Following on our April summary, here’s a brief update on results from last month’s short but regular seawatch sessions from Ngor, as usual all from the Club Calao terrace. Managed a total of 10 sessions between May 10th and May 26th, with more good stuff to report on, including a lifer!
Again, no pictures other than a few old ones that I’m recycling here… and yet again a pretty dull species list.
Wilson’s Storm-Petrel (Océanite de Wilson): unidentified storm-petrels were regularly seen in small numbers, and most likely referred to this species.
Cape Verde Shearwater (Puffin du Cap-Vert) were seen in good numbers on most days, feeding off Ngor or flying NE, with a max. of at least 540 birds in one hour on 26th. Not as many as last year when the maximum counted on a single day exceeded 5,000 birds (!), but the pattern of appearance and behaviour of birds is very much in line with the previous season.
Cory’s / Scopoli’s Shearwater (Puffin cendré / de Scopoli): at least three on 26th when there was a remarkable diversity of shearwaters, with five species noted. Probably also a few on 11th, 14th and 15th but too far or seen too briefly to positively identify.
Two to five Great Shearwater (Puffin majeur) seen flying NE amidst the other shearwaters on 26th – remarkably similar to last year’s record of two birds on May 25th, noted as “apparently migrating north” and thought to be the first May record – see the short paper we published in the latest volume of Malimbus on a “wreckage” of Great Shearwater in the the occurrence in Senegal & Gambia (Barlow et al. 2018), PDF available here on my ResearchGate page.
Sooty Shearwater (Puffin fuligineux): a few seen on 18th, 21st and 26th, with at least 12 birds on the latter date: these records suggest that this Southern Hemisphere breeder is slightly more numerous later in spring.
Boyd’s / Barolo Shearwater (Puffin de Boyd / Macaronésie): one on 21st seen at fairly close range was identified as Barolo Shearwater – for once it was close enough and I was able to follow it over quite a distance. Probably a bird en route to its breeding grounds. Another one, also flying north-east, was either baroli or boydi. The taxonomic situation of these small black and white shearwaters is complex and seems to be constantly changing. with BirdLife and HBW now treating both taxa as subspecies of Audubon’s Shearwater (Puffinus lherminieri). Either way, these are apparently quite rare spring records, though Dupuy (1984) lists what was then known as “Little Shearwater” as an uncommon offshore “summer” visitor. Boyd’s Shearwater breeds exclusively on the Cape Verde islands (only about 5,000 pairs!), while Barolo’s breeds further north on the Macaronesian islands where it is known from Madeira, the Azores, the Selvagems, and the Canary Islands, with a total breeding population of the same order of magnitude.
Northern Gannet (Fou de Bassan): seen in small numbers on most days; all but one were immature birds (and one on 15th may actually have been a Cape Gannet, but I couldn’t rule out a 4th year Northern Gannet as I didn’t see the underwing pattern…).
Red-footed Booby (Fou à pieds rouges): a species I’d never seen before but somehow expected to show up one day at Ngor, two were seen feeding in the surf just beyond the Ngor islet on 17th, nicely showing their pink (not red!) feet, bluish bill and uniform brown plumage. One was seen again the following day and what I assume are the same two birds (both dark morph adults or near-adults) on 22nd, when they appeared to take off from the islet where they may have spent the night. Third record for Senegal! More on this species, which will likely show up more frequently in coming years, in this recent post.
Brown Booby (Fou brun): just one record so far, of an immature (2nd c.y.) on 14th. Looks like the Iles de la Madeleine birds – if they are indeed still present – don’t wander around the peninsula too much.
A few Great While Pelicans were regularly seen, flying about or resting out at sea (and once on the islet), and on 26th a Pink-backed Pelican made an appearance (Pélicans blancs et gris).
Other than an Oystercatcher on 20th and three Whimbrels on 11th (and a few Common Sandpipers), no more waders were seen during May (Huîtrier pie, Courlis corlieu, Chevalier guignette).
Long-tailed Skua (Labbe à longue queue): following several records in the latter half of April, at least three were identified on 11th, one on 18th, and one on 26th – confirming that spring migration of this species occurs up to the end of May off Senegal. Pomarine and Arctic Skuas were much scarcer than in April, with just three records for the former and five for the latter species.
Audouin’s Gull (Goéland d’Audouin): up to three birds seen in any one session, though no notable active migrants as was the case in April; all were immature birds.
Sabine’s Gull (Mouette de Sabine) were recorded up to May 22nd, with four records of 1-9 actively migrating birds. Other gull species included 10 Grey-headed Gulls flying NE on 20th, and three Slender-billed Gulls on 22nd. A single Lesser Black-backed Gull was seen on 22nd, when a probable Kelp Gull was also present.
Single Bridled Tern (Sterne bridée) were seen feeding and flying around quite close to shore on 11th and 15th, bringing the total to three birds so far this season.
Lesser Crested Tern (Sterne voyageuse): seen twice (17th & 20th), unlike African Royal Tern (Sterne royale) which remained present in decent numbers throughout. Caspian Tern (Sterne caspienne) was seen just once, on 22nd.
Roseate Tern (Sterne de Dougall): following a decent passage in April, just one seen on 17th, though others may have passed through further offshore amidst Common and Arctic Terns (Sternes pierragarin et arctique). These two species were seen almost daily, but again in much smaller numbers than in April.
Three Whiskered Terns (Guifette moustac) flew past on 11th, followed by two White-winged Terns (Guifette leucoptère) on 21st. Black Terns (Guifette noire) were less numerous than in April, except on May 11th when about 300 birds were counted.
