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EFFECTS OF HUNTING DISTURBANCE ON WATERFOWL BEHAVIOR IN MANAGED WATERFOWL AREAS AND REFUGES

COREY M. LUCAS Department of Biological Sciences, Western Michigan University Kalamazoo, Michigan, 49008, USA

INTRODUCTION

Hunting has always been an important part of mankind’s survival. Waterfowling is no exception, with a history steeped in tradition and culture. While the impact of hunting on waterfowl abundance can be argued, the disturbance effects of hunting on waterfowl behavior are often overlooked. With a current annual duck bag of over 17 million birds worldwide (Brochet et al. 2009), having greater knowledge of how shorebird and waterfowl behavior changes after and during hunting activities can be an important tool when managers look at refuge design, hunting regulations, and waterbird conservation. In this review the aspects of spatial and temporal behavioral changes by waterfowl as a response to hunting disturbance is investigated. While many studies show that there is a change in the distribution on a spatial scale of waterfowl as a result of hunting (Tamisier et al. 2003), there is interspecies variation in behavior of waterfowl and shorebirds (Ackerman et al. 2006). In this paper three aspects of waterfowl behavior are explored in managed areas and refuges; spatial distribution, habitat preference, and temporal changes due to hunting disturbances.

SPATIAL DISTRIBUTION

Spatial distribution is important when determining the design of waterfowl refuges. Managers must examine how waterfowl respond to hunting pressure and the scale at which they disperse after a disturbance. The distance that waterfowl species travel after the first gunshots heard is an important aspect to research when analyzing disturbance response. Waterfowl have been found to respond to the first 1-7 shots fired but that there is no variation in response from 7 shots to 40+ shots fired. After the first shots fired, dabbling ducks preferred to move to the open water portions of the refuges, while species such as geese and wading birds moved to sites greater than 8 km away (Bregnballe & Madsen 2004). When examining a specific targeted game species such as the mallard (Anas platyrhynchos), mean flight distance after hunting disturbances was determined to be approximately 5 km during the months of September through November, and this distance was reduced to 3 km from December through January (Dooley et al. 2010). Mallards aren’t the only species of duck to exhibit different flight strategies in the fall, as many diving ducks also tend to have greater spatial distribution and spend more time in flight during the fall months after a hunting disturbance (Knapton et al. 2000). This implies that waterfowl could reduce their energy cost of escape during the stressful winter months and use refuges that are closer to the hunting zones than during the earlier months of fall. It’s also noted that the distance of flight could be determined by how a species uses the water. Ducks that utilize water for resting tended to have greater flight distances than those species that used the water for feeding (Mori et al. 2001). Managers should take this into Lucas 2 consideration when managing lands that are within 5 km of the waterfowl hunting area, as these may be important feeding and refuge sites for displaced birds.

HABITAT PREFERENCE

Investigating the habitat choice of birds after a hunting disturbance is necessary to properly assess waterfowl refuge design. Hunting disturbance most certainly increases waterfowl’s energy use during the important months when energy is important for migration, survival in harsh weather, and breeding (Pease et al. 2005). Waterfowl change their behavior in regards to the quality of habitat they choose, often choosing less productive feeding grounds in response to hunting disturbance (Tamisier et al. 2003). Even minimally hunted species of waterfowl, such as the common coot (Fulica atra), are affected by disturbances outside of the refuge that often cause them to disperse to less suitable habitat. They were observed reducing their diving feeding behavior because they were dispersed to deeper water depths because of the hunting activity, possibly leading to a reduction in food consumption (Holm et al. 2011). This suggests that waterbirds may not only change their habitat choice but also change their feeding habits, which may be detrimental to their energy conservation for fall migration. Buffer zones between these shallow water regions of a refuge and the hunting zones could prove to be beneficial for shore feeding waterfowl (Holm et al. 2011). Teal (Anas crecca) are another duck species that shows a change in their habitat choice when hunting is present. Teal show a sharp difference in the use of shorelines when hunting is banned compared to when hunting is allowed in those same areas (Bregnballe et al. 2004). Another game species, the common snipe (Gallinago gallinago) shows similar habitat use when shoreline shooting was prohibited. Game species aren’t the only waterfowl that need to be studied for hunting disturbances on habitat choice. Though non-game birds aren’t targeted by hunters they can often be displaced by hunting activity and their refuge choice has to be factored into management to maintain refuge and reserve biodiversity. When examining some of these species; golden plovers, lapwings, and little bustards, it was found that they showed behavioral responses to hunting disturbance similar to that of targeted species. They increased their flight frequency, flew at greater heights for a greater amount of time during days that were hunted, and were observed using refuge areas more often on hunted days (Casas et al. 2009). This supports the idea that all waterbird species utilizing a refuge need to be researched to develop an appropriate management plan that maintains or increases biodiversity in these areas.

