(Portland, OR)  --  Officials are trying to determine what caused the deaths of several dozen crows along the Willamette River waterfront and at some Portland parks.  Police say several crows were seen having seizures and flopping on the ground at Waterfront Park.  Other crows were found dead at the Lovejoy Fountain and around Chapman and Lownsdale Square parks.  Parks officials say it's possible the birds ingested some kind of toxin.