Behavioral effects of early postnatal lead exposure in herring gull (Larus argentatus) chicks

Lead exposure early in life affects behavioral and intellectual development in humans. In this paper, I use the herring gull, Larus argentatus, as an animal model to examine effects of lead exposure on early development. Like humans, birds rely mainly on visual and vocal, rather than olfactory, modes of communication. Each of 24 one-day-old herring gull chicks was randomly assigned to one of three treatment groups to receive a lead nitrate solution at a concentration of 0.0, 0.1 and 0.2 mg/g. The control dose was an equal volume of sterile saline. The trios were not siblings, but were matched by weight. Behavioral tests were performed either daily, every two to five days, or at the end of the experiment (45 days posthatching), depending on the nature of the experiment. The behavioral tests examined locomotion, balance, righting response, begging, recognition, thermoregulation and visual cliff. Although on most days, begging behavior, balance and righting response did not differ significantly, over the 45 days of the experiment control birds performed better on more days than the lead-injected birds. Balance was disturbed by lead-injection for the first six days following injection. Individual recognition developed by day 5 in control birds, by day 10 for 0.1 Pb mg/g birds, and by day 14 for 0.2 Pb mg/g birds. Depth perception and thermoregulation behavior were also adversely affected by lead.