Ryan Cumbow). A "blue" Snow Goose was observed several times in the SW portion of the checklist area (for example at Booth Dam) in June 2010 or 201 1 (Ryan Cumbow pers. comm.). Alan Van Norman reported a Snow Goose in the Lyman County portion of the Fort Pierre National Grassland on 5 January 2013 (eBird database). ROSS'S GOOSE (Chen rossii) Status: Fairly common but irregular spring and fall migrant. Distribution: The distribution of the Ross's Goose is the same as the Snow Goose. High Counts: Approximately 40 Ross's Geese were with the hundreds of Snow Geese passing over the Cookstove Shelterbelt on 10 November 2014 (DNS). Remarks: Look for this species in large Bocks of Snow Geese. Peak migration periods for Ross's Geese are April and October/November. 17 CACKLING GOOSE (Brcinta hutchinsii) Status: Common but irregular spring and fall migrant, uncommon but irregular winter visitor. Distribution: Cackling Geese use cropland and wetland habitats. Remarks: Watch for this species in flocks of Canada Geese. Cackling Goose (Figure 16) migration peaks in April and October/November. Carey Cooper reported a relatively late Cackling Goose on 17 May 2014 in the Stanley County portion of the Fort Pierre National Grassland (eBird database). CANADA GOOSE (Brcinta canadensis) Status: Abundant spring and fall migrant, fairly common summer resident, abundant but irregular winter visitor. Distribution: Canada Geese use both cropland and wetlands. Nesting Records: Nests and broods are found annually within the checklist area. For example, a brood with 6 goslings was at South Lake Flat Dam on 12 July 2014 (DNS). Remarks: Local numbers swell with migrants from mid-March to late April, and again from October to early November. Early April to mid-August is the peak of breeding. Wintering flocks centered in Pierre are occasionally seen flying over or feeding in the checklist area. TRUMPTER SWAN (Cygnus buccinator) Status: Accidental fall migrant. Distribution: Trumpeter Swans use large reservoirs. Remarks: The only local record for this species pertains to two birds seen at Nels North Pasture on 16 October 2014 (Ryan Cumbow pers. comm.). TUNDRA SWAN (Cygnus columbianus) Status: Accidental fall migrant. Distribution: Trumpeter Swans use large reservoirs. Remarks: The only local record for this species pertains to a bird verified by Doug Backlund in County Line #14 on

A high degree of correlation is shown to exist between the mean water equivalent of the snow pack on March 1 at snow courses in the Snake River region and the mean annual precipitation at nearby precipitation stations. Attempts were made to improve the correlation by introducing various additional parameters, but the resulting changes were not significant. In attempting to introduce length of snow‐accumulation season as a parameter, a relation between elevation, latitude, and average beginning date of continuous winter snow cover with at least one inch of snow on the ground was developed.