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 differences^a 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 observed^c	Overall behavioral difference
	Unmarked birds	Radio-marked birds	No. radio-marked birds observed^c	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	36^d	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	17^f	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 size^a			Egg volume (cm³)^a
		SE	n^b		SE	n^c
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.

U.S. Department of the Interior | U.S. Geological Survey
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