Northeastern Costa Rica Research Articles

Diversity and Distribution of Monocot Understory Herbs during Tropical Forest Succession in Northeastern Costa Rica

Broad-leaved monocot herbs form one of the most common and diverse growth forms of Neotropical plants. Their significance and frequency of occurrence is particularly notable in the understories of tropical rainforests, where they form a dominant element. We assessed and quantified changes in the cover and diversity of understory herb communities in a chronosequence of 1 ha permanent plots established as part of a multidisciplinary study on tropical forest regeneration in the Atlantic lowlands of northeastern Costa Rica. Sampled were two young stands cleared 12 years ago, two secondary forests with 21 and 39 of years of recovery since clearance, and two stands in old-growth primary forest. Changes in species composition during succession were assessed using Chao’s Jaccard similarity index. Observed species richness ranged from 15 to 26 species in individual plots, with the greatest number of species in the 21-year intermediate-age and fewest in the young 12-year plots. Herb species sampled represented 6 families, 15 genera, and 39 species, with the Araceae contributing the largest number of species. Ten species were sampled in all six stands, while fourteen species were found exclusively in one plot. Herb density (ramets m−2) showed a hump-shade trend, with peak density in the intermediate stands and a lower level in mature and young secondary forests. Mean herb cover in 25 m2 quadrats ranged from 2.0% (young stand) to 22.7% (intermediate-age stand) and differed significantly both among stand types and among sites. Both observed and estimated species richness increased along the chronosequence as a whole, with the highest number of species in primary forest, although only slightly higher than in intermediate-age stands. Over half of the species exhibited some degree of clonal growth, with the extent of clonal spread varying among species and forest stands. Although we did not find a clear pattern between clonality and forest age, we observed a greater number of clonal patches in secondary over primary forest stands.

Advancing isotope‐enabled hydrological modelling for ungauged calibration of data‐scarce humid tropical catchments

AbstractRealistic projections of the future climate and how this translates to water availability is crucial for sustainable water resource management. However, data availability constrains the capacity to simulate streamflow and corresponding hydrological processes. Developing more robust hydrological models and methods that can circumvent the need for large amounts of hydro‐climatic data is crucial to support water‐related decisions, particularly in developing countries. In this study, we use natural isotope tracers in addition to hydro‐climate data within a newly developed version of the spatially‐distributed J2000iso as an isotope‐enabled rainfall‐runoff model simulating both water and stable isotope (δ2H) fluxes. We pilot the model for the humid tropical San Carlos catchment (2500 km2) in northeastern Costa Rica, which has limited time series, but spatially distributed data. The added benefit of simulating stable isotopes was assessed by comparing different amounts of observation data using three model calibration strategies (i) three streamflow gauges, (ii) three gauges with stream isotopes and (iii) isotopes only. The J2000iso achieved a streamflow Kling–Gupta efficiency (KGE) of 0.55–0.70 across all the models and gauges, but differences in hydrological process simulations emerged when including stable water isotopes in the rainfall‐runoff calibration. Hydrological process simulation varied between the standard J2000 rainfall‐runoff model with a high simulated surface runoff proportion of 37% as opposed to the isotope version with 84%–89% simulated baseflow or interflow. The model solutions that used only isotope data for calibration exhibited differences in simulated interflow, baseflow and model performance but captured bulk water balances with a reasonable match between the simulated and observed hydrographs. We conclude that J2000iso has shown the potential to support water balance modelling for ungauged catchments using stable isotope, satellite and global reanalysis data sets.

Differential Species Richness and Ecological Success of Epiphytes and Hemiepiphytes of Neotropical Araceae and Cyclanthaceae

Numerous plant functional traits of ecophysiology and morphology associated with an epiphytic life history have promoted relatively high rates of evolutionary diversification and ecological success in tropical families such as the Orchidaeae, Polypodiaceae, Bromeliaceae, and Cactaceae. Epiphytic life histories are relatively uncommon in the Araceae and rare in the Cyclanthaceae which lack key functional traits for epiphytism. Only two lineages of Neotropical Araceae, Anthurium and Philodendron, include examples of epiphyte life histories. The evolution of a hemiepiphytic life history represented an important development for tropical Araceae by providing functional traits that have greatly expanded opportunities for adaptive radiation and ecological success as indicated by species richness and frequency of occurrence. The key adaptive trait allowing the diversification of hemiepiphytic Araceae was the development of heteroblastic growth of leaves and stems. Although hemiepiphytic life histories are present in the Cyclanthaceae, the family has undergone only modest speciation and limited ecological success in both its epiphytes and hemiepiphytes. Extensive sampling of more than 4600 trees from primary forest on four soil groups in northeastern Costa Rica have found a modest diversity of 15 species of epiphytic Araceae but only two species of epiphytic Cyclanthaceae. In contrast, 38 species of hemiepiphytic Araceae and 5 species of hemiepiphytic Cyclanthaceae were sampled, indicating relatively limited adaptive radiation of hemiepiphytic Cyclanthaceae and lower ecological success. Using summed values of frequency of occurrence as a measure of ecological success, epiphytic Araceae were 18 to 42 times more frequent than epiphytic Cyclanthaceae in swamp, alluvial, and residual soil forests. Summed frequencies of occurrence of hemiepiphytic Araceae were 7 to 13 times higher than those of hemiepiphytic Cyclanthaceae. The four soil groups were similar in their floristic composition of epiphytic and hemiepiphytic Araceae and Cyclanthaceae, but the frequencies of occurrence of both epiphytes and hemiepiphytes were, with few exceptions, highest on swamp soil plots, with alluvial soil plots slightly less favorable.

