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Mate Loss In Winter Affects Reproduction Of Mallards

Barbara A. Lercel,Richard M. Kaminski, and Robert R. Cox, Jr.


Abstract: Mallards (Anas platyrhynchos) frequently pair during winter, and duck hunting seasons have been extended until the end of January in several southern states in the Mississippi Flyway. Therefore, we simulated dissolution of pair bonds from natural or hunting mortality by removing mates of wild-strain, captive, yearling female mallards in late January 1996 and early February 1997 to test if mate loss in winter would affect subsequent pair formation and reproductive performance. Most (97%) widowed females paired again. Nesting and incubation frequencies, nest-initiation date, days between first and second nests, and egg mass did not differ (P ≥ 0.126) between widowed and control (i.e., no mate loss experienced) females in 1996 and 1997. In 1997, widowed females laid 1.91 fewer eggs in first nests (P = 0.014) and 3.75 fewer viable eggs in second nests (P = 0.056). Computer simulations with a mallard productivity model (incorporating default parameters [i.e., average environmental conditions]) indicated that the observed decreased clutch size of first nests, fewer viable eggs in second nests, and these factors combined had potential to decrease recruitment rates of yearling female mallards 9%, 12%, and 20%. Our results indicate that winter mate loss could reduce reproductive performance by yearling female mallards in some years. We suggest caution regarding extending duck hunting seasons in winter without concurrent evaluations of harvest and demographics of mallard and other duck populations.

Key words: Anas platyrhyncos, harvest, hunting, mallard, mallard model, Manitoba, mate loss, pairing, recruitment, reproduction


Table of Contents

Tables


Introduction

Results of published studies are equivocal regarding physiological, behavioral, and reproductive consequences of mate loss in waterfowl. Body mass, clutch size, incubation constancy and length, and nesting and hatching success did not differ between paired and widowed female wood ducks (Aix sponsa; Hipes and Hepp 1993, Manlove and Hepp 1998). Similarly, clutch size, hatching success, and other reproductive measurements of lesser snow geese (Chen caerulescens; Cooke et al. 1981, Martin et al. 1985) and Ross' geese (C. rossii; LeSchack et al. 1998) did not differ between paired and widowed females. Female Canada geese (Branta canadensis) paired again after mate loss during hunting seasons (Klopman 1962), as did mallards (Ohde et al. 1983, Bossema and Roemers 1985), common shelducks (Tadorna tadorna; Young 1970), Canada geese (Jones and Obbard 1970), barnacle geese (Branta leucopsis; Owen et al. 1988), and lesser snow geese (Abraham et al. 1981) that lost mates during migration or breeding. In contrast, decreased renesting by wood ducks (Manlove and Hepp 1998), reduced body mass in lesser snow geese (Martin et al. 1985), increased harassment of lesser snow geese and Bewick's swans (Cygnus columbianus bewickii; Scott 1980, Martin et al. 1985), decreased foraging by Bewick's swans (Scott 1980), and temporarily reduced breeding success in barnacle geese (Owen et al. 1988) occurred among females that lost mates. Nest abandonment of lesser snow geese (Abraham et al. 1981) and nest failure of black-bellied whistling ducks (Dendrocygna autumnalis; McCamant and Bolen 1977) also have been reported to occur after mate loss.

Most Holarctic ducks exhibit seasonal monogamy (Oring and Sayler 1992). Females that lose mates in autumn or winter due to natural or hunting mortality could subsequently experience reproductive consequences, including decreased individual survival (Hepp 1984), loss of breeding opportunity during the current annual cycle (Nesbitt 1989), reduced reproductive performance due to delays in physiological and behavioral events preceding breeding (Brodsky and Weatherhead 1985, Pattenden and Boag 1989, Dubovsky and Kaminski 1994), and selection of a potentially inferior mate (Heitmeyer 1995). These constraints could result in less foraging time and reduced nutrient reserves for females (Ashcroft 1976, Patterson 1977, Paulus 1983) and potentially decrease reproductive output (Krapu 1981, Pattenden and Boag 1989). Moreover, mallards in reduced body condition may be more susceptible to hunting mortality (Hepp et al. 1986, Blohm et al. 1987). Thus, mate loss during autumn or winter could impose cross-seasonal consequences on survival and reproduction.

Since the 1970's, waterfowl hunting regulations have permitted greater harvest of male than female mallards, and there is evidence that waterfowl hunters in some seasons and regions harvest males selectively (Metz and Ankney 1991). Because mallards form pairs during autumn and winter (Rohwer and Anderson 1988), potential exists for females to experience disrupted courtship and pair-bond dissolution before the breeding season.

