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Alewife Wildlife Inventory

Friends of Alewife Reservation

Two reports - approximately 80 pages in total - are available. The reports have maps that contain over 150 sightings and have bird and mammal charts with complete description of each species and where it was sighted.
Online versions of the reports are available.
A printed copy of the reports is $15. See bottom of this inventory for contact information.


The Alewife Reservation is owned and maintained by the Metropolitan District Commission (MDC). People familiar with its trails are often amazed at the wealth and diversity of wildlife in the reservation, within an otherwise dense urban setting. Stew Sander’s Alewife Ecology Guide, published in 1994, acquainted many people with the reservation wildlife. In order to obtain an accurate contemporary wildlife census for purposes of planning the area with appropriate habitat protections, the Friends of Alewife Reservation (FAR) obtained a grant from the Massachusetts Department of Fisheries and Wildlife to perform an inventory of reservation wildlife. The grant also included docent training for those that are interested in taking others into the reservation. David Brown of David Brown’s Wildlife Services was contracted to perform the inventory. He is a lifelong naturalist and has tracked for the MDC at Middlesex Fells and Maine Land Trusts and given workshops for numerous state and private organizations, and is regularly a guest speaker at wildlife events.

The following represents an edited version of David’s initial findings. They are for the most part taken verbatim from his report demonstrating both his tracking abilities and renowned knowledge. FAR is extremely grateful to David for both applying and sharing his expertise, teaching us a great deal about the Alewife Reservation. Two final census and observation reports on mammals and birds will be available in early June. Interested parties should contact FAR at info@friendsofalewifereservation.orgto obtain the complete report.



Tracking Beavers

The well known beaver lodge is actually a bank burrow, the entrance of which has been covered by sticks. The clay substrate in the Boston basin is easy to dig through and probably required less work than building a freestanding lodge. The resident beaver is probably a dispersing animal in its first winter away from its natal area. Being slow and clumsy on foot, they are safer in water than on land and so, flood by damming as a means of safely approaching feed areas. The steep channelized banks of the Little River make it impractical for the beaver to dam it in order to flood its way closer to the more outlying aspens, and so it must trek as much as 50 meters inland to reach the choice trees near its lodge. On the north edge of Yates Pond, two trees showed incisor marks and a path through the cattails led to the water. Apparently, the beaver(s) from Little River have come up through the ditch that drains the parking garage and into the pond, cut the trees and dragged them out the same way.

A beaver appeared downriver swimming against the flow. Sensing my presence, it tried to swim underwater past the observation point, but the water was so shallow that its progress was easily followed by rippling on the surface. The animal surfaced once or twice at close range and showed itself to be of moderate size and apparently healthy. So far, sign of beaver has been found downriver as far as Yates Pond and upriver as far as Wellington Brook.


Bird Sightings

Alewife Reservation contains the expected species of more common birds that one should find in the winter in an urban natural area. Common crows and bluejays are frequently sighted, as are black-capped chickadees and other common bark and twig gleaners that are resident in such parks. A male flicker has been seen in the bottomland woods near Perch Pond and downy woodpeckers have been sighted in various trees in the park. Many robins appear to have been in the reservation all winter.


Ring-necked pheasants are native to China and were introduced into N. America. Their hoarse, resonant call was common 20 years ago, but has become increasingly scare as succession and development have erased the fields. I have heard calling birds in widely separate parts of the reservation and believe that there are at least three males present. Alewife has plenty of treeless, brushy habitat with the dense cover favored by this species.


Hairy woodpeckers are larger versions of the familiar downy woodpecker, but with proportionately larger bills. They get their name from a ruff of feathers at the base of the bill. A common species 40 years ago, they have been reported to be in decline in recent times. This male landed in a riverside coppice maple and drilled insistently in one spot. After feeding it explored other trees close by and then flew away.


Yellow-rumped warblers are early migrants that winter just to the south. Their nesting range begins around the New Hampshire line. Unlike most warblers they are habitat generalists, feeding at all levels of the forest. As a result they tend to be abundant and perhaps the most frequently seen spring warbler.


Palm warblers are often the first wood warblers to be seen in the spring. Their arrival is timed with the first insect hatches. They are easy to identify, even in a distant overhead silhouette because they are one of the few wood warblers that twitches its tail. Their presence in the canopy of aspens is appropriate as aspens often host an early insect hatch.


Killdeer are classed taxonomically as “shorebirds” even though their preferred nesting habitat is disturbed sites showing dirt, pebbles and sparse vegetation. The stoniness of such sites conceals their speckled eggs, which are laid on the ground in the open and without nesting material. This pair were feeding on the exposed mud bar in Blair Pond.


Carolina wrens are common birds south of New England. Like many other southern species, however, they have been extending their range northward and are now common on Cape Cod. Their song is loud and arresting so that their presence can hardly be ignored.


