Fig trees (Ficus spp) produce fruit year-round and figs are consumed by a large proportion of frugivores throughout the tropics. Figs are potential keystone resources that sustain frugivore communities during periods of scarcity, but studies have produced contradictory results. Over 1 y we monitored the phenology of 206 trees of five Ficus species in a Colombian cloud forest, to test whether figs produced fruit during periods of low overall fruit availability. We also measured fig tree densities in 18 0.5-ha plots and made 190 h of observations at 24 trees of three species to determine whether figs were abundant and consumed by a large proportion of the local frugivores. The five species produced fruit year-round but fig availability varied monthly by orders of magnitude. Fig trees reached comparatively high densities of 1–5 trees ha−1 and were consumed by 36 bird species (60% of the local frugivore assemblage) and three mammal species. However, there was no season of fruit scarcity and figs represented on average 1.5% of the monthly fruit biomass. Figs in this Andean forest are part of a broad array of fruiting species and at least during our study did not seem to constitute a keystone resource.

The importance of figs as keystone resources depends partly on their year-round fruiting pattern. However, most non-equatorial fig species show seasonality in reproductive phenology. If fig and other species' fruiting peaks coincide, the importance of figs as key resources during lean fruiting periods may be reduced. Fig and other forest tree phenology was studied in a deciduous and an evergreen site in the Western Ghats, southern India, from January 1991 to May 1992. In the deciduous site, most non-fig flowering and leaf flushing occurred during the two dry seasons, while most fruiting occurred during the dry and early wet seasons. In the evergreen site, all non-fig tree phenological stages – flowering, fruiting and leaf flushing – were concentrated during the two dry seasons annually (dry and post-monsoon). Individual fig trees produced crops one to three times annually, at different times of the year for different trees. Fig community fruiting peaks in the evergreen site coincided with fruiting peaks of the other forest trees, but in the deciduous site occurred slightly offset from non-fig fruiting peaks. The role of figs as key resources is likely to differ among forests, and to depend on factors such as diversity of fruiting pattern among fig species, fig tree density and territoriality of frugivores.

We analysed the selection of tree species consumed by an isolated troop of Mexican howler monkeys (Alouatta palliata mexicana) released in a translocation programme on Agaltepec Island, in Catemaco Lake, Veracruz, Mexico. During November 1989–December 1996, howlers used 36 of the 63 tree species present on the island as food. Selection ratios indicated that six Ficus species (particularly F. pertusa) were among the seven most important food species. Data on time spent feeding showed that the six Ficus species were among the eight most important food species for the monkeys. Howlers spent 64.2% of their feeding time on Ficus products with F. pertusa being consumed significantly more often than foods from other Ficus species. However, monkeys fed on only one third of the 81 adult Ficus trees on the island. No significant differences were found in various food constituents (water, ash, fibre, protein, carbohydrates, lipids) of the six Ficus and two other abundant species in the habitat, whether across species, plant parts (young leaves, mature leaves, fruits), or between seasons (wet, dry). Monkeys consumed Ficus fruits rather the leaves. Fruits showed a much higher energy content per g dry weight than leaves. We also estimated the average daily biomass of leaves and fruits of Ficus spp. consumed by howlers and their energetic contribution to the daily diet of these monkeys. We suggest that some of these tendencies to frugivory reflect the abundance of Ficus trees within the home ranges of the howlers; when few fig trees are present, folivory is the dominant tendency, whereas when many fig trees are present, frugivory is dominant.

Infestation rates by palm bruchid beetles (Bruchidae: Pachymerini) on Attalea palm seeds are so high that most endocarps remaining near parent trees contain larvae rather than endosperm a few months after the peak fruiting season. Vertebrates feeding on palm endocarp contents may therefore be feeding on animal rather than plant matter, and the timing of use of endocarps may be influenced by the presence of larvae rather than by background fruit availability. On Maracá Island Ecological Reserve, Roraima State, Brazil, white-lipped peccaries (Tayassu pecari), agoutis (Dasyprocta leporina) and squirrels (Sciurus igniventris) all fed on bruchid beetle larvae from Attalea maripa palm endocarps. Squirrels fed on both larvae and endosperm year-round in all habitat types; agoutis fed on both larvae and seeds only at times and at sites where alternate foods were not available; and white-lipped peccaries fed almost exclusively on bruchid larvae in high-palm-density habitats. Differences in timing and location of endocarp use by these species may provide an index of mammal community dynamics in neotropical forests.