Fruit-frugivore interactions in a Malagasy littoral forest - Universiteit ...

Frugivore guild
RESULTS
Lemurs fed on most fruiting species, their diet comprised 119 plant species. Birds,
rodents, and Pteropus rufus consumed 55, 50, and 39 plant species, respectively.
Different methods of collecting dietary data influenced the outcome of diet lists (Table 2).
In general direct observations (systematic or opportunistic) resulted in the largest
numbers of feeding records. However, five species were difficult to observe. Due to
hunting pressure, observations of P. rufus at night with a headlight were not routinely
possible. Both rodent species could be observed only rarely as they detect the observer
by smell. As explained in the methods, this bias could be limited by systematically
collecting faecal droppings and identifying gnawing marks year-round. Treron australis
and S. picturata were very shy and flew away upon detecting the observer. Moreover
droppings of these bird species as well as of Hypsipetes madagascariensis were found
only rarely. For Alectroenas madagascariensis and E. f. collaris faecal droppings could be
collected more easily, but much less often for the smaller nocturnal lemurs. Characteristic
feeding marks were helpful in particular to identify food species of Coracopsis nigra, both
rodent and all lemur species.
Table 2. Number of consumed plant taxa scored per consumer species is given with
indication of the different methods (O:observations, F: faecal analyses; T: traces). 'Ripeness'
indicates the stage of ripeness (R: ripe, UR: unripe) at which fruit species were consumed.
The effect on seeds by the consumer species is indicated (D: dispersal, N: neutral seed dropping,
P: predation, ?: unknown).
Dietary diversity
N N N
Sampling
effort
Ripeness Effect on seeds
species genera families O F T R UR D N P ?
Treron australis 9 9 9 7 4 0 9 0 9 0 0 0
Alectroenas madagascariensis 18 17 14 16 13 0 18 0 18 1 0 0
Streptopelia picturata 13 13 11 13 0 0 13 0 0 0 0 13
Hypsipetes madagascariensis 21 20 17 21 1 0 21 0 21 2 0 0
Coracopsis nigra 37 32 22 36 2 9 26 24 4 8 36 0
Eulemur fulvus collaris 111 76 43 93 67 21 111 25 100 36 27 0
Cheirogaleus spp. 39 31 20 37 7 24 39 0 28 24 0 0
Microcebus rufus 41 33 24 33 6 25 41 0 27 20 0 4
Pteropus rufus 39 27 21 7 34 5 39 0 37 12 0 1
rodents 50 37 31 3 1 47 50 0 4 2 49 0
Morphological Characteristics
The complete data set of all food species involved mainly large canopy tree species
(59%). Most common plant families are Rubiaceae (10%), Euphorbiaceae (5%), and
Flacourtiaceae, Myrtaceae, Annonaceae, and Areceae (each with 4%). Berries and
drupes were the most common fruit types (83%) with a soft and juicy pulp (62%). Dull
coloured fruits (green, brown, yellow-orange 68%) with odour (65%) made up the majority
of the fruits. Other dominant features were indehiscent fruits with a thin husk (77%) and
seeds could be either protected (54%) or not (46%). The median number of seeds per
fruits was 2 (quartiles 1-4) and median fruit weight was 1.23g (0.49-5.23g), fruit length
was 15.43mm (0.49-5.23mm), and seed length was 8.36 mm (4.85–14.42mm).
Taxonomically, Rubiaceae was the dominant plant family in most diets and
Euphorbiaceae, Areceae, and Annonaceae were important as well but to a lesser extent.
There appeared to be no clear taxonomic preferences within the diet of all frugivores. The
65