Factors Affecting Survival of Mallard Ducklings in Southern Ontario

Hoekman, Steven T.; Gabor, T. Shane; Maher, Ron; Murkin, Henry R.; Armstrong, Llwellyn M.

doi:10.1093/condor/106.3.485

Cited by 16 publications

(23 citation statements)

References 51 publications

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“…Variation among sites reflected the combination of annual, spatial, and sampling variation. Despite wide variation in wetland conditions among sites (Hoekman et al 2004), we found little evidence of large variation in nest survival or in survival of adult females outside of peak hay-cutting periods. Although large but counteracting effects of site and year may have negated each other, low variation in estimates among sites suggested that spatial and temporal variation in these parameters were low for our study.…”

Section: Nesting and Nest Survivalcontrasting

confidence: 61%

Demographics of Breeding Female Mallards in Southern Ontario, Canada

Hoekman

Gabor

Maher

et al. 2006

Journal of Wildlife Management

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Reliable estimates of breeding‐ground demographic rates are needed to develop effective conservation strategies for mallard (Anas platyrhynchos) breeding habitat in eastern North America. We radiomarked 224 female mallards in an agricultural landscape in southern Ontario, Canada, during 1997–2000. At each of 4 sites, 1 during each year, we estimated survival of adult females, breeding incidence, nesting effort, clutch size, nesting habitat use, nest survival, and hen success. We also examined the influence of nest age, date, and habitat on nest survival and the influence of date and female age on survival of adult females. Almost all females remaining on site were observed to initiate ≥ 1 nest (x̄ = 0.97, range = 0.95–0.98), we detected a mean of 2.07 (1.80–2.36) nests per female each season, and full clutch size averaged 9.56 (9.1–10.0). For most sites, females nested in grassland and hay land more than expected relative to habitat abundance, nested in wetlands and woody habitats in proportion to abundance, and avoided cropland and developed areas. Survival of adult females from 25 March to 15 July averaged 0.75 (0.65–0.84). Estimates from our best model showed relatively uniform survival across the breeding season, with the exception of large decreases for 2 sites during the peak of the onset of hay cutting. Nest survival averaged 0.13 (0.11–0.15). Our best model supported increasing survival with nest age but did not include variation relative to habitat or date, except in hay land. Nest survival in hay land was high relative to other habitats early in the nesting season, but declined sharply with the onset of hay cutting. Hen success averaged 0.37 (0.25–0.46). Because estimated nest survival varied little among sites and habitats and because suitable nesting habitat appeared abundant, we suggest that upland habitat conservation will accrue only limited demographic benefits. Incentives to alter hay‐cutting practices may decrease mortality of nests and nesting females, but we believe such incentives are unlikely to be cost efficient and that experiments would be needed to reliably assess benefits.

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Section: Nesting and Nest Survivalcontrasting

confidence: 61%

Demographics of Breeding Female Mallards in Southern Ontario, Canada

Hoekman

Gabor

Maher

et al. 2006

Journal of Wildlife Management

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“…Duckling hatch date.-We detected increased survival among late-hatched ducklings at both study areas. This pattern contrasted with a nearly universal phenomenon of greater survival among early versus late-hatched ducklings at northern latitudes (Grand and Flint 1996, Dzus and Clark 1998, Krapu et al 2000, Hoekman et al 2004.…”

Section: General Modelsmentioning

confidence: 71%

“…In other wood duck studies, adult females had 2-3 times the number of surviving ducklings as yearling females (David 1986 in Bellrose andHolm 1994;Gammonley 1990). In northern breeding areas, however, drought may decrease foraging opportunities for ducklings and increase mortality from predators and exposure independent of age of brood-rearing females (Krapu et al 2000, Gendron and Clark 2002, Hoekman et al 2004.…”

