Bird skins in museum collections: are they suitable as indicators of environmental metal load after conservation procedures?

To find out whether modern conservation treatments alter the level of metals in feathers, we analysed the content of 10 metals in feathers before and after skins were washed with detergent and treated with Eulan U-33 (a commonly used preservative at museums). Feathers of 31 birds of Goshawk Accipiter gentilis, Eagle Owl Bubo bubo. Feral Pigeon Columba livia domest, and Common Eider Somateria mollissima were analysed. We found that in most cases metals were partly washed out of the feathers, but the effects were related to species and type of feather. The value of bird skins as indicators of environmental metal load is therefore affected by this treatment. It is recommended that the conservation techniques used at museums should be reconsidered if skins are intended for specimen banking for future reference in environmental monitoring schemes and research.