Identification: The Egyptian vulture (Neophron percnopterus) is a medium-sized scavenger (average biometrics: size: 55-65 cm; wingspan 155-170 cm; weight ± 2kg). The Canarian subspecies (N.p. Majorensis) is significantly larger than the nominal subspecies (N.p. percnopterus, i.e., about ± 0.5 kg heavier and wings are ± 20 cm longer, Donazar et. al 2002). In flight birds can be easily recognized by long and rectangular wings, a sharply wedged tail and a narrow pointed head. Older individuals show diagnostic plumage in black and white (Forsman, 2016). In general, three distinct plumage-types can be recognized: dark plumage (juveniles), a paler milk-coffee coloured plumage (often mottled) (immatures 2-3 years old) and adult plumage (white, > 4 years, see pictures below, click to enlarge). With close views it is possible to distinguish between 5 plumage-types (see Forsman, 2016). Exact aging according to plumage is often inaccurate because individual-specific moult patterns (M. de la Riva, pers. comm.).
Foraging: Egyptian vultures on Fuerteventura forage solitary, or sometimes in couples. They mainly feed on small and medium-sized (vertebrate) carcasses, but also eats insects and young vertebrates and may scavenge on various kinds of litter, including vegetable matter. They are also frequent visitors of rubbish dumps. A detailed study on the diet of Egyptian vultures on Fuerteventura, based upon 523 pellets, revealed 19 different species of prey: 42,3% dead domestic mammals (96,9% goats) and 39,7% domestic birds (pigeons and chickens). Wild preys were consumed in much lower frequency (16,2%) and included small mammals, birds, insects (beetles, ants and Hemiptera) and even terrestrial molluscs (for details see Medina F.M. 1999).
Migration: As opposed to birds from continental Europe and Asia, Egyptian vultures on Fuerteventura and most other island populations are non-migratory. Very sporadically, continental migrants seem to arrive to the Eastern Canary Islands and interbreed with local birds as was demonstrated by means of genetically analyses (Agudo et al 2011). Migrants from Europe, Western and Central Asia winter predominantly in the Sahel zone (Thiollay 1989; Mundy et al. 1992). First results from GPS-studies suggest that European birds have different overwintering areas: Egyptian Vultures from Spain and France seem to mainly overwinter in Mauritania (Meyburg et al. 2004; Garcia-Ripollés et al. 2010), Italian individuals in central-east Mali (Ceccolini et al. 2009) and the wintering grounds of the Balkan population are mainly in Chad and Sudan, and occasionally in Niger, Nigeria, Ethiopia and Yemen (Meyburg et al. 2004). In the past, wintering Egyptian Vultures formed large congregations, but such groups are now rare (but see Arkumarev et al. 2014 for observations in Ethiopia).
Roosting: Egyptian vultures roost communally throughout its entire range, often in trees (Ceballos and Donázar 1990) and near easy accesible food resources (e.g., Donázar et al. 1996). In areas without trees, such as Fuerteventura, they typically use electricity pylons for roosting, which determines that accidents in power lines are the main cause of non-natural mortality (Donázar et al. 2002) as occur in other arid African regions (Levy and Mendelsohn 1989, Angelov et. al 2012, Arkumarev et al. 2014). On the picture on the left, note the juvenile bird roosting underneath the other birds. The plumage of these subordinate birds is often covered with bird droppings, indicating that position in the roost may incur costs in terms of reduced feather quality.
Mating system: In most populations individuals engage in monogamous relationships and form long-term pair bonds. However, with increasing densities on Fuerteventura, Egyptian vultures show remarkable flexible mating strategies, including both polygenous and polyandrous trios (one male with two females and one female with two males, respectively, see pictures below (click to enlarge)). In one occasion, the same pair formed polygenous and polyandreous trios in different years. Promiscuous mating behaviour has also been observed with some males actively seeking for extra-pair copulations (Donázar et al. 1994, Roldan J. and van Overveld M. pers. obs.). While polyandrous trios are a common phenomenon in the closely related Bearded vultures (Gypaetus barbatus), particularly in the Spanish Pyrenees (e.g. Carrete et al. 2006), the occurrence of both polygeny and polyandry in the same population has not previously been described in other vulture species.
Breeding: Nests are built on ledges or in caves on steep cliffs. In the past, when population numbers were much higher, nesting locations may have been more close to human areas. A record of a pair having a nest on the ground on Fuerteventura (Gangoso and Palacios 2005), indicates that under some conditions they may be highly flexible in their choice of breeding location. They usually lay two egg, on Fuerteventura often only one, between March and April. Fledgling of young occurs in June/July. On mainland Spain, parents provide care to their young for 9-34 days after fledging, during which they sometimes move to specific feeding sites (Donázar and Ceballos 1994). On Fuerteventura the period of postfledging care could be longer since birds are not constrained by the timing of a migratory journey.
Tool-use: Egyptian vultures are among the few bird species that have been observed manipulating objects to use as tools to exploit food resources. Well-known is their use of stones to break the eggs of Ostriches (Struthio carnelus)(Lawick-Goodall and van Lawick (1966). Although this behaviour was first described in Egyptian vultures living in the Serengeti region, further observations revealed similar egg-breaking behaviour in areas without Ostriches. In fact, even captive birds are capable of picking up stones to break eggs, indicating this to be an innate behaviour. Interestingly, recently a pair of Egyptian vultures was observed using stones to break the egg of an Griffon vulture in Northern Spain (Barcell M. et al. 2015). Albeit anecdotal, it shows that this behaviour may be a relevant aspect of their foraging behaviour. Another case of tool-use has been described in Bulgaria, where birds were observed to use twigs to round up wool to facilitate the collection of nesting material (Stoyanova et al. 2010).
Coprophagy: Another peculiar behaviour of Egyptian vultures is their habit of coprophagy, which gives them the Spanish names of “churretero” and “moñiguero”, meaning “dung-eater”. The consumption of faeces is very uncommon among birds, most likely because these substances have very low nutritional value (Negro et al. 2002) and often contain parasites (Hutchings et al. 2001). However, some faeces may contain high levels of carotenoids, particularly those from ungulates grazing on fresh green pastures. In addition, Egyptian vultures are among the few Old World vulture species displaying a brightly ornamented facial skin, which is yellow-coloured by carotenoid pigments. Experimental work by Negro et al. (2002) indeed showed that access to carotenoid-rich feces influenced the expression of the yellow face, indicating that the habit of eating feces has evolved in function of cosmetic purposes. Apart from this, vultures are often found to feed on human feces, which provide an important service to humans living in villages without sewage systems by reducing the risk of infectious disease transmission (Gangoso et al. 2012).
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