Section: General Modelsmentioning

confidence: 99%

“…Research on nesting, other annual-cycle events, population dynamics, habitat use, and harvest has provided an important basis for management of wood ducks (Bellrose 1990, Fredrickson and Graber 1990, Bellrose and Holm 1994. Additionally, studies of broods of most Nearctic waterfowl are relatively recent (Sedinger 1992, Mauser et al 1994, Krapu et al 2000; however, further understanding of duckling ecology will enhance our knowledge of recruitment processes and population dynamics , Dzus and Clark 1998, Hoekman et al 2004.…”

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confidence: 99%

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Survival of Wood Duck Ducklings and Broods in Mississippi and Alabama

et al. 2007

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Although North American wood ducks (Aix sponsa) are well‐studied throughout their range, researchers know little about demographic and environmental factors influencing survival of ducklings and broods, which is necessary information for population management. We studied radiomarked female and duckling wood ducks that used nest boxes and palustrine wetlands at Noxubee National Wildlife Refuge (NNWR) in Mississippi, USA, in 1996–1999, and riverine wetlands of the Tennessee‐Tombigbee Rivers and Waterway (TTRW) system in Alabama in 1998–1999. We estimated survival of ducklings and broods and evaluated potentially important predictors of duckling survival, including age and body mass of brood‐rearing females, hatch date of ducklings, duckling mass, brood size at nest departure, inter‐day travel distance by ducklings, site and habitat use, and daily minimum air temperature and precipitation. At NNWR, survival of 300 radiomarked ducklings ranged from 0.15 (95% CI = 0.04‐0.27) to 0.24 (95% CI = 0.13‐0.38) and was 0.21 (95% CI = 0.15‐0.28) for 1996–1999. Our overall estimate of brood survival was 0.64 (n = 91; 95% CI = 0.54‐0.73). At TTRW, survival of 129 radiomarked ducklings was 0.29 in 1998 (95% CI = 0.20‐0.41) and 1999 (95% CI = 0.13‐0.45) and was 0.29 (95% CI = 0.20‐0.40) for 1998–1999. Our overall estimate of brood survival was 0.71 (n = 38; 95% CI = 0.56‐0.85). At NNWR, models that included all predictor variables best explained variation in duckling survival. Akaike weight (wi) for the best model was 0.81, suggesting it was superior to other models (<0.01 < wi < 0.18). We detected 4 competing models for duckling survival at TTRW. Inter‐day distance traveled by ducklings was important as this variable appeared in all 4 models; duckling survival was positively related to this variable. Patterns of habitat‐related survival were similar at both study areas. Ducklings in broods that used scrub‐shrub habitats disjunct from wetlands containing aggregations of nest boxes had greater survival probabilities than birds remaining in wetlands with such nest structures. Managers may increase local wood duck recruitment by promoting availability of suitable brood habitats (e.g., scrub‐shrub wetlands) without aggregations of nest boxes that may attract predators and by dispersing nest boxes amid or adjacent to these habitats. We did not determine an optimal density of nest boxes relative to local or regional population goals, which remains important research and conservation needs.

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“…However, little is known about the role-specific elements of broodrearing habitat play in determining duckling survival rates, particularly outside of the traditional prairie breeding areas. Survival rates of mallard (Anas platyrhynchos) ducklings vary considerably across the Great Lakes region of the United States and Canada, and this variation might be due to differences in habitat utilized by ducklings (Hoekman et al 2004, Simpson et al 2005. Our goal was to quantify which elements of habitat, specifically water permanency, wetland vegetation, and surrounding upland vegetation, are most critical to the survival of mallard ducklings within the Great Lakes region.…”

mentioning

confidence: 99%

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

Simpson¹,

Yerkes²,

Nudds³

et al. 2007

J Wildl Manag

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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.

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Factors Affecting Survival of Mallard Ducklings in Southern Ontario

Cited by 16 publications

References 51 publications

Demographics of Breeding Female Mallards in Southern Ontario, Canada

Demographics of Breeding Female Mallards in Southern Ontario, Canada

Survival of Wood Duck Ducklings and Broods in Mississippi and Alabama

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

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