4 years ago



over four years

over four years (2000-2003) in Iowa, and found that per-plant egg density on milkweed was on average 3.89 times greater when growing in corn and soybean fields versus non-agricultural habitats. Survival of eggs to adulthood was similar between habitats. In just the 13 years from 1999 to 2012, it is estimated there was a 64 percent decline in overall milkweed in the Midwest, most of which was from croplands (Pleasants in press). However, because cropland milkweed produces nearly four times as many monarchs as plants in other settings, their loss has a disproportionate impact on monarch numbers. Pleasants (in press) estimates that in 2012, the Midwest produced 88 percent fewer monarchs than it did in 1999. Loss of Western Monarch Habitat Due to Glyphosate Glyphosate is also heavily used in the western portion of the monarch’s range, and may be degrading habitat there as well. In 2012 in California, glyphosate was among the top five pesticides (and the top herbicide) in terms of amount used (California Department of Pesticide Regulation 2014, p. 15), and the leading pesticide as measured by cumulative acres treated (California Department of Pesticide Regulation 2014, pp. 66-67; Figure 11, p. 70). In addition to almonds and wine grapes, leading crops treated with glyphosate include cotton and alfalfa. Glyphosate accounts for 74 percent of total pounds of herbicides applied to cotton “due to the large acreage of Roundup Ready cotton,” and its use is rising on alfalfa “because of increased planting of Roundup Ready alfalfa” (California Department of Pesticide Regulation 2014, pp. 85, 89). Genetically engineered, herbicide-resistant cotton rose from 21 percent to 68 percent of total California cotton acres from 2000 to 2013 (USDA ERS 2014b). Heavy use of glyphosate in California, a state with extensive agriculture production, threatens the multiple species of milkweed that provide habitat in California, and thus monarch reproduction and survival west of the Rockies. Loss of Monarch Habitat Due to Agricultural Intensification to Produce Biofuels The 88 percent decline in Midwest monarch production discussed above means that the Midwest produces only 12 percent as many monarchs as it did in 1999. This dramatic decline is driven primarily by loss of milkweed in cropland, which is being lost at the astonishing rate of nearly 50 percent every two years (Figure 21, based on data supplied by John Pleasants). Without conservation and restoration efforts, common milkweed will for all practical purposes disappear from the largely Roundup Ready corn and soybean fields that dominate the Midwest landscape (Pleasants and Oberhauser 2012). Moreover, monarch habitat outside of crop fields is also being rapidly degraded. The majority of remaining Midwest monarch habitat is today found on lands enrolled in the Conservation Reserve Program (CRP). The CRP is a program administered by the U.S. Department of Agriculture that compensates farmers for taking environmentally sensitive land out of crop production for 10-15 year periods and instead planting species (usually grasses) that improve environmental quality by reducing soil erosion, providing wildlife habitat and improving water quality (USDA Farm Service Agency 2014). Because of the precipitous decline in milkweed in cropland, CRP lands that contributed only 16 percent of Midwest monarchs in Monarch ESA Petition 56

1999 accounted for 56 percent of the much-reduced population remaining in 2012 (based on data supplied by John Pleasants). Conversion of CRP acreage to corn and soybean production is being driven by federal biofuels policy. The 2005 Energy Policy Act and the 2007 Energy Independence and Security Act established subsidies and quotas for biofuels production, chiefly ethanol from corn. These incentives drove construction of new ethanol plants, increased demand for corn, sharply rising corn prices, and huge increases in corn acreage (USDA ERS Corn 2014). The share of the U.S. corn harvest processed for ethanol rose from 6 percent in the year 2000 and 14 percent in 2005 to 43 percent in the drought year 2012, and a still substantial 36 percent in 2013 (USDA ERS Feed Grains 2014). To meet this increased demand, corn acreage has increased by 17 million acres since 2006 (USDA NASS 2014). While some of this increased corn acreage has come at the expense of other crops (Wallander 2011), a substantial portion has come from the CRP. Enticed by the greater profitability of corn versus CRP payments, farmers have responded to the ethanol-driven “corn rush” by taking their land out of the CRP to grow corn (Love 2012, Cappiello and Apuzzo 2013). These land conversions are reflected in CRP enrollment figures. Nationally, CRP acreage has shrunk by 11.2 million acres (30 percent) since 2007 (USDA FAS CRP 2014). Over half of this decline has taken place in the twelve Midwest states, which have lost 6.2 million CRP acres (Figure 23). Wright and Wimberly (2013) estimate that 1.3 million acres of grassland in the western Corn Belt (much of it CRP land) was converted to corn and soybean production from 2006 to 2011. CRP acreage has declined substantially since 2011 (Figure 23), suggesting a continuation of this disturbing trend. CRP lands will continue to shrink in the future. In the 2014 Farm Bill, Congress sharply reduced the maximum acreage that can be enrolled in the program. This “CRP cap,” which stood at 39.2 million acres from 2002 to 2009, will decline by 39 percent to just 24 million acres by 2017 and 2018 (National Sustainable Agriculture Coalition undated, National Council of Farmer Cooperatives 2014), ensuring that each year progressively more of monarchs’ most important breeding habitat will be converted to corn and soybean fields stripped of common milkweed by use of glyphosate and other herbicides. CRP land is the major remaining habitat for Midwest monarchs, and conversion to corn and soybeans that are engineered to be resistant to glyphosate (and other herbicides, see next section) will continue to drive monarch population decline in the core of the species’ range. Monarch ESA Petition 57

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