Conversion of forests to agricultural land may require many bird species to use resources in fragmented landscapes in order to persist. Pasture trees can make agricultural landscapes more hospitable for birds, but we do not know what factors promote bird visitation to pasture trees. Bird use of 26 focal trees of a common pasture species, Sapium glandulosum (Euphorbiaceae), was examined in three pastures in a montane landscape in Costa Rica to understand factors influencing bird visitation. Bird visits were analysed in relation to pasture tree size, distance from forest edge, degree of isolation and epiphyte load. Foraging resources (epiphyte or tree substrate) were also measured. From May–July 2012, 52 bird species from 20 families were recorded from 926 unique visits. Bird visitation was best explained by tree size, degree of isolation and epiphyte load such that larger, more isolated trees with higher epiphyte loads attracted more birds. Birds preferred food resources from focal trees (51% of visits) rather than their epiphytes (5% of visits). The results corroborate previous findings that mature pasture trees, even when isolated, may contribute more to species persistence than smaller trees.

Conversion of natural habitats to anthropogenic land uses is a primary cause of amphibian declines in species-rich tropical regions. However, agricultural lands are frequently used by a subset of forest-associated species, and the habitat value of a given land use is likely modified by the presence and characteristics of remnant trees. Here we used mark–recapture methods to examine abundances and movement probability of the poison frog, Oophaga pumilio, at individual trees in forest-fragment edges and adjacent pastures in north-eastern Costa Rica. One hundred and forty-seven trees were surveyed at three replicate sites that each included a forest fragment and adjacent pasture. Trees were sampled at distances of ≤30 m into forest and ≤150 m into pastures for Oophaga pumilio, and local environmental characteristics were measured at each tree. We also measured indices of physical condition (size and endurance) of frogs captured in forest edges and in nearby pastures. Analyses of 167 marked individuals showed no difference in per-tree abundances or sex ratios between pasture and forest edges. We found significant interactions between habitat type and leaf-litter cover, tree dbh and number of logs, indicating greater influence of local variables on abundances in pastures. Movement among trees was infrequent and not predicted by sex, size, habitat type or environmental variables. While results of endurance tests did not differ for individuals from the two habitats, frogs captured in pastures were, on average, larger than frogs captured in forest edges. These data indicate that remnant trees are important habitat features for O. pumilio in pastures and corroborate research in other systems that suggests that large relictual trees should be retained to maximize the potential for altered landscapes to provide habitat for native species.

Of all feeding guilds, understorey insectivores are thought to be most sensitive to disturbance and forest conversion. We compared the composition of bird feeding guilds in tropical forest fragments with adjacent agro-ecosystems in a montane region of south-west Ethiopia. We used a series of point counts to survey birds in 19 agriculture and 19 forest sites and recorded tree species within each farm across an area of 40 × 35 km. Insectivores (~17 spp. per plot), frugivores (~3 spp. per plot) and omnivores (~5 spp. per plot) maintained species density across habitats, while granivores and nectarivores increased in the agricultural sites by factors of 7 and 3 respectively. Species accumulation curves of each guild were equal or steeper in agriculture, suggesting that agricultural and forest landscapes were equally heterogeneous for all bird guilds. Counter to most published studies, we found no decline in insectivore species richness with forest conversion. However, species composition differed between the two habitats, with certain forest specialists replaced by other species within each feeding guild. We suggest that the lack of difference in insectivorous species numbers between forest and agriculture in this region is due to the benign nature of the agricultural habitat, but also due to a regional species pool which contains many bird species which are adapted to open habitats.

Transformation of tropical forests is likely to affect seed-dispersal patterns and influence the composition of epiphytic plant communities in human-altered habitats. We tested this hypothesis by carrying out a comparative study of seed influx, survival and growth of transplanted seedlings of epiphytic bromeliads among isolated trees in six pasture areas, six forest edges and six forest sites in a montane area in Costa Rica. In total, 72 traps trapped 1285 seeds over a 2-mo period in the dry season of 2003. For all four investigated bromeliad genera, Catopsis, Guzmania, Tillandsia and Werauhia, the number of trapped seeds in each habitat followed a pattern similar to the number of fruiting individuals in the vicinity of the traps. Traps in forest edges (30) were 1.9 times more likely to collect seeds than traps at forest interiors (30) and pasture trees (12), the latter showing similar probabilities of catching seeds. After 1 y, survival and growth of 3660 transplanted seedlings from three bromeliad species was significantly higher in forest interiors, providing no explanation for the lower abundance of fruiting adults in that habitat. These results suggest that the successful establishment of epiphytic bromeliads in forest interiors is mainly dispersal-limited. If corroborated, differences in abundance among species at each habitat are likely related to differences in growth rates and reproductive success. Further studies on the growth and mortality of seedlings up to the flowering stage, however, are needed.

On clearing fields, Ntumu farmers in southern Cameroon leave some large trees. The seed rain beneath 30 such remnant trees (12 species) was compared with that 10 m away from the edges of their crowns. Of a total of 39 765 seeds recorded in 90 seed traps over 2 y, 73.6% were of species different from the tree associated with each set of traps (‘foreign seed rain’). Seed rain included 100 morphospecies, two-thirds of which possessed endozoochorous seeds. Seeds of the pioneer tree Musanga cecropioides accounted for 71.4% of total foreign seed rain; seeds of this and other animal-dispersed species accounted for 94.5% of the total. Seed rain was 25 times higher beneath remnant trees than 10 m away. Mean species richness of monthly seed rain was three times higher beneath remnant trees than 10 m away. Both fleshy-fruited and wind-dispersed species of remnant trees attracted seed-dispersing animals which greatly enhanced the seed rain; attraction thus did not depend solely on presence of fleshy fruits. Seed rain was lower when human activity in fields was intense and increased during the period of growth of the last crops, which were not usually weeded. Heavy seed rain just before fallow may contribute significantly to regeneration, as does the presence of remnant trees.