No studies to date have investigated the incidence of pair formation by female mallards after mate loss in winter and subsequent reproductive performance. Anderson et al. (1988:125) remarked, "We need imaginative research to determine the effects of mate loss on overwinter survival and subsequent reproductive performance of individuals, especially by geese and early-pairing female ducks." We reasoned that an appropriate preliminary approach would be to conduct an experiment with captive, wild-strain mallards. Any negative consequences detected in a study with captive mallards fed nutritious food ad libitum may suggest similar or more severe effects on wild mallard populations because of resource constraints in nature. Our general null hypothesis was that reproductive performance of female mallards that experienced mate loss in midwinter (i.e., late Jan-early Feb) and paired again would not differ from females not experiencing mate loss.

Study Area and Methods

Experimental Facility

We conducted experiments in winters 1995-96 and 1996-97 and springs-summers 1996 and 1997 at the Gaylord Avicultural Laboratory at the Delta Waterfowl and Wetlands Research Station (DWWRS) in southern Manitoba, Canada (50°11'N, 19°19'W). We maintained mallards between mid-October and mid-April each year in an indoor aviary divided into 4 68-m2 pens, each with a concrete floor flooded with water to a depth of about 30 cm. Each pen had 4 loafing structures (2.9 m2 each) that were elevated above water and constructed of welded-wire attached to a wooden frame.

In April 1996 and 1997, we moved mallard pairs that formed by free choice in the indoor aviary to an outdoor welded-wire covered aviary consisting of individual breeding pens (3.75 m2). A 30-cm-deep trough containing fresh water bisected the concrete floor. Lercel (1997:20-21) provided additional details concerning experimental facilities.

Husbandry

We maintained mallards using procedures developed at DWWRS (Ward and Batt 1973) and in accordance with an approved animal welfare protocol (DWWRS 96-3). All birds received ad libitum food and water throughout the study. Food consisted of a mixture of poultry pellets (25% crude protein, 4% crude fat, 4% crude fiber), wheat, grit, oyster shell, and supplemental vitamins, minerals, and amino acids.

During winter and spring indoor confinement, we augmented natural light entering through windows in the aviary with fluorescent lights to create photoperiods approximating those at a midlatitude location in the Mississippi Alluvial Valley (MAV; i.e., Greenville, Mississippi), an important wintering region for mallards (Nichols and Hines 1987). We adjusted photoperiods weekly from mid-November 1995-96 to mid-April 1996-97 to simulate changes in day length during winter and spring migration at locations along a hypothetical migrational route from the MAV to Manitoba (i.e., Greenville, Mississippi; Columbia, Missouri; Des Moines, Iowa; Grand Forks, North Dakota; Winnipeg, Manitoba; Bellrose 1980:235). During winter, we maintained air temperatures in the aviary at 5-8°C, similar to December-February ambient temperatures in Greenville, Mississippi (Owenby and Ezell 1992).

Experimental Flocks

We used 240 first-generation, wild-strain mallards (66 yearling males, 66 2-year-old males, and 108 yearling females) for the 1995-96 experiment, and 292 yearling mallards (160 males:132 females) for the 1996-97 experiment. Eggs of wild mallards were collected from nests in southern Manitoba to establish the experimental flocks. We desired yearling birds as experimental subjects, so neither prior breeding experience nor familiarity with conspecifics in the experiment would confound experimental treatments (McKinney 1992). Also, we postulated that if mate loss during winter affected mallard reproductive effort, it would be greatest for yearling females because of lack of prior breeding experience (Krapu and Doty 1979). However, we used yearling and 2-year-old males in the 1995-96 experiment because of inadequate availability of yearling males.

At approximately 8 weeks of age, we fitted ducklings with randomly assigned plastic nasal markers and leg bands for individual identification. In October, we randomly assigned mallards to pens in the indoor aviary for the winter segment of the experiment. Duck density within pens was similar in winters 1995-96 and 1996-97 (i.e., 1.33 ducks/m2 and 1.22 ducks/m2). We maintained equal numbers of yearling and 2-year-old males in each pen in winter 1995-96 (i.e., 22 hatching-year 1995 males and 22 hatching-year 1994 males), and birds were allowed to pair freely. During both winters, we maintained a sex ratio of approximately 1.2 males:1.0 female (132 males:108 females in winter 1995-96 and 160 males:132 females in winter 1996-97), because available data indicated an increasing trend in mallard breeding season sex ratios that approximated 1.2 males:1.0 female in 1994 (J. A. Dubovsky, U.S. Fish and Wildlife Service, Office of Migratory Bird Management, personal communication).

