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The status and ecology of the last wild population of Madagascar Pochard Aythya innotata

  • ANDREW J. BAMFORD (a1), THE SEING SAM (a2), FELIX RAZAFINDRAJAO (a3), HANNAH ROBSON (a1), LANCE G. WOOLAVER (a3) and LILY ARISON RENÉ de ROLAND (a2)...
Summary
Summary

One of the rarest birds in the world, the Madagascar Pochard Aythya innotata was thought to be extinct until a small population was found in 2006. Little is known about this diving duck as it had not been studied prior to its decline and disappearance. Its rediscovery provided the opportunity to study this species in the wild for the first time and to assess the viability of this last remaining population. The population is small, fluctuating around 25 individuals, and mainly utilises two small volcanic lakes in the far north of Madagascar. Nesting occurs on only one of these lakes, Matsaborimena. Nest success (76% in 2007–2008) and hatching success (89% in 2007–2008) are both comparable to other Aythya species, but fledging success (4% in 2011–2012) is extremely low. Duckling mortality rates peak between 14 and 21 days old. We propose that starvation is the major cause of duckling mortality. Examination of faecal samples and stable isotope analysis of feathers and potential food items provide evidence that adult pochards are insectivorous, favouring caddis fly larvae. Macroinvertebrate density in the benthos of Matsaborimena is low. Adults spend 38% of daylight hours foraging, mainly in the shallowest water. However Matsaborimena is steep-sided and has no areas shallow enough for diving ducklings to feed. We conclude that these lakes are not good breeding habitat for this species. The Madagascar Pochard’s persistence here and not at other sites is probably due to a lack of the human-induced habitat degradation that has impacted many other wetlands in Madagascar.

Résumé

Un des oiseaux les plus rares au monde, le Fuligule de Madagascar Aythya innotata a été considéré probablement être éteint jusqu'à la découverte d’une petite population en 2006. Peu d’information est connue sur ce canard plongeur étant donné que très peu d’études ont été faites avant son déclin et jusqu'à sa disparition. Sa redécouverte a pu donner l'opportunité d'étudier cette espèce à l'état sauvage et d'évaluer la viabilité de cette dernière population. C’est une très petite population présentant des fluctuations aux environs de 25 individus, et utilise principalement deux petits lacs volcaniques dans l'extrême nord de Madagascar. La nidification a lieu seulement dans un de ces lacs, Matsaborimena. Le succès de nidification (76% en 2007–2008) et d'éclosion (89% en 2007–2008) sont très élevé par rapport aux autres espèces d’Aythya, mais le succès d'envol de caneton (4% en 2011–2012) est extrêmement faible. Le pic de taux de mortalité de caneton est à l’âge de 14-21 jours. Nous proposons que l’insuffisance alimentaire soit la principale cause de mortalité de caneton. L'examen des échantillons de matières fécales et de l'analyse isotope stable des plumes et des produits alimentaires potentiels montrent que les adultes sont entièrement insectivores dont les trichoptères constituent apparemment les aliments préférés. Les études sur l'habitat montrent que la densité des invertébrés benthiques dans le lac est faible. Les adultes passent 38% de leur temps journalier à la recherche de nourriture dans les parties peu profonds du lac. Cependant, Matsaborimena présente des bords abrupts et n'a pas de zones peu profondes qui seraient appropriés pour les canetons de plonger à se nourrir. Nous concluons que ces lacs ne sont pas un bon habitat de reproduction pour le Fuligule. La persistance des fuligules dans ces lacs et son absence dans les autres sites, est probablement due à l’absence de dégradation de l'habitat d'origine anthropique dont que de nombreuses les autres milieux humides à Madagascar ont fait l'objet.

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Corresponding author
*Author for correspondence; email: andrew.bamford@wwt.org.uk
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Bird Conservation International
  • ISSN: 0959-2709
  • EISSN: 1474-0001
  • URL: /core/journals/bird-conservation-international
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