Effects of hunting pressure and collection method bias on body mass of drake mallards

We weighed hunter-killed mallards (Anas platyrhynchos; n = 4,747) during the 2005, 2008, and 2009 hunting seasons in Manitoba, Minnesota, North Dakota, Saskatchewan, and South Dakota to examine effects of hunting pressure on body mass. Our final model indicated that main effects describing age, hunting pressure, hunting method, season, relative harvest date, and selected interactions were influential in predicting mass of drake mallards during fall. Body mass of hatch-year and after-hatch-year drake mallards harvested in low hunting pressure jurisdictions was 4.3% and 2.5% greater, respectively, than those harvested in high hunting pressure jurisdictions. Body mass of drake mallards from low hunting pressure jurisdictions was 12.1% greater for birds that were harvested using pass or jump shooting hunting methods than those that were harvested by hunters using decoys over dry agricultural fields. When possible, managers should consider disturbance during planning stages of attracting mallards, and not rely upon dry agricultural fields as foraging resources for mallards unless a positive energy balance can be achieved. Finally, studies examining physiological condition of waterfowl must account for collection technique. © 2012 The Wildlife Society.     

Seven polymorphic microsatellite loci for paternity assessment in the mallard (Anas platyrhynchos)

We describe seven polymorphic microsatellite loci for the mallard (Anas platyrhynchos). The microsatellites presented here are highly polymorphic, with on average 12 alleles in a sample of 15 presumably unrelated individuals. Therefore, they enable detailed parentage analysis in wild mallard populations, and can be used to answer many intriguing questions in behavioural ecology and evolutionary biology.     

Paternity in mallards: effects of sperm quality and female sperm selection for inbreeding avoidance

Postcopulatory processes might play an important role in sexualselection. In theory, fertilization success could be controlledby females via selection of particular sperm within their reproductivetract, or it could be determined by sperm competition per se.In practice, these two mechanisms are difficult to disentangle.To assess the relative importance of both mechanisms we usedartificial insemination in combination with measurements ofsperm quality (swimming speed and motility) in mallards. Inthis species, females often lack behavioral control over copulationsand hence may use postcopulatory mechanisms to optimize theirreproductive output. One important factor affecting female fitnessmay be selection of genetically compatible males. To investigatethe influence of sperm quality and parental relatedness on paternitywe inseminated 12 groups of related females with a sperm mixturecontaining equal numbers of sperm from a brother and from anunrelated male. Paternity was independent of the relatednessof the siring male to the female but was significantly affectedby long-term sperm swimming speed and motility. No interactionbetween relatedness and sperm quality on paternity was observed.These results suggest that female mallards are not able to selectsperm on a purely genetic basis and emphasize the importanceof sperm quality in gaining paternity.     

Mourning dove reporting probabilities for web-address versus toll-free bands

Federal migratory bird bands have been inscribed with a postal address and toll-free telephone number (toll-free bands) since 1995 for their reporting, but in 2007 the postal mail address was replaced with an internet address (web-address bands). The reporting rate of web-address bands is unknown, and knowledge of band reporting probabilities is an integral part of bird band-recovery studies designed to obtain unbiased estimates of harvest rates and recovery rates if use of band types differs across space and time. We estimated web-address band reporting probabilities for mourning doves (Zenaida macroura) in the United States by comparing the relative recovery rate (ratio) of web-address to toll-free bands and applying this as an adjustment factor to the known reporting probabilities of toll-free bands. Cooperators banded 132,386 doves representing 57,982 (44%) web-address and 74,404 (56%) toll-free bands in July and August during 2008–2010 across 34 states, 12 regions, and 3 management units. Of the birds banded, 4,642 (3.5%) were direct recoveries, as a result of being shot, and all but 3 were reported via telephone or internet. Nationally, internet reporting accounted for 16.3% of toll-free bands and 42.9% of web-address bands recovered. Web-address bands had a greater recovery rate than toll-free bands (ratio = 1.081, SE = 0.027). We found some evidence of spatial variation in ratio estimates at management unit and regional scales, but the variation was primarily at the regional level where it was not great (range = 1.015–1.213) and statistical support for this variation was not particularly strong (SE = 0.129). Nationally, the web-address band reporting probability was 0.535 (SE = 0.021), an absolute increase of 0.040 compared to the reporting probability of toll-free bands. The additional reporting probability of web-address bands relative to toll-free bands must be accounted for in band-recovery studies used to obtain estimates of harvest rates and recovery rates if use of band types differs across space and time for mourning doves and possibly other species. © 2011 The Wildlife Society.     

