• Zinki, Joseph G
  U.S. Fish and Wildlife Research Service
  
• Henry, Charles J
  U.S. Fish and wildlife research service
  
• DeWeese, Lawrence R
  U.S. Fish and wildlife research service
  

Brain cholinesterase activities were determined in birds from forests sprayed with Dylox2 at 1.13 kg/hectare (1 lb per acre)-Active ingredient {a.i.}) or sevin-4-oil2. for up to 5 days post spray. Of ten birds evaluated from the Dylox spray area, four species represented by six individuals had values which were depressed more than 2 standard deviations below the mean. three of these activities(two species) were about 20% less than the means. of 12 species evaluated from the Sevin-4-oil spraying, three individuals representing three species had depressed values. One value was depressed greater than 20% below the mean. Half of the depressed activities were in canopy dwelling birds collected on the day of the spray.