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Carlton Hill Bird Conservation Area

General Site Information: Carlton Hill BCA consists of the entire Carlton Hill Multiple Use Area. It is a 2,580 acre area of grassland and shrubland habitats located in the town of Middlebury, Wyoming County. These habitats support a diversity of bird species including a number of species at risk such as Henslow's sparrow (threatened), northern harrier (threatened), grasshopper sparrow (special concern), horned lark (special concern), and yellow-breasted chat (special concern). There are also some upland forest, riparian forest, and small wetland areas that provide habitat for pied-billed grebe (threatened).

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Carlton Hill BCA Management Guidance Summary

Site Name: Carlton Hill

State Ownership and Managing Agency: Department of Environmental Conservation

Location: Carlton Hill Multiple Use Area, Town of Middlebury, Wyoming County.

Size of Area: 2,580 acres

DEC Region: 9

Vision Statement: Maintain and enhance the grassland habitat present to ensure continued use by grassland birds. Maintain early successional habitats to prevent reversion of these areas to forests.

Key BCA Criteria: Diverse species concentration site; individual species concentration site; species at risk site (ECL §11-2001, 3.e, f, g, and h). Species of interest include: Henslow's sparrow (threatened), northern harrier (threatened), grasshopper sparrow (special concern), yellow-breasted chat (special concern), pied-billed grebe (threatened), horned lark (special concern). The WMA supports a variety of other grassland and shrubland species, as well as forest and wetland species. Henslow's sparrow may be extirpated. Grasshopper sparrow was once common, but is believed to have declined markedly. Pied-billed grebes and yellow-breasted chats are present in very low numbers.

Critical Habitat Types: Large contiguous areas of grassland and shrubland.

Operation and Management Considerations:

  • Identify habitat management activities needed to maintain the site as a BCA.
    Encroachment of shrubs into a grassland habitat has begun to limit grassland bird species such as Henslow's sparrow, which may already be extirpated from the site. Northern harrier and grasshopper sparrow are still present, although the numbers of grasshopper sparrows appear to be declining. The larger grassland portions need to be maintained through periodic mowing. In areas with less aggressive invasion by shrubs, approximately 30% of the area could be managed for older grassland (herbaceous plants) communities. This should require a mowing rotation of approximately three to four years. Where shrub encroachment is more rapid, the mowing rotation can be shortened until the shrub encroachment is under control. The other portions of the grassland can be mowed more frequently for species that prefer less dense growth with less thatch built up. Goldenrod, aster, and other such herbaceous species will also need to be controlled.

    Henslow's sparrows prefer older fields with a mixture of dense and moderately tall (> 30 cm) grassy vegetation, and relatively high levels of thatch built up. Shrubs should be kept to a minimum, as Henslow's sparrows seldom use grassland areas with more than sparse, low shrubs. Rotational mowing, where portions of the area are mowed every year, and other portions are allowed to stay in old fields for a longer time period, will maintain a good mixture of grassland habitats over time. The older grasslands will be used by Henslow's sparrow, while the more recently mowed areas would be more suitable for other species such as grasshopper sparrow.

    Shrubland habitats support brown thrasher, yellow-breasted chat, and a host of other shrubland birds. Portions of the shrubland should be brush-hogged periodically to prevent succession to forest. Strips or patches could be mowed periodically to maintain a mix of shrub ages, and prevent trees from taking over the shrub lands. Trees should be periodically removed to prevent the shrublands from beginning to revert into forest.

    The dikes that support the marsh and open water habitats will need to be maintained and water levels managed through periodic drawdowns.

  • Identify seasonal sensitivities; adjust routine operations accordingly.
    The timing of mowing is critical. Grassland bird species can begin nesting as early as February or March (horned lark) and may nest into September (sedge wren). The best period for mowing is late July through early October when dry conditions normally persist. Mowing during this period should result in minimal interference with nesting birds.
  • Identify state activities or operations which may pose a threat to the critical habitat types identified above; recommend alternatives to existing and future operations which may pose threats to those habitats.
    The greatest threat to these critical habitat types would be the lack of active management. Periodic mowing is required to maintain the larger contiguous grasslands. Otherwise, vegetative succession will result in the reversion of these areas to shrub lands and then forest. Smaller fields (less than 10 acres) not surrounded by open grasslands could be allowed to revert to shrublands.

    Operational budgets are currently inadequate to meet the need of periodic mowing. Additional funding needs to be secured.
  • Identify any existing or potential use impacts; recommend new management strategies to address those impacts.
    ATV use and horse trail riding have the potential to negatively impact birds. ATVs are already prohibited. If horse riding becomes an issue, access to core bird-nesting habitats could be limited during the peak breeding season (April through August 15). Horse riding could be confined to specific trails during this time.

Education, Outreach, and Research Considerations:

  • Assess current access; recommend enhanced access, if feasible.
    Public access is considered adequate.
  • Determine education and outreach needs; recommend strategies and materials.
    There is a need for an educational effort directed at grassland and shrubland bird management. Grassland birds, as a whole, are declining throughout the Northeast as their habitats decline. Many shrubland and early successional forest birds are also declining. Kiosks and other educational materials should be developed and focus on the need to maintain grasslands and shrublands, and the diversity of associated bird species.
  • Identify research needs; prioritize and recommend specific projects or studies.
    Henslow's sparrows are rapidly declining throughout New York. Research to determine the causes of this decline and specific habitat management recommendations to help halt this decline are needed.

Other Issues:
None identified.

DEC Region 9 Wildlife Manager, 716-851-7010


Bull, John L. 1998. Bull's Birds of New York State. Comstock Publishing Associates, Ithaca, NY.

Jones, Andrea L., and Vickery, Peter D. Conserving Grassland Birds. Three volume set. U.S. Fish and Wildlife Service and Massachusetts Audubon.

Mitchell, Laura R., et al. 2000. Ecology of Grassland Breeding Birds in the Northeastern US. Cornell University.

NYSDEC. 1997. Carlton Hill Multiple Use Area Biodiversity Report. NYSDEC, Albany, NY.

Sample, David W. and MJ Mossman. 1997. Managing Habitat For Grassland Birds. Dept. of Natural Resources, Madison, WI.

Vickery, Peter D. and Peter W. Dunwiddie. 1997. Grasslands of Northeastern North America. Massachusetts Audubon.

Date Designated: 10/2/06

Date Prepared: 4/18/06

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