Mallard Harvest Distributions in the Mississippi and Central Flyways

Abstract: The mallard (Anas platyrhynchos) is the most harvested duck in North America. A topic of debate among hunters, especially those in Arkansas, USA, is whether wintering distributions of mallards have changed in recent years. We examined distributions of mallards in the Mississippi (MF) and Central Flyways during hunting seasons 1980–2003 to determine if and why harvest distributions changed. We used Geographic Information Systems to analyze spatial distributions of band recoveries and harvest estimated using data from the United States Fish and Wildlife Service Parts Collection Survey. Mean latitudes of band recoveries and harvest estimates showed no significant trends across the study period. Despite slight increases in band recoveries and harvest on the peripheries of kernel density estimates, most harvest occurred in eastern Arkansas and northwestern Mississippi, USA, in all years. We found no evidence for changes in the harvest distributions of mallards. We believe that the late 1990s were years of exceptionally high harvest in the lower MF and that slight shifts northward since 2000 reflect a return to harvest distributions similar to those of the early 1980s. Our results provide biologists with possible explanations to hunter concerns of fewer mallards available for harvest.     

Harvest mortality in North American mallards: A reply to Sedinger and Herzog

Sedinger and Herzog (2012) evaluated the evidence for the impact harvest mortality may have on North American duck populations. While doing that, they questioned our review (Pöysä et al. 2004 ) and conclusion that harvest mortality in North American mallards (Anas platyrhynchos) may have shifted from compensatory to additive over the period from the 1960s to the 1980s. In this reply, we correct Sedinger and Herzog's misrepresentations of our 2004 paper and argue that our interpretations of the results published at that time have not been invalidated. © 2013 The Wildlife Society.     

Effect of predation risk, body size, and habitat characteristics on emigration decisions in mallards

Understanding the processes underlying emigrating behavior isfundamental to better understand animal dispersal. Because ofthe difficulties involved in carrying out controlled manipulationof the proximate drivers of emigration over large spatial scales,results from laboratory or small field enclosures suitable forsmall-bodied species remains to be validated in natural habitats.We investigate whether emigration is driven either by intraspecificcompetition or resulted from hunting-risk avoidance and assessedthe effect of phenotypic variation on individual decisions.We made use of a quasi-experimental situation by using huntingrecoveries of mallards (Anas platyrhynchos) released as ducklingsin a fragmented landscape managed for duck hunting. Our resultssuggest an indirect effect of hunting on emigration. Body sizeplays a major role in modulating individual emigrating decisions,with small-bodied individuals emigrating more to escape fromhigh levels of predation pressure while larger bodied individualsbeing more vulnerable to predation.     

Female mate preferences and subsequent resistance to copulation in the mallard

In the majority of socially monogamous bird species, femalessolicit or accept copulations from males other than their partner.Females may gain direct benefits from extrapair males, suchas greater access to resources, or indirect genetic benefitsthat will influence the future success of their offspring. However,one group of birds appears to be the exception to this generalrule; in the wildfowl (Anseriformes), all extrapair copulationsappear to be resisted by females. It has been suggested thatresistance behavior may be a strategy to allow females a greaterchoice of mates, either at the precopulatory level (to promotechoice of copulation partner) and/or the postcopulatory level(to promote multiple mating to increase their choice of sperm).This paper examines the function of female resistance behaviorin one of the dabbling ducks, the mallard (Anas platyrhynchos).Observations on a marked population of wild mallard and experimentswith captive birds found that although females showed a strongpreference for particular males that are the first to molt intotheir breeding plumage, male attractiveness did not influencefemale responses to pair or extrapair copulation attempts. Femaleresistance decreased the likelihood that copulation attemptswould end in successful insemination. The findings did not supportthe hypothesis that females resist copulations to promote femalechoice and the reasons why waterfowl may benefit from avoidingall extrapair copulations are discussed.     

