Alexauken Creek Wildlife Management Area Biological Inventory Report Washington Crossing Audubon Society Introduction The New Jersey Department of Fish and Wildlife recently purchased a tract of approximately 415 acres along Alexauken Creek in West Amwell Township to create the Alexauken Creek Wildlife Management Area (ACWMA). In the summer of 2002, Washington Crossing Audubon Society (WCAS) was contacted by Jamie Kampf and Hal Shute, neighbors of ACWMA, and invited to take a tour of the property. WCAS was also asked to consider conducting a biological inventory of the property and making recommendations for its management, based on information gathered in the inventory. On June 5, 2002 WCAS current and former board members Hannah Suthers, Pat Sziber, Rick Dutko and Herb Lord joined Hal Shute, Jamie Kampf and Gary Robinson for a tour of the property, and agreed that WCAS would conduct the study and provide a report in early 2004. The following sections provide a description of the property, a description of how the inventory was conducted, summaries of the results, and our recommendations for management of the property. View across formerly cultivated field. Old stone wall in the woods. Mantell Cottage. Pond. 1 Location Alexauken Creek Wildlife Management Area is located in the northeastern part of West Amwell Township, Hunterdon County, west of State Highway 31 and south of US Highway 202, on the edge of Sourland Mountain. Access and a parking area are on Rocktown-Lambertville Road, and the property extends northward and westward to Old York Road. A nearby but non-adjacent addition to the area on State Highway 31 was purchased in 2003 but was not surveyed by WCAS. Figure 1 shows the location of the property relative to local roads, Pennington and Hopewell Boroughs, and Sourland Mountain. Count y Highwa y 6 02 G u lic d. k rk R Yo Gulick Old 2 0 2 ACW a y MA h w ig H S C S o ta U u te n C H t y ig St n o H Pa rking h d w . w a w to le o k il H a r y oc rtv Lot y B 6 R e w 3 W 9 0 b 1 7 1 am y y 518 o. Hw 1 L 5 C y 7 w 9 H N te le- a il M t tv ke S er Tp HOPEWELL a mb ell ni a w L pe S Ho BORO t d 4 n 5 d R 6 o R t y r l n w e il u H k S i w H P o o t k t a c b y i r w k t k e s a n c c u o o r H H B R R i g n h o t w g a n i y n 3 n e 1 P PENNINGTON BORO . d R n S r ta e te v a H T law ar e i D e g r . h W w a a e Boroughs Ave. F y B 2 e 9 ACWMA (original) d ACWMA (additions) e r S a t l N Owned a t e C i t Easement H y i g R 0 1 2 3 Miles W E Sourland Mtn. h w d a y S 3 1 Figure 1. Alexauken Creek Wildlife Management Area (ACWMA) location map. Please Note: All of the maps in this report were developed using the New Jersey Department of Environmental Protection Geographic Information System digital data, but these secondary products have not been verified by NJDEP and are not state authorized. Bedrock Geology The property falls within the Piedmont physiographic region, along the edge of Sourland Mountain. The bedrock geology (Figure 2) falls mostly within the Passaic Gray Bed Formation, (sandstone, siltstone, and shale) and Passaic Formation (siltstone and shale). The eastern end of the property and a ridge running to the north of the creek is a Jurassic Diabase Formation. The diabase ridge runs for about seventeen miles from southwest to northeast, and forms the hard spine of 2 Sourland Mountain. The bedrock under most of the land within the WMA is siltstone and shale. Luce (see the Bibliography) provides a mo re detailed discussion about the formation of Sourland Mountain and the geology of the region. Alexauken Creek WMA Geology Lithology diabase, medium- to coarse-grained sandstone, siltstone and shale siltstone and shale N W E S 0 0.1 0.2 0.3 0.4 0.5 Miles Figure 2. Alexauken Creek Wildlife Management Area geology. Topography The elevation varies from about 430 feet near the parking area along Rocktown-Lamb ertville Road to a bit less than 200 feet near Old York Road, with fairly steep slopes along the creek. The areas underlain by the diabase ridge tend to be highest in elevation. Alexauken Creek flows east to west through the property. The creek is dammed about 0.2 miles west of Rocktown-Lambertville Road, forming a pond near the Mantell Cottage (at the end of the access road shown on the map). Upstream of the pond the somewhat muddy creek flows slowly through a relatively flat floodplain, but downstream of the dam the creek has cut a ravine through the land and flows fast and clear over a hard rocky bed. From the southern edge of the property, the land generally slopes gently downward as one moves north, except for the ravine along the creek. The 300 foot contour is sometimes used as the limit of Sourland Mountain; by that criterion a significant portion of the property lies to the north of Sourland Mountain. 