TEMPORAL CHANGES

The effects of hunting disturbances on the spatial distribution and habitat choice of waterbirds has been extensively studied, but one obstacle that managers face is the proper temporal regulations to maintain waterfowl abundance and biodiversity while providing adequate hunting opportunities for those that invest in these areas. A variety of temporal regulations were examined and how they affect waterfowl behavior and abundance in waterfowl managed areas and refuges were determined. There is variation in which hunting activities are more disruptive to waterfowl, with mobile activities such as punt or jump shooting proving to have a greater effect than activities at fixed positions (Madsen 1997). There is also opportunity for a variety of other human disturbances such as fishing, bird watching, and hiking to influence waterfowl dispersal, so these Lucas 3 also have to be included in the conclusions of temporal regulation effects. There is little or no difference between 7 shots fired and 40+ shots fired in an area, which implies that birds respond more to the frequency and not the intensity of a hunting disturbance (Bregnballe & Madsen 2004). Non-hunting activities are also measured to have an effect on waterfowl disturbance, with a study showing little difference between walk-in and shooting disturbances, although mallards travel further when disturbed by shooting activities (Dooley et al. 2010). Interestingly, dabbling ducks within 200 meters of non-hunting disturbances do tend to become more alert and move away from the disturbance (Bregnballe et al. 2004). Seasonal variation also occurs in mallard response to shooting disturbances (Dooley et al. 2010). The return rate of waterfowl must also be evaluated when looking at temporal restrictions on hunting. Mallards specifically tend to change their diurnal patterns in response to anthropogenic disturbance; those birds exposed to disturbance at night exhibited higher movement rates away from the disturbance and reduced their rate of return (Dooley et al. 2010). It can be noted that this isn’t always the case, as sometimes there is a high return rate for disturbed mallards, suggesting that they may be predisposed to use an area or have limited roosting and feeding areas nearby (Bregnballe et al. 2004). Mallards also typically use the same daytime loafing site over the course of a day, but move to a different roosting site at night (Dooley et al. 2010). Although they use different sites they typically maintain the same schedule everyday regardless of hunting activity (St. James et al. 2013). Refuge use is looked at closely when determining hunting frequency. An increase from 20% of the ducks (before hunting season opened) using a refuge area to 63% of ducks occurred immediately following the opening of the hunting season (Vaananen 2001). This shows a clear response by ducks to find a refuge area after a shooting disturbance, and after just a few hunts more than 80% of the dabblers had left the hunting area and adjacent marsh region (Bregnballe et al. 2004). When looking at how many hours or days it takes for duck abundance to return to pre- hunting numbers, research has been fairly inconclusive. However, studies have shown very little variation in duck abundance before and after hunting activities occurred. For instance there is no difference in waterfowl abundance following 1, 2, or 3 week intervals following a one day hunting period, with mallard abundance only being significantly lower after the first day of the hunt, with teal and widgeon having a lesser effect (Bregnballe et al. 2004). Only 1 or 2 days may be enough for waterfowl abundance to recover to pre-hunting levels (Dooley et al. 2010). There are also relatively low effects of hunting disturbance in terms of duck abundance between hunting that occurred 2 days a week and 4 days a week in waterfowl managed areas open to hunting (St. James et al. 2013). Research suggested that there is no effect on the frequency of weekly hunting on duck abundance or duck abundance in refuges, and that duck use in refuges increased by 30% during the morning regardless of whether hunting was allowed on the area (St. James et al. 2013). With all of the inconsistencies in research done on temporal effects of waterfowl hunting, no fail-proof management techniques can be recommended. The addition of the potential of waterfowl habituation to hunting activity (Madsen 1995) presents a difficult situation when determining waterfowl temporal behavior. This is one area that could greatly benefit from further research, and should be done on controlled sites such as waterfowl managed areas that are closely related.

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CONCLUSION

Spatial distribution and habitat choice are more thoroughly studied than temporal distribution, so management strategies could be enacted to increase waterfowl use of refuges and managed areas. Creating refuge areas in coastal or marsh units adjacent to hunting zones and coordinating habitat management of private and public land within 5 km of these hunting areas would help ensure that waterfowl had access to high quality habitat during hunting seasons. This would have a two-fold benefit, as it would increase their energy storage for migration as well as increase survival. With hunting being a known contributor to species poor waterbird communities, refuge creation near hunting zones could improve the biodiversity of these waterfowl managed areas (Madsen 1998).

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