Let’s see what June brings! Assuming that I manage to make it out to the Calao…
Quick update on this past month’s seawatch sessions from Ngor, as there have been a few good species lately. As usual, most of these are from short sessions at the Calao, with a few from Pointe des Almadies and from a mini-pelagic on April 22nd. Here’s a rather dull species list, but given that still fairy little is known about the phenology of spring seabird migration off Dakar, I thought it would be worthwhile reviewing them here. I don’t really have any recent pictures to illustrate these records, except for a really poor header picture of a Sabine’s Gull actively migrating past the Pointe, and a few older pics that I’m recycling in this blog post.
So here we go:
Cape Verde Shearwater (Puffin du Cap-Vert): the first few birds were seen on 3.3 (min. 2), then ca. 20 on 16-17.3, and a regular presence was noted throughout April when seen during most sessions from 4th, typically 50-100 birds feeding offshore, at most ca. 490 birds on 27th (but just a handful the next day and none seen on 29th!).
Scopoli’s Shearwater (Puffin de Scopoli): at least one during our boat trip on 22.4, with Cory’s or Scopoli’s noted from Ngor on 28th (as well as on March 3rd & 11th).
Sooty Shearwater (Puffin fuligineux): first seen on 16.3, then again singles on 31/3 and 7/4, and at least three birds on 20th. Not much… and note that we didn’t see a single bird during our boat trip.
European Storm-Petrel (Océanite tempête): after a good presence during the first half of February, the species was seen again on 22.4 from the boat, with a minimum of two birds.
Wilson’s Storm-Petrel (Océanite de Wilson): at least six were seen on 22.4, again during our boat trip. Unidentified storm-petrels migrating past the Calao on 7th (min. 8), 11th (3), 20th (3) and 29th (1) were likely this species, though others can’t be ruled out – when seen from land, these birds can be incredibly difficult to identify due to either the distance or the very brief sightings as they always fly low over the water surface and are typically seen only for a second or two before they disappear again in between waves.
Northern Gannet (Fou de Bassan): at most ca. 175 on 31.3, with numbers gradually decreasing throughout April. Curiously, no marked NE-ward passage was noted.
Grey (Red) Phalarope (Phalarope à bec large): four migrating on 29th was a good spring record! Other than these, the only waders seen during this period were a few groups of Whimbrel (Courlis corlieu).
Long-tailed Skua (Labbe à longue queue) single adults passing through on 20, 21 & 25.4, two on 26th, and an immature flew past on 29th. Pomarine and Arctic Skuas were seen in small numbers on most days, many of which were flying NE (though rarely more than five in any one session).
Lesser Black-backed Gull (Goéland brun): usually present in small numbers, either feeding in the surf or migrating past Ngor. There was obviously a peak around mid-March, with 107 passing through in just 40 minutes on 16.3, and 52 in half an hour the next day.
Audouin’s Gull (Goéland d’Audouin): typically between one and five birds seen on any one session, but on 16.3 there were 27 (incl. three adults) migrating past in 40 minutes and 14 the following day (in 30 minutes) – thus coinciding with the peak of the previous species.
Sabine’s Gull (Mouette de Sabine): after the first five on 4.4, becomes increasingly frequent towards the end of the month, with a max. of ca. 40 during our 22.4 boat trip, and 31 on 27th in just one hour. Actual numbers must be quite a bit higher as this species mostly passes through far out, typically in small groups. Sometimes a few birds would migrate closer to shore, and occasionally some would be feeding or resting just in front of the Calao. Other gull species included a surprising flock of 31 Grey-headed Gulls flying NE on 27th, and six Slender-billeds at Pointe des Almadies the following day.
Bridled Tern (Sterne bridée): one passing to the NE at fairly short range on 26.4 was a very nice surprise, as I’d only seen the species once before here (and more generally, away from the Iles de la Madeleine breeding grounds). It also appears to be an early date for the species, as it is typically seen in May-July. My only previous Ngor record was of three birds flying SW on 10 June ’16. Sauvage & Rodwell give the range of 27/4 – 9/7 for PNIM, and A. R. Dupuy recorded the species no less than eleven times from Pointe des Almadies from 26 May to 14 July ’92.
Lesser Crested Tern (Sterne voyageuse): seen in small numbers throughout the month, with a good max. of at least 178 birds passing through on 9th, in just 65 minutes. African Royal Tern (Sterne royale) was seen on most days, typically in small numbers. Much less frequent were Caspian Tern (Sterne caspienne; singles on 31.3 and 28.4) and Little Tern (Sterne naine; one on 6.4, and a group of 16 migrating on 29th).
Roseate Tern (Sterne de Dougall): first seen on 31.3, then regular until the middle of the month with a max. of no less than 56 on 9th in just over an hour. Also singles on 26th and 28th. Most birds were actively migrating, with a few feeding locally with the mixed tern flock.
Arctic Tern (Sterne arctique): the first four birds were seen on 16.3, becoming regular from the end of March and seen on most sessions in April, max. ca. 70 on 24th though numbers probably higher as 1) species difficult to count, and many common/Arctic terns noted.
White-winged Tern (Guifette leucoptère): one flew past on 16.3, and a fine adult in summer plumage was feeding among the numerous Black Terns on 28.4 (Guifette noire). The latter species is seen pretty much during every session, with a maximum towards the end of the month: probably more well over 1,200 birds on 28th. An adult Whiskered Tern (Guifette moustac) was seen on 22nd, flying NE.
That’s about it for now.
On the raptors front, Osprey has been a regular sighting, as always during winter, until 31.3 at Ngor, after which one was seen on 13.4 at Mamelles and on 14.4 at PNIM. A few young birds may still hang around of course. The wintering pair of Peregrines was last seen on 20.4 roosting on the Diarama hotel, and two birds were seen roosting in the Mamelles cliff on 22.4 – pretty intriguing!
Sortie dominicale de routine au Technopole avant-hier 29/4, avec comme presque toujours quelques observations intéressantes à la clé.