3 0 0.1 0.2 0.3 Miles N W E S Figure 3. Alexauken Creek Wildlife Management Area topography. Alexauken Creek Madtell Cottage 4 Aerial Photographic Image Figure 4, from the NJDEP 2002 digital ortho-photos of the state, provides a bird’s eye view of the property. About 270 acres of the property are wooded, about 90 acres are recently farmed fields, and about 50 acres are brush/shrub areas that were farmed some years ago. Hedgerows separate fields, and only about three acres of the fields are agricultural wetlands. Of the wooded area, about 9 acres are classified as deciduous wooded wetland, about 82 acres as coniferous/deciduous forest, and about 180 acres as (upland) deciduous forest. There is an occupied private residence that is almost surrounded by the property, and there is a currently unoccupied cottage (the historic Mantell Cottage) on the property. Alexauken Creek runs from east to west through the property, forming the southern boundary toward the western end of the property. Near the eastern end of the wildlife management area, the creek is dammed to form a small pond. Several small intermittent tributaries feed the creek, but all were dry during the study period. Figure 4. Infrared digital image of Alexauken Creek Wildlife Management Area. 5 Geographic Information System Land-Use/Land-Cover Map The New Jersey Department of Environmental Protection has made Geographic Information System (GIS) data available to the public through a series of CD-ROMs. Some of the street locations in Figure 1 of this report, the geology map of Figure 2, and the digital image in Figure 3, are examples of this data. Figure 5 illustrates another form of the NJDEP GIS data, a land-use/land-cover map of the Alexauken Creek Wildlife Management property. Land-use/land-cover maps were developed from digital imagery; analysis of the digital images by DEP analysts permitted each area of the map to be classified based on its apparent use or vegetation cover. Figure 5. Land-Use/Land-Cover map of Alexauken Creek Wildlife Management Area. In our surveys of Alexauken Creek Wildlife Management Area, we took advantage of the land-use/land-cover classification data, in combination with some obvious dividers such as hedgerows, to divide up the property into about 30 habitat patches, each with a unique designator. The patches varied in size from about two acres to nearly ninety acres, but each patch was reasonably uniform habitat. Locations of observations were specified by the habitat patch designations. Each field and forest area has a designation – see Figure 5 for details. Hedgerows were not included in the land-use/land-cover data, and were not named, but observations in hedgerows were specified by descriptions such as “CP6-CP7 hedgerow.” Agricultural lands classifications that were used for Alexauken Creek Wildlife Management Area were 1) Cropland and Pastureland, designated as CPx, and 2) Agricultural Wetlands, one patch, designated AW1. Brushland/Shrubland areas were designated BSx. 6 Forested land classifications that were used for Alexauken Creek Wildlife Management Area were: · Deciduous Forest (designated as DFx), · Coniferous/Deciduous Forest Designated as CDFx), and · Deciduous Wooded Wetlands (designated as DWWx). Most of the features on the map of Figure 5 represent unmodified DEP data, but some modifications and additions were made. Hedgerows, as mentioned above, were not included, so we created that coverage from the digital imagery. The DEP data for streams did not include the minor, intermittent tributaries to Alexauken Creek, so we created the streams coverage through a combination of surveys employing a small handheld Global Positioning System (GPS) receiver and careful examination of the aerial photo image. We also mapped the trails along the field edges and through the wooded areas using a combination of GPS and the photo imagery. Other Data Sources The Endangered and Nongame Species Program Landscape habitat maps use five wildlife habitat categories based on the land-use/land-cover maps: beach/dune, emergent wetland, grassland, forest, and forested wetland.