The Effects of Seasonal Flooding on Seed Availability for Spring Migrating Waterfowl

Greer, Andrew K.; Dugger, Bruce D.; Graber, Dave A.; Petrie, Mark J.

doi:10.2193/2006-376

Cited by 29 publications

(26 citation statements)

References 15 publications

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“…Although many studies have reported depletion of local waterfowl food sources (e.g., Percival et al 1996, Amano et al 2006, Nolet et al 2006, Greer et al 2007, ours is the first to document depletion of a food in an area the size of the MAV. Regional depletion of an important food source is not unequivocal evidence that wintering waterfowl populations are limited by food availability, but it is consistent with the hypothesis.…”

Section: Discussionmentioning

confidence: 59%

Depletion of Rice as Food of Waterfowl Wintering in the Mississippi Alluvial Valley

et al. 2009

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Waterfowl habitat conservation strategies in the Mississippi Alluvial Valley (MAV) and several other wintering areas assume carrying capacity is limited by available food, and increasing food resources is an effective conservation goal. Because existing research on winter food abundance and depletion is insufficient to test this hypothesis, we used harvested rice fields as model foraging habitats to determine if waste rice seed is depleted before spring migration. We sampled rice fields (n = 39 [winter 2000–2001], n = 69 [2001–2002]) to estimate seed mass when waterfowl arrived in late autumn and departed in late winter. We also placed exclosures in subsets of fields in autumn (n = 8 [2000–2001], n = 20 [2001–2002]) and compared seed mass inside and outside exclosures in late winter to estimate rice depletion attributable to waterfowl and other processes. Finally, we used an experiment to determine if the extent of rice depletion differed among fields of varying initial abundance and if the seed mass at which waterfowl ceased foraging or abandoned fields differed from a hypothesized giving‐up value of 50 kg/ha. Mean seed mass was greater in late autumn 2000 than 2001 (127.0 vs. 83.9 kg/ha; P = 0.018) but decreased more during winter 2000–2001 than 2001–2002 (91.3 vs. 55.7 kg/ha) and did not differ at the end of winter (35.8 vs. 28.3 kg/ha; P = 0.651). Assuming equal loss to deterioration inside and outside exclosures, we estimated waterfowl consumed 61.3 kg/ha (48.3%) of rice present in late autumn 2000 and 21.1 kg/ha (25.1%) in 2001. When we manipulated late‐autumn rice abundance, mean giving‐up mass of rice seed was similar among treatments (48.7 kg/ha; P = 0.205) and did not differ from 50 kg/ha (P = 0.726). We integrated results by constructing scenarios in which waterfowl consumed rice at different times in winter, consumption and deterioration were competing risks, and consumption occurred only above 50 kg/ha. Results indicated waterfowl likely consumed available rice soon after fields were flooded and the amount consumed exceeded our empirical estimates but was ≤48% (winters pooled) of rice initially present. We suggest 1) using 50 kg/ha as a threshold below which profitability limits waterfowl feeding in MAV rice fields; 2) reducing the current estimate (130 kg/ha) of rice consumed in harvested fields to 47.1 kg/ha; and 3) increasing available rice by increasing total area of fields managed, altering management practices (e.g., staggered flooding), and exploring the potential for producing second or ratoon rice crops for waterfowl.

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Section: Discussionmentioning

confidence: 59%

Depletion of Rice as Food of Waterfowl Wintering in the Mississippi Alluvial Valley

et al. 2009

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“…Therefore, priorities for continental‐scale conservation planning should continue to recognize the importance of protecting, restoring, enhancing, and managing wetland habitats used by spring‐migrating ducks in large regional landscapes such as the UMRGLR. At more local scales we encourage wetland managers to consider waiting to flood some wetlands until late winter or early spring because this has been shown to increase seed biomass availability (Heitmeyer 2006, Greer et al 2007). Our estimates of plant, invertebrate, and total duck food biomass during spring migration should be used to refine wetland habitat objectives of the UMRGLR JV.…”

