Steppe Whimbrel migration route revealed

Following the unexpected discovery of two Steppe Whimbrel Numenius phaeopus alboaxillaris on wintering grounds in early 2016, one was fitted with a satellite tag and was found to make a 5,659 km journey – in six days – to Aden, Yemen, rendering its migration route consistent with the direction of travel for known breeding areas of the little-known subspecies. The tracking data represents the first firm evidence of a long-suspected African transcontinental migration route.

A key identification feature of Steppe Whimbrel (right-hand bird) is the strikingly white axillaries, compared here with nominate phaeopus Whimbrel (Callan Cohen/Gary Allport).

In February 2016 two birds were found with a wintering population of 30 Whimbrel in Maputo Bay, Mozambique. One was estimated to have departed on 28 February of that year, while the other was tagged before setting off on 25 March. Unfortunately, the tag fell off the bird in Yemen so the breeding destination of the Steppe Whimbrel found in Maputo is still to be clarified.

Steppe Whimbrel is one of the rarest and least understood waders in the world and was considered extinct 25 years ago. The threat of extinction remains, particularly as so little is known about the birds, which is one of four subspecies of Whimbrel. A recent review of the subspecies status estimates that there are a mere 100 individuals left, at most, and the population trend is declining.

For 30 years, this wader managed to escape the notice of humans but, three years after the birds were incorrectly consigned to history, they were re-found in Russia, during search efforts for the closely-related Slender-billed Curlew in 1997. Researchers stumbled upon Steppe Whimbrels close to the Ural Mountains and this initial discovery was followed by regular sightings in the late 1990s and early 2000s. It wasn't until 2016, however, that the wintering grounds were found, the first time the subspecies had been recorded in Africa for 51 years.

Steppe Whimbrel, Maputo Bay, Mozambique, February 2016 (Gary Allport).

Reference

Allport, G A, Carvalho, M, Atkinson, P W, & Clark, N. 2018. Local site use and first northbound migration track of non-breeding Steppe Whimbrel Numenius phaeopus alboaxillaris (Lowe 1921). Wader Study Group Bulletin 125(3):219-227. DOI: 10.18194/ws.00126