Primates at the newly established Camaquiri Conservation Initiative, Limon, Costa Rica


 
 
 In Costa Rica, Geoffroy’s spider monkey (Ateles geoffroyi ornatus) is classified as ‘Endangered’ according to the IUCN Red List of Threatened Species. Given the threats it faces, this spider monkey was included in the most recent ‘Top 25 Endangered Primate Species’ list published by the IUCN (Schwitzer et al. 2019). The newly established Camaquiri Conservation Initiative (CCI) site, located on 200 ha in northeastern Costa Rica in Caribbean lowland rain forest, harbors a population of these monkeys that has yet to be studied. The population size of these primates and the extent to which their habitat may be fragmented is unknown. We conducted transect surveys of spider monkeys, mantled howling monkeys (Alouatta palliata) and Panamanian white-faced capuchins (Cebus imitator) at Camaquiri in 2019, 2020 and 2021 over the course of 13.5 days, covering 32 km total, to establish baseline information important for this new reserve’s conservation management plan, and for providing a rough estimate of the number of study subjects available for potential researchers. We recorded, minimally, 10 different individual spider monkeys in at least one community, at least three different howling monkey groups and at least one capuchin monkey group resident at CCI. Given that large patches of healthy, intact tropical forest are rarely conserved in Central America, Camaquiri provides an opportunity to conserve endangered primate species and to contribute to our knowledge of these animals. Additionally, its proximity to other field stations provides opportunities for studies of patch connectivity, habitat quality and other characteristics that influence primate populations in this region.
 
 

Successional trajectories of seed dispersal mode and seed size of canopy tree species in wet tropical forests

Despite the critical role of seed dispersal for tree colonization during forest succession in wet tropical forests, successional trajectories of seed dispersal modes are poorly documented at the community level. Overall successional trends in wet tropical forests indicate that, over time, animal-dispersed and large-seeded species increase in relative abundance in woody vegetation, whereas wind-dispersed and small-seeded species decline. Increased abundance of animal-dispersed trees during succession may be attributed to higher rates of seed deposition by animals and higher survival rates of animal-dispersed species with larger seeds (diaspores) compared to wind-dispersed species. We compiled categorical information on seed size (maximum seed length) and dispersal mode (anemochory, autochory, or zoochory) for 240 canopy tree species in six naturally regenerating forests (11–45 years since the abandonment of pasture) and two old-growth forests in lowland wet forests in northeastern Costa Rica. We evaluated dispersal mode and seed size among tree species classified as second growth and old growth specialists, and generalists based on relative abundance data in these plots. Further, we compared long-term trajectories in the dispersal and seed-size profile for 240 species of canopy tree species for seedlings, saplings, and trees ≥5 cm dbh using annual vegetation survey data from 1997 to 2013. Seed size was significantly associated with dispersal mode, which was driven by anemochorous species with intermediate seeds 6 mm to 15 mm and autochorous seeds with large seeds >15 mm. Dispersal modes of canopy tree species exhibited clear directional trajectories, with decreasing relative abundance of anemochory and increasing relative abundance of zoochory. Zoochorous seedlings showed higher survival rates than anemochorous seedlings. Species with seeds ≤ 6 mm decreased in relative abundance through succession, while species with seeds >15 mm increased within seedling and sapling communities. Seedlings with seeds >15 mm showed higher survival rates than smaller seeds in second-growth forests. The study further demonstrates the importance of seed traits, such as dispersal mode and seed size, for community assembly during forest regrowth, and the importance of frugivorous animals in this process. The abundance of animal-dispersed tree species in different size classes can be a useful indicator of the recovery of biodiversity and species interactions during forest succession in wet tropical regions.

