Waterfowl hunting is important culturally and economically in North America. Few studies have evaluated the relationship between weekly hunting frequency and rate of ducks harvested. We evaluated the effect of hunting 2 or 4 d/wk on rate of ducks harvested on three Mississippi Wildlife Management Areas, USA, during three waterfowl hunting seasons, December–January 2008–2011. Harvest of all ducks combined, mallard Anas platyrhynchos, northern shoveler Anas clypeata, or green-winged teal Anas crecca per hunter day did not differ between areas hunted 2 or 4 d/wk, but increased with hours spent afield. We suggest Wildlife Management Areas may be hunted 4 d/wk without reducing duck harvest per hunter day. We recommend continued evaluations of weekly hunting frequency on rate of ducks harvested to sustain science-guided management of waterfowl hunting on Mississippi public lands and elsewhere.
Waterfowl hunting is important to conservation, culture, and economy. Waterfowl hunting directly funds habitat and population initiatives, provides sustenance and recreation for humans, builds and sustains a conservation ethic in society, and provides financial support to rural communities (Leopold 1949; Miller and Hay 1981; Gray and Kaminski 1994; Grado et al. 2001, 2011; North American Waterfowl Management Plan [NAWMP] 2012). To sustain and recruit waterfowl hunters and address their concerns about waterfowl hunting experiences, conservation agencies endeavor to provide abundant and quality hunting opportunities on public lands (Miller and Hay 1981; Vaske et al. 1986). St. James et al. (2013) evaluated the influence of weekly hunting frequency on duck abundance; however, few studies have evaluated effects of hunting frequency on harvest of waterfowl (cf., Macaulay and Boag 1974; Bromley 1996). Thus, managers have limited science-based information available for developing weekly hunting frequency.
Hunter success can be affected by duck abundance, habitat quality and quantity, weather, disturbance, and other factors, some of which can be influenced by habitat and hunting management (Dooley et al. 2010; Schummer et al. 2010; Stafford et al. 2010). Managers create temporal and spatial sanctuaries for waterfowl to lessen and manage disturbance in and near hunting areas (Fox and Madsen 1997; Madsen 1998b). The goal of creating sanctuaries is to promote waterfowl use, harvest, viewing, and survival for continued and increased use of public and private wetlands by waterfowl and users of this resource (NAWMP 2012); however, Nichols and Johnson (1989) and Johnson and Case (2000) suggest there is no direct relationship between waterfowl abundance and harvest. Rate of ducks harvested may decrease when areas are hunted consecutive days (Bregnballe and Madsen 2004; Dooley et al. 2010); thus, periods of time and areas with no hunting may be necessary to maintain or increase rate of ducks harvested (Fox and Madsen 1997). Alternatively, if decreasing hunting frequency is not possible, creation of spatial sanctuaries near hunted areas may be necessary to sustain rate of waterfowl harvest on hunting areas (Madsen 1995, 1998b; Evans and Day 2002).
Habitat use by waterfowl may be related to food abundance and disturbance, juxtaposition of resources, weather severity, or a combination of these effects (Jorde et al. 1984; van Eerden 1984; Reinecke et al. 1989; Madsen 1998b; Schummer et al. 2010; Dooley et al. 2010). Indeed, trade-offs between energy acquisition by waterfowl and survival risks related to predation, hunting, or related disturbance have been demonstrated (Lima 1986; Nagy 2005; Ackerman et al. 2006). Increased frequency of disturbance may cause ducks to leave foraging areas for refugia or adapt behavior to reduce risk of mortality (Thornburg 1973; Madsen 1995; Evans and Day 2002; Bregnballe and Madsen 2004). In addition, food may become functionally unavailable in hunted areas concomitant with hunting disturbance, and ducks may avoid such areas diurnally or forage nocturnally (Morton et al. 1989; Perry and Deller 1996; Cox and Afton 1997; Fox and Madsen 1997). Decreased use or avoidance of areas can decrease numbers of birds seen and harvested by hunters (Delnicki and Reinecke 1986; Fox and Madsen 1997; Ringelman 1997; Madsen 1998a). Conversely, low hunting frequency or absence of hunting may result in a loss of hunting opportunity or cause a sanctuary effect whereby ducks forage and reduce food resources below a foraging threshold where the cost of obtaining food resources outweighs the benefits of consumption, resulting in their movement to other foraging habitats (Reinecke et al. 1989; Greer et al. 2009; Hagy and Kaminski 2012b). Ducks relocating to refugia because of disturbance elsewhere may reduce survival risk, but their body condition may decrease by increasing energy expended by such movements (i.e., flight and vigilance) and foraging in depleted habitats (Hockin et al. 1992; Madsen and Fox 1995; Hagy and Kaminski 2012b).