Correlation Between Nest and Duckling Survival of Mallards Breeding in Saskatchewan

Abstract: Few studies have estimated reproductive and survival parameters of breeding ducks simultaneously, although such efforts can reveal relationships among vital rates. We estimated survival of mallard (Anas platyrhynchos) nests and duckling on 8 study sites in south-central Saskatchewan during spring and summer 2000 and 2001. We observed a strong positive correlation between these parameters (r = 0.914) and through analysis of residual values found 14% of the relationship was explained by a predator-removal treatment, 26% by year effects, 44% by spatial variation, and 16% unexplained. Potential mechanisms include similar environmental factors influencing both parameters (e.g., predators) and positive density dependence. Information regarding covariation among vital rates is important in construction and interpretation of population growth models describing population dynamics of mallards and other upland-nesting ducks.     

Effects of Habitat on Mallard Duckling Survival in the Great Lakes Region

Abstract: Habitat provides food and shelter resources for prefledgling waterfowl and thus plays a critical role in their growth, development, and survival. However, few studies have examined whether and how particular elements of habitat affect duckling survival. We investigated relationships of duckling survival rates with distance of overland travel, wetland vegetation composition, water permanency, and surrounding upland vegetation for 116 mallard (Anas platyrhynchos) broods in the Great Lakes region from 2001 to 2003. We found that the probability, on hatch day, that a mallard duckling will survive to 55 days was positively related to the proportion of wetland area that was vegetated and negatively related to the proportion of forest cover within 500 m of duckling locations. We found little support for relationships between duckling survival rates and the proportions of grasslands or seasonal wetlands or to distances traveled overland by broods. Our results suggest that conservation groups and wildlife managers in the Great Lakes region can improve mallard duckling survival rates by managing for, creating, and protecting vegetated wetlands and focusing efforts within lightly-forested areas.     

Not all sanctuaries are created equal: variation in protected area selection by wintering mallards

Public lands managed for wildlife frequently provide various forms of sanctuary to increase residency times and allow access to energetic and other habitat resources for waterfowl. The influence of sanctuary type and disturbance regime on resource use and fine-scale movements of waterfowl has not been investigated extensively using currently available transmitter technologies. We examined mallard (Anas platyrhynchos) use of various types of waterfowl sanctuary and non-sanctuary areas in the Mississippi Alluvial Valley region of eastern Arkansas, USA, during winters of 2019–2021. We deployed 105 global positioning system transmitters on mallards at 4 closed-access spatial sanctuaries on or adjacent to Dale Bumpers White River National Wildlife Refuge. We used hourly transmitter locations to examine mallard use of public sanctuary areas, public hunt areas, and private lands using integrated step selection analysis. Public sanctuary areas provided varying levels of protected status, public hunt areas allowed for varying levels of hunting intensity by duck hunters, and private lands were open to waterfowl hunting and other forms of private uses but may or may not have been hunted at any specific frequency. Mallards selected spatial sanctuary and avoided public hunt areas, other sanctuary types, and private lands during the day. In contrast, mallards selected for private lands over spatial sanctuary at night. Mallards tended to avoid areas that allowed duck hunting or used them during the night when risk of harvest mortality was removed. After the hunting season closed, mallards began using areas that previously allowed duck hunting during the day, suggesting that risk was the primary factor influencing site use. Moreover, mallards were 1.6 times more likely to use public daily hunt areas and 2.1 times more likely to use private lands potentially open to hunting during the day than spatial sanctuary 2 weeks after the close of duck hunting season in February. Spatial sanctuaries appear more effective in influencing mallard use than temporal sanctuaries or inviolate sanctuaries, which are commonly used by state and federal agencies. Partial daily, daily, or activity-specific (e.g., no hunting past noon, no hunting 3 days/week, no waterfowl hunting) closures to encourage mallard use of temporal sanctuaries do not appear to reduce the perceived harvest-related risk to mallards enough for them to view these areas as accessible or significantly increase their use.     

