Waste Rice for Waterfowl in the Mississippi Alluvial Valley

Abstract

Flooded rice fields are important foraging habitats for waterfowl in the lower Mississippi Alluvial Valley (MAV). Waste rice previously was abundant in late autumn (140–492 kg/ha), but early planting and harvest dates in recent years may have increased losses of waste rice during autumn before waterfowl arrive. Research in Mississippi rice fields revealed waste‐rice abundance decreased 79–99% during autumns 1995–1996 (Manley et al. 2004). To determine if this trend existed throughout the MAV, we used multistage sampling (MSS) to estimate waste‐rice abundance during September–December 2000–2002. Averaged over years, mean abundance of waste rice decreased 71 % between harvest (x̄ = 271.0 kg/ha, CV= 13% n = 3 years) and late autumn (x̄ = 78.4 kg/ha, CV= 15% n = 3). Among 15 models formulated to explain variation in rice abundance among fields and across years, the best model indicated abundance of waste rice in late autumn differed between harvester types (i.e., conventional > stripper header) and was positively related to initial waste‐rice abundance after harvest. Because abundance of waste rice in late autumn was less than previous estimates in all 3 years, we concluded that waterfowl conservationists have overestimated carrying capacity of rice fields for wintering waterfowl by 52–83% and recommend 325 duck‐use days/ha (DUDs) as a revised estimate. We suggest monitoring advances in rice harvest dates to determine when new surveys are warranted and recommend increased management of moist‐soil wetlands to compensate for decreased rice abundance.

Avian Foods, Foraging and Habitat Conservation in World Rice Fields

“…For example, in Mississippi in 1995, Manley et al (2004 documented a mean decrease in waste rice of 79% from 492 kg/ha in August-September to <60 kg/ha in early December. Similarly, Stafford et al (2006) reported that waste rice abundance in Arkansas, Louisiana, Mississippi and Missouri, declined an average of 71% from 271 kg/ha after harvest in early autumn to 78 kg/ha in early winter during [2000][2001][2002]. Because experimental evidence suggests that waterfowl cease foraging and depart rice fields when seed abundance decreases to a "giving-up" density of ~50 kg/ha (Reinecke et al 1989;Greer et al 2009), waste rice apparently contributes less to winter carrying capacity of waterfowl in the MAV than previously thought (Loesch et al 1994;Stafford et al 2006).…”

“…The majority of this food is in the form of grain spilled or not collected during harvest and commonly referred to as "waste rice" (Stafford et al 2006). Additionally, many birds forage on recently-planted rice seeds, seedlings and grains maturing in seed heads before harvest.…”

“…stripper vs. conventional cutter-bar). Regarding the latter, Miller and Wylie (1996) documented less waste rice in California fields harvested with stripper-header equipped combines, whereas Stafford et al (2006) and Kross et al (2008) detected no difference in post-harvest abundance of waste rice in MAV fields harvested with the two equipment types. In Japan, Shimada (1999Shimada ( , 2006) estimated waste rice was at least 8.7 times more abundant in fields harvested by conventional combines compared to those harvested using a reaper-binder, a device that cuts and binds the stalks for field drying.…”

“…An interval of two-three months now occurs between harvest in August or early September and arrival of large numbers of wintering waterfowl in late November and December. Most waste rice is lost during this period to germination, decomposition and granivory (Stafford et al 2006;Kross et al 2008). For example, in Mississippi in 1995, Manley et al (2004 documented a mean decrease in waste rice of 79% from 492 kg/ha in August-September to <60 kg/ha in early December.…”

Dispersal of viable row-crop seeds of commercial agriculture by farmland birds: implication for genetically modified crops

“…For example, economic losses due to blackbird depredations on rice in USA are estimated at US $ 21 million annually (Cummings et al, 2005). After harvest, waste rice remaining in the fields can be a significant source of food for waterfowl (Manley et al, 2004;Stafford et al, 2006). Post-harvest birds in agricultural fields can be beneficial in some situations by gleaning crop seeds not removed by mechanical harvesting and thus reducing the potential for volunteers in a subsequent growing season.…”