Otter Brook: A Vital Corridor for Wildlife
by Ed Robinson and Rob Bryan
In the December introductory article about HHLT’s Otter Brook Project, we noted the area’s importance as a wildlife corridor. We’ll look at this topic in more depth here so you can fully appreciate the project’s value to local flora and fauna, and to those of us who enjoy living with healthy, diverse wildlife populations.
All species, including humans, have specific habitat requirements for survival – food, water, and shelter. The habitat requirements for one animal may vary from other similar species, even among those that co-exist in the same general area. For example, one song bird breeding around Curtis Farm Preserve’s four acre field may prefer to build a nest in the field’s vegetation. Another bird may choose a nest site a few yards into brushy cover, seeking more protection from winged predators.
The habitat needs of many species vary throughout the calendar year. During the winter months, whitetail deer living in northern climates leave open terrain and seek shelter in forests with heavy overhead cover, to avoid harsh winds and deep snow. The monarch butterflies that we see in late summer feeding on milkweed nectar are storing energy for their long annual migration to a tiny haven in the Sierra Madre region of Mexico. Woodcock have specific needs for the kinds of open cover they use during the spring breeding season, versus the thicker cover they need for nesting, feeding and raising their young in summer. Wild turkeys savor fresh green grass in spring, insects and clover buds in summer, acorns and beechnuts in autumn and left-over wild grapes in winter.
The natural balance among wildlife species worked well until mankind began the dramatic population surge of the last 150 years. As our health improved and survival rates increased, we began to push into new territories to build our homes and to work the land. With better building materials and the benefits of fossil fuels, it became feasible for humans to live in more remote mountain regions and along exposed ocean shorelines. As our population increased, we logged more forests for farmland, and we began to over harvest native populations of terrestrial and aquatic foods. Ongoing development has resulted in thousands of miles of highways, large swaths of the West being broken up into five acre ranchettes and increasing density of housing along the New England coast.
The resulting habitat fragmentation has caused significant negative impacts on many wildlife species. Development in the beautiful valleys of the Rocky Mountains has deprived elk of safe access to many winter ranges. Other species suffer heavy losses as they travel from one habitat to another, such as turtles crushed while crossing roads as they migrate from winter hideaways to sandy nesting sites. While some species are able to adapt to moderate habitat fragmentation, other species suffer reduced genetic diversity and lower survival rates when they are deprived of traditional migration routes and critical resources.
Animals such as white-tailed deer can handle fractured habitats, surviving in close proximity to humans and their buildings. Many other wildlife species require large contiguous blocks of relatively undisturbed forest, fields and wetlands for their cycles of life. For example, fishers and several of the forest warblers are known to prefer larger, quieter blocks of habitat. When you consider that change is a constant in nature, the larger the habitat that is available for a species, the better it will be able to handle natural disruptions like drought or fire, the loss of a desired food species or a change in the options for shelter.
So we can consider a wildlife corridor as an extended area, or a series of connected habitats, that allow a variety of wildlife to move as needed during their life cycles in order to maintain healthy populations. Corridors may be land-based strips of forest, a series of streams and wetlands, or a combination of the two. It won’t surprise you that the more expansive the corridor, the more diversity of habitat it will contain from edge to center, and the more valuable the corridor becomes to a wide range of species. For a tiny insect, a line of shrubs connecting your neighbor’s woods to your garden may be perfect. Larger animals like moose or lynx require many square miles of suitable habitat to survive.
In areas where development has already caused severe disruption to wildlife populations, man-made wildlife corridors have been constructed by placing large culverts under highways to allow the passage of reptiles, amphibians and other small animals. In addition, huge overpasses with local vegetation have been built over a number of Western highways to allow migratory animals like mule deer, elk and mountain lions to move without undue exposure to humans. Obtaining approval for such projects is not easy, and the costs can be massive, so it makes sense to preserve wildlife corridors where they still exist.
HHLT’s Otter Brook Project is a fine example of efforts to protect a natural wildlife corridor. Covering 3,000 feet along the stream and marshes, the Otter Brook land to be acquired represents a critical segment of the woodlands that extend several miles from Brunswick to Harpswell’s Mill Cove, south of Mountain Road. With a width of several hundred yards, the land also provides plenty of security cover for animals like mink and osprey that are shy of human habitation. While there are scattered homes and driveways along the corridor, there is still sufficient room for wildlife to travel. This corridor would be in jeopardy should these lands ever host residential development.
While Harpswell has seen considerable development in the last century, we are fortunate to still have several areas with large contiguous blocks of undeveloped land. These are featured within the 12 conservation Focus Areas identified in the Town’s Open Space plan of 2009. HHLT and the town have worked together to keep parts of Harpswell wild for the animals, clean water, our enjoyment and our quality of life. The Otter Brook Project is another joint conservation project with many benefits. Thank you for your support!
To learn more about the Otter Brook Project and how you can help, click here.