Phoebes are flycatchers that perch prominently on outlooks and dart out at flying insects. They have the interesting habit of adapting to civilization by building their nests on man-made structures. This pair seems to be building on the culvert at Wellington Brook.


Cowbirds are nest parasitizers, reproducing by placing their eggs in the nests of smaller birds. They might more properly be called “buffalo birds”, since they apparently adopted the tactic of nest-parasitism so that they could continue a nomadic existence, following bison in the plains without having to return to a fixed nest.


White throated sparrows are native to the mountainsides of northern New England where their loud clear song lends a lonely feel among the stunted, windblown spruce. Here they are winter visitors, feeding on seeds on winter-dried plants as do other sparrows. The abundant brush and herbage in Alewife apparently supplied enough of an attraction to keep this one around while its fellows have headed north.


At least two pairs of cardinals have been seen in the riverside and brookside brush. This species was rare and local in New England a few decades ago but has moved northward in response to a warming climate and/or the numerous bird feeders provided for seedeating birds.


A flock of twenty redpolls were feeding in riverside alders. This is a winter visitor from the north that only appears in numbers in Massachusetts during so-called “irruption years”, presumably years in which a poor seed crop in Canada forces these birds southward. Alder catkins, the winter seed structures that hang on alders like tiny Japanese lanterns are a staple for this species. Alder is a very common bush in northern bogs, but less common in the transition forest in central and southern New England. It grows along the Little River and presumably its familiarity to these birds brought a flock of them to this grove in Cambridge.


Red-winged blackbirds are one of the species that favor cattail marshes for nesting. In this case five males, more or less, circled a small marsh just south of the river, practice-displaying for females not yet arrived.


Two mated pairs of green-winged teal have been hanging out in Blair Pond for at least the latter half of the winter. These are surface feeders as opposed to divers and so need shallow water. Blair Pond provides this to a greater degree than nearby Fresh Pond, a traditional wintering area for many species of waterfowl.


Great blue herons have been seen regularly in Little River and especially at its outlet from Little Pond. In colder winters these birds winter at the coast where salt water doesn’t freeze. In this warm winter they have been hunting in unfrozen shallows in the park.


Black-crowned night herons are migratory birds. This is the first returnee of this species to the reservation. Like other herons, it feeds on fish, frogs and other aquatic invertebrates. The fish, at least, are forced near the surface around the outlet from Little Pond, where they can be preyed upon by both night herons and great blues.  



More Bird Sightings!

 Hooded mergansers spend the winter in the coastal estuaries, ready to move inland to fresh water as soon as they clear of ice. As this winter has been unusually warm, they have the luxury of overwintering on such inland ponds as have remained unfrozen. Mergansers are mainly fish eaters that nest in tree holes. As the eastern forest has rematured they have been increasingly able to find nest holes closer and closer to the metropolitan area.


 Wood ducks are often associated with hooded mergansers, occasionally raising each other’s offspring in cases where egg dumping has occurred across species. Since both species nest in natural cavities in old trees or in nest boxes and both use the same sort of water bodies, this occasionally happens. Unlike mergansers, which dive after fish, wood ducks are vegetarians and edge feeders, relying on emergent plants at the margins of ponds and streams for food.


Bizarre looking shoveller ducks breed in western North America. The birds in Little Pond are overwintering and can be expected to leave within the month.  



Hawks and Falcons

 A small accipiter, the sharp-shinned hawk, flew into dense sumac near a woodcock lek at dusk. It was hunting and moved off northward after a few minutes. It was probably a migrant although most adults stay on expanded territory during the winter. Once again only a spring display flight will decide whether it is resident or migratory.


 An immature red-tailed hawk regularly patrols the reservation, perching conspicuously in trees along its length. This species is a member of the buteo family of soaring hawks. Small mammals such as voles, squirrels and even rabbits are its principal prey. All of these species are common to abundant in the park. Open country is best for this sort of hunting and the low vegetation along the river is ideal, since it provides good sight lines for the bird either perched in a tree or soaring overhead.


 Merlins are small, fast-flying falcons whose nearest nesting area is in extreme northern New England and eastern Maine. This bird was clearly migrating northward, close to the ground where it could catch the small birds that are often its prey. A passing attack on a song sparrow was unsuccessful. Merlins mostly nest in open country and tend on migration to be attracted to areas that resemble their nesting habitat, such as the open fields and marshes of Alewife.