Determining Pair Members

In January 1996 and 1997, we identified pairs based on the following criteria: precopulatory swimming, copulation, sustained proximity, intolerance and avoidance of conspecifics by pair members, female inciting behavior, mutual courtship displays, and synchronized resting and comfort movements (Johnsgard 1965; McKinney 1969, 1975). We designated males and females as pair members when ≥1 behavioral criteria were observed ≥2 times.

Mate Loss

On 31 January 1996 and 3 February 1997, we randomly selected half of all pairs in each pen and permanently moved male pair members to a different randomly selected pen. Prior mates were visually and physically isolated, but vocalizations may have been audible by previous pair members. We used a Pesola scale to measure body mass ( ± 25 g) of females on the date that pair members were separated each year. We kept group size and sex-ratio constant within each pen during the experiment. Date of pair dissolution was planned for 31 January 1996 and 1997; however, pair identifications required 3 additional days in 1997. We selected 31 January as the date for separating pair members, because it was the latest date that legal duck hunting has occurred in the Mississippi Flyway (U.S. Fish and Wildlife Service 1998). After pair dissolution, widowed females were free to pair with males in the same pen.

Reproductive Variables

We resumed daily observations of mallards in early April 1996 and 1997 to determine pair status of males and females. On 22 April 1996 and 30 April 1997, previously widowed females that paired again and control females and their mates were assigned randomly to separate outdoor breeding pens. Late April was chosen as the time to move experimental pairs outdoors because wild mallards begin nesting in southern Manitoba about this time (Sowls 1955, Bluhm 1988). We delayed moving pairs outside 1 week in 1997 because a spring storm filled pens with snow. We provided each female with a nest box containing straw, and food was replaced and pens were cleaned daily.

We measured the following reproductive variables in 1996 and 1997: frequency of female pair formation after mate loss, frequencies of initial nesting and renesting (i.e., second nests only because few females laid >2 clutches) followed by normal incubation, date of first-nest initiation, mean egg mass per clutch, clutch size (number of eggs laid and incubated per nest), percentage of fertile eggs per clutch, number of viable (i.e., fertile) eggs per clutch, and number of days between first and second nests. We used a Pesola scale to weigh eggs ( ± 1 g) on date of laying. Females were allowed to incubate a clutch for 7 consecutive days. We then removed the clutch to candle eggs, to determine fertility (Weller 1956) and to stimulate renesting.

Statistical Analyses

We designated widowed females that subsequently paired as the treatment group and those that did not experience forced mate loss in winter as controls. Because winter body mass of females differed between years (1996: 1,296 ± 14 g [ mean of x SE], n = 63; 1997: 1,023 ± 12 g, n = 77) and could affect subsequent reproductive performance, we used analysis of covariance (PROC GLM; SAS Institute 1990) to test for differences in reproductive variables relative to treatment (widow or control), male age (yearling or 2-year-old [1996 data only]), and pretreatment body mass (continuous covariate). We performed separate analyses for each year because male age was a factor only in 1996, and because annual differences in winter body mass of females would have confounded tests of year effects. We initially fit fully specified models (all interactions included) and used backward stepwise procedures to eliminate nonsignificant (P > 0.05) terms, beginning with the highest-order interactions.

We used a chi-square contingency test (Steel and Torrie 1980:492-493) to test the following null hypotheses: (1) widowed and control females paired with yearling and 2-year-old males in similar proportions before mate loss in 1996, (2) widowed females paired with yearling and 2-year-old males in similar proportions after mate loss in 1996, and (3) widowed females paired with males originally assigned to their pens and with previously paired males moved to their pens from other pens in similar proportions after mate loss in 1996 and 1997.

We defined the combination of initial nesting and incubating frequency as the number of females per treatment group that completed and incubated first nests, and renesting and incubating frequency as those birds by treatment category that completed and incubated second clutches. We used Fisher's exact test to determine whether these frequencies were independent of treatment (SAS Institute 1990). We performed separate tests within each male age class for 1996 data.

Sample sizes for certain reproductive variables differed from those for nesting (and renesting) and incubating frequencies for several reasons: (1) some females died during the experiments, thus all reproductive data could not be collected from those hens; (2) some females completed clutches but did not incubate eggs; and (3) eggs not incubated by females were artificially incubated to determine fertility and viability.

