Cuckoo Finch, New to Senegal

Following the addition of Turati’s Boubou (Ziguinchor, October 2018) and Willcocks’s Honeyguide (Dindefelo, January 2019), another scarce Afro-tropical species was recently added to the avifauna of Senegal: Cuckoo Finch, Anomalospiza imberbis (in French: Anomalospize parasite). Three birds were found on 17 February in moist grassland north of Oussouye in Basse-Casamance, by Bruno Bargain, Gabi Caucal and Adrien de Montaudouin.

While not necessarily straightforward in the field, their identification could be confirmed based on a few pictures that the team were able to obtain: small, compact drab-yellow finch with a short yet deep conical bill, short tail with pointed central rectrices, pale central crown stripe, small beady black eye, long pale claws. The two-toned bill (pale base of lower mandible contrasting with darker upper mandible) is typical of juveniles, while the yellowish underparts and throat suggest that this bird is a young male.

Cuckoo Finch / Anomalospize parasite imm. male, Kagnout, Feb. 2019 (G. Caucal)

 

Several birds were seen again a couple of weeks later by Bruno, including two singing males: it’ll be interesting to see whether this little group is resident here and whether more will be found in nearby locations in coming months… there’s definitely a lot of potential, with quite a bit of suitable habitat elsewhere in the area.

As with the boubou, the discovery of this species in SW Senegal was to be expected given that it has been seen several times in recent years just across the border in Gambia, prompting me to include the Cuckoo Finch on our list of the birds of Senegal with a question mark (“presence to be confirmed”) when I initially compiled the list last year. The checklist is accessible through this new page that was recently added to the Resources section of this website. Cuckoo Finch is species number 679 on the national list! (though to be fair, this includes five for which definite proof is lacking, and which remain to be confirmed)

Cuckoo Finch is indeed a widespread yet local and uncommon species throughout Sub-Saharan Africa, and particularly in West Africa its status and patchy distribution remain poorly known. It occurs in Sierra Leone, Liberia, Cote d’Ivoire as well as in southern Mali, and probably also in Guinea and Guinea-Bissau though as far as I know there are no records in the latter country. The presence in Guinea is based on an old specimen from Mount Nimba, which I was fortunate to examine in the collection of IFAN here in Dakar, picture below. In Gambia it was first recorded in 1969, on 24 September by O. Andrew. The only further details I found on this record are in Morel & Morel (1990), who state that “about a dozen were seen well in Sept.-Oct. 1969 near Banjul”. It then took more than 40 years for the next record to be obtained, more precisely at Kartong Bird Observatory where three birds were caught and ringed on 24 Feb. 2013; in subsequent years the species was again caught or seen on a few occasions at KBO, at most 14 birds on 27 April 2014, and again several birds in May-October 2017. All were non-breeding or young birds, with no evidence of local breeding (O. Fox, J, Cross).

The only Guinea specimen of Cuckoo Finch, from near Mt Nimba in Sept. 1946 (Dekeyser & Villiers), in the collection at IFAN in Dakar (photo BP)

Given these more or less regular sightings at Kartong, which lies right on the border with Casamance, it would make sense if the species were also present around Abene, Kafountine, Diouloulou or other nearby locations. We’ll try to explore some of these sites in coming months, particularly during the breeding season, i.e. during the rains. The finders are currently writing up a note to formally publish their discovery.

Also known as Parasitic Weaver, the “unusual finch” as per its scientific name is the unique representative of its genus, having previously been linked to weavers and even canaries. It is now included in the viduids as it is most closely related to the whydahs and indigobirds (see e.g. Lahti & Payne 2003). Just like these birds, it is a brood parasite, laying its eggs in nests of cisticolids (cisticolas and prinias), apparently up to c. 30 eggs per season (!), in batches of 1-4 eggs per “set”. Zitting Cisticola and Tawny-flanked Prinia may be the most likely host species in Senegal and Gambia.

There’s of course a lot more to be said about this peculiar songbird, for instance how females adopted a mimetic strategy to fool its hosts: Feeney et al. (2015) demonstrated how “female Cuckoo Finch plumage colour and pattern more closely resembled those of Euplectes weavers (putative models) than Vidua finches (closest relatives); that their Tawny-flanked Prinia hosts were equally aggressive towards female Cuckoo Finches and Southern Red Bishops, and more aggressive to both than to their male counterparts; and that prinias were equally likely to reject an egg after seeing a female cuckoo finch or bishop, and more likely to do so than after seeing a male bishop near their nest.” Fun fact: I happened to meet Claire Spottiswoode, one the co-authors of the paper and specialist of brood parasites, on their southern Zambian study site while they were conducting field work in March 2013… but I failed to find any Cuckoo Finches!

For some more on parasitic birds, here’s a good start.

Plenty of other good birds were seen in Casamance last month, including the first White-tailed Alethe (Alèthe à huppe rousse) in many many years, Lesser Moorhen (Gallinule africaine), Ovambo Sparrowhawk (Epervier de l’Ovampo), Bluethroat (Gorgebleue à miroir), Forbes’s Plover (Pluvier de Forbes), European Golden Plover (Pluvier doré), Yellow-legged & Kelp Gulls (Goélands leucophée et dominicain), and quite a few more scarce species. With a bit of luck, Gabi and Etienne will find some time to write up the highlights of what was once again an epic trip across Senegal.

Meanwhile in Dakar, seabird spring migration is in full swing, with the first Long-tailed Skuas, Sooty Shearwaters, Roseate Terns and so on passing through in recent weeks (Labbe à longue queue, Puffin fuligineux, Sterne de Dougall). More on this in due course.

 

Forbes’s Plover / Pluvier de Forbes, Casamance, Feb. 2019 (B. Bargain)

 

Many thanks to the finders for allowing me to write up this post, and to Olly Fox for providing info on the Kartong records.