pipits, and horned larks. Evergreen forests, particularly those with hemlocks, protect pine siskins and kinglets, as well as the more common chickadees. Reptiles and amphibians--turtles, snakes, frogs, and salamanders--are particularly reliable Focal Species because of their vulnerability to development. They usually use a variety of wetland and upland habitats, move surprisingly long distances (hundreds of yards to several miles) during migration, and are small and slow moving so they are often run over. They literally cannot move fast enough to get out of the way of the bulldozers. Consequently, their habitats are especially vulnerable to fragmentation by development and roads. Turtles are also particularly subject to collection. Amphibians, such as salamanders, are sensitive to water pollution caused by non-point run-off because they breed in water and breathe through their skins. Turtles, salamanders, and frogs are relatively popular while snakes are all too often maligned and therefore disregarded.
Blanding’s turtle: This state threatened species has a disjunct population in the SuAsCo and Nashua River watersheds and therefore deserves particular protection. Blanding’s turtles use marshes, ponds, sluggish rivers, and associated vernal pools. They nest on sandy uplands often more than 500 feet away from wetlands. It is likely that their habitat in the SuAsCo Watershed will be part of the MNHESP BioMap project.
Box turtle: These woodland turtles live a long time and are particularly hard to find. Despite the difficulty of inventorying them, it is clear they are declining in our area as they are elsewhere in the state. They are vulnerable to collection if found. Box turtles are particularly traditional to their territories and therefore a box turtle should not be moved except to help it safely across a road in the direction it is going. Biodiversity Sites in the forested, sandy, outwash plain of the Assabet to Sudbury River Greenway are critical to sustaining a population of box turtles in the watershed.
Wood turtle: Wood turtles are a particularly good indicator of healthy stream systems because they use both the stream and adjacent riparian habitat at different times of the year. Their nests can be 400 feet from the wetland edge. Protection of streams, the adjacent shrub cover, and their upland buffers is essential to the survival of wood turtles.
Spotted turtle: Spotted turtles use vernal pools, beaver ponds, bogs, and shrub swamps. Once more common perhaps than painted turtles, they have declined significantly in numbers since the 1950s, in part due to habitat fragmentation and perhaps due to stocking of fish in ponds. Vernal pool clusters and beaver meadows are particularly good habitats. While frequently reported to the NHESP, spotted turtles are usually found in small numbers and often as road kill. These little gems deserve contiguous habitat.
Marbled salamander: These relatives of spotted salamanders are found only in the western part of the watershed along the Shrewsbury Ridge. Unlike spotted salamanders, which breed in vernal pools in spring, marbled salamanders breed on the dry margins of vernal pools next to water in the fall. They use the surrounding woodlands the rest of the year from low swampy areas to relatively dry hillsides. This species will be an excellent indicator of the success of protecting biodiversity in the Shrewsbury Ridge, an area under extreme development pressure.
Blue-spotted and spotted salamanders: These two species are prime ambassadors for vernal pools because they are well known by the public and indicate good quality vernal pool habitat. Large populations also serve as food sources for a variety of predators such as spotted turtles, which eat the eggs, and herons and raccoons, which eat the larvae and adults.
Dusky and two-lined salamanders: These two species are indicators of small stream habitats with flat rocks for cover and nesting. These habitats are at a premium in the watershed which is why they are unusual. The easternmost documented site for dusky salamanders is the Nobscot Mt./Baiting Brook Site.
Leopard frog: Often hard to distinguish from the more common pickerel frog by a beginner herpetologist, leopard frogs are excellent Focal Species for grasslands, wet meadows and marshes. They are generally not common in Massachusetts but are locally common in the SuAsCo watershed along the wet meadows and river floodplains of Great Meadows. Local naturalists have observed a noticeable decline of this species in recent years for unknown reasons.
Wood frog: These frogs with the mask are included because they are excellent indicators of vernal pool habitat. Their quacking choruses in spring are familiar to many.