We used the mallard productivity model (Johnson et al. 1987) to evaluate the effect of mate loss in winter on recruitment rate of yearling females. Recruitment rate was defined as the number of females recruited into the fall population per female in the breeding population, assuming equal sex ratios at flight stage (Johnson et al. 1987). We set user-specified input variables to default values to simulate, long-term average environmental conditions. However, we changed the proportion of adult females in the spring population from 60% (default) to 0% because we used only yearling females in our study and thus could not extrapolate results to adults. For all simulations, we used data from Arrowwood National Wildlife Refuge, North Dakota (file name ARNWI101; Township 150, Range 63, Section 4), where 50% of the landscape was grassland, hayland, or enrolled in the Conservation Reserve Program. We completed 50 simulations (each representing a breeding season) with the model set at default values, and 50 simulations after adjusting reproductive variables (singly and in combination) that were significantly influenced by winter mate loss (P ≤ 0.05).

Results

1996

Both experimental groups of females selected yearling over 2-year-old males as mates before the date of pair dissolution (χ² = 9.53, P = 0.002). All 30 females widowed on 31 January 1996 paired before 22 April 1996, when pairs were moved to outdoor pens. After mate loss, widows did not exhibit any preference for male age (χ² = 1.21, P = 0.273). Widowed females also paired at similar rates with previously unpaired males originally assigned to females' pens and with previously paired males from other pens (χ² = 0.118, P = 0.731). Frequencies of initial nesting followed by incubation did not differ between control (n = 10 of 14 females and n = 7 of 8 females paired with 1- and 2-year-old males) and widowed females (n = 7 of 11, n = 8 of 12; P > 0.9). Similarly, frequencies of renesting and incubation did not differ between control (n = 2 of 3, n = 4 of 6) and widowed females (n = 4 of 5, n = 6 of 6; P ≥ 0.455).

Date of initial nesting did not differ between control and widowed females (P = 0.968; Table 1). However, females paired with 2-year-old males nested earlier than those paired with yearling males (P = 0.020; Table 2). Number of days between first and second nests did not differ between control and widowed females (P = 0.568; Table 1).

Neither mean egg mass of first and second nests (P = 0.469 and P = 0.933) nor size of first and second clutches (P = 0.294 and P = 0.595) differed between control and widowed females (Table 1); however, females laid 1.1 (SE = 0.56) more eggs in first clutches for each 100-g increase in winter body mass (F1,33 = 3.95, P = 0.055). Fertility of first clutches was similar between widowed and control females (P = 0.688; Table 1). However, females paired with 2-year-old males exhibited greater egg fertility in first clutches than females paired with yearling males (P = 0.002; Table 2). Females laid 1.52 (SE = 0.64) more viable eggs in first clutches for each 100-g increase in winter body mass (F1,32 = 5.66, P = 0.024), but mean number of viable eggs in first nests was similar between control and widowed females (P = 0.537; Table 1). Females paired with 2-year-old males laid more viable eggs in first nests than females paired with yearling males (P = 0.004; Table 2). Number of viable eggs in second nests did not differ (P = 0.982) between control and widowed females (Table 1); however, females paired with 2-year-old males laid more viable eggs in second nests than females paired with yearling males (P = 0.010; Table 2). Winter body mass of females, age of male mates, and treatment had interacting effects on fertility of second clutches (F1,11 = 6.59, P = 0.026). There were no other interactions affecting reproductive variables (Ps = 0.084-0.967).

1997

Thirty-nine (95%) of 41 females widowed on 3 February 1997 paired before 30 April 1997, when pairs were moved to outdoor breeding pens. Widowed females paired at similar rates with previously unpaired males in their pen and with previously paired males from other pens (χ² = 0.641, P = 0.423). Nesting and incubating frequencies did not differ between control (n = 18 of 25 hens [72%]) and widowed females(n = 22 of 26 [85%]; P = 0.324). Likewise, renesting and incubating frequencies did not differ between control (n = 4 of 4 hens) and widowed females (n = 9 of 10; P > 0.9).

Date of initial nesting (P = 0.241) and number of days between nests (P = 0.191) did not differ between control and widow females (Table 1). Mean egg mass in first (P = 0.673) and second (P = 0.160) nests also did not differ between experimental groups (Table 1). First clutches of widowed females contained 1.91 fewer eggs on average than those of controls (P = 0.014), but mean size of second clutches did not differ (P = 0.126; Table 1). Fertility of first clutches was positively related to female winter body mass (F1,48 = 9.18, P = 0.004); however, mean fertility of first (P = 0.094) and second (P = 0.398) clutches did not differ between control and widowed females (Table 1). Females laid 1.4 (SE = 0.64) more viable eggs in first clutches for each 100-g increase in winter body mass (F1,46= 4.88, P = 0.032), but mean number of viable eggs in first clutches did not differ between control and widowed females (P = 0.665; Table 1). However, widowed females laid 3.75 fewer viable eggs in second nests on average than controls (P = 0.056; Table 1). No interactions of treatment and female winter body mass were detected for any reproductive variables (Ps = 0.081-0.953).