To our knowledge, the effect of weekly hunting frequency on rate of ducks harvested has not been investigated previously. Typically, managers have used conservative or historical management schemes to regulate hunting on public and private areas (e.g., 2–3 d/wk, morning hunting only; Ringelman 1997). Historically, the Mississippi Department of Wildlife, Fisheries, and Parks permitted waterfowl hunting 2–3 mornings/wk on Wildlife Management Areas (WMAs) during the regular waterfowl hunting season, but no experiments have been conducted to assist in management of waterfowl hunting on public lands in Mississippi. Our study builds on St. James et al. (2013) by evaluating the influence of hunting frequency on rate of ducks harvested to further develop an understanding of the relationship between waterfowl abundance and harvest. Thus, our objectives were to test 1) the effect of hunting 2 versus 4 d/wk on ducks harvested per hunter day and 2) whether harvest per hunter day of dabbling duck species with different life-history strategies differed between experimental hunt frequencies.
We conducted our experiment at the Mississippi Department of Wildlife, Fisheries, and Parks' Howard Miller WMA (971 ha; 32°49′48.93′N, 90°58′51.61′W), Muscadine Farms WMA (316 ha; 33°13′29.32′N, 90°59′01.51′W), and Trim Cane WMA in Mississippi, USA (324 ha; 33°31′30.27′N, 88°50′47.19′W; Figure 1). Between 2008 and 2009, Muscadine Farms WMA increased in area by 48% with acquisition of an additional 291 ha (33°12′48.62′N, 90°57′55.49′W; Table 1). All WMAs had established sanctuaries prior and during our study. Hunt units and sanctuaries were managed for moist-soil vegetation (Fredrickson and Taylor 1982; Kross et al. 2008) and occasionally supplemented with plantings of browntop millet Panicum ramosum, corn Zea mays, Egyptian wheat Sorghum vulgare var. rosburghii, grain sorghum Sorghum bicolor, Japanese millet Echinochloa esculenta, rice Oryza sativa, soybean Glycine max, or Sudan-grass Sorghum bicolor var. drummondii. St. James et al. (2013) presented additional details of our study areas.
Experimental hunting frequencies
We divided each WMA into two experimental treatment areas of approximately equal area of hunting units and similar cover types of moist soil vegetation, harvested rice fields, and non–mast-producing trees (Table 1; St. James 2011; St. James et al. 2013). We randomly assigned treatment areas a hunting frequency of 2 or 4 d/wk, with morning-only hunting (0.5 h before sunrise to 1200 hours; Figure 1). We chose these treatments because morning-only hunting 4 d/wk doubled the previous hunting frequency at Muscadine Farms and Trim Cane WMAs. At Howard Miller WMA, the previous hunting frequency was 3 mornings/wk. Hunters were selected by the Mississippi Department of Wildlife, Fisheries, and Parks using an online prehunting season random lottery system, or they arrived on the morning of the hunt as standby hunters and selected hunting sites not selected by reservation holders. On the day of each hunt, reservation-holding hunters selected first from available hunt units based on a random draw system, followed by standby hunters who selected from among remaining units. Hunters were allowed to have one to four people within a hunt unit.
Rate of duck harvest and hunter use
We conducted our study over three Mississippi waterfowl hunting seasons from December–January 2008–2011. We placed waterfowl check stations at exits of WMAs. As hunters departed WMAs, we recorded the number and species of ducks harvested by each hunter. We also recorded hunters' assigned hunt unit, number of hunters per hunting unit, and duration (minutes) each party hunted. Each hunter's effort during a single hunt represented 1 hunter day, although time afield ranged less than or equal to 6 h/hunter.
We calculated weekly mean harvest of all ducks (total ducks per hunter day) for areas hunted 2 or 4 d/wk at WMAs (see Data S1, Tab 1, Tab 2, Supplemental Material). We used AN ANOVA with week of hunting season as the repeated measure in a randomized complete block design (i.e., WMAs as blocks) to test whether all duck, mallard Anas platyrhynchos, northern shoveler Anas clypeata, and green-winged teal Anas crecca harvests differed between areas hunted 2 or 4 d/wk (PROC MIXED; SAS 2002; Gutzwiller and Riffell 2007). We selected these species to evaluate because mallard, northern shoveler, and green-winged teal were the most commonly harvested ducks, comprising 13, 27, and 41% of total duck harvest, respectively (St. James 2011; see Data S1, Tab 1, Tab 2, Supplemental Material).
We imposed both hunting frequency treatments on each WMA. An alternate experimental design would have been to assign treatments randomly to individual WMAs, but adequate replicate WMAs did not exist and local environmental variations of WMAs would have confounded experimental results, hence our use of a block design. Residuals of all duck, mallard, northern shoveler, and green-winged teal data were not distributed normally, following natural log transformation. Nonetheless, we used ANOVA to analyze untransformed data, because ANOVA is robust to departures from normality (Littell et al. 2006; McDonald and White 2010). We selected compound symmetry from a suite of covariance structures for all analyses, because variances generally were homogenous (Littell et al. 2006). We designated α = 0.10 for all models (Tacha et al. 1982). In addition, we tested for a relationship between minutes hunted and ducks harvested per hunter day using linear regression (PROC REG; SAS 2002).
