February becomes March, and the winter weather still fails to vacate the British Isles. As winter fails to leave our shores we fondly remember last week’s issue featuring the Glass Catfish. This week we meet a bird of prey with a seemingly unique portion of its diet, hope you guys enjoy. _________________________________________________________________
Issue #163 – Palm-Nut Vulture
Kingdom – Animalia
Phylum – Chordata
Class – Aves
Order – Acciptiriformes
Family – Acciptitridae
Genus – Gypohierax
Species – angolensis
Related Species - The Palm Nut Vulture is the only member of the genus Gypohierax
Not your average Culture Vulture
The Palm Nut Vulture is among the smallest of the old world vultures, with a body length of 60cm and a wingspan of 150cm. This species of vulture has white plumages with the exception of the dark feathers on the tips of the wing. Unlike the majority of other vulture species, the Palm Nut Vulture’s head is completely feathered save for a dark red patch of skin around the eyes. Like the rest of its kin, the Palm Nut Vulture has no feathers on its feet, a feature shared by other birds of prey that feed on carrion or catch fish and other aquatic animals. The Palm Nut Vulture is a powerful filer, and flies predominantly via powered flight, then by soaring on thermal updrafts like larger vultures.
Unlike many other birds of prey the Palm Nut Vulture is an omnivore, with around half of its diet consisting of the fruit of the oil palm (Elaeis sp), and can even feed on this resource when hanging upside down from a branch. The remainder of its diet consists of bats, fish and crabs, something that accounts for the bird’s alternate name, the Vulturine Fish Eagle (2). This species only occasionally can be found feeding on carrion when food is scarce, and is often the last species of vulture to gain access to a corpse due to its small size.
Palm Nut Vultures display to their mates in a synchronised flight by rolling and diving from to show off their strength and speed. The pair of vultures then create a large scruffy nest in the boughs of a tree before laying a single egg, something that both the parents incubate until it hatches (3). After three months the vulture chick fledges, and then leaves the nest to find its own food, becoming sexually mature after four years, where their brown feathers become the white plumage of the adults.
CSI Ecology: The Case of the Dead Vulture
The Victim is an adult female Lappet-Faced Vulture (Torgos tracheliotos) found a few meters away from the body of a dead African Elephant (Loxodonta africana). There are no visible wounds on the vulture, and while fairly old, she seems to have been in good health prior to her death, showing no signs of disease, and pristine plumage albeit a little bloody presumably from feeding on the elephant.
It should be noted that the elephant itself appears to have been killed by poachers due to the sawn off tusks, gunshot to the head and the pair of poison tipped arrows shot into its flank.
The ‘Crime Scene’
The body of the dead African Elephant takes up much of the glade in the scrubby savannah where the two animals died. The body of the elephant is not yet badly decomposed, and has been here for a few days. Signs of at least two vehicles including spilled fuel and tyre tracks are visible, showing signs that humans, possibly poachers, have been in the area. The only other significant feature is an acacia tree that has been damaged, possibly by the elephant as it tried to flee from its killers.
As with any corpse left in the African Savanah there are signs of multiple scavengers having visited the body of the elephant. Tracks indicate that lions (Panthera leo) jackals, hyenas, marabou stork (Leptoptilos crumenifer) and monitor lizards have all been in the area, and bite wounds correlating to all said species are evident on the elephant. In addition the sky overhead features vultures circling over the body, with the birds waiting patiently for you to leave.
In addition to these predators it should be noted that humans in the form of poachers, have been in the area. As well as these signs the shed skin of a green mamba (Dendroaspis angusticeps) was found near the broken acacia tree, suggesting that the snake may have been taking refuge inside before it was uprooted.
After much detective work we’ve narrowed down the cause of the vulture’s death to one (or more) of the following causes;
a) The poison on the arrows that killed the elephant contaminated the body, killing the vulture when it fed on the body.
b) The vulture died after its stomach burst from overfeeding on the body of the elephant.
c) The vulture came across the green mamba after it finished feeding and was bitten on the leg, quickly succumbing to the serpent’s venom.
d) The vulture accidently drunk from the pool of spilled petrol and was poisoned by the chemicals found in the fuel.
e) The vulture was old, after feeding she fell asleep and died peacefully
f) The poachers deliberately poisoned the corpse of the elephant with insecticide to kill vultures, due to the birds presence potentially alerting park rangers.
The answer to this question will be supplied next week.
2 - Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). "Bats as prey of diurnal birds: a global perspective".Mammal Review
3 - Ferguson-Lees, J. and Christie, D.A. (2001) Raptors of the World. Christopher Helm, London
1 - http://www.hbw.com/sites/default/files/styles/ibc_2k/public/ibc/p/Palm-nut_Vulture_perched.jpg?itok=KCuz4Xsf
2 - http://www.planetofbirds.com/Master/ACCIPITRIFORMES/Accipitridae/maps/Palm-nut%20Vulture.jpg
3 - http://cdn2.arkive.org/media/98/98DC4890-C832-4F22-A0F3-95012F15F5D0/Presentation.Large/Female-palm-nut-vulture-with-palm-fruit.jpg
4 - http://d2qtpn53ex22nh.cloudfront.net/uploads/gallery/lappet-faced-vulture_gallery_1_1.jpg
Well this is a mystery to be sure. Next week things become a little clearer as we hunt down a familiar riparian predator. But until then make sure to critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary
Want more IGTA? For a tougher, altogether meaner looking vulture, click here to see the lordly Lammergeyer. Or to see an eagle with a taste for small children, click here to meet the awesome African Crowned Eagle.