Ngor and Technopole 4 May
Yesterday (3 May) sitting on the the cliffs at Ile de Ngor we witnessed a large movement of shearwaters (predominantly Cape Verde, with some Cory’s (borealis) and a few sooty), skuas (pomarine, arctic and three adult long-tailed) and terns (common, Sandwich and a few black) and sighted again a group of bottle-nosed dolphins. This encouraged optimism in planning a brief Saturday boat trip, but we motored within the area of yesterday’s migrating birds and saw frustratingly little – though still some close views of Cape Verde shearwaters and a few Wilson’s storm-petrels. Such is the unpredictability of observing seabird migration.
More successful was picking through the couple of hundred terns perched on the pirogues and sports fishing boats moored in the natural harbour of Ngor bay, before our exit into the open sea. Cutting the motor, we drifted close and amongst the predominant Sandwich and common terns found two lesser crested (one above in the first picture) and the hoped for roseate tern in adult, pink washed breeding plumage.
The roseate (above, front right) was ringed, though not with readable code. Roseate tern is always an exciting bird to find. Though not strictly rare or in decline globally, sitting in Birdlife’s dry category of “Least Concern” and with a wide, if patchy global population, it is quite elusive. This comes from its propensity to breed on small, offshore islands and perhaps the difficulty of separating its identification from common terns when it is not in pink flush.
Senegal’s birds are, for conservation purposes, within the NW Europe/West African flyway population of c5500 birds, most breeding in the Azores and Ireland, with a few in the UK and NW France. Ringing recoveries from the UK and Ireland show that birds wander down the east Atlantic coast as far as Nigeria. So far, with 1% of this population, defining an Important Bird Area (IBA) or Ramar Site, set at 55 birds, only two IBAs have been defined for West Africa; the Densu Delta and Songor, both in Ghana, with a combined mid-winter count of 1150 birds. The web-based Critical Site Network tool, presenting waterbird data up to 2007 and soon to be up-dated, records no records elsewhere than Ghana for West Africa. This must be mostly be due to the difficulties of identification, though there is some suggestion that birds spend a lot of time well offshore. Senegal had very few records until recent seawatching at Ngor revealed an October migration of up to 50 birds over a week (2008) and more recently (2011-12) Ngor Bay has revealed similar numbers in a day in early May, becoming therefore the first west African site outside of Ghana to qualify on IBA criteria for this species.
Reasonably inexpensive digital cameras make reporting individually coded ringed birds a fun and useful adjunct to identifying and counting. The same day in Ngor bay turned up another Senegal speciality; this lesser crested tern. Senegal’s birds are from Libya, which holds all of the small breeding population (4000 adults) of the emigrata sub-species, endemic to the Mediterranean. This is another species that becomes elusive on leaving Libya. It is assumed to winter along the NW African coast down to Senegal, but recent counts at Ngor and nearby Yoff are the only to exceed the magic 1%. Thanks to Abdul Hamza, currently completing his doctoral thesis on the species at the University of Hull, for helping track this one down to the main breeding colony at Geziret Garah where it was ringed as a chick in 2010.
I did not even realise this Sandwich tern has a readable ring until looking at the image on my laptop. Ewan Weston of the Grampian Ringing Goup reports it as a 2011 bird ringed at the colony on the Ythan Estuary near Aberdeen, from which immature birds have also been resighted in Namibia.
Meanwhile at Technopole two African spoonbills were new and the usual red-chested swallows had a few barn swallows flying with them. The wintering yellow wagtails have left so it was not entirely surprising but very nice that a calling bird proved, on landing, to be a fine black-headed male of the thunbergii Scandinavian sub-species, which passes through Senegal in small numbers in late April and May. We also had two new species (190 and 191) for Technopole; two green-backed eremomela foraging with northern crombecs in the bushes and a yellow-fronted canary with the regular group of white-rumped seedeaters by the fishermen’s hut.