De Roma, J. C.

Guix, Juan Carlos

Souza, F. L.

Revistes Catalanes amb Accés Obert

Misc. Zool. 16. 1992 
CONSUMPTION OF DIDYMOPANAX PACHYCARPUM UNRIPE 
FRUITS BY BIRDS IN SOUTHEASTERN BRAZIL 
Unripe fruits frequently contain high 
concentrations of chemical components in 
the pulp that act as palatability inhibitors 
(e.g., tannins) or as toxins (e.g., alkaloids) 
for animals (ROBINSON, 1979; HERRERA, 
1982; IZHAKI & SAFRIEL, 1989; STILES, 
1989). As i t  occurs with leaves, these 
"secondary compounds" may constitute 
defense against predation. In general, at this 
stage of development they are considerably 
more difficult for a vertebrate to digest and 
they may contain toxins that make them 
less nutritive than ripe fruits (see STILES, 
1989). 
Thus, large-scale consumption of unripe 
fruits is  a potentially dangerous and 
metabolically expensive enterprise 
(FREELAND & JANZEN, 1974; FOSTER, 1977; 
STILES, 1989) and under food abundance 
conditions unripe fruits are habitually 
rejected. In this work the consumption of 
u ~ p e  fruits of Didymopanax pachycarpum 
(Araliaceae) are described and its 
implications for the seed dispersaltpredation 
process are discussed. 
During July and August 1990 fruit 
production and fruit removal of D. 
pachycarpum was monitored in a 4ha study 
plot located within the 2.320ha Sertgozinho 
Reserve (2P08' S, 4759' W), State of Sao 
Paulo, southeastern Brazil. The Sertaozinho 
Reserve is composed of four woodlots of 
subtropical and mesophytic secondary forest 
according to the classification of HUECK 
(1956, 1972). The woodlots have a total 
surface area of 675ha, and are separated by 
pastures and plantations. 
246 
Didymopanax pachycarpum trees 
frequently reach heights of 20-26m, forming 
part of the forest canopy or as emergents. 
Nevertheless, they can produce fruits when 
they reach heights of 7-9m. The ripe fruits 
are dark violet with two, three and 
occasionally four seeds, surrounded by a 
thin mesocarp. 
During July and August, only trees with 
green fruits or without fruit were found in 
the Reserve. Examination of seeds showed 
that they were whitish and still soft. 
Seeds of D. pachycarpum (n=136) were 
collected in fresh faeces of unidentified bird 
species under the top of six fruiting adult 
trees. They were put on moist filter paper in 
a covered petri dish. A similar sample of 
seeds (n=140) from fruits picked off a tree 
was placed under the sarne conditions. 
Six months later none of the seeds had 
germinated in either sample. It was assumed 
that the fruits were unripe and that seeds 
were not completely developed. 
In 14 hours of observation seven species of 
birds were seen feeding regularly (July- 
August) on these unripe fruits: Leptotila 
verreauxi, Elaenia flavogaster, Pitangus 
sulphuratus, Tyrannus melancholicus, Turdus 
amaurochalinus, Tersina viridis, and Thraupis 
sayaca. Three other species were observed 
feeding occasionally (during one month): 
Myiozetetes similis, Tangara cayana (July) and 
Nemosia pileata (August). Also, Ramphastos 
toco was seen in the fruiting trees, but fruit 
ingestion was not confirmed. Al1 the above 
species made more than one feeding visit 
during a minimum interval of one hour. 
Although T. amaurochalinus sometimes 
defended the fruiting trees, on some 
occasions more than one species was 
observed eating simultaneously at the sarne 
crown (e.g., T. amaurochalinus + E. 
flavogaster + M. similis). 
Leptotila verreauxi, when consuming 
ripe fruits of other plants, rnay be a 
digestive-predator of developed seeds 
(Guix, unpublished data). In Central Brazil, 
Tangara cayana and Thraupis sayaca were 
observed selecting the ripe pulp of 
Didymopanax morototoni fruits and 
discarding seeds under the mother trees 
(MOTTA, 1990). The other species are 
considered potential seed dispersers of 
Didymopanax spp (KUHLMANN & KUHN, 
1947; MO'ITA, 1990). 
