Tuesday, April 3, 2012

Trout Brook Valley wildlife and habitat survey updates - spring is in the air!

As was reported earlier on this blog, Connecticut Audubon Society's Science & Conservation staff is working closely with the Aspetuck Land Trust to develop a conservation and management plan for the Trust's 1,000+ acre Trout Brook Valley Preserve. This preserve straddles the Easton and Weston town lines and is located between the Saugatuck and Aspetuck reservoirs. It protects high quality watersheds (the land was historically owned by the Bridgeport Hydraulic water company) and constitutes a sizable part of what is now the largest continuous remaining forest block in Fairfield County. The foundation of the proposed conservation and management plan that we are preparing is formed by a series of targeted wildlife and habitat surveys that our staff is carrying out in the preserve over the course of a whole year. Monitoring the area over a longer time period ensures that we can account for seasonal patterns in emergence and occurrence of local plants and animals.
Mammal surveys this past winter turned out to be more difficult to do than we anticipated. Since there was no snow cover to find identifiable tracks in we had to make do with observational data and the occasional muddy footprint, such as these raccoon tracks. 
 Usually during the winter months our survey activity focuses on habitat use by wintering birds and, whenever possible, we'll try to use relatively warm days with fresh snow to carry out mammal track surveys. As you can imagine the latter ended up being impossible this past winter. In addition, only very few winter irruptive birds appeared in Connecticut due to the widespread mild weather and lack of snow and ice cover to our north. Nevertheless, we spent our time well researching existing data relevant to Trout Brook Valley Preserve and carrying out preliminary habitat assessments to determine where we are most likely to encounter areas of unusually high biodiversity within the overall area, or where we expect sensitive species and/or habitats to be.
All over the woods our wetlands are turning green as mosses come back alive and wetland plants such as Skunk Cabbage and False Hellebore send their leaves up through the leaf litter and mud. 
  Now that spring is upon us with a bout of above average temperatures the woods are coming alive at a rapid pace with native species emerging from a winter torpor and non-native species that are rapidly colonizing the still empty habitats, as described by Scott in yesterday's blog entry. We have switched gears and are now documenting spring ephemeral species and habitats, as well as mapping the distribution of non-native invasive plant species in Trout Brook Valley. The area's vernal pools are all active and during last week's warm weather even the frogs that usually don't emerge until later in spring, such as Bullfrogs and Gray Tree Frogs, were already out and about.
Spotted Salamander eggs in a vernal pool - several of our native frogs and salamanders are closely tied to these unique ephemeral habitats and rely for their survival on functional vernal wetlands and quality upland habitat.

Wood Frogs are probably among the most noticeable amphibians in our vernal pools, and their duck-like quacking emerging from wetlands can even be heard during the day in early spring
 Vernal pool surveys will continue for at least another month or two, depending on the water levels in these wetlands. Not only do we want to know what species utilize the different wetlands in the preserve to lay their eggs in, we also want to know whether these pools in their current form are suitable to allow the resident species to successfully complete their development. We also want to know whether the surrounding upland habitat can provide the resources needed to sustain these animals during most of their life when they are not in the water. To date we have examined 23 wetlands on the property and all have shown evidence of amphibian breeding (for more information and pictures see this previous blog entry). Several more potential vernal pools and other wetlands are found at Trout Brook Valley Preserve which will be surveyed in the next few weeks. No fewer than 13 species of amphibians have been found in the area so far, including Wood Frogs and Spotted Salamanders, which are usually associated with vernal wetlands, but also more elusive species such as Marbled Salamander and Jefferson's Salamander occur in the preserve. The latter is a species included in the State's Threatened and Endangered Species Act and is listed as of 'Special Concern'. Clearly, Trout Brook Valley is starting to show its importance as a haven for rare and endangered species in Fairfield County! We are convinced that future surveys will reveal additional species of conservation need in the area.
Spotted Salamander - a commonly seen species in our vernal pools
Jefferson's Salamander - a State-listed Species and obligate vernal pool breeder
  As mentioned previously, the winter surveys that we had planned initially did not exactly pan out as we had anticipated. Nevertheless, surveys of existing data combined with a few site visits have still resulted in an already impressive base list of vertebrate species known from Trout Brook Valley Preserve. At the moment we have 118 bird species and 11 mammals on our list, which include 9 state-listed species (Threatened and Endangered Species Act) and 56 species considered of 'Greatest Conservation Need', as identified in  Connecticut's Comprehensive Wildlife Conservation Strategy (produced by the DEEP in 2005). Considering that things are barely starting to warm up and that field surveys are only just getting started this promises to be an exciting field season! We'll make sure to keep you updated as the season progresses and we embark on wildflower surveys, migratory and breeding bird monitoring and dragonfly & damselfly inventories, among other things.
The first native wildlflowers, such as these Dutchman's Breeches, were already present at Trout Brook Valley before April 1st!  
Twan Leenders
Conservation Biologist
All photos ©  Twan Leenders and not to be reproduced without explicit permission

No comments:

Post a Comment