Recruitment Rate Simulations

Simulated recruitment rates (mean of x ± SE) derived via default values of reproductive parameters averaged 0.54 ± 0.003 female offspring in the fall population per yearling female in the breeding population. Incorporating the observed effect of 1.91 fewer eggs in first clutches of widows in 1997 decreased mean recruitment rates to 0.49 ± 0.003, a relative decrease of 8.7%. Because number of viable eggs in second nests of widows was nearly significantly less than controls (P = 0.056), we elected to include this variable in the simulations. Simulations of the observed effect of 3.75 fewer viable eggs in second nests of widows reduced recruitment rates to 0.47 ± 0.004, or 12.4% less than the mean recruitment rate without this effect. Mean recruitment rate for simulations incorporating both effects was 0.43 ± 0.002, or 20.1% less than the recruitment rate without these effects.

Discussion

We forced mate loss on captive, yearling female mallards that had formed pair bonds by free choice during winter to determine the effect of this potential life-cycle constraint on female reproductive performance. Generally, mate loss was temporary: most (97%, n = 71) widowed females paired again between winter and spring. Additionally, mate loss in winter did not significantly affect most reproductive variables. However, several important differences were detected.

Because almost all widowed females paired again, any negative reproductive consequences of mate loss in winter were not related to their ability to form a new pair bond by spring. Instead, we hypothesize that reproductive consequences may have been related to time and energy constraints resulting from temporary mate loss (perhaps exacerbated by or linked to lower winter body masses of widowed females [Lercel 1997:33]), by pairing with inferior males, or a combination of these factors. Male-biased sex ratios in this study (similar to wild mallard populations) provided several males as potential mates for widowed females, but we could not determine if subsequent mates of widows were inferior to original mates. Nonetheless, there appears to be strong selective pressure to form new pair bonds after mate loss, even for yearling females inexperienced at breeding.

Widowed females laid about 2 fewer eggs in first clutches than control females in 1997, but numbers of viable eggs in first clutches were similar. Widowed females also laid 3.75 fewer viable eggs in second clutches in 1997 than control females, but this difference may have been a consequence of Type I error, use of yearling males with no previous mating experience, captivity, or a combination of these potential effects. Similar trends were observed in 1996 for clutch size of first nests and number of viable eggs in second clutches, but no significant differences were detected. Although our results could be construed as inconclusive because mate loss evoked a significant effect on reproductive variables only in 1997, our results also are consistent with the notion that midwinter mate loss could induce negative consequences on reproductive performance of yearling female mallards in some years. Decreased body mass of widowed females at the end of winter indoor confinement and at initiation of first and second nests may have contributed to reduced production of eggs in first clutches and fewer viable eggs in second nests in 1997 (Lercel 1997:36, 43). Low body mass may reflect lower nutrient reserves for egg production (Krapu 1981, Pattenden and Boag 1989). Although not significant, reduced clutch size and decreased egg fertility in second nests of widows in 1997 also may have contributed to the decline in viable eggs that year. Decreased egg viability resulting from reduced egg fertility may indicate inferior reproductive effort or performance by yearling mates of widowed females.

Simulations with the mallard productivity model indicated recruitment rates of yearling female mallards could be negatively influenced by midwinter mate loss due to reduced clutch size of first nests, decreased egg viability in second clutches, and these factors combined. Egg fertility and viability do not appear to be problematic in wild mallard populations (Johnson et al. 1992), although Amat (1987) noted declines in egg fertility of wild mallards as breeding season progressed. The relatively large decrease in viable eggs (3.75) in second nests of widowed females may be greater than would occur in wild mallard populations, particularly considering our small sample sizes for estimating this effect. Thus, we place more credence in the effect of reduced clutch size in first nests (1.91) on recruitment rate than the effect of decreased number of viable eggs in second clutches, or the combined effect of these variables. Our simulation results indicated that the effect of reduced clutch size decreased recruitment rate of yearling female mallards by 9%, but our study did not address effects on overall reproductive performance of mallard populations. Reduction in recruitment rates among wild mallards resulting from temporary mate loss in winter would depend on at least the following: (1) effects of winter mate loss on survival and reproductive performance; (2) habitat conditions during late winter, spring, and summer (resulting in greater differential in recruitment rates as habitat conditions become increasingly favorable); (3) age ratios of females in the breeding population if effects of mate loss differ between yearling and adult females; and (4) proportion of females that are widowed in winter.