A commencer par ces trois Goélands dominicains (Kelp Gull), espèce rarement observée au Technopole et à Dakar de manière générale : en scannant un groupe de laridés essentiellement composé de Goélands d’Audouin (quelques 85 inds. en tout, un bel effectif pour le site; Audouin’s Gull), un oiseau costaud sort du lot et lorsque j’arrive à voir son bec massif, je peux confirmer qu’il s’agit bien de Larus dominicanus, pas de doute possible cette fois. Un individu adulte ou presque, de taille nettement supérieure aux quelques Goélands bruns (Lesser Black-backed Gull) dans le même groupe, au bec énorme, un manteau bien sombre, et des pattes grises très claires tirant vers le vert. L’iris sombre est conforme à la ssp. vetula (Goéland du Cap, Cape Gull). A côté de lui se tiennent deux immatures avec la même structure et des pattes de la même couleur que l’adulte, soit trois Dominicains en tout. Les deux jeunes ont un âge similaire, ayant un plumage de type “2e cycle”, donc dans ce cas précis ce seraient des oiseaux nés en 2016. A part la taille et la forme du bec, la couleur des pattes est diagnostique et permet de rapidement repérer l’espèce au milieu de groupes de Goélands bruns, qui ont des pattes jaunes (adultes et subadultes) ou roses (immatures). Les trois oiseaux sont visibles sur la photo ci-dessous.
Pour plus d’infos sur l’identification des Goélands dominicains, voir notamment cet article de Jiguet et al. paru dans Birding World (2002), et aussi ici pour ce qui est des oiseaux de premier cycle.
Clive Barlow et Tim Dodman se sont penchés sur la population ouest-africaine, dont le petit noyau se trouve dans le delta du Saloum où l’espèce niche de manière régulière depuis 1980 au moins, lorsqu’un couple présumé mixte G. dominicain x G. brun fut trouvé sur l’Ile aux Oiseaux. Par la suite, des nidifications par des couples purs sont prouvées dès 1983 par Erard et al. Quelques individus fréquentent régulièrement la Gambie et la Mauritanie, et s’y reproduisent parfois, peut-etre aussi en Guinée-Bissau? Et avec l’intérêt grandissant que portent les ornithos européens au Sahara occidental – ou Sahara atlantique marocain, selon quel point de vue politique on adopte! – l’espèce est vue plus ou moins régulièrement en très petits effectifs plus au nord sur le continent, et il y a même quelques observations récentes au Portugal et en France. Clive et Tim émettent l’hypothèse que notre petite population isolée soit établie par quelques oiseaux égarés depuis l’Afrique australe (Afrique du Sud / Namibie), et que cette population soit maintenant autonome sans qu’il n’y ait de mouvements réguliers entres les populations australes et celle d’Afrique de l’Ouest. Il y aurait ainsi entre 20 et 50 couples dans la région. Une étude génétique est en cours ou du moins est-elle prévue, sauf erreur.
En région dakaroise, ce goéland hautement côtier est assez régulièrement signalée par des observateurs de passage, mais je ne suis pas sûr que toutes les observations soient réellement fiables… D’après mes propres données de ces trois dernières années le Goéland dominicain est très peu fréquent. Cela dit, je ne suis pas un larophile et si je faisais plus attention à ce groupe difficile que sont les grands goélands, j’en verrais probablement plus souvent!
Ainsi, Niklas Holmström et collègues en signalent pas moins de 20 entre le 13 et le 27/10/03 devant Ngor, mais un seul entre le 3 et le 16/10/05. Une équipe danoise en compte même 57 en « en migration vers le sud » du 22 au 29/10/04 – vraiment étonnant vu que l’espèce n’est présente qu’en très faibles effectifs plus au nord, et qu’en plus ils ne signalent aucun Goéland brun alors que c’est l’espèce dominante à cette période. En 2010, on passe à des effectifs plus raisonnables me semble-t-il, avec trois individus entre le 30/9 et le 8/10 (R. Lebrun) et autant du 25 au 31/10/10 (P. Crouzier & co.). Plus récemment, un Goeland dominicain est rapporté le 24/2 de Ngor par un groupe de naturalistes belges.
Pour ma part, ma seule autre observation au Technopole datait du 6/8/17, d’un immature que j’avais identifié comme dominicain et dont je reprends une des photos floues ci-dessous (l’autre est là) – commentaires bienvenus! Puis avec Manuel en février dernier on a également soupçonné un dominicain, mais trop loin et pas de photos pour confirmer l’identité de l’oiseau. Idem les 11 et 30/8/17 lorsque des probables dominicains passent devant Ngor.
Autre observation intéressante, celle d’un probable Heron « pâle », la sous-espèce monicae du Héron cendré qui ne niche qu’au Banc d’Arguin et peut-être ailleurs sur les côtes en Mauritanie et que certains considèrent même comme une espèce à part entière (“Pallid” or “Mauritanian” Heron). L’aspect très clair était frappant, et malgré la distance on arrive à bien voir les petites stries noires, fines et courtes, sur le cou qui comme le reste des parties inferieures parait presque aussi blanc que la Grande Aigrette. Le manteau était d’un gris pâle à l’exception d’une tache plus sombre à « l’épaule ». Il y a juste le dessin de la tête qui peut sembler un peu top contrasté pour un monicae classique, mais en regardant de près les quelques photos d’oiseaux mauritaniens cela semble encore rentrer dans la normale pour cette sous-espèce. Pour compliquer la chose, il y aurait des oiseaux intermediaires, et peut-être que c’est donc aussi le cas pour notre oiseau du Technopole (visibement un adulte nuptial). Bien entendu je suis preneur d’autres avis!
