Gannets & Boobies

Gannets

Genus Morus
This genus includes three species that are obviously very closely related and sometimes considered to form a superspecies.

  • Northern Gannet Morus bassanus
  • Cape Gannet Morus capensis
  • Australasian Gannet Morus serrator

Distribution

The Northern occurs in the North Atlantic and moves outside the breeding season tot the northern Caribbean Sea and African west coast. The Cape Gannet breeds along the coast of South Africa up to the equator and moves north along both east and west African coasts. The Australasian is a bird from Australia and New Zealand and is more or less sedentary. Since there is no overlap of the distribution it is hardly possible to encounter two species in one region, although a few straggling specimens of the two southern species have been found in each others range.

Osteology

The skulls of all three species are very similar, the Northern Gannet about 20% larger than its most southern counterpart. The Cape Gannet is only slightly smaller than the Northern.



Northern Gannet Morus bassanus, The Netherlands.
Culmen: 97.4 mm; total: 184 mm, unsexed adult.
morus capensis Cape gannet skull dorsal
Cape Gannet Morus capensis, Saldanha Bay, South Africa.
Culmen: 93.3 mm; total: 177 mm, unsexed adult. Courtesey of Marc van Leeuwen
Australasian Gannet skull dorsal Morus serrator
Australasian Gannet Morus serrator, Ahipara, NI, New Zealand.
Culmen: 88.0 mm; total: 166 mm, unsexed adult.

Boobies

Genus Sula
This genus counts six species, all substantially smaller than the Gannets, but otherwise very similar in shape and behavior.

  • Peruvian Booby Sula variegata, South America.
  • Blue-footed Booby Sula nebouxii, Pacific coast of Central and South America.
  • Masked Booby Sula dactylatra, tropical zone of all three major oceans.
  • Nazca Booby Sula granti, Galapagos Archipelago.
  • Red-footed Booby Sula sula, tropical zone of all three major oceans.
  • Brown Booby Sula leucogaster, tropical zone of all three major oceans.


Peruvian Booby Sula variegata, Peru, Photo: Marcello Stucchi
Blue-footed Booby Sula nebouxii skull dorsal
Blue-footed Booby Sula nebouxii, Isla de Plate, Ecuador.
Culmen: 102.8 mm; total: 153 mm, unsexed adult.

Nazca Booby Sula granti, Isla de Plate, Ecuador.
Culmen: 105.5 mm; total: 169 mm, unsexed adult

Brown Booby Sula leucogaster, Peru, Photo Marcello Stucchi

Genus Papasula
One species. A small booby with a slightly hooked bill

  • Abbott’s Booby Papasula abbotti, Christmas Island.

Osteology

  • Skull
  • Flight aparatus
  • Pelvis and legs
  • Vertebrae and ribs

Atlas Osteológico del Piquero Peruano: An interesting publication on the osteology of the Peruvian Booby by Marcello Stucchi

References