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Size characteristics of stones ingested by common loons

January 1, 2001

Common Loon (Gavia immer) carcasses recovered in New England had more stones of greater combined mass in their stomachs than loons from the southeastern United States. Stones retained in sieves with mesh sizes between 4.75 and 8.00 mm accounted for the greatest percentage (by mass) of grit in loon stomachs. The median longest dimension of the largest single stone in each stomach was 12.5 mm in loons from New England and 10.7 mm in loons from the southeast (maximum = 23.1 mm and 16.8 mm, respectively). A recent national proposal to restrict the use of certain fishing weights in the United States called for a ban on lead fishing sinkers of 25.4 mm or less in any dimension. Our findings suggest it is unlikely that Common Loons would ingest lead fishing weights greater than 25.4 mm in any dimension, if such ingestion was solely the result of their search for replacement stones for their stomachs. However, this does not preclude the possibility that loons may ingest larger fishing weights under other circumstances, such as the consumption of fish with attached sinkers.

Publication Year 2001
Title Size characteristics of stones ingested by common loons
DOI 10.1650/0010-5422(2001)103[0189:SCOSIB]2.0.CO;2
Authors J. Christian Franson, Scott P. Hansen, Mark Pokras, Rose Miconi
Publication Type Article
Publication Subtype Journal Article
Series Title The Condor
Index ID 1003599
Record Source USGS Publications Warehouse
USGS Organization National Wildlife Health Center