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

Table 1


Table 1.  Daily energy expenditure (DEE; kJ/day), daily energy required from body reserves (DERres; kJ/day), daily energy obtained from food (DERfood; kJ/day), and food intake (g dry mass/day) of individual adult male and female northern pintails from wetlands and rice fields (Rice) during a dry (1980-81) and a wet (1981-82) winter in the Sacramento Valley, California.
Periodb Sex Dry winter (1980-1981) Wet winter (1981-1982)
DEE DERres DERfooda Food intake (g) DEE DERres DERfood Food intake (g)
Wetlands Rice Wetlands Rice Wetlands Rice Wetlands Rice
Aug-Sep M 794 3 791 0 56 0 836 4 832 0 59 0
F 786 0 786 0 56 0 700 8 692 0 49 0
Sep-Oct M 1,003 0 1,003 0 74 0 976 0 976 0 72 0
F 860 0 860 0 64 0 804 0 804 0 60 0
Oct-Nov M 1,022 1 255 766 19 53 890 2 222 666 16 46
F 1,002 0 250 752 19 52 1,044 0 261 783 19 54
Nov-Dec M 982 46 47 889 4 61 911 53 43 815 3 56
F 912 64 42 806 3 56 881 70 41 770 3 53
Dec-Jan M 971 116 43 812 3 56 997 0 50 947 4 65
F 908 64 42 802 3 55 930 2 46 882 4 61
Jan-Feb M 1,180 1 59 1,120 5 77 1,136 1 57 1,079 4 74
F 998 0 50 948 4 65 956 1 48 907 4 63
Feb-Mar M 957 39 46 872 4 60 1,032 1 52 979 4 68
F 888 54 42 792 3 55 925 0 46 879 4 61
a Proportion of food energy obtained in August-September and September-October = 100% from wetlands (diurnal); October-November = 25% from wetlands, 75% from rice fields (nocturnal); November-March = 5% wetlands, 95% rice fields (see METHODS and Table 2).
b Assumes 30 days between monthly midpoints (e.g., Aug-Sep = 15 Aug to 15 Sep).

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