Abstract
Herring Gulls Larus argentatus, Slaty-backed Gulls L. schistisagus, Common Gulls L. canus and Black-tailed Gulls L. crassirostris were observed to forage a reddish compound on the concrete wall of a berth at the Choshi fishing port, Chiba Prefecture, on 27 February, 2011. A high concentration of lead was detected in this compound. The lead was speculated to have come from incinerated ash used for reclamation in the 1960s. By spontaneously eating lead, this foraging behavior by gulls seems to be an example of allotriophagy, which is the abnormal consumption of a substance not typically considered as food. At the site of the consumption, the birds did not show any symptoms of poisoning, but it may be expected to affect their reproduction and survival rates.
