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Thiebault A.,Institute Of Recherche Pour Le Developpement | Mullers R.,University of Cape Town | Pistorius P.,Percy FitzPatrick Institute of African Ornithology | Meza-Torres M.A.,Instituto del Mar del Peru IMARPE | And 4 more authors.
Auk | Year: 2014

Seabirds forage in a highly dynamic environment and prey on fish schools that are patchily distributed. Colonially breeding seabirds regularly commute back and forth from their colony to foraging areas and need to acquire information on the location of food before and/or during each foraging trip. The use of conspecifics as cues to locate prey has long been debated, and although the hypothesis was backed up by modeling studies, observations have been contradictory. We deployed GPS devices coupled with micro video cameras on Cape Gannets to observe the social context of foraging seabirds and the influence of conspecifics on the movement of individuals. The Cape Gannets reached their first patch using a succession of flights interrupted by stops on the water, during which the birds were mainly preening. During flight, the birds reacted to conspecifics by changing direction, either flying in the opposite direction of conspecifics that were flying toward the colony or following conspecifics outward. The time to reach the first patch was significantly reduced (by half) when the birds reacted to conspecifics in these different ways, compared with the birds that did not react. The use of conspecifics flying toward the colony to find food is consistent with the hypothesis that colonies can act as a focal place for information transfer, with foragers updating their flying direction when they detect conspecifics flying toward the colony. The fine-scale reaction of seabirds toward each other at sea, and the associated improved foraging efficiency, as well as the division of trips into a succession of flights, constitute elements that indicate the existence and the use of a structured network among foraging Cape Gannets. © 2014 American Ornithologists' Union.

Mandiwana-Neudani T.G.,University of Cape Town | Mandiwana-Neudani T.G.,Percy FitzPatrick Institute of African Ornithology | Kopuchian C.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Louw G.,University of Cape Town | Crowe T.M.,Percy FitzPatrick Institute of African Ornithology
Ostrich | Year: 2011

Modern taxonomies of francolins recognise 41 congeneric species, forming the largest genus of terrestrial gamebirds (Galliformes). Recent molecular, ecological and behavioural studies challenge this view, suggesting that they comprise two unrelated, monophyletic groups. There are 'true' francolins (Francolinus, Dendroperdix, Peliperdix and Scleroptila spp.) that are relatively small, ground-roosting birds, and spurfowls (Pternistis spp.) that are large birds that can roost in trees. This study explores gross morphological and histological syringeal anatomy of francolins, spurfowls and sister taxa to test whether differences are concordant with a molecular-based hypothesis. Differences found were the presence of a shield-versus diamond-shaped tympanum among francolins and spurfowls respectively. The first bronchial half rings are mineralised among francolins except in Dendroperdix sephaena, whereas almost no mineral deposition was observed among spurfowls. Histologically, francolins have a small, rounded pessulus (except in D. sephaena, which has a rounded, larger pessulus) contrary to the larger pessulus observed among spurfowls, which is rounded and triangular in Pternistis capensis and P. natalensis. Both gross and histological similarities within, and differences between, francolin and spurfowl syringes support this division. However, D. sephaena shows intermediate features between francolins and spurfowls. © 2011 Copyright Taylor and Francis Group, LLC.

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