Bone Breaker

A dassie (Procavia capensis) in Hermanus, South Africa,
a prey item of G.barbatus (User: Amada44, 2009).

This time we’re going to go and look at a raptor with a rather unique diet, Gypaetus barbatus otherwise known as the lammergeier or bearded vulture. The species has somewhat of a patchy distribution from Western Asia all the way to East Africa and even some in South Africa (Ferguson-Lees and Christie, 2001). So, you might be wondering about the title of this post, although you could say that yeah, falcons break the necks of their prey with their beaks or that eagles and hawks sever the spinal cord of their prey with their talons, but none of them EAT the bones! That’s right, G.barbatus aside from carrion as part of their diet, they also eat bones as a large part of their diet as well as tortoises (Ferguson-Lees and Christie, 2001). The way G.barbatus goes about eating these bones is something seen across several bird species as a way to break seeds or kill prey, if the bones are small enough the lammergeier will swallow it whole, however if the bones are large then what they do is take it up high (up to 150m) and drop it on hard rocks to break it (Ferguson-Lees and Christie, 2001). They may also smash the bones on the ground while holding onto it in the beak (Ferguson-Lees and Christie, 2001). What do they do with the tortoises? I hear you ask, well tortoise shells are quite hard and they treat them like bones, meaning they’ll take them up high and drop them onto rocks to kill them, they also do this with the super cute rock hyraxes, also known as dassies (Procavia capensis) (Ferguson-Lees and Christie, 2001). Aside from this, in my opinion the most amazing thing is that lammergeiers will use the bone-dropping sites known as ossuaries for decades, probably centuries and large mammals have been known to be attacked by beating wings until they fall off cliffs and die (Ferguson-Lees and Christie, 2001).

A G.barbatus in Gran Paradiso National Park (User: Aangelo, 2014)

Unfortunately though these birds’ populations have declined in the last 2 centuries especially in Europe (Godoy et al., 2004). The species is listed as near threatened by IUCN red list but was close to extinction in Europe and is locally extinct in many countries (Godoy et al., 2004, BirdLife International, 2014). Genetically there are two distinct populations by analysing mitochondrial DNA, a European lineage and an African Lineage, due to the bottlenecking of the population in Europe the population have lost tremendous genetic diversity making it important to protect the remaining European populations (Godoy et al., 2004).

BIRDLIFE INTERNATIONAL. 2014. Gypaetus barbatus [Online]. The IUCN Red List of Threatened Species. Version 2014.3: The IUCN Red List of Threatened Species. Available: www.iucnredlist.org [Accessed 10 May 2015.

FERGUSON-LEES, J. & CHRISTIE, D. A. 2001. Raptors of the world, Houghton Mifflin Harcourt.

GODOY, J. A., NEGRO, J. J., HIRALDO, F. & DONÁZAR, J. A. 2004. Phylogeography, genetic structure and diversity in the endangered bearded vulture (Gypaetus barbatus, L.) as revealed by mitochondrial DNA. Molecular Ecology, 13, 371-390.

USER: AANGELO 2014. Gypaetus Barbatus.

USER: AMADA44 2009. Rock Dassie 005.