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Effects of Harness Transmitters on Behavior and Reproduction of Wild Mallards

Tables


Table 1. Sample sizes and Hotelling's T 2-values (Johnson and Wichern 1988) used to assess behavioral differencesa between unmarked and radio-marked female mallards on 2 study sites in the prairie pothole region, 22 April-30 June 1989-91.
  Total observation time (hr)b No. radio-marked birds observedc Overall behavioral difference
Unmarked birds Radio-marked birds T 2 P
Detroit Lakes, Minn.
1989 92 105 13 37.3 0.0004
1990 60 44 13 16.2 0.0128
1991 38 36 10 18.3 0.0129
All years 190 185 36d 47.4 <0.0001
Kulm, N.D.
1989 78 42 14 20.2 0.0050
1990 113 8 3 e e
All years 191 50 17f 23.3 0.0018
a Test evaluates combined differences in feeding, resting, and preening behaviors.
b Calculated from number of data points collected at 30-second intervals rounded to the nearest hour.
c Radio-marked birds observed in >1 year were counted separately for each year.
d Three or 4 radio-marked birds were each observed in 2 years. Second year observations totaled 5-7 hours for the 3-4 birds combined.
e Not tested because of insufficient data on radio-marked birds.
f One radio-marked bird possibly observed in 2 years (observed 1.4 hr in second year).

 

Table 2. Clutch sizes and egg volumes for unmarked and radio-marked female mallards nesting on 3 study sites in the prairie pothole region, 1988-91.
  Clutch sizea Egg volume (cm3)a
mean of x SE nb mena of x SE nc
Detroit Lakes, Minn.
  Unmarked 9.7(9.1) 0.20(0.24) 56(37) 50.0(49.9) 0.23(0.27) 331(252)
  Radio-marked 8.0(8.0) 0.18(0.18) 51(50) 48.4(48.4) 0.25(0.26) 552(542)
Kulm, N.D.
  Unmarked 9.2(8.8) 0.15(0.22) 80(39) 49.4(49.8) 0.20(0.29) 351(161)
  Radio-marked 7.9(7.9) 0.22(0.25) 34(29) 46.5(46.7) 0.24(0.28) 338(264)
Jamestown, N.D.
  Unmarked 9.7(9.4) 0.17(0.19) 54(35) 49.5(49.7) 0.25(0.31) 230(124)
  Radio-marked 8.3(8.6) 0.51(0.69) 20(14) 46.3(45.9) 0.29(0.31) 156(110)
a Parenthetical values are for data subsets that only included nests initiated during the time interval in which both unmarked and radio-marked females initiated nests.
b Number of clutches.
c Number of eggs.

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