Monday, June 14, 2010

CAS Croft Preserve Breeding Bird Survey & more

During the month of June CAS science and conservation staff is in the field as much as possible, carrying out breeding bird surveys and other types of monitoring studies. Miley is out on the Long Island Sound surveying tern, egret and heron nests as part of the Colonial Waterbird Survey, while Scott and I are busily surveying CAS sanctuaries and other nature preserves across the state in order to collect the data needed to best manage them. Today I visited the Richard G. Croft Memorial Preserve in Goshen, which consists of 700 acres of upland forest and several wetlands. In addition, Connecticut Audubon Society carries out wildlife habitat management projects in the preserve, creating early successional habitat patches for several conservation priority species. I do survey transects and point counts there on a regular basis to see whether our habitat work is benefitting the species we target.

Since we are currently in the height of the songbird breeding season, many of the species detected in appropriate habitat are potentially breeding there, so now is a good time to survey! However, most birds that are on nest right now tend to stay very quiet to escape detection, making these surveys quite challenging at times -- especially in a large and densely forested area like the Croft preserve. Nevertheless I ended up having a very productive morning with 53 species of birds recorded. The unique character of the Croft Preserve -- with several "northern" species due to its geographic location in the northwest hills -- became clear as soon as I got out of my car and was greeted by singing White-throated Sparrows. As I hiked the first half mile or so to the closest habitat management area I logged good numbers of forest interior birds such as Ovenbird, Black-throated Green and Black-throated Blue Warbler, American Redstart, Black-and-White Warbler, and Scarlet Tanager. Red-eyed Vireo calls were everywhere, occassionally interrupted by the less frenetic and more melodic song of the Blue-headed Vireo.

Fledgling Dark-eyed Junco - one of several seen today

Just before arriving at the first clearing I was startled by a clumsy fuzzy creature that fell from the sky and landed in the trail in front of me. As I was wondering who this little guy was, a concerned parent Dark-eyed Junco showed up and hovered around nervously. Yet another example of a species that only winters in much of Connecticut but breeds in the Croft Preserve.

Apart from its location, another factor that contributes enormously to the reserve's diversity is the fact that it is part of a huge, contiguous forest block. Species that require swaths of undisturbed habitat thrive here (I had amazing looks at a Ruffed Grouse today, which was just hanging out along the road where I had parked my car). For example, I counted no less than 14 Wood Ducks and 5 Hooded Mergansers, many of which were young from this year, in the largest wetland on site. These birds require large and quiet forested wetlands to breed successfully and are doing great at Croft!
Large beaver empoundment that is home to breeding Wood Ducks and Hooded Mergansers

It was encouraging to find good numbers of Eastern Towhee and Chestnut-sided Warbler in the early successional habitat areas we created in our habitat management areas. The most recently opened clearing, a 20-acre plot cleared in late summer of 2008, has now formed an almost complete herbaceous ground cover. To my delight I was not able to find any non-native invasive plant species among the colonizers! This area promises to be a great natural resource for scrubland species in a year or two.

The most recently created habitat management area is growing in nicely with native herbaceous ground cover

One of my favorite sights at this time of year is the blooming Mountain Laurel (Kalmia latifolia) that can be seen everywhere in the Croft Preserve.
Blooming Mountain Laurel (Kalmia latifolia)

Far less showy, but fascinating in its own kind, is the Round-leaved Sundew (Drosera rotundifolia). I found a population of this carnivorous plant near one of the bogs today. Sundew plants trap insects with a sticky secretion that is exuded from hairlike extensions of their leaves and absorb nutrients from their catch.
Round-leaved Sundew (Drosera rotundifolia), a carnivorous plant

Clearly, our surveys often include more than just birds. Even though birds are excellent environmental indicators, other organisms can provide additional information on the health of a natural area. For example, every vernal pool I checked today lacked salamander or frog larvae, even though a few weeks ago there were literally thousands. Most pools still held water today so all tadpoles must have completed their metamorphosis in time before the water dried up -- it is nice to know that our vernal pool breeding amphibians had a good year because that does not always happen. Nine different species of amphibians were observed at Croft this morning.

Apart from Gray Squirrels Eastern Chipmunks and White-tailed Deer we usually don't encounter many mammals on our surveys. However, we're always on the lookout for telltale signs, such as scat, tracks, scrapes, etc., that indicate the presence of certain species.

Pile of moose droppings in one of the habitat management areas

In order to get a better feel for the mammal diversity in an area I sometimes install trail cameras that automatically photograph anything that trips their infrared trigger beam. One such cameras was in use at the Croft Preserve since last winter but its batteries had run out, so I retrieved it today. Many of the images taken by this camera showed leaves blowing in the wind in front of the lens, but there were some very good shots as well. Below are a few pictures of some of the animals it documented:

White-tailed Deer

This one unfortunately moved out of range too fast, but this is the unmistakable back-end of a moose! Hopefully I'll be able to get some better images in the future. You'll see them here if I do!
All photos by Twan Leenders

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