Brain cholinesterase activities of birds from forests sprayed with trichlorfon (Dylox) and carbaryl (Sevin-4-oil).

Brain cholinesterase activities were determined in birds from forests sprayed with Dylox(2) at 1.13 kg/hectare (1 lb/acre - active ingredient [a.i.]) or Sevin-4-oil(2) at 1.13 kg/hectare (1 lb/acre - a.i.) for up to 5 days postspray. Of ten bird species 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 mean. 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 spray.

Brown pelicans: improved reproduction off the southern California coast.

Although still about 30 percent too low for population stability, productivity of California brown pelicans at their two northern colonies has improved significantly since 1971. Numbers of adults breeding probably reflect food supplies and recruitment from more successful colonies to the south, but improving fledging rates (up to 0.9 young per nest in 1974) reflect better egg survival and improving eggshell condition, with declining DDE contamination in anchovies, their major food source.