Pintail and Mallard Survival in California Relative to Habitat,Abundance, and Hunting

ABSTRACT The influence of habitat, waterfowl abundance, and hunting on winter survival of waterfowl is not well understood. We studied late August-March survival of 163 after-hatch-year (AHY) and 128 hatch-year (HY) female mallards (Anas platyrhynchos) radiotagged in Sacramento Valley (SACV) and 885 AHY female northern pintails (A. acuta) radiotagged throughout the Central Valley of California, USA, relative to flooded habitat (HAB), January abundance of each species (JMAL or JPIN), hunter-days (HDY), and a hunting pressure index (HPI) that combined these variables. From EARLY (1987–1994) to LATE (1998–2000), HAB increased 39%, JPIN increased 45%, JMAL increased 53%, HDY increased 21%, duck-hunting season increased from 59 days to 100 days, and the female daily bag limit doubled to 2 for mallards but remained 1 for pintails. Survival (± SE) was greater during LATE versus EARLY for pintails radiotagged in each region (SACV: 93.2 ± 2.1% vs. 87.6 ± 3.0%; Suisun Marsh: 86.6 ± 3.2% vs. 77.0 ± 3.7%; San Joaquin Valley: 86.6 ± 3.1% vs. 76.9 ± 4.1%) but not for SACV mallards (AHY: 70.6 ± 7.2% to 74.4 ± 7.7% vs. 80.1 ± 7.2% to 82.8 ± 5.6%; HY: 48.7 ± 9.1% [1999–2000 only] vs. 63.5 ± 8.8% to 67.6 ± 8.0%). Most pintail (72%) and mallard (91%) deaths were from hunting, and lower HPI and higher JPIN or JMAL were associated with reduced mortality. Increased HAB was associated with reduced winter mortality for pintails but not for SACV mallards. Pintail survival rates that we measured were within the range reported for other North American wintering areas, and during LATE were higher than most, even though our study duration was 68–110 days longer. Winter survival rates of SACV mallards were also within the reported range. However, with higher bag limits and longer seasons, mallard survival during LATE was lower than in most other wintering areas, especially during 1999–2000, when high winds on opening weekend resulted in high hunting mortality. Habitat conservation and favorable agriculture practices helped create a Central Valley wintering environment where natural mortality of mallards and pintails was low and survival varied with hunting mortality. We recommend regulations and habitat management that continue to minimize natural mortality while allowing sustainable harvest at a level that helps maintain strong incentive for management of Central Valley waterfowl habitats, including the large portion that is privately owned.     

Population Dynamics of Breeding Mallards in the Great Lakes States

Abstract: Mallard (Anas platyrhynchos) populations in the United States portion of the Great Lakes region increased through the 1990s but have since declined. To promote sustainable growth of this population, managers need to understand how perturbation of vital rates will affect annual population growth rate (Λ). We developed a stage-based model representing the female mallard population in the Great Lakes using vital rates generated from a landscape-level study documenting reproductive parameters from 2001 to 2003. We conducted perturbation analyses (i.e., sensitivity analyses) to identify vital rates that most influence Λ and variance decomposition analyses to determine the proportion of variation in Λ explained by variation in each vital rate. Perturbation analyses indicated that Λ was most sensitive to changes in nonbreeding survival, duckling survival, and nest success. Therefore, changes in these vital rates would be expected to result in the greatest ΔΛ. Process variation in breeding season parameters accounted for 63% of variation in Λ. Breeding season parameters explaining the most variation were duckling survival (32%) and nest success (16%). Survival of adult females outside the breeding season accounted for 36% of variation in Λ. Harvest derivation, high harvest, and high sensitivity of Λ to nonbreeding survival for Great Lakes female mallards suggests there is a strong potential for managing the Great Lakes mallard population via harvest management. Because Λ was highly sensitive to changes in duckling survival, we suggest programs that emphasize wetland protection, enhancement, and restoration as a management strategy to improve population growth for breeding mallards.