 The Woodcock

 The presence of woodcock was documented in Stu Sanders’ Alewife Ecology Guide. These birds continue to thrive in the special habitat provided by the reservation, however there has been some shift in the location of leks, or male display areas. The two on or south of the bike path do not seem to contain displaying males at this writing (one of them having been built over by a parking lot). Two new sites not shown in the Guide are currently supporting singing males — in the field near Alewife Brook and east of the ADL parking lot, north of the Little River. At the moment I find at least five occupied leks in the park with one of these in the private holdings north of Acorn Park Drive and one near the property line between these holdings and the reservation. In all cases these leks are open grassy areas often with some shrubs in them or nearby. Woodcock males need flying room for their spiral ascent and twittering descent to the ground. They also need bottomland earth containing earthworms to feed. Both are supplied and in close proximity in Alewife Reservation. Woodcocks are not listed as a species of concern in Massachusetts, but the decline in the number of grassy areas in the state has become a cause for concern as far as biodiversity is concerned. As fields succeed to forest and bottomlands are built upon, important habitat for this species is lost.


A small animal up ahead is bobbing its head up and down and strutting around. Suddenly, it spirals upward to a height of more than 200 feet. In less than a minute, it spirals back down to earth, zig-zagging and swooping while making a musical, chirping sound. Once back on the ground, it starts "peenting" again. What you've just witnessed is the male woodcock performing a mating ritual. (from Wisconsin DNR website  



Animal Sightings

The presence of white-tailed deer in the reservation have been reported sparingly in the past, but this was the first sign of their presence during the current inventory. The scat was of the summer type and was deposited in a field. Deer often gravitate to grassy areas early in the spring before other herbage “greens up”. Normally grass is not a favored food since it contains abrasive crystals that wear down teeth, an anti-grazing protection that grass has developed over eons, but when deer have been slowly starving all winter, they will graze virtually upon anything green despite the harm. The identification of this scat as that of deer has a high level of certainty. A small shrub growing in the middle of a field shows definite signs of deer browsing.


Many burrow entrances found on the reservation. An opening diameter of approximately 6” suggests woodchuck as the initial burrower. This species constructs elaborate tunnel systems, usually with two or more entrances. These tunnels are often appropriated by other animals for shelter and birthing. Skunks and opossums sometimes use them, as is. Red fox and coyote dig them out to accommodate their larger size and use them for birthing and raising offspring. Thus, although the woodchuck may have done the initial construction, it may no longer be the tenant.


Two scats were found on the grassy trail through the “crabapple orchard”. These were consistent in size, composition and placement with red fox, a species that has been noted sparingly in the literature on the reservation. Identification as red fox has a moderate degree of reliability.


The scat of a small carnivore was found near a raccoon latrine on the raised root hump of a tree leaning over the Little River. Mink generally travel along the margins of waterways in search of prey and place their scat on raised objects found along the way. The presence of the scat of other animals often provokes a deposit by passing predators. More prey generalists than otters, mink live not only on fish and crayfish but also on small prey mammals such as voles and rabbits, both of which abound in the grassy opening north of the river near the scat placement. A principal prey species for mink is muskrat, a population of which exists in the Little River. The identification of the scat has moderate reliability.


A light snowfall provided an opportunity to get an idea of the density of prey species on the reservation. Here and nearly everywhere else in the park on this day, cottontail tracks were found in large numbers. This suggests a peaking of the local populations. In rich habitat, such as is provided by the many grassy openings and impenetrable brush and briar patches in the park, their numbers can reach very high density, followed by a crash as predator numbers increase to meet the abundance. It suggests that the isolation of Alewife from other natural areas has provided a low predator to prey ratio that may be slow to catch up with the abundance due to the difficulty of reaching the park from natural areas to the west.


Both scat and canid tracks were found that are consistent with the presence of eastern coyote. Scat was found in the Belmont Uplands whose size, placement and composition identifies it as Eastern coyote with a high degree of reliability. It was a hair scat, copious and 1 inch in diameter, composed of fur and with the mandible of a vole showing on its surface. As the Belmont Uplands where this was found is the area most remote from human visitation, it is not surprising to find this sign here. A large prey base of cottontails and voles in the grassy and brushy areas which abound in the reservation provide a potential attraction to many predators adept at their capture. A woodchuck den was discovered nearby that is in the process of being enlarged by another user. The new inhabitant of the den may be a coyote. A single canid track appeared in the muddy grass behind ADL and near the river. This and other evidence suggests that one or more coyotes is laying up during the day in the Belmont Uplands and ranging downriver to the cottontail/vole habitats around the south end of the river at night.





The wildlife report contains multiple references to scat used to identify both predators and prey. The following are typical:


Root humps of trees leaning over water are frequent sites for mammals to deposit scat as they patrol the bank. This site has been the location of raccoon and probably mink scat in the past. Some of the raccoon deposit was still in place when a weasel happened along, prompting it to deposit its own scat in response. This is often a habit of predators.


The identification of this scat as that of deer has a high level of certainty. It was probably deposited last spring. By the time roughage … passes out through its gut, there is little of bacterial interest left, and so it lies in place for a long time until it finally weathers away.


Friends of Alewife Reservation

P.O. Box 161

1770 Massachusetts Ave.

Cambridge, MA 02140-2808

Phone, FAR office: 617 661-1730