The status of Pied Crow in south-western corner of Western Palearctic

On our recent trip with Avescapes to Morocco 1 May 2017 when driving on the highway E1 in Oum Azza South-East of Rabat we were surprised to spot an unexpected Pied Crow (Fig. 1). The bird flying next to road took height rapidly and after soaring headed North with a Black Kite which apparently was on migration. Therefore we made the conclusion that the crow itself was probably migrating too. Later on, however, it turned out that the land fill of Rabat city is situated very next to the place where the crow was initially seen. More likely has the bird been foraging in the land fill and left the place a bit after noon when we saw it. This doesn’t of course exclude the possibility that it left for migration, but maybe more probable is that the bird after feeding left to roost (or to whatever else a Pied Crow does in the afternoon).

5th Pied Crow in Morocco

Fig 1. Pied Crow in Oum Azza near Rabat 1 May 2017 © Petteri Lehikoinen

Pied Crow is still quite a rare bird in Western Palearctic although observations seem to have increased in during this decade. Many of the observations seem to be deemed as ship-assisted and to categories D & E which are usually out of interest among birders. There are however quite a few recent observations from southern Morocco and Western Sahara where the species has even bred in 2010 (Batty 2010). In Chtoukan, province Oued ed Dahab, 2 birds were first seen in 2009, and 3 individuals (including a breeding pair in 2010) stayed until 2011 (Bergier et al. 2011a,b & 2012). This was apparently the first observation for Morocco and first breeding record for WP.

Quick review through the literature available online present following records. From Morocco other observations include a long staying bird in Mhamid, Eastern Sahara, Morocco (which has been present since November 2015) and also in North Morocco in Fnideq (seen in the town rubbish dip since March 2015) (Fareh et al. 2016). Also there is a recent observation from Khnifiss lagoon in southern Morocco where a bird was seen in January 2017. There is speculations that the bird in Fnideq rubbish dip is the same bird which than in Ceuta (Fareh et al. 2016), northern tip of Africa belonging to Spain, where a bird was seen in July and October 2014 (source: Rare Birds Spain Facebook pages).

There is also observation of Pied Crows on the other side of Gibraltar Straight and even an observation where a bird has been seen crossing it! In November 2013 a bird was found in Playa La Línea de la Concepción and later on moved to Tarifa and again more west to El Palmar. Probably the same bird later on returned to Tarifa in mid-February 2014 and again in early April 2014 to Gibraltar. Last observation from the area is when a bird was seen migrating over the Gibraltar straight from Spain to Morocco on 26 April 2014. Moreover this bird could actually be the same individual which was found couple of months later in Ceuta and again in Fnideq. Although Pied Crow is quite distinctive and often associated with humans, it would be quite uncommon if a single rarity could be followed so well based on different observations. Nevertheless it isn’t impossible and the observations might indeed consider only a single individual (Fig. 2).

Map of pied crow movements

Fig 2. Suspected movements of a single Pied Crow in the Staright of Gibraltar on Nov 2013 to Mar 2015

In Pontevedra, Galicia, Spain a single bird stayed at least from 2006 to 2007. It was paired with a Carrion Crow and they even tried nesting but apparently failed as the nest was found abandoned. Also in A Coruña, Galicia, a long-staying bird was last seen in November 2007 as it was originally found in autumn 2006. There is at least two observations from Portugal, one in late June 2015 from Cape Espichel, Sesimbra (near Lisbon) and another from Porto in late April 2015.

Birds in Gran Canaria mid-June 2004 were suspected to have escaped from a local zoo, yet some years earlier few birds have been reported arriving to the island on a Russian fishing vessel. There is no justification given for the putative origin of escapes, so it remains unclear – at least to me – whether it is speculation or has some more information into it. Again one bird was seen in Gran Canaria airport (Martínez & Barone 2006) and three birds appeared on the island in October 2016 (source: Rare Birds Spain Facebook pages). It is notable that all the European records are from the Atlantic coast, which has probably affected to the general opinion of ship-assisted birds. If I’ve understood correctly the origin of Pied Crows in Spain has been puzzling for quite a while and most likely due to possibility of ship-assistance the species has been placed in category D. There is however a bit funny discrepancy that on the Moroccan side of the border (the bird seen in Fnideq) it is considered to be genuine vagrant (Fareh et al. 2016) but on Spanish side probably human-assisted although it is speculated that we speak of the same bird.

