Annual rings are not commonly produced in tropical trees because they grow in a relatively aseasonal environment. However, in the subalpine zones of Hawaiʻi's highest volcanoes, there is often strong seasonal variability in temperature and rainfall. Using classical dendrochronological methods, annual growth rings were shown to occur in Sophora chrysophylla, a native tree species on Maunakea, Hawaiʻi. Chronologies were established from nearby non-native, live conifer trees and these were used to verify the dates from a total of 52 series from 22 S. chrysophylla trees, establishing an 86-y chronology (1926–2011). Ring-width patterns were significantly correlated with monthly rainfall from August of the previous year. This study is the first in the eastern tropical Pacific region to demonstrate annual growth rings in trees.

Amphibian populations have been declining worldwide, with multiple potential causes. At La Selva field station in north-eastern Costa Rica, previous work has shown that populations of many amphibians have decreased significantly since the 1970s, especially in primary forest. Starting in 1998, we investigated one of the most common frog species at La Selva, the poison-dart frog Oophaga pumilio (= Dendrobates pumilio). In a survey of 50 plots of 100 m2 in 1998, adult frogs were 4.6 times more abundant in secondary forest than in primary forest. Tadpoles were found only in secondary-forest plots. Almost all (89%) of the tadpoles were found in leaf axils of Dieffenbachia spp., which were much more abundant in secondary-forest than in primary-forest plots. The greater abundance of Dieffenbachia spp. in secondary forest was confirmed in a broad survey of ~11 km of trails within La Selva in 2002. When the same trails were resampled in 2012, Dieffenbachia spp. had been extirpated from 72% of the 50-m segments where plants were present in 2002; abundance was greatly reduced in the few trail segments where any Dieffenbachia spp. remained in 2012. The loss of Dieffenbachia spp., especially in secondary forest, removed the species most often used by O. pumilio for tadpole rearing. Based on counts of calling frogs in 2010, there was no difference in O. pumilio abundance in primary versus secondary forest, in striking contrast to multiple earlier surveys that found much greater frog abundance in secondary forest. We propose that the reason for the rapid decline in Dieffenbachia spp. is herbivory by the collared peccary (Pecari tajacu), which has increased in abundance at La Selva in recent years. A likely consequence is continued reduction in O. pumilio populations.

Recently, human activities have impacted biodiversity-rich forest in western Rwanda, creating a need to enhance restoration activities of degraded lands in the region. To evaluate the effects of reforestation activities on the community composition of soil-litter ants, research was conducted in Gishwati tropical montane forest, located in northern-western part of Rwanda. The ant fauna was studied in reforested lands dominated by regenerated native species and exotic tree species. Further, a primary forest made of native trees served as a reference. In each forest type, nine sampling points were used to sample ants. Ant specimens were collected using pitfalls, hand sampling and Winkler extractor. They were identified to subfamilies, genus and species levels using dichotomous keys, and also statistically analysed for species richness, diversity, evenness and community composition. We collected a total of 2,481 individuals from 5 subfamilies, 18 genera and 35 species. Higher abundance, diversity and species richness were found in soil-litter under natural primary and secondary forests dominated by regenerated native plant species compared to exotic tree forest. The ant community composition analysis indicated higher similarities in ant species sampled under primary native forest and secondary forest dominated by regenerated native species. Reforestation by regenerating native species may be given priority in restoration of degraded lands due to their importance in species richness and species diversity.

Among nectarivorous birds, the highest niche partitioning occurs between hummingbirds and plants. Although hummingbirds tend to visit morphologically well-matched resources, as ornithophilous species, they can also visit flowers with other traits. Here, we investigated whether the niche partitioning in hummingbird-plant interactions is also observed with ornithophilous species only. We also explored if hummingbird traits predicted resources use. We recorded a plant-ornithophilous species network in a semi-deciduous forest in Brazil. We quantified interaction partitioning through network connectance, complementary specialisation, and modularity. The influence of hummingbirds’ traits into their visits was investigated through methods of functional ecology and ecological networks. We recorded 948 interactions between nine hummingbirds and seven ornithophilous plants. We detected similar patterns of niche partitioning between hummingbirds and ornithophilous plants in comparison to networks considering the entire plant community. However, hummingbird species with the most specialised interactions are different from those when the whole system is evaluated. Therefore, we cannot downscale the patterns from one scale to the other. The pattern of interaction with ornithophilous plants was not related to hummingbirds’ traits. Therefore, the coexistence of species with shared traits might be occurring through facilitative and competitive processes, leading to trait mismatching and maintaining niche partitioning among ornithophilous plants.

Despite a clear consensus about the major roles that predators play in shaping ecological communities, descriptive studies of interactions between ecologically important top predator species are underreported. Native cane toad consumption of predatory bullet ant nests was verified through multiple, independent observations taken on Pipeline Road, Panama. Cane toad predation led to the extirpation of 42% of the nests within a 1.05 km2 area that is characterized as a late-successional wet forest. This predation pressure could be significant given the high rate of predation events and low bullet ant nest density observed here (0.12 nests ha−1). Implications of this interaction for the local bullet ant population, possible top-down effects and trophic cascades resulting from this top predator interaction are discussed.