We do not believe availability of 2-year-old males in the 1996 experiment obscured any negative effects of mate loss by allowing widows to choose older and perhaps superior males. Both widow and control females initially selected yearling over 2-year-old males as mates before pair bonds were dissolved. After mate loss, widows exhibited no preference for male age, even though females with 2-year-old mates nested earlier, had greater egg fertility, and laid more viable eggs. Future research could test if older females ( ≥2 yr) forced to pair with a yearling male after loss of an older mate are less productive than older pair members that remain intact. Finally, we do not believe that any negative effects of mate loss in either year were obscured by widowed females pairing with possibly dominant, previously paired males that were moved to new pens as a consequence of mate separations. After mate loss, widowed females paired with males originally assigned to their pens and with previously paired males moved from other pens at similar rates.

Management Implications

Our results indicate temporary mate loss in winter by captive, yearling female mallards could reduce their subsequent reproductive performance in some years. Simulation modeling indicated that these effects could reduce recruitment rates of wild yearling females by 9-20%; however, we speculate that reduced egg viability in wild populations may not be as dramatic as observed in our study. Because patterns detected in our study of captive mallards occurred in the presence of ad libitum nutritious food, more severe consequences possibly could occur in wild mallard populations because of social, environmental, or resource constraints. In free-ranging mallard populations, acquisition of food and other resources affects breeding success (Krapu 1981, Hepp 1984). Thus, we suggest caution regarding extension of duck hunting seasons through late January.

Investigation of the effect of timing of mate loss in winter on mallard reproduction was beyond the scope of this study. Thus, our study was not a direct evaluation of possible effects of extension of duck hunting seasons in southern states, because we compared reproductive performance of females experiencing mate loss in late January or early February with females that did not lose mates. A more direct test of hunting season extension on mallard reproductive performance would compare females that experience mate loss on the current, last framework date of duck hunting (20 Jan) with those losing mates on 31 January. Our study was conducted with wild-strain mallards in captivity; hence, results may not represent wild mallard populations. Therefore, we emphasize need for a field experiment to evaluate effects of hunting season extension on mallard (and other duck) population parameters, including winter abundance and geographic distribution, harvest and harvest rate, geographic distribution of harvest, posthunting season survival, breeding population size, and recruitment rate. Any implemented experiment should be closely integrated with Adaptive Harvest Management (Williams and Johnson 1995, Johnson et al. 1996).

We detected several positive relations between winter body mass of females and reproductive variables (i.e., clutch size, number of fertile and viable eggs). Moreover, the effect of mate loss on female reproductive performance was greater in 1997, when body mass of females in winter was lower than in 1996 (Lercel 1997:33). Thus, heavier birds tended to be more productive, implying continued need for conservation and management of quality foraging habitats for migrating and wintering waterfowl (Smith et al. 1989).


Acknowledgments

This study was supported by the Delta Waterfowl Foundation through DWWRS and the Forest and Wildlife Research Center (FWRC), Mississippi State University. The Patricia Robert Harris Fellowship through the Mississippi State University Graduate School and the University Women's Club Scholarship provided partial support for the senior author. The following people assisted with this project, reviewed our manuscript, or both: T. Arnold, C. Bluhm, W. Burger, B. Davis, S. Erstad, P. Gerard, D. Johnson, P. Klyne, G. Knutsen, B. Leopold, W. Newton, F. Rohwer, J. Scarth, T. Shaffer, and F. Vilella. This article has been approved for publication by the FWRC as Journal Article WF-107.


Literature Cited

Abraham, K. F., P. Mineau, and F. Cooke. 1981. Re-mating of a lesser snow goose. Wilson Bulletin 93:557-559.

Amat, J. 1987. Infertile eggs: a reproductive cost to female dabbling ducks inhabiting unpredictable habitats. Wildfowl 38:114-116.

Anderson, M. G., G. R. Hepp, F. McKinney, and M. Owen. 1988. Workshop summary: courtship and pairing in winter. Pages 123-131 in M. W. Weller, editor. Waterfowl in winter. University of Minnesota Press, Minneapolis, Minnesota, USA.

Ashcroft, R. E. 1976. A function of the pairbond in the common eider. Wildfowl 27:101-105.

Bellrose, F. C. 1980. Ducks, geese and swans of North America. Stackpole Books, Harrisburg, Pennsylvania, USA.

Blohm, R. J., R. E. Reynolds, J. P. Bladin, J. D. Nichols, J. E. Hines, K. H. Pollock, and R. T. Eberhardt. 1987. Mallard mortality rates on key breeding and wintering areas. Transactions of the North American Wildlife and Natural Resources Conference 52:246-257.

Bluhm, C. K. 1988. Temporal patterns of pair formation and reproduction in annual cycles and associated endocrinology in waterfowl. Current Ornithology 5:123-185.