Il doit s’agir d’un des ardéidés les plus rares au monde, la population totale ne comptant que quelques milliers d’individus, avec une aire de répartition très restreinte. Si c’est bien un mauritanien, alors il s’agirait de ma première observation d’un oiseau manifestement rare à Dakar. Ces derniers mois il y a eu au moins deux autres observations dans la région : un le 13/2 au parc de Hann (Gottlieb Dandliker, Cyril Schönbächler; photo ci-dessous) et un le 24/2 aux Iles de la Madeleine (M. Demeulemeester et al.). Monicae est plus fréquente en hiver dans les zones côtières du nord du pays, notamment autour de la Langue de Barbarie et Saint-Louis, mais même là le taxon reste d’observation plutôt aléatoire. Les observations d’Ornithondar permettent d’en savoir plus sur le taxon dans le Bas-Delta, et de comparer les photos avec l’oiseau du Technopole: articles bien instructifs ici et là.
Tout cela pour dire qu’en gros, aussi bien l’identification que le statut et la distribution au Sénégal restent encore à préciser! On trouvera quelques infos résumées sur la page dédiée au Héron cendré sur le site du groupe HeronConservation.
Troisième espèce inattendue, vue par chance alors que j’étais en train de quitter le site : six Bengalis zébrés (Zebra [Orange-breasted] Waxbill). Ce sympathique petits passereau avait été vu pour la première fois au Technopole en janvier-mars 2017, et depuis j’ai pu en voir également à Yène, plus précisément le 1er janvier dernier. On peut donc supposer que ce nicheur du Bas-Delta sénégalais et du Saloum soit un erratique plus ou moins régulier dans la région dakaroise.
Pour le reste, il y a de nouveau un petit groupe de Flamants roses (10 ind.), les premiers poussins d’Echasses blanches – juste trois pour le moment, déjà vus le 21/4 – et plusieurs adultes en train de couver; également un poussin de Vanneau éperonné; quelques Bécasseaux variables et surtout une bonne présence de Sanderlings (+150) et de Sternes caugeks notamment; une Hirondelle de rivage retardataire; et toujours quelques Spatules blanches et d’Afrique (Greater Flamingo, Black-winged Stilt, Spur-winged Lapwing, Dunlin, Sanderling, Sandwich Tern, Sand Martin, Eurasian & African Spoonbill). Sinon assez peu de limicoles, la plupart des chevaliers, pluviers, combattants et autres bécasseaux étant de retour en Europe maintenant: on attend déjà leur retour, d’ici deux mois à peine pour les avant-coureurs. Par contre, il y a toujours autant de Bihoreaux gris: une bonne trentaine (Black-crowned Night-Heron).
Le Souimanga cuivré est vu à chaque sortie en ce moment, et la semaine passée il y avait également un superbe mâle de Souimanga éclatant, photo ci-dessous (Copper & Splendid Sunbird).
(in case you missed the first part, you may want to read this post first)
Thanks to the important research and conservation efforts targeting Audouin’s Gull, a substantial proportion of the population carry colour-rings, to the extent that in any given group one encounters here in Senegal (and elsewhere of course), there are bound to be some ringed birds, usually up to around 15% of all birds. As far as I know this is far more than for any other species that spends the winter here in Senegal; only Black-tailed Godwit comes close (often 5-10%) and maybe Osprey. For instance at Palmarin last month I managed to read 32 rings out of a total of ca. 400 birds, out of which some 200-250 were either close enough to read rings, or were standing (rather than sitting, in which case rings aren’t visible). That’s roughly 13 to 16% of individuals carrying coded rings!
The first mention that I found of a colour-ring recovery is from Delaporte & Dubois (1990) who on 26/1/88 at Saint-Louis observed a bird ringed as a chick in spring 1981 on the Chafarinas islands. Del Nevo and colleagues also noted that many of the birds they counted were ringed, e.g. on 30/9/92, no less than 24 (14%) of 167 birds were ringed: 18 had a darvic [=plastic ring with alphanumerical code] and six had a metal ring only. In 1994 in Palmarin, a Scandinavian team were able to read 16 colour-ringed birds from Spain (out of at least 456; Bengtsson 1994), while Sauvage & Rodwell mention nine colour-ringed birds originating from Spain, in Saint-Louis. The Dutch 1997 expedition managed to read nine rings, out of the 858 gulls that they counted, noting that “these birds presumably all originated from the Ebro Delta, Spain” (and certainly not from the Canary Islands as stated by Triplet 2014! The species doesn’t even breed there… not sure where this error originated).
The rings (or “bands” for our American friends) are either white with a black inscription (3 or 4 alphanumerical characters), or blue with a white 4 character code, and can often be read with a telescope or a good camera. White rings are used in Spain (starting with letters A, B, C or a number) and Italy (I or K), while blue rings are in use in Portugal (with first character P). French birds have a combination starting with F (since 2013; prior to this Italian rings were used); Moroccan ones with M. The images below show an Italian and two Spanish birds (“BDCT” appears twice, photographed in Aug. 2016 and Sept. 2017).
Origin of wintering birds in Senegal
I now have close to 50 ring “recoveries” related to 44 birds, most of which are from Palmarin (39), the others being from Technopole. Adding other sightings in Senegal of these same birds (mostly by Ngoné Diop), we have a total of 103 recoveries.
Here’s a quick summary of their origin:
- As can be expected, the vast majority are from Spain, particularly from the Ebro delta which accounts for about a third of all birds for which I know the origin (15 out of 44). Six are from Valencia (PN de l’Albufera, Salinas de Torrevieja), three from Tarragona (Salinas de Sant Antoni), three from the tiny Isla de Alboran between Morocco and Spain, and two each from the Balearic islands (Mallorca and Menorca), from Murcia (Parque Regional San Pedro del Pinatar and Isla Grosa), the Laguna de la Mata in Alicante, and the Chafarinas islands.
- Six birds are from Portugal, but I’m still awaiting information for full details of the five most recent birds (all from Palamarin early September); thanks to Ngoné I know that at least four birds (and likely all six) originate from the colony on Ilha da Barreta (the southernmost tip of the country, near Faro).
