The Zoological Society of London (ZSL) is conducting research for the UNEP Convention on Migratory Species (CMS) into the effects of climate change on species protected by CMS. Species have been identified as having a high, medium or low vulnerability to the threat of climate change and have been categorised on the basis of a standardised assessment process. This leaflet summarises the emerging results from an assessment of CMS Appendix I species, in order to provide guidance to policy makers at the earliest opportunity.