We did not detect a difference in rate of harvest of all ducks combined (F1,1.91 = 0.61; P = 0.519), mallard (F1,1.12 = 9.03; P = 0.183), northern shoveler (F1,1.26 = 3.98; P = 0.254), or teal (F1,2.18 = 0.48; P = 0.987) between areas hunted 2 or 4 d/wk (Table 2). However, harvest of all ducks (F1,1,227.63 = 283.19; R2 = 0.07; P ≤ 0.001), mallard (F1,28.22 = 65.18; R2 = 0.02; P ≤ 0.001), northern shoveler (F1,70.06 = 68.28; R2 = 0.02; P ≤ 0.001), and green-winged teal (F1,171.47 = 76.47; R2 = 0.02; P ≤ 0.001) increased with time spent hunting (Figure 2). Specifically, harvest of all ducks increased by 0.47 duck per hunter for each hour spent afield, whereas mallard, northern shoveler, and green-winged teal harvest increased 0.07, 0.11, and 0.18 duck/h, respectively. Across WMAs and hunting seasons, areas open for hunting 4 d/wk were hunted 1.7 times more than areas open for hunting 2 d/wk (i.e., 2,473 hunter days and 1,462 hunter days, respectively). In addition, hunters spent similar amounts of time hunting (&xmacr ± SE) on areas of WMAs hunted 2 d/wk (202.5 ± 1.8 min) and 4 d/wk (196.7 ± SE 1.5 min).
We evaluated rate of ducks harvested in response to hunting 2 vs. 4 d/wk at WMAs in Mississippi to aid biologists in planning and managing waterfowl hunting on public lands in Mississippi and elsewhere. We found no difference in rate of harvest of all ducks combined, mallard, northern shoveler, or green-winged teal between areas open to hunting 2 or 4 d/wk. Harvest results were consistent with the findings of St. James et al. (2013) that hunting frequencies did not influence duck abundance on WMAs. In addition, mean daily rate of total duck harvest also was similar during our study (2008–2011; 1.98 ducks/hunter day) compared to previous recent hunting seasons at the same WMAs (2006–2008; 1.82 ducks/hunter day), suggesting that increasing hunting frequency from 2 or 3 d/wk to 4 d/wk did not reduce hunter harvest rates.
Harvest rates of mallard, northern shoveler, and green-winged teal did not differ between experimental hunt frequencies. However, comparison between abundances of these species with composition of harvested ducks suggests differential susceptibility to harvest among species (Gilmer et al. 1989; St. James et al. 2013). During our study, mallard comprised 30% of all ducks observed in hunt units during standardized counts (St. James et al. 2013) but composed only 16% of all ducks harvested. In contrast, green-winged teal were 16% of ducks counted (St. James et al. 2013) but accounted for 41% of the harvest. Northern shoveler abundance (20% of ducks observed) and harvest (27% of ducks harvested) were more closely related (St. James et al. 2013). Our findings suggest hunters at the WMAs may have experienced fewer harvest opportunities for mallards, even if they were relatively abundant during surveys conducted on nonhunt days (St. James et al. 2013).
Differences in life-history strategies among duck species may determine risk behavior and susceptibility to harvest (Ackerman et al. 2006). Species with relatively greater lifespan and body size (e.g., mallard) may take fewer risks than species with lesser longevity and body size (e.g., teal; Bellrose 1980; Ackerman et al. 2006). Physiological costs associated with decreasing foraging are less in large-bodied species, because these ducks have increased capacity to store nutrients and decreased metabolic rates relative to their larger body size (Nagy 2005; Ackerman et al. 2006). Thus, increased frequency of hunting on areas may decrease harvest of large-bodied ducks as they may postpone foraging to reduce risks. In contrast, smaller, shorter-lived species that take more risks to find food resources may be less affected by hunting frequency and remain relatively more available to hunters than large-bodied ducks.
Ducks may become conditioned to use spatial sanctuaries during hunting hours even on days closed to hunting (Hockin et al. 1992; Madsen and Fox 1995; Fox and Madsen 1997). Indeed, duck density increased approximately 30% in nearby sanctuaries within the first 1.5 h after sunrise regardless of hunting on the studied WMAs (St. James et al. 2013). Hunters who remained afield longer harvested more ducks, but only 28% hunted more than 4 h of the approximately 5.5-h hunt period provided at WMAs. Thus, ducks may have used sanctuaries during mornings when hunter numbers were greatest and gradually moved to hunting units later in the morning when they became available to remaining hunters.
