Browsing UVM Bailey-Howe Library by Subject "Habitat"

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Browsing UVM Bailey-Howe Library by Subject "Habitat"

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  • Puryear, Kristen (University of Vermont. Dept. of Botany, 2004-05
      Executive Summary Grassland birds are declining throughout most of their range. As a result, artificial habitats such as the agricultural fields of Vermont's Champlain Valley have been identified as important for grassland bird conservation. In order to address the regional and statewide concerns about grassland bird populations, Audubon Vermont has recognized two Important Bird Areas (IBAs) in the Champlain Valley, Dead Creek and Little Otter Creek. Audubon Vermont has also proposed the development of a Landscape-Level Important Bird Area Complex that would encompass these two IBAs and contribute to regional grassland bird conservation efforts as they are developed by the North American Bird Conservation Initiative and Partners in Flight. In the summer of 2003 I surveyed grassland birds in the two IBAs to assess the effects of agricultural management on breeding success. I also developed a habitat model that identifies the best potential habitat for grassland birds in the Champlain Valley , to help Audubon Vermont develop a strategy towards landscape-level grassland bird conservation. The following considerations for Audubon Vermont summarize my findings. For additional information about each consideration, please refer to the associated chapter, noted below. Grassland Bird Inventory (Chapter 1) Develop and implement a more extensive Upland Sandpiper monitoring program within Dead Creek and Little Otter Creek Important Bird Areas (IBAs) that will assess breeding success on an annual basis. Regularly monitor the same fields using a method that can detect breeding success (such as behavior mapping with a reproductive index [Vickery et al. 1992] or nest searching), which can provide information on breeding success, demographics, and responses to field management. Broadcasting surveys could be used as a supplemental tool for identifying additional survey fields and previously undetected individuals, and to help measure abundance. Monitor fields within the IBAs more than once during the breeding season to increase ,the chance of detecting rare species, assess breeding success, and help detect whether fields are ecological traps or sinks. Share field inventory results with the Vermont Department of Fish and Wildlife to help inform future revisions to their management plans for Dead Creek and Little Otter Creek Wildlife Management Areas (WMAs). Breeding Success and Field Management (Chapter 2) To maximize the potential for young to fledge, encourage a delay of mowing on hayfields until at least July 15, but preferably August 1. The later date will help protect species that fledge late or are attempting a second clutch after a failed nest attempt. On pastures being managed for grassland birds, encourage the reduction of stocking densities and delayed pasturing until July 15. Encourage a delay of mowing the pasture for forage until after July 15 (preferably August 1). Gather data on the day-to-day mowing trends within the two week period from late June to early July and on farmers needs for forage cut at that time. Assess the costs and benefits to the farmer and the grassland birds of delaying mowing for a few additional days during this critical breeding stage. Grassland Bird Survey Methods ( Chapter 3) If the monitoring objective is to calculate density, abundance and species richness values for grassland bird species, then point count surveys are recommended as a time efficient and informative method. This method is capable of detecting relative differences between survey areas. If the monitoring objective is to collect as much information as possible regarding species richness (i.e., detecting less abundant species or individuals that are sitting on nests and would likely be missed by a stationary observer), to detect breeding- related activity or breeding success, or to monitor trends as they change through the breeding season or with field management, then behavior mapping using a reproductive index (Vickery et al. 1992) is recommended as the most useful and potentially informative method. This is a reliable method for recording the progress of birds through the stages of breeding behavior (when compared with ground-truthed nest data), and provides a better approximation of bird abundance (when compared to point counts, which survey a smaller area). Landscape Level Grassland Bird Conservation Area (Chapter 4) The zones that are mapped as the "best" potential habitat should be ground- truthed in order to test the accuracy of the Scored Grassland Bird Habitat Map, and 1) verify that the mapped conditions currently exist (i.e., landcover type or amount of edge), and 2) test the assumptions made in terms of what constitutes the best habitat for grassland birds in the Champlain Valley. Gaps in knowledge of grassland bird distribution should be addressed, especially for species that could serve as focal species (Upland Sandpiper) or are rare and will require extra attention for management and protection (Grasshopper Sparrow and Sedge Wren). To enhance monitoring, land protection, management, and advocacy for grassland birds, a collaborative effort between interested organizations and agencies will be important. Collaborate with The Nature Conservancy of Vermont to create a strategy for grassland bird conservation that does not conflict with future Valley Clayplain Forest restoration. To maximize the potential for maintaining grassland bird species richness, abundance, number of breeding pairs, and potential for protecting species with large area requirements, consider protecting a complex of fields that together provide at least 50 ha but preferably 200 ha of habitat. Adjust the size, location, and management of protected fields according to species, population, or habitat conservation goals as those goals are developed. Consider the costs and benefits of locating grassland bird conservation efforts in heavily agricultural areas, where economic needs for higher productivity and intense field management decrease the chance that birds will breed successfully. Consider locating grassland bird conservation efforts in less agricultural areas that still contain suitable habitat but may be surrounded by land that is managed with less intensity. Less productive or wet fields should also be considered, as they are less likely to be managed as intensively. Within these areas, alternative farming practices (such as delayed mowing) may be more practical and more accepted by landowners and conservation organizations. Combining Grassland Bird and Marsh Bird Conservation (Chapter 5) Address the habitat needs of both grassland and marsh bird species by protecting and managing land where their habitat overlaps, such as upland fields that are adjacent to marshes.

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