Tracking Cuban Martin (Progne cryptoleuca) migration to wintering location and back using geolocators: solving a mystery

The Cuban Martin (Progne cryptoleuca) is an aerial insectivorous bird that breeds only in Cuba. It can be widely observed on the Cuban archipelago between late January and October but is then absent the rest of the year. Cuban Martins are presumed to migrate to South America, but basic knowledge of their migration is lacking. In July 2017, we tagged seven breeding Cuban Martins in Havana with light-level geolocators to identify their migration routes, stopover sites, and wintering distribution. We recovered one unit in May 2018 and used BASTrak software to retrieve and interpret the data. On 22 September 2017, the bird left the Cuban breeding grounds. It traveled east and then southeast (across the Caribbean Sea and South America), arriving on 5 November to its wintering grounds in Brazil in the western part of the state of Bahia and a portion of the north of the state of Minas Gerais. The total distance traveled along this route was ~6690 km. Between 16 March and 9 April 2018, the bird made the return trip to the breeding area following a similar route. Six stopover sites were identified during each migration phase, but the bird’s pre-breeding migration was faster than its post-breeding migration. Our tracking data confirmed that Cuban Martins may visit other Caribbean islands during migration and identified eastern Brazil as the likely winter destination for the species. This is the first report of the full migration cycle of Cuban Martins and the first confirmed record of the species in continental South America.