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2008 Update to the Alewife Mammal Tracking Survey
+ Otter, fisher, grey and red fox, coyote thrive at Alewife (with map)
by David Brown
Added to website January 13, 2008
This report updates the extensive mammal tracking survey conducted in 2002 by David Brown’s Wildlife Services. That larger assessment still applies to the “greater Alewife ecosystem”, and may be referred to for extensive discussion of habitat characteristics as they apply to both mammal and bird life.
Location of survey update
Ellen Mass commissioned DBWS to update the larger mammal study with a 2-hour visit in good tracking conditions and to confine the search to the “Uplands” area in and around the planned development of low-income housing. In walking the ground, observations were restricted to an area within a 300 meter radius of the high point of land, presumably the center of the proposed building footprint. This radius was decided upon as the likely area of major impact from the development. The search area, then, was bounded by Acorn Drive on the east side, Little Pond on the west, the partly overgrown field to the south and the roadways to the north.
The major central portion of the search area, the location of the planned footprint of the development, is a floodplain forest composed of mixed-age silver maples along with several other species of trees. Downslope to the west the ground gives away to a wooded area broken by low earth ridges. Here are a number of large black cherry trees, a bottomland swampy area of pools that seem to have been isolated by past soil disturbance, a small cattail marsh and finally the wooded shoreline of Little Pond. To the south the land gradually declines toward an old field currently encroached upon by a large stand of invasive giant reed (phragmites). This field ends at the Little River.
Timing of survey update
The first visit on January 4th involved a 2-hour circuit through the bottomland swampy area to the south and southwest of the planned development, then along the shoreline of Little Pond and back out to Acorn Drive through the heart of the silver maple woodland. On this occasion the snow was heavily crusted so that the record of animal passage was incomplete. Dissatisfied with the conditions on the first visit, the surveyor made another on January 7, 2008, after an overnight thaw had softened the snow surface. The total time spent searching was approximately 3 hours.
On previous visits since the 2002 assessment the surveyor had observed some species whose presence was either sparingly detected or not found at all during that survey, which was conducted in a winter with little snow. On these visits tracks of striped skunk, mephitis mephitis, and Virginia opossum, didelphis virginiana, were both found on the downslope west and south from the development site. In addition sign of red fox, vulpes vulpes, which was sparingly reported in the original survey, was observed in hunting mode within 100 meters of the development footprint. Sign of white-tail deer, odocoilus virginianus, which was also sparingly reported in 2002 survey, has been found plentifully in recent years in the general area north of the Little River.
River otter. Sign of river otter, lontra canadensis, was first reported and photographed by Mike Arnott along the Little Pond shore two or three years ago. In the course of the present update, sign of this same species was once again found in this area. In fact four haul-outs were located along that shore and within the 300 meter radius search area. Haul-outs or “rolling sites” are places where this animal leaves the water to excrete and eliminate. This eastern shoreline is the only remote place on the pond where these animals can leave the water securely.
Red fox. On both visits in the current update tracks of red fox were located in the search area. In the first instance one track was found in the field to the south where it was sufficiently sunny to melt the surface crust. There it was discovered among cottontail rabbit sign. On the second visit an additional trail was found within the development footprint. In this case the animal left a long enough trail to show that it was hunting rather than simply traveling through.
Eastern coyote. Two instances of this large predator/scavenger were found during the current update. On the first visit on January 4 a urine scent mark was found near the Little River. On the second visit two walking trails were located in the area of the development footprint. In these latter sightings, possibly evidence of the same animal, there was enough evidence to indicate that it was hunting rather than passing through. Scats from this species were found in the same area during the 2002 survey.
Gray fox. On the second visit the walking trail of a gray fox, urocyon cinereoargenteus, was also located near the footprint of the development. This is a new species for the Alewife mammal list, although a road killed specimen was found a couple of years ago in the general area. The trail was extensive enough to satisfy this surveyor that it also was hunting. Of the two native species of fox the gray fox is the more arboreal, nearly always restricting itself to wooded areas. Long absent from the region (Thoreau noted that the last one in Concord was shot for bounty in the early 1800s), this species has been moving northward in recent decades, reclaiming some of its ancestral range. The first modern instance of this species in the northern suburbs that the surveyor was able to detect occurred in 1995. The gray fox is the more elusive and secretive of the two foxes, normally keeping away from human and pet disturbance. Its occurrence in Alewife, this close to the city is remarkable.
Fisher. On the second visit the trail of a fisher, martes pennanti, was located downslope to the northwest of the proposed development. This large member of the weasel family is also a new addition to the Alewife mammal list. It first began to appear in metropolitan parks around Boston in 1992, another species reclaiming its traditional range. Unlike its wilderness behavior where it concentrates on rabbits and hares, in the Emerald Necklace it seems to have adapted to a life as a squirrel specialist. Its presence in the vicinity of Alewife Reservation probably owes to the plentiful availability of both kinds of animal prey. Long regarded as a wilderness animal, its presence in Alewife is also remarkable.
Total mammal list for the Alewife Reservation area 2002-2008:
Once again Alewife surprises with its content of wild mammals. Few would reasonably expect that this tiny urban reservation would harbor such a population of “wilderness species”. This surveyor regularly conducts wildlife assessments and tracking programs in the Quabbin region of central Massachusetts as well as in various locations in northern New England. In none of those “wildernesses” is there a greater density and variety of wild mammal sign than at Alewife and its contiguous natural areas. The current update supports the conclusion, presented originally in the full mammal tracking survey of 2002, that the “uplands” area is core wild mammal habitat for the Greater Alewife ecosystem. Any significant development in this area can be expected to have profound impact on this function. The effects of a large, populous structure in the center of this core area will radiate out into the surrounding natural habitats and severely diminish their usefulness to wildlife. Some species that adapt well to human presence, such as raccoons, skunks and squirrels, will persist. However, mammals like fishers and foxes that need larger habitat and relief from constant human presence are unlikely continue using the area. As for river otters the only secure location around Little Pond where they can haul out to eliminate is along the east shore of the pond, within the affected zone of the planned development. Water attracts people. Since otters are diurnal hunters, regular visitation and recreation by people along this shoreline will certainly diminish if not eliminate its usefulness to this attractive species. The same can be said for the great blue herons and other birds that hunt the shallows at the exit of the river from the pond, the only location on the pond that is shallow enough for wading birds to catch fish. It should be noted that Little Pond is currently infested with introduced carp that dominate native fish and, due to their method of feeding, create turbidity in the water. Both herons and otters feed on these fish.
It is the opinion of the surveyor that the planned development will greatly diminish if not effectively end the function of Alewife Reservation and the surrounding ecosystem as an “urban wild”. What remains will be just another city park largely bereft of the interesting and varied species of mammals and birds that it currently harbors.
Table of tracks and sign
Coordinates are NAD 27 UTM 19T
PDF file of map, suitable for printing.
To read the Adobe Acrobat file, you can get the Adobe Acrobat reader, available free at www.adobe.com/products/acrobat/readstep2.html