- Earlier this month I found my first Italian gulls at Palmarin, three adults (ICTD, ILBJ and K7T). I have not yet received details from the ringing scheme, other than that K7T was ringed in 1998 – so far my oldest bird! Ngoné kindly provided me with info for ICTD and ILBJ as these were already known to her, which allowed me to include Cagliari (Sardinia) and Isola del Giglio on the map below; I will add further info here when it becomes available [Olly Fox kindly informed me that K7T was seen at the Kartong Bird Observatory in The Gambia in November 2016; it was born on Isola dei Cavoli off southern Sardinia].
At least one Corsican bird has been found in The Gambia (Recorbet et al. 2011) and Ngoné has recorded a few French birds in Palmarin. One can assume that some Moroccan birds may also winter in Senegal, and maybe Algerian and Tunisian birds as well. Not quite sure where the Eastern Mediterranean populations spend the winter, but I read that at least some remain around their breeding grounds.
Here’s an example of the “life history” of one of our oldest birds¹, 45P from Spain, pictured in the header image of this post. It was ringed as a chick in 1999 on the Chafarinas islands, and was seen in The Gambia during the 2004/05, 2006/07, 2007/08 and 2011/12 winters, then in October 2014, October 2015, and September 2017 it was spotted in Palmarin (plus a few times on its native island, in April-June). Could it be that many Audouin’s Gulls spend the initial 4-5 months of the non-breeding cycle in Senegal, then move to The Gambia for the remaining 2-3 months of the northern winter?
The age composition of our wintering Audouin’s Gulls varies considerably between areas and apparently also through the season. This was first documented by del Nevo et al.: “Adult birds dominated both surveys and proportionately more adults than first year birds were present during September 1992 than in February 1991. Our observations are consistent with the view that adult Audouin’s Gulls tend to arrive in Senegambia before first year birds; the ratios of first year to adult were 0.1:1 in September and 0.54:1 during February.” Delaporte & Dubois reported an overall proportion of 15% of immatures. These ratios have likely changed now, at least in terms of the seasonality now that some immatures can spend their first summer in the region. Ngoné and colleagues reported estimates of 278 adults and 167 immatures (= 37,5%) in Palmarin for the 2013-2015 period. They also found that adults, 3rd and 2nd winter birds arrive earlier than 1st winter birds, a difference which “is probably due to differences in experience among age classes.”
The differences in “immature-to-adult” ratio between Palmarin and Technopole are striking, and I wish I knew what causes this. Immatures are by far outnumbering adults at Technopole, as opposed to the high proportion (70-80%?) of adults further south, particularly in the Saloum delta. Interestingly, this may not have always been the case: Oro & Martinez mention that juveniles winter further south than older 2-3y gulls, in the Senegambia region: “After the breeding season, 2-3y and older gulls were recovered mainly at the E and S Iberian Peninsula coasts. During the winter season these gulls moved southwards, especially to the Atlantic coast of Morocco. Juveniles behaved differently, moving further south than 2-3y and 4y or older gulls, reaching the Senegambia coast in high percentages (81,8%).” Is it possible that this was at a time when a new generation of young birds was in process of establishing an overwintering tradition in Senegal and The Gambia, returning in subsequent winters? That would explain why there are currently more adults than juveniles.
Two ringed individuals show how birds wintering in Senegal will typically spend their first year around the Cap-Vert peninsula, before moving on to the Saloum delta once they are older: BNH5 was ringed as a chick in June 2011 in the Ebro delta, after which it was seen at Technopole in July 2012, but during its third winter in Dec. 2013 (N. Diop), and again in Sept. 2017, it was in the Palmarin lagoons. AWNV, born in 2010 in Mallorca, was first at Technopole while in its second summer (July 2012), while in 2015 and 2016 it was in Palmarin. Some birds already move to Palmarin during their 2nd winter (e.g. BWU9), or even 1st winter (BPZ9, seen by Simon in January 2013, then by Ngoné in December of the same year and in Oct. 2015, and last month I saw it again. Talk about site fidelity!
All ringed birds recovered from Technopole were at most two years old, though of course there are some older birds and every now and then a full adult will show up. BYPB is a typical first-year bird, seen here in March 2017.
Among the ringed birds that I have found there are quite a few old individuals, the oldest being nearly 20 years old. Indeed, Audouin’s Gull is a long-lived species with a high adult survival rate (and relatively low fertility). The oldest bird I have is from Italy, at 19 years, while from Spain there’s 45P and 66P, both born in 1999; Ngoné had already seen both in 2014 and 2015 in Palmarin; 45P and was again at Palmarin earlier this month, while I saw 66P there last year at the end of August last year.
The little chart below shows the distribution by age at the time of the last sighting, for 43 birds for which I have the ringing year (birds are typically ringed as chicks, usually in June, so we know their precise age). One can clearly see the predominance of birds in their first year (= juveniles and 1st winter), though this is hardly surprising given that these all correspond to Technopole recoveries. I don’t know how to explain the near-absence of two- and three-year old birds.
Ngoné’s systematic visits to Palmarin have resulted in some 500 ring readings, which of course allow for a more thorough analysis than my anecdotal observations. Through modeling the team has estimated annual survival rates and the size of the wintering population in Palmarin, which are summarised in this informative poster presented at PAOC just about a year ago. There are of course also a few interesting individual stories in the lot, such as two Spanish birds that were ringed on the 15th and the 19th of June 2015 respectively, and that were seen within a few weeks after they left their colony (25/8/15 and 15/9/15).
To be continued…
Many thanks to Ngoné Diop for her input!
¹ The oldest bird we have is “FDA”, ringed as a chick in June 1988 (!) at Islas Columbretes, Castellon, and seen in 2015 and 2017 in Palmarin, and in Dec. 2017 in The Gambia.
