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 ± 112 barley seeds and pheasants 192 ± 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.Keywords: 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

37 are reported for Claytonia virginica L. from the St. Louis, Missouri area. Those plants with 2n = 24 and 30 are by far the most frequent. Morphologically the species separates into two groups: plants having narrow leaves which are characteristic of the lower polyploid cytotypes, and those having broad leaves which are typical of the higher polyploid races.

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