Effects of No. 2 fuel oil on hatchability of marine and estuarine bird eggs.

Eggs of Louisiana herons, sandwich terns, and laughing gulls were oiled with either 0, 5, or 20 microliter of No. 2 fuel oil in the field and in the laboratory. After 5 days of natural incubation, field-oiled and control eggs were opened and embryonic mortality was determined. No. 2 fuel oil produced 61% mortality in Louisiana heron eggs, 56% in sandwich tern eggs, and 83% in laughing gull eggs. Hatching success of artificially incubated, oiled eggs appeared to be lower than in control eggs. However, stress during shipment to the laboratory and problems within the incubator probably contributed to reduced hatchability in both groups.