When I started birding nearly 30 years ago, Audouin’s Gull was one of those near-mythical birds, endemic to the Mediterranean and listed as an Endangered species on the IUCN Red List. Plus, it’s a real pretty gull, much more attractive than the standard “large white-headed gull”. Fortunately, this highly coastal species has seen substantial increases in its breeding population and has (re)conquered new localities, mostly during the nineties.
It is now found in Portugal (where it didn’t used to breed 30 years ago), Spain (where the bulk of the population breeds), France (Corsica), Morocco, Algeria, Tunisia, Italy, Croatia, Greece, Cyprus, and Turkey. The largest colonies are in the Ebro delta (14,177 in 2007) and the Chafarinas islands off NW Morocco (2,700 pairs in 1997). The Ebro colonies now represent about two thirds of the global population, so it is particularly of note that the species wasn’t even breeding there in 1980: Audouin’s Gull established itself in 1981 when 36 pairs bred, with as many as 4,300 in 1990, +10,000 pairs in 1993… and now certainly more than 15,000 (I didn’t immediately find any recent figures).
The species’ global population is now thought to number 63,900-66,900 individuals, with 21,300-22,300 breeding pairs: to write that this is “a significant increase from an estimated population of 1,000 pairs in 1975” certainly is an understatement… This remarkable feat is thought to be a result of the increased availability of effectively protected areas during the 1980s and of discarded fish from trawlers, particularly around the Ebro delta. Although it may still be vulnerable due to its small number of colonies, it was downlisted to “Least Concern” during the 2015 revision of the Red List, previously being considered Near Threatened (2004), “Lower Risk/conservation dependent” (1994), and Threatened (1988) (IUCN). Quite a conservation success story.
Following a good harvest of ring readings a few weeks ago in the Saloum delta, I wanted to find out a bit more about its history, trends, abundance and distribution in Senegal – and decided to turn it into a blog post here. This wasn’t too difficult given that a ton of research has been done on Audouin’s Gull, resulting in decent knowledge on its population dynamics and structure, distribution, breeding ecology, dispersal, feeding and migratory strategies, etc. The main challenge was to identify the most relevant resources and to distill everything into something relatively concise. And for once there’s even fairly abundant literature on the species in its wintering grounds here in West Africa.
First, let’s have a look at historical records of Audouin’s Gull in Senegal, and see if we can reconstruct the trends for the country.
The ’60s and ’70s – the first records for Senegal
We automatically turn to our rapidly deteriorating copy of Morel & Morel (1994), who only list a handful of records – essentially, the first four records for the country:
An immature collected at Saint-Louis, 11/5/61 and an adult seen on Gorée island (Dakar) on 13/3/64; one photographed at “the entry of the Sine-Saloum” [wherever that may be! I assume near the Saloum river mouth?] on 1/2/75, and one record near Dakar at the end of December 1981.
Dupuy (1984) adds the observation of an adult in the north of the Saloum delta on 13/12/80 but this record was either overlooked, or not retained by M&M. Interestingly, De Smet & Van Gompel (1979) did not encounter the species even though they covered large chunks of the coast between lac Tanma and the western Saloum delta, as well as the Senegal river delta, during the 1978/79 winter. This seems to confirm that Audouin’s Gull at the time was still a rare or very scarce visitor here – something which was about to change very soon.
The ’80s and ’90s – establishment of a wintering tradition
Moving on, Sauvage & Rodwell (1998) consider Audouin’s Gull to be “frequent at PNLB (Langue de Barbarie NP) and Saint-Louis, Jan.-Apr. with max. 17 birds, Jan. 1994, nine ringed in Spain. Up to 10 were wintering around Saint-Louis, 1990-91.” It is “frequent to common Dakar off Pointe des Almadies and Toubab Dialao, Jan.-Mar., max. 104 (four ads.), Toubab Dialao, Jan. 1992. Frequent to abundant Saloum delta. Max. 321 wintering.” The latter figure, obtained in 1985 (Baillon 1989) is significant as it is the first mention of a substantial number of birds in Senegal, and can likely be linked to the “explosion” of the Ebro delta colony. In Jan.-Feb. 1988, Delaporte & Dubois counted gulls all along the Senegambian coast, from the Mauritanian border to Casamance, and counted 81 Audouin’s Gulls (6 near Saint-Louis, 3 along the Petite Cote, 72 around Palmarin) though they estimate a total of 130 birds. They also mention the presence of 185 in the northern Saloum (probably Palmarin/Joal-Fadiout) on 6/12/88. Del Nevo et al. (1994) conducted counts in February 1991 and in September-October 1992, noting a total of 459 birds in Senegal and 72 in Gambia (1991), and 276 in Senegal the following year, mainly at Sangomar and Joal-Fadiouth.
A few eBird records from the early nineties provide some more context for that decade, in particular the count of no less than 470 birds at the Somone lagoon on 28/2/91, with two at Mbodiene (south of Mbour) a couple of days earlier, and 12 at Plage de Hann (Dakar) on 18/2/91 (O. Benoist). Bengtsson (1995) reports a minimum of 456 near Palmarin in Nov.-Dec. 1994. Based on these records, it looks like the species became a regular winter visitor to Senegal in the early to mid ’80s, and rapidly established a number of traditional wintering areas during that decade.
The next comprehensive figures are reported by Schepers et al. (1998) based on waterbird counts from January 1997 in the Saloum delta and along the Petite Côte. The team counted a total of 858 Audouin’s Gulls between Dakar and the delta, with the majority (673) found in the Saloum, and 185 along the Petite Côte. They estimated the wintering population to number around 1,000 birds, while in 1988 the same areas (incl. Saint-Louis) held at least 80, but more likely at least 130 Audouin’s Gulls (Delaporte & Dubois 1990, though Baillon & Dubois in 1991 estimated the number of wintering birds to be around 500, without providing further details). Regardless, these numbers suggest that Ichtyaetus audouini continued to increase in numbers throughout the late eighties and nineties, and confirmed that Senegal plays an important role for the species during its non-breeding cycle.
