New York Natural Heritage Program
Grasshopper Sparrow
Ammodramus savannarum (Gmelin, 1789)
Birds

Threats [-]
Habitat loss from declining agriculture in New York is likely the major cause of decline. The 42% decline in the distribution of Grasshopper Sparrows and the scale of agricultural loss in the state, indicate that the scope of this threat may be affecting a large percentage of the population (McGowan and Corwin 2008). The Breeding Bird Survey found a decline of 8.36% per year from 1966-2014 (Sauer et al. 2014). In addition, intense agricultural grassland management results in less suitable habitat for grasshopper sparrows in some of the remaining fields.

Conservation Strategies and Management Practices [-]
Disturbances, such as haying, during the breeding season from mid-April to late-August should be avoided. Mowing may be the preferred habitat management practice for Grasshopper Sparrows instead of burning or grazing (Bollinger 1988). Mowing should occur either several weeks before or after the breeding season (Whitemore 1981) and every 2 to 3 years (Bollinger and Gavin 1992). Bollinger and Gavin (1992) found that birds in New York preferred old hayfields that have not been reseeded for 10 years. Grazing may be an effective management strategy if grasses are tall. This allows for a patchwork of tall and short grasses (Whitemore 1981). However, grazing can also create less suitable habitat. Kantrud and Kologiski (1982) found that lightly grazed fields had the highest densities of Grasshopper Sparrows, while moderately grazed had moderate densities and heavily grazed fields had the lowest densities. Extensive grasslands should be managed in a patchwork system. Bollinger and Gavin (1992) suggested that management of larger areas in New York should include patches that are 10-15 hectares. The mosaic of grasslands should include different successional stages. Fragmentation appears to affect the return rate and nesting success of Grasshopper Sparrows (Balent and Norment 2003). Larger fields have a higher adult return rate, more fledgling per female, and more young fledged. Smaller fields may support immigrants rather than returning birds (Balent and Norment 2003).

Research Needs [-]
Additional research is needed to determine the best management strategies for Grasshopper Sparrows and other grassland birds to maximize grassland bird diversity in New York. Researchers have noted that a large portion of grassland bird research has taken place in western states, noting that natural prairie habitat has different vegetative characteristics compared to the hayfield habitats that are more typically used in the east (Bollinger 1995). Additional data are needed to understand grassland bird source-sink dynamics in the northeast.