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Northern Prairie Wildlife Research Center

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Effects of Radio Transmitters on Nesting Captive Mallards

Tables


Table 1.  Number of captive mallard females with radios (nr) and number with radios that produced a clutch (n1), Northern Prairie Wildlife Research Center, Jamestown, North Dakota, 1991.
Treatmenta Clutch
1 2 3 4 5
nr n1 nr n1 nr n1 nr n1 nr n1
Control b 8 8 8 7 8 6 8 2 8 0
4-g sutured 6c 6 3 3 2 2 2 1 1 0
10-g harness 7d 7 7 6 7 6 7 2 7 0
18-g harness 8 8 8 7 8 7 8 4 8 2
a Initial sample size for all treatments was 8
b Females did not have radios attached.
c Two females lost radio packages before their first nest initiation.
d One pair removed 7 days into study after drake died.

 

Table 2.  Mean (± SE) clutch sizes (eggs) and nesting intervals (daysa) for captive mallards at Northern Prairie Wildlife Research Center, Jamestown, North Dakota, 1991.
Treatmentb Clutch
1 2 3 4
Eggs Days Eggs Days Eggs Days Eggs Days
Control 10.4 (0.5) 19.0 (2.1) 10.4 (0.3) 7.1 (0.4) 9.3 (0.2) 9.7 (1.9) 9.0 (1.0) 10.5 (0.5)
4-g sutured 10.7 (0.5) 17.0 (3.5) 10.7 (0.7) 6.3 (0.3) 9.5 (1.5) 7.0 (1.0) 9.0 (– –) 7.0 (– –)
10-g harness 10.1 (0.4) 19.6 (2.9) 10.0 (0.3) 7.3 (0.7) 9.5 (0.6) 8.0 (0.8) 9.0 (1.0) 8.0 (0.0)
18-g harness 10.2 (0.6) 17.9 (2.0) 9.6 (0.3) 7.3 (0.2) 9.0 (0.3) 8.4 (1.3) 8.2 (0.5) 7.2 (0.3)
a Nesting interval is the number of days between removal of a clutch and initiation of a successive clutch.  Nesting interval for clutch 1 is the number of days between radio package attachment and initiation of first clutch.
b Sample size (n1) for each clutch and treatment are presented in Table 1.

Table 3.  Analysis of variance of clutch size for captive mallards held on experimental ponds,  Northern Prairie Wildlife Research Center, Jamestown, North Dakota, 1991.a
Source of variation df Sum of
squares
F P Estimated
power
b
Pond 15 45.00      
Treatmentc 3 7.78 1.94  0.187 0.25
Error (a) 10 13.37      
Clutch number 3 25.29 12.47 < 0.001     
Clutch number × treatment 9 2.91 0.48 0.881 0.48
Error (b) 41 27.71      
a Excludes fifth clutches
b After Kirk (1982:142)
c Treatments were 3 types of radio packages (4-g sutured and glued [Wheeler 1991], 10- and 18-g harnesses [Dwyer 1972]), and control.

 

Table 4.  Analysis of variance of nest interval for captive mallards held on experimental ponds, Northern Prairie Wildlife Research Center, Jamestown, North Dakota, 1991.a
Source of variation df Sum of
squares
F P Estimated
power
b
Pond 15 687.30      
Treatment 3 17.70 0.26 0.854 0.28
Error (a) 10 229.28      
Clutch number 3 1,253.87 31.49 < 0.001     
Clutch number × treatment 9 24.03 0.20 0.993 0.48
Error (b) 41 544.23      
a Excludes fifth clutches
b After Kirk (1982:142)

 

Table 5.  Analysis of variance of average egg mass per clutch for captive mallards held on experimental ponds, Northern Prairie Wildlife Research Center, Jamestown, North Dakota, 1991.a
Source of variation df Sum of
squares
F P Estimated
power
b
Pond 15 420.57      
Treatment 3 14.69 0.14 0.935 0.28
Error (a) 10 354.35      
Clutch number 3 33.68 1.91 0.142  
Clutch number × treatment 9 68.50 1.30 0.268 0.33
Error (b) 41 240.59      
a Excludes fifth clutches
b After Kirk (1982:142)

 

Table 6.  Mean mass changea for captive mallard females held at Northern Prairie Wildlife Research Center, Jamestown, North Dakota, 1991.
Treatment mean of x SE
Control (8)b -18.8 16.3
4-g sutured (1)   90.0  
10-g harness (7) -64.3 36.5
18-g harness (8) -53.8 26.5
a Change calculated as mass at end of study minus mass at time of treatment.
b Numbers of birds that retained radio packages until end of study are in parentheses.