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Northern Prairie Wildlife Research Center

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Le Conte's Sparrow:
Ephemeral Jewel of the Northern Great Plains

The Palmer Drought Severity Index

The Palmer Drought Severity Index is a meteorological index used by the National Climatic Data Center to assess the severity of dry or wet periods in different regions throughout the United States. The index is calculated monthly and incorporates information on both moisture and temperature, and expresses the severity of a wet (positive values) or dry (negative values) spell by incorporating past and present conditions. More specifically, values of zero to -0.5 indicate normal moisture conditions, -0.5 to -1.0 indicate incipient drought, -1.0 to -2.0 indicate mild drought, -2.0 to -3.0 indicate moderate drought, -3.0 to -4.0 indicate severe drought, and less than -4.0 indicate extreme drought. Similar adjectives are associated with positive values and wet periods.

Response to Moisture Population Changes of Le Conte's Sparrow
Figure 3: Species' Response to Moisture Figure 4: Le Conte's Sparrow Population Changes in Kidder County, N.D.

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