Seasonal deposition of marine debris on an important marine turtle nesting beach in Costa Rica

Marine debris pollution poses a threat for wildlife and can negatively impact the economy of communities whose livelihoods depend on tourism. Playa Norte, in northeastern Costa Rica, is an important nesting ground for four marine turtle species identified as vulnerable or endangered on the IUCN Red List. It is highly polluted but has low human occupancy. We conducted accumulation rate surveys following a standardized marine debris protocol from March 2016 to January 2018. Macro-debris was categorized by size and material type. Of the 191,030 debris items retrieved during the two-year study period, 96.2% of them were plastic. Debris accumulation was higher during the dry season (January – September). This study contributes towards understanding the drivers of marine debris pollution in critical wildlife nesting habitats; and informs managers and the local community on possible strategies to prevent and reduce marine pollution, thereby aiding in tourism derived economies.

Conspecific and Predator Perception of the Red Oophaga pumilio Morph from the Central Caribbean of Costa Rica

Strawberry Poison Frogs (Oophaga pumilio) are common members of leaf litter lowland communities in Central America and exhibit several color morphs throughout their distribution. Color plays a determinant role during intra- and intermorph interactions in many insular populations, but little is known about the variation and perception of visual signals in mainland populations. In this study, we investigated color variation of four body parts—head, back, belly, and throat—in a bright red O. pumilio population of northeastern Costa Rica. We incorporated frog- and bird-specific visual modeling to evaluate the differences in color and brightness between the sexes, from the perspective of conspecifics and avian predators. Furthermore, we measured the color and brightness contrast against natural backgrounds commonly used by these frogs to forage and patrol within territories. Our results revealed that, from the perspective of conspecifics, there is no dichromatism between males and females. However, females had a greater contrast against green and brown backgrounds than males. The bird visual models indicated that males and females are highly conspicuous against common background substrates but that females are easier to detect than males. This study detailing color variants between sexes within a mainland population of O. pumilio contributes to our understanding of color differences in populations of this species.

Detecting successional changes in tropical forest structure using GatorEye drone‐borne lidar

AbstractDrone‐based remote sensing is a promising new technology that combines the benefits of ground‐based and satellite‐derived forest monitoring by collecting fine‐scale data over relatively large areas in a cost‐effective manner. Here, we explore the potential of the GatorEye drone‐lidar system to monitor tropical forest succession by canopy structural attributes including canopy height, spatial heterogeneity, gap fraction, leaf area density (LAD) vertical distribution, canopy Shannon index (an index of LAD), leaf area index (LAI), and understory LAI. We focus on these variables’ relationship to aboveground biomass (AGB) stocks and species diversity. In the Caribbean lowlands of northeastern Costa Rica, we analyze nine tropical forests stands (seven second‐growth and two old‐growth). Stands were relatively homogenous in terms of canopy height and spatial heterogeneity, but not in their gap fraction. Neither species density nor tree community Shannon diversity index was significantly correlated with the canopy Shannon index. Canopy height, LAI, and AGB did not show a clear pattern as a function of forest age. However, gap fraction and spatial heterogeneity increased with forest age, whereas understory LAI decreased with forest age. Canopy height was strongly correlated with AGB. The heterogeneous mosaic created by successional forest patches across human‐managed tropical landscapes can now be better characterized. Drone‐lidar systems offer the opportunity to improve assessment of forest recovery and develop general mechanistic carbon sequestration models that can be rapidly deployed to specific sites, an essential step for monitoring progress within the UN Decade on Ecosystem Restoration.

Headwaters drive streamflow and lowland tracer export in a large‐scale humid tropical catchment

AbstractHeadwaters are generally assumed to contribute the majority of water to downstream users, but how much water, of what quality and where it is generated are rarely known in the humid tropics. Here, using monthly monitoring in the data scarce (2,370 km2) San Carlos catchment in northeastern Costa Rica, we determined runoff‐area relationships linked to geochemical and isotope tracers. We established 46 monitoring sites covering the full range of climatic, land use and geological gradients in the catchment. Regression and cluster analysis revealed unique spatial patterns and hydrologically functional landscape units. These units were used for seasonal and annual Bayesian tracer mixing models to assess spatial water source contributions to the outlet. Generally, the Bayesian mixing analysis showed that the chemical and isotopic imprint at the outlet is throughout the year dominated by the adjacent lowland catchments (68%) with much less tracer influence from the headwaters. However, the headwater catchments contributed the bulk of water and tracers to the outlet during the dry season (>50%) despite covering less than half of the total catchment area. Additionally, flow volumes seemed to be linearly scaled by area maintaining a link between the headwaters and the outlet particularly during high flows of the rainy season. Stable isotopes indicated mean recharge elevations above the mean catchment altitude, which further supports that headwaters were the primary source of downstream water. Our spatially detailed “snap‐shot” sampling enabled a viable alternative source of large‐scale hydrological process knowledge in the humid tropics with limited data availability.

