Birds are most likely to ingest shot in areas with high shot densities and little grit, a situation that exists in many of the heavily hunted river deltas of the Mediterranean, where shot densities of to 2 million pellets per hectare accumulate in popular spots such as the Carmargue and Evros deltas. Acid moorlands and the acidic conditions at the bottom of many lakes render lead most biologically available, to the degree where it is concentrated enough to affect other aquatic wildlife, such as fish and plants; shot from a clay pigeon shoot in the UK has killed plants over 6 hectares and resulted in lead concentrations in the remaining vegetation of 250 times those regarded as acceptable for grazing animals. Species which most frequently ingest shot are not necessarily the most susceptible to lead poisoning (species with diets rich in protein, calcium and phosphorous reduce the toxic effects of lead), but diving ducks and swans are especially affected because of the bottom-feeding habits and also because they ingest anglers' split-lead shot used to weight lines.