Snakes: A few snakes are included as Focal Species with the understanding that the public often reacts negatively to them. Snakes are hard to inventory and many are not very habitat specific. Even so, some species appear to be in decline. They are noted here to raise awareness of their vulnerability. Green snakes are found in grasslands. Ribbon snakes are fairly uncommon species found along edges of ponds, streams, slow rivers, emergent wetlands, and shrub swamps. Northern black racers are in decline perhaps because their habitat, which consists of abandoned fields, grasslands, and brushy areas, is being lost and because of their large home range requirement. The status of hognose snakes is unknown and, therefore, they are not listed here as a Focal Species; however, populations are possible in sandy habitats such as the Desert Area Site. Hognose snakes have the defensive response of puffing up like a cobra, and then playing dead when disturbed.
Most of our waterways are populated by introduced or highly adaptable warm water fish. Three noteworthy exceptions have been included as Focal Species.
Native eastern brook trout: These relatives of salmon are found in a few cold water streams in the western part of the watershed. They are good indicators of healthy stream systems. These streams and adjacent lands need and deserve top priority for protection.
Shortnose-dace: These are found in similar habitat to eastern brook trout.
Alewife: These anadromous fish were reintroduced into the Concord River in spring 2000. In April the frye were dropped off at four locations along the Concord River to spawn young. The young will have left in July or later in September when there was a sufficient flow for water to sweep them over the dam. They will swim to the ocean and return in three to four years to spawn. Eggs typically are found in the floodplain areas of the Concord, Sudbury, and lower Assabet River where the water is slow moving, providing lake-like conditions. The young fish are bait fish for game species such as striped bass. Recent restoration efforts have centered around re-establishing the anadromous fish run at the North Billerica Dam. Conservationists are beginning to recognize the value of insects as Focal Species. In the SuAsCo Watershed, there are several professional naturalists who have been studying butterflies, moths, dragonflies and damselflies (odonates), and tiger beetles. To date, butterflies are the best potential group of Focal Species because of their popular appeal, host plant specificity, and available information. The drawbacks are that butterflies are not necessarily indicators of intact natural communities as many species are found in field edges, powerline rights-of-way, etc. Only a few species are particularly good indicators for natural communities, such as bogs and little bluestem fields. Even so, certain habitats such as grasslands, wet meadows, shrublands, and forests that have a representative suite of butterflies should be noted. These habitats may be good small-patch habitats that can be protected on a more local scale contributing to the overall diversity of the region. Insects are the most diverse groups of organisms in the SuAsCo Watershed and are worthy of protection.
Dragonflies are wide ranging and their habits are little understood. Dragonfly larvae are some of the many invertebrates now being studied as a means to determine the relative ecological health of stream reaches. Inventory work on both the larvae and adult stages of dragonflies is still in the early phase. More research of these colorful insects is warranted.
Unusual plants are usually localized in distribution and therefore require thorough inventories of a site to be detected. Focal Species for the SuAsCo Watershed are Britton’s violet, river bulrush, and river birch. These species are all indicative of the river floodplain of the mainstem Sudbury and Concord Rivers. They are rare elsewhere in the state. River birch is restricted to the Merrimack River and its tributaries. Britton’s violet is “threatened.” Wild rice is also a Focal Species as it was once a significant part of the native flora along the river. Recently the populations have declined and are supplemented by wildlife managers. Wild rice is perhaps the most preferred food for migratory ducks and is also used by bobolinks.
Other Focal Species need to be researched by reviewing local floras and consulting local field botanists. Some initial groups include the following:
• Spring ephemerals and other perennial forest wildflowers such as bloodroot, trilliums, and red baneberries are indicators of richer soils, consequently they rare in our acidic oak and pine forests. Because many of the seeds are dispersed by ants, populations are unlikely to return once they are gone. • Unusual grasses and sedges are hard to identify and therefore are often ignored. More research is needed as to how they may be indicative of good quality natural communities. Twig-rushes (Cladium mariscoides) and beak-rushes (Rhynchospora spp.) are good peatland indicators. • Bog plants, such as bog rosemary, bog andromeda, Labrador tea, and rose pogonia and arethusa orchids, were once reported in bogs in Concord and Littleton. Cotton grass, pitcher plant, and sundews are currently common indicators of good quality peatlands. • Unusual ferns, such as woodsia, maidenhair, and ebony spleenwort, need to be noted as they are habitat specific. |