Thursday, June 6, 2013

[Ornithology / Behaviour • 2013] Fight Club: a Unique Weapon in the Wing of the Solitaire, Pezophaps solitaria (Aves: Columbidae), an extinct flightless bird from Rodrigues, Mascarene Islands

A pair of male solitaires Pezophaps solitaria fight over territory
in the valley of Saint François, Rodrigues.

An artistic reconstruction by Julian P. Hume. |

The solitaire (Columbidae; Pezophaps solitaria) of Rodrigues was an extinct giant flightless pigeon and the sister taxon to the dodo (Columbidae; Raphus cucullatus) from neighbouring Mauritius. The appearance and behaviour of the solitaire was recorded in detail by two observers before it became extinct in the mid 1700s. They described a prominent wing structure termed the ‘musket ball’ (carpal knob), which was used as a weapon and to produce an audible signal by either sex in territorial combat. Our study of subfossil solitaire bones from cave localities shows that the carpal knob formed after skeletal maturity, and reached its greatest size in adult males. We describe the morphology of the carpal knob, including its histology in thin section. It is an outgrowth of the processus extensorius of the carpometacarpus, but differs morphologically from homologous structures in other bird taxa, and thus is unique in Aves. We also compare the pectoral and wing osteology of the solitaire with that of the dodo, which had a similar morphology, but lacked any bony outgrowths on the wing. Furthermore, we suggest some biological and environmental factors leading to the evolution of this remarkable and unique carpal weapon.

Keywords: bird behaviour; intraspecific combat; Pezophaps solitariaRaphus cucullatus; sexual dimorphism; territory


Carpometacarpus of male Pezophaps solitaria with carpal knob

Figure 4. Comparison of adult male and female carpometacarpi of P. solitaria, showing specimens with and without carpal knob. Left side, ventral aspect:
A, male without carpal knob (NHMUK PVA9044); B, male with carpal knob (NHMUK PVA3505);
C, female without carpal knob (NHMUK PVA9046); D, female with carpal knob (NHMUK PVA9045).

Julian P. Hume & Lorna Steel. 2013. Fight Club: a unique weapon in the wing of the solitaire, Pezophaps solitaria (Aves: Columbidae), an extinct flightless bird from Rodrigues, Mascarene Islands. Biological Journal of the Linnean Society.

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