USGS - science for a changing world

Northern Prairie Wildlife Research Center

  Home About NPWRC Our Science Staff Employment Contacts Common Questions About the Site

Homing and Reproductive Habits of Mallards,
Gadwalls, and Blue-winged Teal

Results


Return Rates and Homing Rates

The return rates of SY and older mallard hens that nested successfully were significantly higher ( = 17.77, 1 df, P < 0.001) than the return rates of unsuccessful hens in the same age classes (Table 7). Return rates varied from 0.233 for unsuccessful SY hens and 0.440 for successful SY hens to 0.111 for unsuccessful ATY hens and 0.750 for successful ATY hens. There was no significant difference ( = 1.04, 2 df, P = 0.59) in return rates among mallards due to hen age. The return rate for HY mallard hens was 0.288, All nasal-marked HY mallard hens that returned did so the first spring after being marked (Table 8). Mallard nestlings marked with web tags returned in a similar pattern to that for nasal-marked HY hens, and 89% of the 36 recaptured hens were trapped the first year after being marked.

Table 7.   Return rates and homing rates of resident mallard hens on the Koenig and Woodworth study areas, North Dakota, 1976-81.
Age Breeding success No. of residents No. returned Return rate Survival ratea Homing rate
HY   52 15 0.288 0.560 0.515
SY Unsuccessful 30 7 0.233 0.670 0.348
SY Successful 25 11 0.440 0.681 0.646
ASY Unsuccessful 42 6 0.143 0.670 0.213
ASY Successful 32 16 0.500 0.681 0.734
ATY Unsuccessful 9 1 0.111 0.670 0.166
ATY Successful 12 9 0.750 0.681 1.01
AHY Unsuccessful 81 14 0.173b 0.670 0.258b
AHY Successful 69 36 0.522b 0.681 0.766b
AHY Total or 150 50 0.333b   0.494b
a Survival from summer year t to 1 May of t + 1 year (see Methods).
b Weighted average.

ASY and older gadwall hens that nested successfully returned at a significantly higher rate ( = 7.14, 1 df, P = 0.01) than unsuccessful hens in the same age classes (Table 9). The difference between the 2 groups was less than for mallards because unsuccessful gadwall hens returned at a higher rate than unsuccessful mallard hens. Return rates were not different for successful and unsuccessful SY gadwall hens. Gadwall return rates increased significantly ( = 12.98, 2 df, P < 0.001) with age, ranging from 0.338 for SY hens to an average of 0.667 for ATY hens. The return rate for HY hens was only 0.087. Fifty-two percent of HY gadwall hens that subsequently returned were not observed initially until their third summer of life (Table 8). Female gadwall ducklings marked with web tags at nests exhibited a recapture rate that was similar to the return rate of HY hens marked with nasal tags. Sixty percent of 25 recaptured web-tagged hens were first retrapped in the year following marking, and 40% were first retrapped the second year after marking.

Table 8.   Pattern of first returns in the 2 years following marking for resident HY mallard and gadwall hens on the Koenig and Woodworth study areas North Dakota, 1976-81.
Species and year HY hens were marked No. marked Year HY hen first seen on study areas
First year Second year
Mallard
   1976 0 0 0
   1977 4 2 0
   1978 20 2 0
   1979 17 5 0
Total 41 9 0
Gadwall
   1976 27 1 6
   1977 12 0 0
   1978 77 6 5
   1979 53 8 5
Total 169 15 16

Table 9.   Return rates of resident gadwall hens on the Koenig and Woodworth study areas, North Dakota, 1976-81.
Age Breeding success No. of residents No. returned Return rate Survival ratea Homing rate
HY   184 16 0.087 0.540 0.161
SY Unsuccessful 43 14 0.326 0.778 0.418
SY Successful 22 8 0.394 0.792 0.459
ASY Unsuccessful 46 17 0.370 0.77812 0.475
ASY Successful 41 26 0.634 0.792 0.801
ATY Unsuccessful 19 10 0.526 0.778 0.676
ATY Successful 259 22 0.759 0.792 0.958
AHY Unsuccessful 108 41 0.380b 0.778 0.488b
AHY Successful 92 56 0.609b 0.792 0.768b
AHY Total or 200 97 0.485b   0.618b
a Survival from summer year t to 1 May of t + 1 year (see Methods).
b Weighted average.

