Category Archives: Third River

Montclair’s Alonzo Bonsal Wildlife Preserve!

Alonzo F. Bonsal Wildlife Preserve

Welcome to the 20.68 acre Alonzo F. Bonsal Wildlife Preserve! The preserve is located and owned by the Township of Montclair, New Jersey and was purchased with NJ DEP Green Acres funds. The City of Clifton is located to the north, and residential development surrounds the preserve to the south, east and west. There are 9.12 acres of adjacent lands located to the north of the preserve which are controlled by the North Jersey District Water Commission for its Wanaque Reservoir Balancing Tank which provide additional habitat for wildlife.  A citizens group lobbied to save the woodland from development in the 1970’s. The Bonsal Preserve was named after a local resident whose family’s contribution augmented Green Acres funding of the site.

Alonzo F. Bonsal Wildlife Preserve

The preserve consists of remnant wetlands and uplands surrounding the Third River, a major tributary of the lower Passaic River watershed.  The Third River headwaters are located in Rifle Camp Park in Woodland Park.

Third River

The headwaters were impounded in 1899 to form the Great Notch Reservoir which greatly reduced the river’s flow. The Third River’s current name was derived from the fact that it lies north of two other Passaic River tributaries (1st & 2nd Rivers).

Years ago, the river was known as Pearl River due to the discovery of the Queen Pearl aka Paterson Pearl . Freshwater pearls are found in a river’s mussel population. The Paterson Pearl, a 93 grain pink pearl, was one of the first freshwater pearl to be discovered in the United States. Other pearls were found in the Third River but none matched the Paterson Pearl.

Today, the mussels are long gone and the name Pearl River has been replaced by Third River as designated by cartographers.

The preserve has been left in its natural state with the exception of an old sewer line built in the early 1900’s. The sewer is owned by the City of Clifton. In 2008, around 10 trees in the preserve and a 12 foot wide woods road was constructed near Daniels Road, a dead end street in Clifton, to access a ruptured section of the pipe. Plans are being made to remove and reroute the sewer as of January 2014.


Bridge over Third River

The main entrance to the Bonsal Preserve is located in a right of way off of Riverview Drive in Montclair. After crossing the bridge over the Third River, you can continue north to Daniels Drive in Clifton or head east or west to explore the wetlands near the Third River. The trails are not blazed but due to the size of the preserve, you can’t get lost physically without soon discovering a spot you previously traveled.

Bonsal Preserve Trail

Small preserves in urban settings really provide a great opportunity to take your time and enjoy nature right in your own backyard.


The richest concentration of wildlife found in the Third River watershed is found in the Bonsal Preserve. Baltimore Orioles, Red-Eyed Vireos, Red-Winged Blackbirds, White-Tailed Deer and Raccoon have all been spotted among others. I spotted the guys in the pictures below the day I visited:

Mourning Cloak Butterfly

White Throated Sparrow

Song Sparrow


Because a good percentage of the Bonsal Preserve consists of forested floodplains, obligate wetland plants such as Skunk Cabbage may be found in abundance.

Skunk Cabbage

Other species include the below among others:

American Beech

Black Cherry

 Check out Plant Communities of New Jersey to learn more about the high diversity of plant life found in the Garden State!

NJ’s geology, topography and soil, climate, plant-plant and plant-animal relationships, and the human impact on the environment are all discussed in great detail. Twelve plant habitats are described and the authors were good enough to put in examples of where to visit!

Click here for more information!

The preserve, known locally as Montclair’s paradise, is a great place to take a walk, birdwatch and just kick back and enjoy. Click here for directions!

For more information on this fantastic preserve be sure to contact Friends of the Bonsal Preserve at the email address

Great Ecology/Birding Books!

1. Pocket Guide to Eastern Streams – This book is perfect for nature-lovers, hikers, anglers, naturalists, and wildlife professionals
* Includes information on restoring and preserving threatened or damaged stream ecosystems!

Click Here for more information!

2. Stream Ecology: Structure and function of running waters – Great working reference for stream ecology and related fields!

Click Here for more information!

3. Birds of Eastern North America – This wonderful book’s format allows for quick and easy reference using detailed artworks, maps and text!

Click Here for more information!

 Feel free to comment below with any bird sightings, interesting plants, memories or suggestions! Thank you and have fun exploring!

Check out the latest bird sightings here!