Some of the bird species observed are 
probably passage migrants (T. 
amaurochalinus, E. flavogaster, T. cayana) 
or vagrants (T. melancholicus, P. 
suphuratus, M. similis, T. viridis) that 
exploit the winter fruiting peak of severa1 
plant species in the remanescent woodlots of 
the region (WILLIS, 1979). 
Other birds that often eat fruits of 
different plants were detected in the same 
area dunng the study period, but these were 
not seen eating D. pachycarpum (e.g., 
Columba cayenensis, Hemithraupis 
ruficapilla, Brotogeris chiriri, Pionus 
maximiliani, Trogon surrucura). 
The consumption of unripe fruits of D. 
pachycarpum rnay be a consequence of local 
food scarcity. Between June and September, 
the area was subjected to freezing days that 
induced a subsequent fa11 of leaves, flowers, 
and fruits (ripe and at development) of other 
plant species. The low temperatures and the 
seasonal scarcity of rainfall during this 
penod was not favorable to insect activity. 
Although this subtropical region is subjected 
to freezing in some years, the 1990 winter 
rnay be considered atypical, because of the 
low temperatures (minima below 3°C). 
Under food scarcity conditions, some bird 
communities rnay have been compelled to 
eat unripe fruits. 
The consumption of unripe fruits by 
birds does not necessarily destroy certain 
types of seeds. "Unripe" fruits of Ardisia 
revoluta, largely consumed by Chiroxiphia 
linearis during a period of fruit scarcity, 
rnay genninate almost as frequently as ripe 
fruits (FOSTER, 1977; see also LEVEY, 1987). 
Nevertheless, in most cases, seed predation 
during the predispersal stage (the period 
between ovule formation and seed ripening) 
by the "conventional seed destroyers" 
(parrots and parakeets, seed-eating monkeys, 
fruit-eating pigeons, etc.) rnay decrease the 
number of viable diaspores potentially 
dispersed (JANZEN, 197 1). 
Our data suggest that the fruits consumed 
contained seeds which were still not 
completely developed. In the ecological 
conditions described for the Sertiiozinho 
Reserve during the study period the potential 
seed dispersers could act as predispersal 
seed predators. 
ACKNOWLEDGMENTS 
To Washington M. Ferreira Neto of Departament of 
Biology, F.F.C.L.R.P., USP for Didymopanax 
species identification. To Estaca0 Experimental de 
Zootecnia de Sertzozinho for working permission in 
the area. To Pedro Jordano (Estación Biológica de 
Doñana) and D.J. Levey (University of Wisconsin) 
for comments, criticisms and suggestions. We also 
thank Robin Rycroft of Escola #Idiomas Moderns, 
University of Barcelona for English revision. 
ABSTRACT 
Consumption of Didymopanax pachycarpum unripe 
fruits by birds in southeastern Brazi2.- For two 
months, the fruit production of Didymopanax 
pachycarpum trees was studied in a remanescent 
woodlot of subtropical and mesophytic secondary 
forest at Sáo Paulo State, Brazil. Ten species of 
birds were observed feeding on the unripe fruits. It is 
suggested that the potential seed dispersers could act 
as seed predators of these tree species under food 
scarcity conditions. 
Key words: Frugivory, Seed dispersal, Predispersal 
seed predation, Birds, Unripe fruits, Southeastern 
Brazil. 
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(Rebut: 25 XI 92; Acceptació condicional: 19 N 93; Acc. dejnitiva: 25 V 93) 
Franco Leandro de Souza, Depto de Biologia, FFCLRP, USP, 14040-901 RibeirEo Preto, SP, Brasil (Brazil).- 
Júlio César Roma, Depto. de Zoologia, Museu Paraense Emilio Goeldi, Cx Postal 399, 66017-970 Belém, PA, 
Brasil (Brazil).- Juan Carlos Guix, Unitat de Vertebrats, Dept. de Biologia Animal, Fac. de Biologia, Univ. de 
Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Espanya (Spain). 


Consumption of Didymopanax pachycarpum unripe fruits by birds in southeastern Brazil

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