Previous studies have detected decreases in rate of ducks harvested when areas are hunted consecutive days (Fox and Madsen 1997). In our study, consecutive days of hunting occurred once each week on areas hunted 4 d/wk (e.g., Saturday and Sunday). Although we did not detect statistically significant differences in ducks harvest rate between areas hunted 2 vs. 4 d/wk, harvest rate of all ducks was reduced 15% on areas hunted 4 d/wk. Part of this reduction in harvest rate may have been related to consecutive weekend days of hunting and related disturbance on the WMAs.
We imposed hunting frequencies of 2 and 4 d/wk at each WMA, thus we cannot ascertain that hunting frequency treatments were completely independent. Dabbling ducks become more alert to, or move away from nonhunting disturbances within 200 m (Pease et al. 2005; Bregnballe et al. 2009). Shooting disturbances cause ducks to move less than 5 km, with 15–20% ducks returning to the disturbed areas (Bregnballe and Madsen 2004; Dooley et al. 2010). Therefore, hunting disturbance in one hunting frequency treatment could have influenced duck movements and harvest rate in the other. Despite potential for interrelationships between treatments, we chose this study design instead of our alternative (i.e., each WMA as a single treatment). Imposing a single treatment on each WMA had a greater potential to confound as WMAs are spread throughout Mississippi, due to distances between WMAs being greater than the winter home range of dabbling ducks (Jorde et al. 1984; Cox and Afton 1997) and differences in local conditions (i.e., hunt unit water levels, hunt unit size, landscape juxtaposition, food availability, and weather). Thus, we interpreted and compared our results with available literature recognizing this potential, and we hope to stimulate additional research, which will refine waterfowl hunting management on public areas.
Monitoring movements of radiomarked ducks in relation to hunting frequency would help to provide an understanding of how hunting and related disturbances influence spatiotemporal use of WMAs by individual ducks. Radiomarked female mallards used Mississippi WMAs similarly (P ≥ 0.22) whether they were hunted 2 or 4 d/wk (Lancaster 2013). Hence, Lancaster (2013) also recommended continued allowance of hunting 4 d/wk on Mississippi WMAs. We think harvest data presented herein and from related studies (Lancaster 2013; St. James et al. 2013) provide justification for currently providing hunting opportunity at Mississippi WMAs 4 d/wk without diminishing rate of ducks harvested. However, our models predict that hunting WMAs 4 d/wk will double the total number of ducks harvested during the hunting season compared with hunting 2 d/wk.
Please note: The Journal of Fish and Wildlife Management is not responsible for the content or functionality of any supplemental material. Queries should be directed to the corresponding author for the article.
Data S1. Harvest and hunter use data were collected at Howard Miller, Muscadine Farms, and Trim Cane WMAs in Mississippi, USA, during three waterfowl hunting seasons, Dec–Jan 2008–2011. Data used for this manuscript are provided in the spreadsheet entitled “Tab 1-Harvest Data”. We also included a spreadsheet entitled “Tab 2-Column Title Descriptions,” which provides a detailed description of the column titles for “Tab 1-Harvest Data.”
Found at DOI: http://dx.doi.org/10.3996/012014-JFWM-009.S1 (876 KB XLS).
Reference S1. Fredrickson LH, Taylor ST. 1982. Management of seasonally flooded impoundments for wildlife. U.S. Fish and Wildlife Service, Resource Publication 148, Washington, D.C., USA.
Found at DOI: http://dx.doi.org/10.3996/012014-JFWM-009.S2 (2561 KB PDF).
We thank the Mississippi Depart of Wildlife, Fisheries, and Parks for funding our study through the Federal Aid in Wildlife Restoration (project WR-48-56). In addition to funding, we thank K. Brunke, S. Chunn, S. Edwards, J. Fleeman, W. Gordon, L. Harvey, H. Havens, B. Williamson, and J. Woods of the Mississippi Department of Wildlife, Fisheries, and Parks for providing housing during field studies, assistance at hunter check stations, and essential guidance. We also thank J. Callicutt, R. Hardman, J. Lancaster, C. Wilson, and E. Zlonis for assistance in data collection. We thank K. Hunt for serving as a graduate committee member to E.A.S.J. Lastly, we thank the anonymous reviewers and the Subject Editor of the Journal of Fish and Wildlife Management for reviewing the manuscript. This article has been approved for publication as Mississippi State University Forest and Wildlife Research Center article FWRC-WF.
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Citation: St. James EA, Schummer ML, Kaminski RM. Penny EJ, Burger LW. Effect of weekly hunting frequency on rate of ducks harvested. 2014. Journal of Fish and Wildlife Management 6(1):247–254; e1944–687X. doi: 10.3996/012014-JFWM-009
The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service.