Bossema, I., and E. Roemers. 1985. Mating strategy, including mate choice in mallards. Ardea 73:147-157.

Brodsky, L. M., and P. J. Weatherhead. 1985. Time and energy constraints on courtship in wintering American black ducks. Condor 87:33-36.

Cooke, F., M. A. Bousfield, and A. Sadura. 1981. Mate change and reproductive success in the lesser snow goose. Condor 83:322-327.

Dubovsky, J. A., and R. M. Kaminski. 1994. Potential reproductive consequences of winter-diet restriction in mallards. Journal of Wildlife Management 58:780-786.

Heitmeyer, M. E. 1995. Influences of age, body condition, and structural size on mate selection by dabbling ducks. Canadian Journal of Zoology 73:2251-2258.

Hepp, G. R. 1984. Dominance in wintering Anatinae: potential effects on clutch size and time of nesting. Wildfowl 35:132-134.

_____, R. J. Blohm, R. E. Reynolds, J. E. Hines, and J. D. Nichols. 1986. Physiological condition of autumn-banded mallards and its relationship to hunting vulnerability. Journal of Wildlife Management 50:177-183.

Hipes, D. L., and G. R. Hepp. 1993. Effect of mate removal on nest success of female wood ducks. Condor 95:220-222.Johnsgard, P. A. 1965. Handbook of waterfowl behavior. Cornell University Press, Ithaca, New York, USA.

Johnsgard, P. A. 1965. Handbook of waterfowl behavior. Cornell University of Press, Ithaca, New York, USA.

Johnson, D. H., J. D. Nichols, and M. D. Schwartz. 1992. Population dynamics of breeding waterfowl. Pages 446-485 in B. D. J. Batt, A. D. Afton, M. G. Anderson, C. D. Ankney, D. H. Johnson, J. A. Kadlec, and G. L. Krapu, editors. Ecology and management of breeding waterfowl. University of Minnesota Press, Minneapolis, Minnesota, USA.

_____, D. W. Sparling, and L. M. Cowardin. 1987. A model of the productivity of the mallard duck. Ecological Modelling 38:257-275.

Johnson, F. A., B. K. Williams, and P. R. Schmidt. 1996. Adaptive decision-making in waterfowl harvest and habitat management. International Waterfowl Symposium 7:26-33.

Jones, R. N., and M. Obbard. 1970. Canada goose killed by arctic loon and subsequent pairing of its mate. Auk 87:370-371.

Klopman, R. B. 1962. Sexual behavior in the Canada goose. Living Bird 1:123-129.

Krapu, G. L. 1981. The role of nutrient reserves in mallard reproduction. Auk 98:29-38.

_____, and H. A. Doty. 1979. Age-related aspects of mallard reproduction. Wildfowl 30:35-39.

Lercel, B. A. 1997. Mate loss in winter and mallard reproduction. Thesis, Mississippi State University, Mississippi State, Mississippi, USA.

LeSchack, C. R., A. D. Afton, and R. T. Alisauskas. 1998. Effects of male removal on female reproductive biology in Ross' and lesser snow geese. Wilson Bulletin 110:56-64.

Manlove, C. A., and G. R. Hepp. 1998. Effects of mate removal on incubation behavior and reproductive success of female wood ducks. Condor 100:688-693.

Martin, K., F. G. Cooch, and R. F. Rockwell. 1985. Reproductive performance in lesser snow geese: are two parents essential? Behavioral and Ecological Sociobiology 17:257-263.

McCamant, R. E., and E. G. Bolen. 1977. Response of incubating black-bellied whistling ducks to loss of mates. Wilson Bulletin 89:621.

McKinney, F. 1969. The behavior of ducks. Pages 593-626 in E. S. E. Hafez, editor. The behaviour of domestic animals. Second edition. Balliere, Tindall, and Cassell, London, United Kingdom.

_____. 1975. The evolution of duck displays. Pages 331-357 in G. Baerends, C. Beer, and A. Manning, editors. Function and evolution in behaviour. Clarendon Press, Oxford, United Kingdom.

_____. 1992. Courtship, pair formation, and signal systems. Pages 214-250 in B. D. J. Batt, A. D. Afton, M. G. Anderson, C. D. Ankney, D. H. Johnson, J. A. Kadlec, and G. L. Krapu, editors. Ecology and management of breeding waterfowl. University of Minnesota Press, Minneapolis, Minnesota, USA.

Metz, K. J., and C. D. Ankney. 1991. Are brightly coloured male ducks selectively shot by duck hunters? Canadian Journal of Zoology 69:279-282.

