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 d Unpublished data, U.S. Fish and Wildlife Service and California Department of Fish and Game.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. |
|||||||||||||
Previous Section -- Table 1
Return to Contents
Next Section -- Appendix A
