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Issue Environ. Biosafety Res.
Volume 7, Number 4, October-December 2008
Page(s) 241 - 252
DOI 10.1051/ebr:2008021
Published online 16 December 2008

Environ. Biosafety Res. 7 (2008) 241-252
DOI: 10.1051/ebr:2008021

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

John L. Cummings1, Levis W. Handley2, Bruce MacBryde2, Shelagh K. Tupper1, Scott J. Werner1 and Zachary J. Byram1

1  U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, CO 80521, USA
2  U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Biotechnology Regulatory Services, 4700 River Road, Riverdale, MD 20737, USA

Received April 25, 2008; accepted October 3rd, 2008; published online 18 December 2008

Abstract - To address some concerns about the expansion of genetically engineered pharmaceutical and industrial crops to outdoor plantings and potential impacts on the human food supply, we determined whether commercial agriculture seeds of maize or corn Zea mays L., barley Hordeum vulgare L., safflower Carthamus tinctorius L. and rice Oryza sativa L. are digested or pass viably through the digestive tract, or are transported externally, by captive mallard ducks Anas platyrhynchos L., ring-necked pheasants Phasianus colchicus L., red-winged blackbirds Agelaius phoeniceus (L.) and rock pigeons Columba livia Gmelin (with the exception of whole maize seeds which were too large to feed to the blackbirds). These crop seeds, whether free-fed or force-fed, did not pass through the digestive tract of these bird species. The birds nonetheless did retain viable seeds in the esophagus/crop and gizzard for several hours. For example, after foraging for 6 h, mallards had retained an average of 228 $\pm $ 112 barley seeds and pheasants 192 $\pm $ 78 in the esophagus/crop, and their germination rates were 93 and 50%, respectively. Birds externally transported seeds away from the feeding location, but in only four instances were seeds found attached to their muddy feet or legs and in no case to feathers. Risk of such crop seeds germinating, establishing and reproducing off site after transport by a bird (externally or internally) or movement of a carcass by a predator, will depend greatly on the crop and bird species, location, environmental conditions (including soil characteristics), timing, and seed condition.


Key words: barley / corn / digestion / dispersal / genetically modified organisms / maize / mallard / pharmaceutical and industrial crops / red-winged blackbird / rice / ring-necked pheasant / rock pigeon / safflower / seed / viability

Corresponding author: john.l.cummings@aphis.usda.gov

© ISBR, EDP Sciences 2008


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