Nesbitt, S. A. 1989. The significance of mate loss in Florida sandhill cranes. Wilson Bulletin 101:648-651.

Nichols, J. D., and J. E. Hines. 1987. Population ecology of the mallard: VIII. Winter distribution patterns and survival rates of winter-banded mallards. U.S. Fish and Wildlife Service Resource Publication 162.

Ohde, B. R., R. A. Bishop, and J. J. Dinsmore. 1983. Mallard reproduction in relation to sex ratios. Journal of Wildlife Management 47:118-126.

Oring, L. W., and R. D. Sayler. 1992. The mating systems of waterfowl. Pages 190-213 in B. D. J. Batt, A. D. Afton, M. G. Anderson, C. D. Ankney, D. H. Johnson, J. A. Kadlec, and G. L. Krapu, editors. Ecology and management of breeding waterfowl. University of Minnesota Press, Minneapolis, Minnesota, USA.

Owen, M., J. M. Black, and H. Liber. 1988. Pair bond duration and timing of its formation in barnacle geese (Branta leucopsis). Pages 23-38 in M. W. Weller, editor. Waterfowl in winter. University of Minnesota Press, Minneapolis, Minnesota, USA.

Owenby, J. R., and D. S. Ezell. 1992. Monthly station normals of temperature, precipitation, and heating and cooling degree days 1961-90: Mississippi. Climatography of the U.S. Number 81. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Asheville, North Carolina, USA.

Pattenden, R. K., and D. A. Boag. 1989. Effects of body mass on courtship, pairing, and reproduction in captive mallards. Canadian Journal of Zoology 67:495-501.

Patterson, I. J. 1977. Aggression and dominance in winter flocks of shelduck. Animal Behavior 25:447-459.

Paulus, S. L. 1983. Dominance relations, resource use, and pairing chronology of gadwalls in winter. Auk 100:947-952.

Rohwer, F. C., and M. G. Anderson. 1988. Female-biased philopatry, monogamy, and timing of pair formation in migratory waterfowl. Current Ornithology 5:187-221.

SAS Institute Inc. 1990. SAS/STAT user's guide. Version 6. Fourth edition. SAS Institute, Cary, North Carolina, USA.

Scott, D. K. 1980. Functional aspects of the pair bond in winter in Bewick's swans. Behavioral and Ecological Sociobiology 7:323-327.

Smith, L. M., R. L. Pederson, and R. M. Kaminski, editors. 1989. Habitat management for migrating and wintering waterfowl in North America. Texas Tech University Press, Lubbock, Texas, USA.

Sowls, L. K. 1955. Prairie ducks: a study of their behavior, ecology, and management. Stackpole Books, Harrisburg, Pennsylvania, USA, and Wildlife Management Institute, Washington, D.C., USA.

Steel, G. D., and J. H. Torrie. 1980. Principles and procedures of statistics. McGraw-Hill, New York, New York, USA.

U.S. Fish and Wildlife Service. 1998.Framework-date extensions for duck hunting in the United States. U.S. Department of the Interior, Washington, D.C., USA.

Ward, P., and B. D. J. Batt. 1973. Propagation of captive waterfowl. Wildlife Management Institute, Washington, D.C., USA.

Weller, M. W. 1956. A simple field candler for waterfowl eggs. Journal of Wildlife Management 20:111-113.

Williams, B. K., and F. A. Johnson. 1995. Adaptive management and the regulation of waterfowl harvests. Wildlife Society Bulletin 23:430-436.

Young, C. M. 1970. Territoriality in the common shelduck. Ibis 112:330-335.


This resource is based on the following source (Northern Prairie Publication 1051):

Lercel, B.A., R.M. Kaminski and R.R. Cox Jr. 1999. Mate loss in winter affects reproduction of mallards. J. Wildl. Manage. 63(2): 621-629.

This resource should be cited as:

Lercel, B.A., R.M. Kaminski and R.R. Cox Jr. 1999. Mate loss in winter affects reproduction of mallards. J. Wildl. Manage. 63(2): 621-629. Jamestown, ND: Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/resource/birds/mateloss/index.htm (Version 22JUL99).


1Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, MS 39762, USA, and Delta Waterfowl and Wetlands Research Station, Rural Route 1, Portage la Prairie, MB R1N 3A1, CANADA
Present address: Ducks Unlimited, Inc., 29 Liberty Street, Suite 1, Batavia, NY 14020, USA.
2Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, MS 39762, USA
Email rkaminski@cfr.msstate.edu
3U.S. Geological Survey, Northern Prairie Wildlife Research Center, 8711 37th Street SE, Jamestown, ND 58401, USA
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