Are Sunflower Fields for the Birds?

ARE SUl\FLOWER FIELDS FOR THE BIRDS? HEATH M. HAGY , North Dakota State University , Department of Biological Sciences , Fargo , ND, USA GEORGE M. LINZ, USDA, APHIS , Wildlife Services, National Wildlife Research Center , Bismarck , ND, USA WILLIAM J. BLEIER , N011h Dakota State University , Department of Biological Sciences, Fargo , ND , USA Abstract: The northern Great Plains are home to a variety of birds throughout the year, particularly during migration. Migratory species use native and restored grasslands, shelterbelts, and agricultural fields for food and shelter in North Dakota. Blackbirds (Xanthocephalus xanthocephalus) have been documented to cause economically important damage to some crops and thus , are sometimes the target of concerted harassment efforts. Few studies have assembled an inventory of non blackbirds using small grain fields during the fall and spring in North Dakota that may be inadvertently affected by blackbird management. At least 94 nonblackbird species use crop fields in the spring and fall in North Dakota. Sunflower fields appear to be a particularly important stopover habitat for a variety of migratory birds , with 78 species and 29 species using sunflower in the fall and spring, respectively . We encourage a joint blackbird management / wildlife habitat system including Wildlife Conservation Sunflower Plots (lure plots) as part of an integrated pest management plan to reduce blackbird damage to sunflower and provide habitat for nonblackbirds. Key words: blackbirds , decoy plots , lure plots, nonblackbirds , stopover habitat , WCSP Proceedings of the l ih Wildlife Damage Management Conference (D.L. Nolte , W.M. A1:jo, D.H. Stalman , Eds) . 2007 INTRODUCTION use crop fields and shelterbelts in the NGP. The northern Great Plains (hereafter These areas have become important habitats NGP) of North America provide stopover for some migratory species , especially as habitat for a wide variety of migratory birds. some North American birds have Forest species , grassland species , and habitat experienced population declines (Robbins et generalists migrate across a patchwork of al. 1989, Askins et al. 1990, Askins 1993, agriculture that fragments the once 1999 , 2000 , Murphy 2003) . continuous grasslands of the NGP into a Population and habitat selection mosaic of commercial grain crops , hay studies of farmland birds are heavily biased lands , grazing pastures , and shelterbelts. towards the breeding grounds , with little Presently , patches of Conservation Reserve information available about the wintering Program (CRP) grasslands, grazing pastures , ground habitat and even less regarding and wildlife-managed lands represent the stopover site selection. Though site selection majority of the prairie remnants within the is likely hierarchical , studies quantifying cultivated landscape of NGP. With reduced habitat variables in stopover locations are grassland habitats available, migratory birds lacking (Wiens 1973, Johnson 1980). 61 Peterjohn (2003) describes understanding of pho eniceus) , common grackles (Quiscafus the habitat requirements of many farmland quis cula), and yellow-headed blackbirds birds during non-breeding seasons as (Xantho cephalu s xantho cephalu s), con "rudimentary. " Quality stopover habitat is gregate in large mixed-species foraging vital for migrants , especially when they are flocks and may do substantial damage to bound for breeding grounds as lean birds commercial crops. The close proximity of may not be as attractive to females nor be commercial agriculture and abundant able to defend a territory until they feed and roosting habitat , cattail-emergent wetlands, increase their fat stores (Moore and Simons make this region attractive to blackbirds . As 1989) . Fat depleted birds must also remain No11h Dakota and South Dakota sunflower longer at stopover sites increasing the risk of production supports a regional economy predation . Stopover sites which provide worth over $906 million , significant crop cover and large amounts of accessible forage losses could reduce future sunflower spread over a large area may lead to reduced plantings and negatively affect rural stopover time. economies in the region (Bangsund and Many migratory bird species inhabit Leistritz 1995). the Prairie Pothole Region of the NGP, Many methods have been researched using small , isolated wetlands , prame and implemented in the last 50 years to patches , emergent wetland vegetation, and reduce blackbird damage to com and agricultural crops for food , nesting habitat , sunflower in the NGP (A very 2003 , and cover. Though the NGP is highly Cummings and A very 2003 , Linz et al. fragmented, grassland birds and other 2003) . Producers and researchers have tried species inhabit row-crop fields , roadsides , hazing birds with airplanes, frightening grass patches , and other areas (Best et al. devices, propane cannons, and firearms , and 1998, Herkert 1998, McCoy et al. 1999, have implemented roost habitat management Schaaf 2003 , Galle 2006 , Hagy 2006). Best with mixed success (Linz et al. 1992, 2003) . et al. ( 1998) found more wintering species in In the early 1980s, Cummings et al. ( 1987) row-crop fields than in CRP fields in six showed that ''decoy" plantings of sunflower Midwestern states . Martin ( 1980) observed might reduce bird damage to commercial n1ore than 65 avian species using sunflower fields , though strategic placement shelterb elts as stopover habitat during spring of the plots was critical for their success. migration in eastern South Dakota. Researchers have documented bird use of Shelterbelts provide forest islands that have agriculture in North Dakota comparing both contributed to the westward expansion of blackbird and nonblackbird use across some forest birds (Spnmt 1975, Johnson and common row-crops. [n this paper , we will Beck 1988) . Clearly , the NGP provide focus on three studies which examined a habitat for a large number of migratory variety of row-crops in central and eastern birds . North Dakota in order to demonstrate the Though crop fields may provide importance of agricultural habitat to adequate habitat for birds , not all of these migratory nonblackbirds , especially migrants are welcomed visitors , especially sunflower. by sunflower producers . An estimated 75 million blackbirds migrate through the NGP STUDY AREA in the fall to feed on waste grain and These studies were conducted within standing crops , the latter including corn and central and eastern North Dakota. Schaaf sunflower (Linz et al. 2003). Blackbirds, (2003) conducted observations in Barnes including red-winged blackbirds (Agelaius and Stutsman counties in the Southern Drift 62 Plains physiographic subregion. Galle were significant relationships between bird (2006) conducted observations across l 8 abundance and surrounding habitats. counties within the Southern Drift Plains of Hagy (2006) examined bird use east- central part of the state. Hagy (2006) throughout east- central North Dakota in 35 worked in the Southern Drift Plains, the locations , each site including 1 commercial Northern Drift Plains , and the Missouri sunflower field, One Wildlife Conservation Coteau subregions of east and central North Sunflower Plot (hereafter WCSP) , and one Dakota within a 14-county area. Although non-sunflower commercial agricultural row this area was once dominated by tall- and crop field ( corn , wheat , soybeans, field pea, mixed-grass prairies , it is now heavily canola, or flaxseed) in the fall of 2004 and cultivated (Barbour et al. 1999). Agriculture 2005. Additionally , his study examined is a valuable industry in North Dakota, as it habitat variables within and surrounding contributes to 25% of the state's economic each field type using model selection to base and over 8% of its gross state product elucidate relationships between avian (Leistritz et al. 2002). abundance and habitat variables. Sunflower is an important crop , both These authors used different ecologically and economically , in North methodologies , but all gathered valuable Dakota, as well over I billion pounds of information regarding avian use of crop sunflower seed is produced annually on 0.44 fields. Schaaf (2003) and Hagy (2006) million ha (USDA 2005) . In 2005, North conducted 50 m fixed radius circular point Dakota produced 45% of all oilseed , 39% of counts with supplemental mist-netting to all confectionary, and 42% of the total thoroughly evaluate species richness in sunflower grown in the United States sunflower (Reynolds et al. 1980, Poulin et (USDA 2005). al. 2000). They conducted 8 min point counts beginning shortly after sunrise until METHODS all fields were surveyed (~ 2-5 hr). Hagy rn fall of 2000 and 200 l, Schaaf (2006) and Schaaf (2003) used mist nets in (2003) identified and quantified WCSP and commercial sunflower fields , nonblackbirds in 12 ripening sunflower respectively . Hagy (2006) conducted point fields in Barnes and Stutsman counties, counts only in commercial sunflower and North Dakota. This study also measured non-sunflower crop fields . Galle (2006) used habitat parameters in and around the fields , a line-transect method to count birds, which in order to examine possible co1Telation is more efficient than other methods for between these factors and nonblackbird migration monitoring , especially 111 open abundance using Pearson product-moment habitats (Wilson et al. 2000). correlations . The aim of this study was to develop infom1ation to evaluate the RESULTS importance of sunflower as habitat for

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