Herbivores use a wide range of factors to choose their host, including their own physiological states, physical characteristics of plants and the degree of competition. Field observations of herbivores in their native habitats provide a means for simultaneously estimating the relative importance of these factors, but statistical analysis of all these factors may be challenging. Here we used a 7-week dataset of leaf-cutting ant (Atta cephalotes) foraging in a diverse Neotropical arboretum containing 193 tree species (822 trees) to examine the relative role of tree phylogeny, territoriality and tree functional characteristics using a phylogenetic generalized least squares (PGLS) model. We observed that 54 tree species (117 trees) were foraged by the ants. This pattern was not random, but reflected known features of leaf-cutting ant foraging behaviour, such as a preference for larger trees and the decreased likelihood of foraging at the periphery of a colony’s territory. However, random effects such as tree phylogeny, the identity of individual trees and colony-specific effects explained most of the variation in foraging data. A significant phylogenetic effect on foraging likelihood (λ = 0.28), together with repeated measures of foraging on the same tree species, allowed estimation of relative palatability for each plant species. PGLS models can be flexibly scaled to include other covariates for even more complex investigation of foraging behaviour, and the link function can be modified to include the amount of plants foraged. As a result, PGLS can be used as a flexible framework for the study of LCA foraging.

Great attention has been drawn to the impacts of habitat deforestation and fragmentation on wildlife species richness. In contrast, much less attention has been paid to assessing the impacts of chronic anthropogenic disturbance on wildlife species composition and behaviour. We focused on natural small rock pools (sartenejas), which concentrate vertebrate activity due to habitat’s water limitation, to assess the impact of chronic anthropogenic disturbance on the species richness, diversity, composition, and behaviour of medium and large-sized birds and mammals in the highly biodiverse forests of Calakmul, southern Mexico. Camera trapping records of fauna using sartenejas within and outside the Calakmul Biosphere Reserve (CBR) showed that there were no effects on species richness, but contrasts emerged when comparing species diversity, composition, and behaviour. These effects differed between birds and mammals and between species: (1) bird diversity was greater outside the CBR, but mammal diversity was greater within and (2) the daily activity patterns of birds differed slightly within and outside the CBR but strongly contrasted in mammals. Our study highlights that even in areas supporting extensive forest cover, small-scale chronic anthropogenic disturbances can have pervasive negative effects on wildlife and that these effects contrast between animal groups.

Tropical dry forests (TDF) are one of the most threatened and poorly protected ecosystems in the Americas. Although there are international efforts for the restoration of TDF, how stress factors such as herbivory or water limitation due to changes in precipitation, impact the regeneration dynamics of these forests is poorly understood. Specifically, how seedlings of key tree species for TDF restoration cope with current abiotic pressures such as the intensification of climatic events, and biotic factors like herbivory, is not yet fully understood. Here, we compared seedling performance, and allocation of biomass, and water to roots vs. shoots for three legume, and one non-legume TDF tree species, as a response to water limitation and herbivory in an 8-month greenhouse experiment. Contrary to our expectations, we found that the non-legume species, G. ulmifolia, had the best performance compared to legumes, while N-fixing and non-fixing legumes showed similar performance. Based on our findings, we suggest the use of G. ulmifolia in TDF restoration projects due to its high performance despite abiotic and biotic stress factors, its allocation of biomass and water to belowground structures. We also recommend the use of N-fixing legume species owing to their ability to fix nitrogen, which guarantees an N input to the soil, important in the first stages of succession. However, the legume species used in this experiment do not appear to resist the abiotic and biotic stressors studied. Thus, more studies exploring the response of dry forest plant species to stress factors are key for informing and assuring more effective TDF restoration efforts.

For large mammals, area expansion is a key conservation measure to prevent species’ decline and extinction. Yet, its success depends on whether animals discover and later use these areas. Here, using GPS data, we investigated how herds of elephants detected and used an area made available to them after the removal of a fence. We studied the elephants’ behaviour before and after the fence removal, accounting for seasonal changes in movement patterns. In contrast to previous studies, herds visited the newly available area within a month of the fence removal, and the maximum distance they moved into the new area was reached between 5 and 9 months after the fence removal. Yet, elephants did not preferentially visit the new area at night. By the second year, all herds had shifted their seasonal home ranges and incorporated the new area, in contrast to a previous range expansion event. Our analyses show that the regular proximity of elephants to the original fence, and the fact that the new area was generally composed of preferred habitats of the elephants, probably explained the rapid discovery and use of the area. Our study improves our understanding of animal exploration and the role of habitat quality, and thus may improve range expansion and corridor programmes.

Thirty-four spedes of mosquitoes (Diptera: Culicidae) were collected at a series of human-bait catches designed to study evening crepuscular biting activity using the Nielsen crep unit, at a site at Peradeniya, Sri Lanka. Crepuscular biting profiles of seven species (Armigeres subalbatus, Aedes albopictus, Culex pseudovishnui, Cx. gelidus, Cx. fuscocephala, Cx. tritaeniorhynchus and Mansonia uniformis) were obtained. Modal periods for the onset of biting were analysed in six species: Cx. pseudovishnui, Cx. fuscocephala, Cx. gelidus, Cx. tritaeniorhynchus, Cx. quinquefasciatus and Ma. uniformis. Successions in the biting peaks and in modal onset of biting were seen in these species. Analysis of biting in Ar. subalbatus and Cx. pseudovishnui under high (clear sky) and low (cloud-overcast sky) light intensities showed earlier biting in both species under the latter conditions. The value of the Nielsen crep unit in making latitudinal comparisons is illustrated in Ma. uniformis, for which parallel data are available from Africa.