Les fruits dans le régime alimentaire de Penelope marail (Aves, Cracidae) en forêt guyanaise : frugivorie stricte et selective ?

Abstract

The diet of the Marail Guan (Penelope marail) was studied by analysis of the digestive tract contents of birds hunted at different seasons, from 1977 to 1983, in a pristine lowland rainforest along the Arataye river in French Guiana. The characteristics of the fruits consummed, and of the fruiting plants, were given special attention. This guan preys only occasionally upon insects or other invertebrates and feeds almost exclusively on fruits the seeds of which it disseminates. It looks for fruits both in the canopy and in the understorey. Most ingested fruits are black or yellow, soft-skinned, thick fleshy or with a juicy soft pulp, and less than 30 mm wide. They are mostly drupes or berries which enclose 1-4 seeds (usually a single one) less than 15 mm wide and protected within a very hard envelope. They belong to high standing crop plants that are frequent to abundant in the forest. By comparison with the three other large frugivorous bird species (Tinamus major, Crax alector and Psophia crepitans) which were studied at the same time on the same spot, Penelope marail appears to be a selective frugivore. Four plant species account for 75 % of its diet (two of them representing 60 %) which includes 23 plant species, against 80 for the Black Curassow, 55 for the Common Trumpeter, and at least 38 for the Great Tinamou. This selectivity and the role the guan plays in forest dynamics are discussed, particularly in term of foraging behaviour.