Heavy fall of migrating land-birds on board of a ship off Central America

Between 4 and 7 October 1973, during a spell of unfavourable weather, 85 North American migratory birds were found dead on board a ship sailing between Costa Rica and Belize and in the roads of Belize. They were donated to the Institute of Taxonomic Zoology, University of Amsterdam, where they were identified and examined on gonads, skull pneumatisation, amount of fat, etc. Some of the species were recorded only once before from Belize under comparable weather conditions. A possible relation between difference in spring and autumn weight, and length of migration route is mentioned. Reliability of age determination by gonads and by skull pneumatisation is discussed.