Seven HY gadwalls marked on the Koenig study area in 1976 subsequently returned, but only 1 was first seen during the drought year of 1977. In 1977 there were few wetlands on the study area and several marked but unidentified gadwalls were seen in flocks of waterfowl oil large nearby wetlands, Only 1 gadwall nest was found on the entire Koenig study area in 1977. Wetland conditions also were below average in 1980, but larger wetlands were present. On a 20-ha wetland we counted 400 gadwalls as late as 22 May. In 1980 on the adjoining 5.2 km2, only 13 gadwall nests were found, Most AHY gadwall hens homed in consecutive years. Six (6%) hens were an exception in that they homed 2 years after initial residence. These birds were absent during the drought year of 1977 and the dry year of 1980.

The overall return rate of female blue-winged teal averaged 0.044 (Table 10). Blue-winged teal return rates did not vary significantly with respect to hen age at the Koenig study area ( = 0.53, 1 df, P = 0.47) or previous breeding success at the Koenig study area ( = 3.12, 1 df, P = 0.28) or Woodworth study area ( = 0.01, 1 df, P = 0.91). Although we did not apply nasal markers to HY blue-winged teal, we did band 226 HY hens on the Koenig study area. Three (1.3%) of the banded HY females were recaptured on the Koenig study area the next year. This is the only known record of HY blue-winged teal returning reported in the literature.

Table 10.   Return rates and homing rates of resident blue-winged teal hens on the Koenig and Woodworth study areas, North Dakota, 1977-81.
Age Breeding success No. of residents No. returned Return rate Survival ratea Homing rate
SY Unsuccessful 11 0 0.000 0.609 0.000
SY Successful 31 1 0.032 0.614 0.052
ASY Unsuccessful 11 3 0.273 0.609 0.448
ASY Successful 17 0 0.000 0.614 0.000
Unknown Unsuccessful 21 0 0.000 0.609 0.000
Unknown Successful 45 2 0.044 0.614 0.072
AHY Unsuccessful 43 3 0.070b 0.609 0.115b
AHY Successful 93 3 0.032b 0.614 0.052b
AHY Total or 136 6 0.044b   0.072b
a Survival from summer year t to 1 May of t + 1 year (see Methods).
b Weighted average.

In 1977, wetlands were few in number (Table 2), and only 1 of 21 AHY mallard hens captured and nasal marked on the Koenig study area became a resident (Table 11). Most mallard pairs apparently did not settle at a breeding area and moved about the nesting region. However, when considering all years combined, there was not a significant relationship (r = 0.38, 5 df, P = 0.46) between May pond numbers and the proportion of nasal-marked mallard hens that became residents.

There was a significant relationship (r = 0.81, 5 df, P = 0.05) between May pond numbers on the Koenig study area and the proportion of captured and nasal-marked AHY gadwall hens that became residents (Table 11). In the dry years, hens were less likely to breed than in wet years, and a reduced number of marked hens established a breeding territory.

Table 11.   Relationship of May pond numbers to the proportion of captured and marked mallard and gadwall hens that became residents on the Koenig study area, North Dakota, 1976-81.
Year No. of May ponds Mallard hens Gadwall hens
No. captured Proportion that became residents No. captured Proportion that became residents
1976 136 9 0.22 20 0.65
1977 16 21 0.05 18 0.17
1978 165 28 0.61 26 0.88
1979 165 60 0.65 44 0.75
1980 49 87 0.71 78 0.53
1981 62 120 0.56 126 0.74
Total or 593 325 0.57 312 0.66

We used return rates as the primary measurement of a hen's affinity to come back to a previous breeding site. However, we also estimated homing rates for the 3 species because they are of interest to biologists and managers and they estimate the percent of hens that return, given they are alive to do so. We have not applied statistics to these homing rate patterns as they are nearly a mirror image of return rate patterns and they were derived from our estimates of survival from year t to 1 May of year t + 1.

Estimated homing rates for successful mallard hens were high, ranging front 0,646 for SY hens to 1,101 for ATY hens (Table 7). Like return rates, the average homing rate for unsuccessful AHY mallard hens (0.258) was considerably lower than the homing rate for successful AHY mallard hens (0.766). A homing rate of 0.515 was estimated for HY mallard hens. Successful ASY and ATY gadwall hens homed at a rate that exceeded 80% (Table 9). Unsuccessful ASY and ATY gadwall hens homed at lower rates of 0.475 and 0.676, respectively. The rate of homing increased with increasing hen age. The homing rate for HY gadwalls was only 0.161. The average horning rate for AHY blue-winged teal was 0.072 (Table 10). There was no apparent difference in blue-winged teal homing rates due to hen success or age.


Previous Section -- Results - Clutch Size
Return to Contents
Next Section -- Results - Nasal Marker Biases

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/birds/homingdk/return.htm
Page Contact Information: Webmaster
Page Last Modified: Friday, 01-Feb-2013 19:32:12 EST
Sioux Falls, SD [sdww55]