2000 – 2017 – stability
Fast-forward a few years to the first decade of the 21st century: hardly any published data! The only citations of the species that I could find are from seawatch sessions and a few trip reports. For instance from 2006, when a Swedish team counted migrating birds off Ngor, from 10–14 and 25–26 November: 28 Audouin’s Gulls were noted on three separate days (Strandberg & Olofsson 2007). A year later, a more comprehensive migration study at Ngor, with impressive numbers of seabirds counted from 5-28 October, resulted in a total of 692 birds. In the Senegal delta, a maximum of c.15 birds were counted in 2002 (Triplet et al. 2014).
In January 2011, some 50 Audouin’s Gulls were counted by Ottvall et al. at Lac Rose, providing “more evidence of the increasing numbers […] wintering along the coast north of Dakar.” Later that year, Paul Robinson reports two 2nd calendar years from Lac Tanma, which seems to be the first mention of the species here (I’ve seen two birds on 28/8/16 here, but not during other visits in 2015-17). Paul also recorded the species in Popenguine, where on 12/2/12 the pond had “a few” Audouin’s gulls amongst the gulls.
In July 2012, Paul counted c.150 Audouin’s Gulls at Technopole, noting that these were “all sub-adult birds from 2010 and 2011, represents a real increase in summering birds south of the Sahara and a West African summer record count. Several had Spanish rings.” Indeed, Audouin’s Gull can now be seen year-round in Senegal.
Ngoné and colleagues estimated the Palmarin “winter” population to number 445 individuals (278 adults, 167 immatures) based on the modelling they performed on their monthly counts and ring recoveries from the end of 2013 up to end 2015. This seems rather on the low end given that at peak times in October they recorded up to around 700 birds, and that in recent years it’s easy to find more than 300 birds together in the lagoons along the Samba Dia road – surely there are many others scattered throughout the western Saloum delta, e.g. around Sangomar and further south. More on the findings of their study, which was presented under the form of a poster at last year’s PAOC, will be discussed further down.
Current distribution in Senegal
The winter range of the species in Senegal probably hasn’t changed much in the last 20-30 years, with the following areas being regularly used by Audouin’s Gulls:
- La Grande Côte: Langue de Barbarie and elsewhere in the Senegal delta around Saint-Louis (shores, beach and lagoons), though never in large numbers, with a maximum of c.65 birds in Jan. 2013 (Triplet et al. 2014). On the southern end of the coast, the species is regularly seen at Lac Rose and sometimes at Lac Tanma. It probably also occurs along the beach throughout (I need to ask Wim about this!), especially around the larger fishing towns and villages: Kayar, Mboro, Lompoul, etc. At Lac Rose, ca. 350 birds were seen on 11/2/18, suggesting that this is still an important roosting site for the species, at least during part of the northern winter.
- Cap-Vert peninsula: Regular at Lac Rose (e.g. c.60 on 8/8/15, 2 on the beach on 22/1/17, 5 on 14/5/17) and Technopole, where most numerous in January-March, but records from all months except for September (when I rarely visit Technopole); so far my highest count has been a modest 50 birds on 12/3/17. Birds are also regularly seen from Ngor, either migrating or, more often, feeding out at sea. In autumn and winter, one should be able to see Audouin’s Gull pretty much all along the coast from the Pointe des Almadies along Yoff all the way to Lac Rose. I really need to check out the Hann bay from time to time, as there are often lots of gulls and terns. The species has also been reported from Yene-Bargny where is likely still a regular visitor, and may well be numerous at times (in autumn maybe? Birds may favour Technopole later in winter).
- La Petite Côte: the Somone lagoon seems to be the most regular site, but birds also show up at least irregularly at Popenguine and Mbodiene, and likely feeds off-shore along the entire coast here.
- Saloum delta: this is of course the main wintering area, that likely holds about 80% of the Senegalese wintering population. Birds are typically concentrated in the lagoons to the north of Palmarin, and do not gather far inland. It should also occur further south in the delta but I have no data from there.
- Coastal Casamance: the only record I know of is of two birds on 12/10/16 flying north along the beach at Diembering. There certainly are more records (though none on eBird nor observado.org) as Casamance must be the far end of their regular range, given the absence of sightings in nearby Guinea-Bissau.
In terms of population size, my own conservative guestimate puts the current number on 800-1,000 birds, so not any different than the 1,000 birds estimated to winter in Senegal in January 1997, which logically reflects the species’ stable global population trend.
Elsewhere in West Africa
Isenmann et al. (2010) enumerate lots of records for Mauritania, but little or no info is provided on the evolution of the wintering population in the country, probably because of a lack of historical data. The current status is that of a regular migrant and wintering bird, with at least several hundreds of birds along the coast. Far more birds are said to winter along the Western Sahara coastline. The Gambia is also part of its regular winter range, mainly on and around the Bijol Islands, Tanji Bird Reserve. In 2007/08, about 500 Audouin’s Gulls were counted there. The first Gambian record, as per Morel & Morel, is of a bird at the Bakau Lagoon on 21/2/82.
Surprisingly, the species hasn’t yet been seen in Guinea-Bissau, which is most likely right outside the regular winter area, but surely a few individuals must reach the NW corner of the country, and particularly the Bijagos, given that they are recorded at least from time to time (it would seem) in Casamance and that Gambia is less than a 100 km away from the border. My Oct. 2016 observation near Diembering was barely 20 km from the border and both birds were moving north… In Guinea, the first record was obtained just last year by gull expert Peter Adriaens, a first-winter near Cap Verga on 28/10. The lack of other records from Guinea (and Guinea-Bissau) most likely reflects the absence of observers in the country, rather than a real absence of Audouin’s Gull which surely must at least from time to time reach Guinean waters. This is not the case in relatively well-watched Ghana, where the species is a true vagrant: a first-winter on 13/1/14 was quite an unexpected first for the country, as it had not previously been reported south of Senegambia (Kelly et al. 2014). [note that the species certainly doesn’t winter in Gabon, contra BirdLife International’s species fact sheet].
