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Wetland Use, Settling Patterns, and Recruitment in Mallards

Tables


Table 1. Characteristics of 9 50.8-km2 study areas in eastern North Dakota (study areas 1-6) and westcentral Minnesota (study areas 7-9) where radioequipped female mallards (1988-90) and unmarked pairs were monitored during spring and summer (1987-91). Percentages of study areas in cropland, grassland, and wetland habitat are based on status in May 1988.
Study Areaa Habitat Class (%) No. Wetland Basins by Classb Basin Area (ha) by Class No. Females Monitored
Crop Grass Wet T S SP L T S SP L 1988 1989 1990 Total
1 34 34 19 531 689 130 2 98 275 562 17 5 3 1 9
2 28 41 18 495 319 156 3 70 162 520 148 7 c   7
3 55 17 13 169 203 111 2 116 181 337 18 0 11 1 12
4 64 5 13 513 371 35 1 115 201 339 1 5 3 0 8
5 80 3 9 899 277 69 1 150 140 174 2 1     1
6 58 10 18 768 258 99 1 149 170 463 123 3 6 0 9
7 62 5 17 270 292 133 9 55 110 272 451   3 6 9
8 64 5 11 205 321 137 31 64 225 190 252 8     8
9 49 10 14 218 315 156 38 45 78 207 354 10 10 8 28
Totals       4,068 3,045 1,026 88 862 1,542 3,064 1,366 39 36 16 91
aStudy area locations: 1 (46°27'N, 98°56'W); 2 (46°16'N, 99°12'W); 3 (46°11'N,98°53'W); 4 (47°11'N, 98°40'W); 5 (46°49'N, 98°49'W); 6 (46°43'N, 98°06'W); 7 (46°59'N, 96°12'W); 8 (46°55'N, 96°02'W); 9 (46°51'N, 96°13'W).
bWetland basin classes: temporary (T), seasonal (S), semipermanent (SP), and lake (L) after (Cowardin et al. 1988a). Class of each wetland basin was obtained from digitized maps of study areas prepared by the U.S. Fish and Wildlife Service National Wetland Inventory (NWI) with wetland classification based on water regime (Cowardin et al. 1979). Basin class is named after the most permanent water regime present within the basin and neither class nor area changed among years.
cBlanks represent years when radiotelemetry studies were not conducted on a study area. Zeros represent years when some females were radioequipped on a study area, but insufficent data was obtained because most birds left early due to drought conditions.

 

Table 2. Number and area of pondsa by wetland basin class (Cowardin et al. 1988a) during 1987-91 in eastern North Dakota (study areas 1-6) and in westcentral Minnesota (study areas 7-9). Wetland basin classes were temporary (T), seasonal (S), semipermanent (SP), and lake (L).
Study Area Year
1987 1988 1989 1990 1991
T S SP L T S SP L T S SP L T S SP L T S SP L
No. Ponds
1
96 552 116 2 4 122 115 2 77 534 124 2 0 41 51 1 0 35 62 1
2
120 281 148 3 33 112 133 3                        
3
32 120 108 2 9 55 95 2 16 113 106 2 1 9 41 0 1 21 35 1
4
119 276 35 1 22 100 32 1 88 177 28 1 1 16 16 1 0 10 14 0
5
149 203 60 1 7 23 33 1                        
6
51 131 92 1 3 11 40 1 129 134 82 1 4 3 26 1 42 53 47 1
7
24 102 109 9 5 57 96 9 62 162 120 9 21 74 101 9 7 31 87 9
8
17 94 84 22 6 52 79 30                        
9
36 188 146 38 14 114 132 38 65 203 137 38 17 139 126 37 33 134 125 37
Pond Area (ha)
1
15 252 530 17 <1 34 316 15 6 143 298 16 0 6 43 8 0 6 78 7
2
        7 40 380 135                        
3
8 68 307 27 3 28 183 12 2 41 197 12 <1 <1 24 0 <1 2 12 <1
4
49 168 255 1 5 36 166 1 10 40 101 <1 <1 2 29 <1   3 55  
5
        1 6 26 3                        
6
27 77 277 128 <1 6 54 120 23 58 162 118 <1 1 11 109 2 8 18 109
7
6 45 273 450 <1 22 189 412 8 52 220 389 4 20 145 353 1 10 101 325
8
        3 58 89 168                        
9
7 53 206 406 2 30 151 378 8 46 161 382 3 26 120 336 3 17 94 323
aPonds were defined as wetland basins that contained water (Cowardin et al. 1982) and were typed according to basin class.

 

Table 3. Wetland basin use by radioequipped female mallards by reproductive stage in eastern North Dakota and westcentral Minnesota during spring and summer 1988-90.
Wetland Basin Class % Use by Reproductive Stagea
Pre-nest Egg production Incubation Post-nest
Temporary 8.8 8.5 8.9 4.3
Seasonal 25.2 25.9 23.1 18.0
Semipermanent 40.8 48.9 57.1 59.4
Lakes 25.2 16.8 11.0 18.3
aWeighted average with number of locations across all basin classes as the weighting value. Number of females by reproductive stage is as follows: pre-nesting (58), egg production (56), incubation (20), and post-nesting (48).

 

Table 4. Percent of pond use by wetland basin class and dry basin use by radioequipped female mallards during prenesting and egg production in southcentral North Dakota and westcentral Minnesota during 1988-90. Percent wetland habitat use, ranks of use, ranks of wetland habitat availability, the differences between ranks, and relative preference (indicated by letter) are presented for each of the 5 wetland habitats available with Johnson's (1980) ranking method.
Habitat Reproductive Stage
Pre-nestinga Egg Production
% Useb Use Rank Avail. Rank Diff.c % Use Use Rank Avail. Rank Diff.
Temp 2.6 4.2 5.0 -0.8A 3.2 3.9 4.9 -1.0A
Seas 17.3 3.0 3.7 -0.7A 16.0 3.1 3.6 -0.5B
Semi 38.1 1.9 1.8 0.1B 50.5 1.9 1.8 0.1C
Lakes 26.1 2.6 2.0 0.6C 16.5 2.8 2.3 0.5C
Dry 15.9 3.3 2.5 0.8C 13.8 3.3 2.4 0.9C
aSample size of radioequipped females (in parentheses by reproductive stage is: pre-nesting (52), egg production (18).
bWeighted average with number of locations across all basin classes as the weighting value.
cAverage difference in ranks. Negative values indicate preference, positive values indicate less than predicted (Johnson 1980). Within reproductive stage, alphabetical order of letters follows order of habitat preference; ranks with the same letter did not differ (P ≥ 0.05).

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