Summary 2001

No counties reached a high weekly dead crow density in 2001. The 5 boroughs of New York City and 4 surrounding counties reached moderate density during the weeks beginning: Bronx (6/3-6/10, 7/15, 7/29, 8/12-9/2); Brooklyn (6/3-6/10, 7/8, 7/29-9/16, 9/30); Manhattan (7/8, 7/29, 8/12-9/2, 9/30); Queens (5/13, 6/24, 7/22, 8/5-9/2); Staten Island (5/13, 6/3-6/17, 7/1, 7/15-9/2); Nassau (6/3, 7/8-9/30); Rockland (6/17, 7/8-7/29, 8/26-9/30); Suffolk (7/8-9/16); and Westchester (7/8-7/15, 9/2).

County	Dead Crow Density*
Albany	Low
Allegany	Low
Bronx	Low
Brooklyn	Low
Broome	Low
Cattaraugus	Low
Cayuga	Low
Chautauqua	Low
Chemung	Low
Chenango	Low
Clinton	Low
Columbia	Low
Cortland	Low
Delaware	Low
Dutchess	Low
Erie	Low
Essex	Low
Franklin	Low
Fulton	Low
Genesee	Low
Greene	Low
Hamilton	Low
Herkimer	Low
Jefferson	Low
Lewis	Low
Livingston	Low
Madison	Low
Manhattan	Low
Monroe	Low
Montgomery	Low
Nassau	Low
Niagara	Low
Oneida	Low
Onondaga	Low
Ontario	Low
Orange	Low
Orleans	Low
Oswego	Low
Otsego	Low
Putnam	Low
Queens	Low
Rensselaer	Low
Rockland	Low
Saratoga	Low
Schenectady	Low
Schoharie	Low
Schuyler	Low
Seneca	Low
St. Lawrence	Low
Staten Island	Low
Steuben	Low
Suffolk	Low
Sullivan	Low
Tioga	Low
Tompkins	Low
Ulster	Low
Warren	Low
Washington	Low
Wayne	Low
Westchester	Low
Wyoming	Low
Yates	Low

*Dead Crow Sightings per Square Mile

Because reporting was interrupted by the events of September 11, it is not possible to interpret density levels in the NYC area. Low density may be an effect of decreased reporting, or environmental changes may have forced crows away from the area.

Note: Dead crow sightings are a possible early warning of, but not definitive confirmation of, West Nile virus activity. Crows die of many causes and reporting levels may vary among counties.

In 2000 an association was noted between the weekly dead crow density and human cases of West Nile virus. Dead crow density may provide, along with other surveillance indicators, a forecast of human WNV risk. No human cases occurred in counties with low weekly dead crow densities (less than 0.1 per sq. mile). Occasional human cases occurred within a few weeks after counties reported moderate dead crow densities. In the only county with a high dead crow density (greater than 1.5 per sq. mile), an outbreak of human cases began approximately two weeks later.