 

Potential of vagrancy

The closest breeding areas known to Morocco are situated in Mauritania South of the latitude 17°N which is 800 km south from the WP’s first breeding in Western Sahara (Batty 2010). It is know that the species has some movement during the rainy season as vagrants are recorded e.g. in Nouakchott (18°N) and Boutilimit (17°28’N) (Fig. 3). If the birds breeding in Western Sahara are genuine vagrants the species does show potential to move larger distances. Another 800 km – as the crow flies – from the breeding site in Western Sahara towards North-East would take a bird already to Agadir in western coast of Morocco. There’s still distance to Gibraltar Straight, but again, corvids are quite capable travelers despite their normally sedentary nature. For example with ring recoveries Finnish Hooded Crows are shown travelling up to 2000 km (Valkama et al. 2014) and on the other hand Carrion Crows have been seen as vagrants as high up North as in Finnish Lapland 1500 km away from the nearest breeding sites in southern Sweden (where it is very scarce breeder). It is hard to believe that the bird in Mhamid, far inland of southern Morocco, would be ship-assisted and if it wasn’t an escape of any other kind it would be nearly 1500 km away from the normal range of the species.

Map showing Pied Crow observation in Western Palearctic

Fig. 3. The observation sites of Pied Crow in southwestern WP and sites of known vagrancy outside  normal breeding range

Despite there is at least one observation of a proved escape in Spain, in Tarragona where colour-ringed bird originating from Barcelona Zoo was seen in March 2011, there is also an observation, which might support possibility of natural vagrancy overseas. In late-November 2002 a bird appeared on a longline fishing vessel out in the sea (25°51’390”N 16°42’132”W) between Western Sahara and Canary Islands, over 100 nautical miles from both (Martínez & Barone 2006). After couple of hours stay the bird disappeared from the boat. In Punta de la Aldea, Gran Canaria a bird was seen on 24-31 December 2002 (Anonyme 2003). It might consider the same individual (Martínez & Barone 2006), although around this time the Russian-vessel-transported few individuals were reported.

What it comes to ship-assisting the Association of European Records and Rarities Committees (AERC) guidelines are that (1) Only species considered capable of making an unassisted crossing should be accepted in cat A (otherwise cat E) and (2) Individuals that are known to have been provisioned, sheltered or retrained in any way should not be accepted in cat A (but cat E indeed) (AERC 2009). So as itself, presence on a ship and ship-assistance would not exclude classifying such observation into category A, but only if the bird has intentionally been helped by people or it wouldn’t obviously make the trip by its own. Of course judging which species are capable of flying long distances overseas is not straightforward. Nevertheless I presume that a journey to Canary Islands would be easier for a crow than a journey over the whole Atlantic for a North-American sparrow (of which many species are placed in category A in European countries). It may not be coincidence that observations of many North-American passerines have become more common since late 1900s when trans-Atlantic shipping has increased significantly. Moreover one may ponder if ship-hopping is much different from other human induced changes in the environment (for example human settlements in Sahara) which can aid species to reach new areas.

 

Literature:

Anonyme 2003: Western Palearctic News. — Birding World 16(1): 9-13.

AERC 2009: Minutes of the 8th Conference of European Records and Rarities Committees in Blankenberge, Belgium (Nov 27-29 2009).

Batty, C. 2010. Pied Crows in Western Sahara, Morocco. — Dutch Birding 32(5): 329.

Bergier, P., Qninba, A. & Thévenot, M. 2011a: Notes naturalistes au Sahara Atlantique marocain – 3. — Go-South Bulletin 8 : 67-103.

Bergier, P., Franchimont, J., Thévenot, M. & la CHM 2011b: Les oiseaux rares au Maroc. Rapport de la Commission d’Homologation Marocaine, Numéro 16. — Go-South Bulletin 8: 1–20.

Bergier, P., Franchimont, J., Thévenot, M. & la CHM 2012: Les oiseaux rares au Maroc. Rapport de la Commission d’Homologation Marocaine, Numéro 17. — Go-South Bulletin 9: 13–32.

Fareh, M., Franchimont, J., Maire, B. & la CHM 2016: Les oiseaux rares au Maroc. Rapport de la Commission d’Homologation Marocaine, Numéro 21. — Go-South Bulletin 13: 18–35.

Martínez, J.M. & Barone, R. 2006. Observation d’un Corbeau Pie Corvus albus en haute mer près des îles Canaries et du Sahara occidental. — Alauda 74 : 275-276.

Valkama, J., Saurola, P., Lehikoinen, A., Piha, M., Sola, P. & Velmala, W. 2014. Suomen Rengastusatlas Osa II – the Finnish Bird Ringing Atlas Vol II — Luonnontieteellinen keskusmuseo ja ympäristöministeriö.

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