Diet and Gut Morphology of Male Mallards During Winter in North Dakota

Olsen, Richard E.; Cox, Robert R.; Afton, Alan D.; Ankney, C. Davison

doi:10.1675/063.034.0107

Cited by 8 publications

(8 citation statements)

References 30 publications

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“…Based on the contents of the foregut, some of the diets were clearly animal-based, while some tracts containing few seeds were otherwise empty. Empty intestinal tracts are not uncommon in diet studies, with up to 69% (N = 134) of empty tracts in a study on mallard in winter in North Dakota (Olsen et al, 2009). Nonetheless, in a study by Brochet et al (2010), samples of teal Anas crecca (Anatidae) in the Camargue, which were collected in the early morning when the birds returned from their foraging sites, contained many more seeds than the mallards in this study.…”

Section: Diet Variabilitymentioning

confidence: 60%

“…Based on the contents of the foregut, some of the diets were clearly animal‐based, while some tracts containing few seeds were otherwise empty. Empty intestinal tracts are not uncommon in diet studies, with up to 69% ( N = 134) of empty tracts in a study on mallard in winter in North Dakota (Olsen et al ., ). Nonetheless, in a study by Brochet et al .…”

Section: Discussionmentioning

confidence: 99%

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Seed dispersal potential by wild mallard duck as estimated from digestive tract analysis

2016

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Summary Dispersal of plant seeds by ducks and other waterbirds is of great importance to the ecology of freshwater habitats. To unravel the mechanisms of waterbird‐mediated seed dispersal, numerous laboratory experiments have been conducted, but effects of seed and waterbird traits on dispersal potential have rarely been investigated under field conditions. Through analysis of the digestive tracts of 100 wild mallards (Anas platyrhynchos) across a winter season in the Netherlands, we assessed (i) the inter‐individual and seasonal variability of seeds in the digestive tract, (ii) the variability of digestive tract organ size and gizzard grit mass, and (iii) the potential effects of seed species traits and gut traits on the survival potential of ingested seeds. We found 4548 ingested seeds of at least 66 plant species from a wide range of habitats, most of which were retained in the gizzard. Nineteen species had not previously been reported from mallard diets. Individual tracts contained anywhere between 0 and 1048 seeds, of up to 14 species (median of three species). Diet composition and digestive tract size varied substantially between individuals and over the course of the winter season. As predicted from controlled feeding studies, we found that also in wild mallards, size‐dependent gut passage survival favours the dispersal of small‐seeded species. Despite the large variation in gizzard and small intestine size in this study, their effect on the dispersal potential of ingested seeds in the field remains unclear. We found no difference in dispersal potential between plants species growing in wet or dry habitats. This study demonstrates that wild mallards are opportunistic seed consumers with a very diverse diet as reflected by seed species composition in both the foregut and hindgut. However, we also show that serious limitations of field‐based analyses compared to controlled experiments can impede drawing conclusions about gut passage survival of seeds. The large variability in diet composition among individuals and over time indicates high endozoochorous dispersal potential for a wide range of plant species by wild mallard in aquatic and wetland, as well as surrounding terrestrial habitats.

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Section: Diet Variabilitymentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Seed dispersal potential by wild mallard duck as estimated from digestive tract analysis

2016

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“…Variability in temperatures between years may have also influenced the levels of fish consumption by scaup, i.e., more fish were consumed by scaup concomitant with colder winter temperatures (Clements et al 2020). Similar behaviors were observed in mallards (Anas platyrhynchos) wintering in North Dakota below the Garrison Dam where rainbow smelt (Osmerus mordax) were found in greater proportion in mallards collected during colder than in relatively warmer winters (Olsen et al 2011). Unlike scaup, winter snowfall amounts during the Olsen et al (2011) study may have shifted diets, as increased snowfall would Table 2.…”

Section: Discussionmentioning

confidence: 74%

Scaup Depredation on Arkansas Baitfish and Sportfish Aquaculture

Clements

Dorr

Davis

et al. 2021

Wildlife Society Bulletin

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Lesser scaup (Aythya affinis) and greater scaup (A. marila), hereafter scaup, consume a variety of aquatic invertebrates, plants, and occasionally small fish. Scaup have foraged on commercial aquaculture farms in the southern United States for decades. However, the types, abundance, and rate of fish exploitation by scaup on baitfish and sportfish farms are not well documented. Thus, information is needed to understand how fish and other foods influence scaup use of aquatic resources, and any potential economic effects of depredation of fish. From November-March in winters 2016-2017 and 2017-2018, we conducted 1,458 pond surveys to estimate the abundance and distribution of scaup on Arkansas baitfish and sportfish farms that commercially produce species such as golden shiners (Notemigonus crysoleucas), fathead minnows (Pimephales promelas), goldfish (Carassius auratus), and sunfish (Lepomis spp.). We also collected and processed 531 foraging scaup and quantified the proportion of scaup consuming fish and the proportion of their diet obtained from fish. Fish consumption was highly variable between years. In our survey area, we estimated total fish consumption at 1,400 kg and 60,500 kg for winters 2016-2017 and 2017-2018, respectively. Sunfish ponds experienced the maximum loss (18,000 fish/ha) during winter 2017-2018, while goldfish ponds experienced a loss of just 2,600 fish/ha during the same winter. The estimates of baitfish and sportfish loss to scaup revealed potential management strategies for minimizing fish loss and can inform economic analysis of the financial impact of scaup on producers.

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“…The completely new behavior exhibited by this group is even more significant considering that vertebrate consumption has rarely been described in this species and almost only on fish (Carboneras 1992; Olsen et al 2011). Even Pekin (domestic) ducks (A. platyrhynchos domesticus) do not exhibit a tendency for aggressive and predatory behavior in commercial farming compared to other species such as Muscovy Ducks (Cairina moschata) (Riber and Mensh 2008).…”

Section: Resultsmentioning

confidence: 99%

“…They are regarded as omnivorous, feeding by dabbling in shallow water under 1 m in depth and by grazing on land (Snow and Perrins 1998). Their diet primarily consists of aquatic and terrestrial plants as well as various terrestrial and aquatic invertebrates (Dessborn et al 2011), but may occasionally include amphibians or fish (Carboneras 1992;Olsen et al 2011). The digestible protein content of the food, especially animal protein from insect larvae, appears to be a major factor for the survival and growth rate of the ducklings (Street 1978).…”

mentioning

confidence: 99%