Ok, so maybe the seeds aren't actively killing the Long eared owls (LEOs) as my post title might suggest but they are dying as a result of seeds. I came across a very interesting article in the Bird Watcher’s Digest that details some strange dangers that birds face including slugs attacking warblers, hurricanes impacting chimney swift populations, and high altitude collisions with planes. In the case of the Long eared owls, research by Airam Rodríguez, Felipe Siverio, Rubén Barone, Beneharo Rodríguez and Juan J. Negro shows that LEOs and Barn Owls are prone to getting stuck in adhesive vegetation. The same specialized feathers (barbules) on the upper side of the flight feathers that give owls feathers a velvety look also make them prime candidates for getting caught in sticky seed producing plants such as burr bristle grass. Their research in the Canary Islands showed that nearly 5% of Leos and 2% of Barn owls that were admitted to local rehab centers in Tenerife had been entangled in bristle grass. Amazingly nearly 20% of those owls died from the incident.
If you don't get Bird Watcher's Digest I would highly recommend it. Each month there are several interesting articles in there by birding legends such as Bill Thompson, Julie Zickefoose and more.