Seed Recovery, Germination, and Dispersal Distances of Herbicide-Resistant Amaranthus hybridus and Invasive Eragrostis plana by Birds

Seed dispersal by birds (endozoochory) may contribute to the spread of herbicide-resistant weed species and invasive species in agricultural systems. We evaluated seed recovery, germination, and estimated dispersal distances of Amaranthus hybridus (glyphosate-resistant) and Eragrostis plana (invasive) following gut passage through budgerigars (Melopsittacus undulatus) and quails (Coturnix japonica). Endozoochorous seed retention times and recoveries differ between bird species. Seed germination after gut passage was low but not completely suppressed. Estimated seed dispersal distances reach up to 1.6 km per day via bird movement. These findings demonstrate that even small-seeded weeds can survive gut passage and be dispersed over ecologically relevant distances, emphasizing the role of bird-mediated endozoochory in the spread of problematic weeds across agroecosystems.