Section: Management Implicationsmentioning

confidence: 99%

Wetland food resources for spring‐migrating ducks in the Upper Mississippi River and Great Lakes Region

et al. 2011

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Wetlands in the Upper Mississippi River and Great Lakes Region (UMRGLR) must annually sustain populations of migrating waterfowl from the mid‐continent of North America. We used multi‐stage sampling to estimate plant and invertebrate food biomasses (kg/ha) for ducks in 3 wetland habitat types at 6 stop‐over locations in the UMRGLR during 2006 and 2007. Total biomass was greatest in palustrine emergent (PEM; ${\bar {x}}$ = 208 kg/ha, SE = 23, median = 120), followed by palustrine forested (PF; ${\bar {x}}$ = 87 kg/ha, SE = 7; median = 43), and lacustrine–riverine (LR; ${\bar {x}}$ = 52 kg/ha, SE = 7; median = 27) wetlands. Ducks that foraged in forested and LR wetlands encountered the least food abundance during spring in the UMRGLR. Our estimates of food abundance were the lowest reported among other landscape scale surveys from mid‐continent North America. About 1 in every 5 PEM wetlands and over half of our PF and LR wetlands that we sampled contained <50 kg/ha of food, suggesting many had little or no forage value to ducks during spring. Biomass of plant foods generally exceeded invertebrate biomass in all habitat types, although invertebrate biomass estimates exceeded plant biomass in 8 of 29 sites when considered by wetland type and year. Total food biomass estimates varied widely (${\bar {x}}$ = 6–425 kg/ha) between years and among habitats; thus, using global arithmetic means to estimate food abundance for conservation planning obscures fine scale temporal and spatial variation that may be necessary for management on local and sub‐regional levels. Distributions of food biomass estimates were right‐skewed, causing us to question whether arithmetic means realistically represent levels of food abundance that all ducks encounter during spring migration. Alternative measures of central tendency (e.g., median) may be more biologically realistic, particularly if spring‐migrating ducks are not distributed in an ideal‐free manner with respect to food abundance. Future research should determine how ducks distribute themselves in relation to variation in food abundance in space and time during spring migration to strengthen the biological approach to conservation planning in non‐breeding Joint Venture areas of the North American Waterfowl Management Plan. © 2011 The Wildlife Society.

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“…We washed samples with water over a graduated series of 2-3 sieves (mesh sizes 18 [1.00 mm], 35 [500 mm], and 60 [250 mm]) depending on the quantity of vegetation present (Penny 2003;Reinecke and Hartke 2005;Greer et al 2007). We separated seed heads and seeds from plant debris and dried for 24 h at 87uC (Manley et al 2004;Stafford et al 2006a (Greer et al 2007). We classified seeds as large if they were retained by the #35 sieve (e.g., largeseed smartweed Polygonum pensylvanicum, millets Echinochloa spp., and beggarticks Bidens spp.)…”

Section: Estimating Moist-soil Plant Seed Abundancementioning

confidence: 99%

Seed Abundance for Waterfowl in Wetlands Managed by the Illinois Department of Natural Resources

Stafford

Yetter

Hine

et al. 2011

Journal of Fish and Wildlife Management

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Managed wetlands on public lands in Illinois, United States, provide foraging habitats for migrating and wintering waterfowl. However, few studies have estimated abundances of waterfowl foods in mid-migration regions of North America, yet such information is needed to inform management and conservation decision-making. During 2005-2007, we used a multistage sampling design to estimate moist-soil plant seed production (kg/ha, dry mass) and energetic carrying capacity at sites managed by the Illinois Department of Natural Resources and modeled variation in seed biomass. Average seed biomass among all sites ranged from 1,030.0 6 64.1 (SE) kg/ha in 2005 to 501.5 6 124.1 kg/ha in 2007. Our overall estimate (2005)(2006)(2007) of moist-soil plant seed biomass was precise (691.3 6 56.4 kg/ ha; CV: 8.2%), equaling 5,128 energetic use-days/ha. This value was similar to or slightly greater than previous estimates from other regions of North America and exceeded the estimate used the Upper Mississippi River and Great Lakes Region Joint Venture for waterfowl conservation planning (514 kg/ha). We formulated eight models to predict abundance of moist-soil plant seeds within sampled wetlands. The best approximating model included the number of desirable plant species within wetlands and study year. The second best model included the categorical effect of management intensity and indicated that, although variable, actively managed wetlands produced about 240 kg/ha more seed than those that were passively managed. As with other regions, wetland management practices that encourage diverse plant communities over monotypes and growth of early successional plants should yield substantial increases in waterfowl food abundances at Illinois Department of Natural Resources sites, especially given that only 27% of our study wetlands were actively managed. Such efforts would also help reduce deficits in energetic carrying capacity identified by the Upper Mississippi River and Great Lakes Region Joint Venture.

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The Effects of Seasonal Flooding on Seed Availability for Spring Migrating Waterfowl

Cited by 29 publications

References 15 publications

Depletion of Rice as Food of Waterfowl Wintering in the Mississippi Alluvial Valley

Depletion of Rice as Food of Waterfowl Wintering in the Mississippi Alluvial Valley

Wetland food resources for spring‐migrating ducks in the Upper Mississippi River and Great Lakes Region

Seed Abundance for Waterfowl in Wetlands Managed by the Illinois Department of Natural Resources

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