Now, I still wanted to talk about the origin of wintering birds in Senegal and summarise current knowledge based on ringing recoveries, but my blog post is already getting a bit long… that part will have to wait for a second installment, hopefully a week or two from now.
A pleasure of Technopole for Dakar birdwatching is the easily visible, sometimes unpredictable change in birds. Some of this is seasonal, with regional and continental migration, but I suspect there is also a lot of local movement of birds between here, the other nearby lakes of the Niayes and the coast. The first visit of the year on 8 January also produced four puzzles.
On our last visit all the gulls were inter-African migrants. Today, they were all of European or at least Mediterranean origin; several hundred lesser black-backed and black-headed gulls and 40+ Audouin’s gulls. The Audouins were a mix of ages, though mostly first and second calendar year birds, with only one adult. The preponderance of young birds around Dakar is also noted by observers at the seawatching point of Ile de Ngor, whilst adults dominate the large roost at Palmarin, 100km to the south. This split of age classes is a mystery.
Amongst the usual wader species five avocet were new and c350 black-tailed godwit was a good count. The godwits were ignoring the water and feeding on short, dry grassland. The current knowledge is that most of the godwits wintering along the West African coast, mainly Dutch breeders, move rapidly to the rice fields of Casamance and Guinea Bissau and remain there until moving back to the Netherlands via the Iberian peninsula rice fields, so it is interesting to find hundreds in Dakar in January, not feeding on rice grains. Interest in the species has grown recently due to its population decline and classification as globally Near Threatened.
The Technopole list increased to 164 with three not very surprising additions; woodchat shrike, chiffchaff and redstart. More interesting was this lovely southern grey shrike. This is a species that is probably being seen more often south of 15 degrees north than formerly in Senegal – Morel has only two records up to 1980 from these latitudes, when it was frequent further north. From the limited literature to hand here, it is difficult give this bird a sub-specific identification. Three sub-species breed in Mauritania. Senegal birds are assumed or known to be elegans of the central and northern Sahara. Our bird would fit this with the lack of a strong white line above the black mask (white is confined to a small eyebrow), but not with elegans’ pure white underparts. This bird is grey at least on the side and the white eyebrow is not a feature visible in the field. This would point to algeriensis, the breeding species of NW Africa down to coastal NW Mauritania, not yet recorded in Senegal. This will need further checking!
Puzzle four was what hundreds (low thousands?) of yellow wagtails had found to eat. The very bad photo (mine) shows birds perched in bushes of Prosopis juliflora.
This small tree is itself interesting. It is related to acacias, but native to Mexico and further south in the New World. It is a popular, but sometimes invasive introduction to poor soils in the Sahel across to Ethiopia, with a large scientific literature on its usefulness. At Technopole, with no livestock to eat the pods, which look like green beans, it just seems to be ornamental. It had a huge number of flies, whilst most of Technopole lacked flying insects. The wagtails were feeding on, and in aerial capture from, the bushes, the leaves of which were covered with their droppings.
Yesterday morning, (August 3), as a treat I took the pirogue to Ile de N’Gor on the second day of Ramadan and sat on a favourite rock for two hours, seawatching at the famous point.
Early August is not a period people have watched here, so anything would be interesting, though my expectations were not high, having seen very few seabirds during the last three weeks from the apartment or on trips to the beach fish market at Yoff. I was unfortunately not surprised, seeing only less than a hundred royal terns flying in no dominant direction, single figures of Sandwich tern and white-breasted cormorant and no birds fishing. The tern roost at Calao remains empty.
In the early evening the first big rains of the year reached Dakar, causing a river outside the apartment. Today the morning visit to Technopole saw a big increase in water levels and waterbirds, though some of the waders might just be squeezed into fewer suitable shallow waters. Amongst the big birds, the main increases were in great white egrets (400+) and pink-backed pelicans (c80). Ruff and wood sandpiper each passed 100, though black -tailed godwits were fewer than recently.
The picture shows a typical view of wood sandpiper in the wet grassland fringing the main lake. New wader species were a juvenile kentish plover (new species for Technopole) and a female painted snipe, for which I eventually got this poor record shot.
The female is the colourful partner in this polyandrous species, laying eggs in several nests where all incubation is done by the males.
The small group of gulls and terns included the now regular two Franklins gulls, a first summer/second winter Audouin’s gull, but new for this season for me a white-winged black tern and a first winter little tern. As with roseate tern, discussed in the previous blog entry, the ageing of terns in West Africa at this time of year is not always obvious. This bird, for which I have no photo, had a strong dark carpal bar, but what would a first summer bird look like? Is there a distinct first summer plumage? There is a small breeding population, not always located each year, in the Sine Saloum, which it seems reasonable to think is the area of origin of many of the gulls and terns dropping in here. It is intriguing and frustrating to wonder what could be being seen along the rest of Senegal’s coast at the moment, while no-one is watching!
This very approachable green-backed heron in breeding plumage (red legs, yellow around eye (lores) , all black bill) fishing rounded off the visit.
p.s. This evening my first flock of returning whimbrel (18) flew high along the beach at Yoff Tonghor.
p.p.s. 5 August at Technopole produced a rather similar collection of birds, with c500 great white egrets and 150 pink-backed pelicans in the western corner, one of the Franklin’s gulls, 1 roseate tern and 2 first summer/second winter Audouin’s gulls in the gull and tern flock and a female painted snipe near where yesterday’s bird was seen.