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Population Energetics of Northern Pintails
Wintering in the Sacramento Valley, California

Table 2


Table 2.  Mean daily populations (n) and total and period use-days, estimated food intake, and habitat (ha) requirements of adult male and female northern pintail populations during a dry (1980-81) and a wet (1981-82) winter in the Sacramento Valley, California.
Periodc Sex Dry winter (1980-1981) Wet winter (1981-1982)
n (103)d Use-days (103)e Food intake
(103 kg)a
Hectares requiredb n (103) Use-days (103)e Food intake
(103kg)
Hectares Required
Wetlands Rice Wetlands Rice Wetlands Rice Wetlands Rice
Aug-Sep M 211 6,330 358 0 228 0 241 7,230 429 0 274 0
F 38 1,140 64 0 41 0 42 1,260 62 0 40 0
Sep-Oct M 388 11,640 865 0 551 0 422 12,660 916 0 583 0
F 187 5,610 357 0 228 0 203 6,090 363 0 231 0
Oct-Nov M 420 12,600 238 666 199 2,413 609 18,270 300 839 250 3,038
F 280 8,400 156 435 130 1,577 406 12,180 235 658 196 2,383
Nov-Dec M 641 19,230 69 1,179 58 4,271 983 29,490 97 1,658 81 6,009
F 483 14,490 47 805 39 2,917 741 22,230 69 1,181 58 4,279
Dec-Jan M 1,017 30,510 100 1,708 84 6,189 1,034 31,020 119 2,027 99 7,343
F 901 27,030 88 1,495 73 5,416 916 27,480 98 1,672 82 6,056
Jan-Feb M 677 20,310 92 1,569 77 5,686 663 19,890 87 1,479 72 5,359
F 625 18,750 72 1,226 60 4,441 612 18,360 67 1,148 56 4,161
Feb-Mar M 86 2,580 9 155 8 562 211 6,330 25 427 21 1,549
F 79 2,370 8 129 6 469 194 5,820 21 353 17 1,279
Total     180,990 2,523 9,367 1,782 33,941   218,310 2,888 11,442 2,060 41,456
a Use-days × daily food intake (g; Table 1).
b hectares = food intake food density in wetlands (diurnal feeding) at 1,570 kg/ha (Aug-Sep) and 1,200 kg/ha (Sep-Mar), and rice fields (nocturnal feeding) at 276 kg/ha.
c Assumes 30 days between monthly midpoints (e.g., Aug-Sep = 15 Aug to 15 Sep).
d Unpublished data, U.S. Fish and Wildlife Service and California Department of Fish and Game.
e 30 days/period.

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