Oviposition Site Selection in Three Glass Frog Species

Oviposition site selection is critical for the reproductive success of oviparous organisms. We investigated oviposition site selection in three species of glass frogs—Espadarana prosoblepon, Hyalinobatrachium valerioi, and Teratohyla spinosa—in northeastern Costa Rica. We conducted nocturnal visual encounter surveys to estimate glass frog egg mass abundance and characterize oviposition site features in streams of three different habitats (pasture, secondary forest, and mature forest). Our results show differential oviposition site selection among all three species depending on vegetation and stream features. Hyalinobatrachium valerioi and T. spinosa, which oviposit almost exclusively on the underside of leaves, selected smooth leaves, while E. prosoblepon, which oviposits on the upper side of leaves or in moss, used moss eight times more than expected on the basis of availability. Hyalinobatrachium valerioi was found on larger leaves than T. spinosa and E. prosoblepon. Teratohyla spinosa and E. prosoblepon both oviposited most frequently above slow-moving water, while H. valerioi oviposited most frequently above fast-moving water. Espadarana prosoblepon was the only species affected by habitat type and had higher abundances of egg masses in mature forest than in secondary forest and pasture. Our results suggest that microhabitat plays a larger role in oviposition site selection than larger habitat classification. We propose that appropriate riparian microhabitat is a critical factor in sustaining glass frog populations in modified habitats and highlight the importance of preserving riparian corridors in altered landscapes.

Assessing the role of habitat and species interactions in the population decline and detection bias of Neotropical leaf litter frogs in and around La Selva Biological Station, Costa Rica

Worldwide, amphibian populations have been declining rapidly. This decline can be attributed to many factors including climate change, pesticide exposure, and emerging infectious diseases, among other important factors, but few studies have examined the influence of species interactions. In this study, we examined how habitat factors and co-occurring avian and mammalian species, as well as humans, exert direct and indirect effects on Neotropical amphibian population dynamics. We further examined how these habitat and species interactions could affect our ability to reliably detect amphibian presence to robustly estimate population trends. We conducted amphibian visual encounter surveys at 26 randomly selected sites in the La Selva Biological Station, in northeastern Costa Rica, as well as 26 sites across five additional forest fragments in the region. Furthermore, we used camera traps to collect data on avian and mammalian communities and human visitation at those amphibian survey plots. From these data, we were able to estimate species occupancy probabilities for leaf litter frogs across sites and their relationships to habitat and interspecific species interaction covariates. We also conducted an experiment with plastic model frogs to estimate detection probabilities when a population is known to occur at a site with certainty. Our results suggested that strawberry poison dart frog (Oophagapumilio) occupancy was positively related to secondary forest and their detection was negatively related to increasing air temperatures at the times of the surveys. Leaf litter frog occupancy was negatively related to core La Selva sites and human detections at sites, yet their detection was positively related to human trail presence, which might be related to reduced leaf litter cover due to heavy trampling. Our experimental surveys suggested that Neotropical leaf litter frog communities are difficult to detect when present and future studies should explicitly account for this detection bias to effectively monitor population trends.

Correction to 'The demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths'.

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Garcés-Restrepo Mario F., Peery M. Zachariah and Pauli Jonathan N. 2019Correction to ‘The demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths’Proc. R. Soc. B.2862019100620191006http://doi.org/10.1098/rspb.2019.1006SectionYou have accessCorrectionsCorrection to ‘The demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths’ Mario F. Garcés-Restrepo Mario F. Garcés-Restrepo http://orcid.org/0000-0002-9937-7902 Google Scholar Find this author on PubMed Search for more papers by this author , M. Zachariah Peery M. Zachariah Peery Google Scholar Find this author on PubMed Search for more papers by this author and Jonathan N. Pauli Jonathan N. Pauli http://orcid.org/0000-0001-5908-6628 Google Scholar Find this author on PubMed Search for more papers by this author Mario F. Garcés-Restrepo Mario F. Garcés-Restrepo http://orcid.org/0000-0002-9937-7902 Google Scholar Find this author on PubMed Search for more papers by this author , M. Zachariah Peery M. Zachariah Peery Google Scholar Find this author on PubMed Search for more papers by this author and Jonathan N. Pauli Jonathan N. Pauli http://orcid.org/0000-0001-5908-6628 Google Scholar Find this author on PubMed Search for more papers by this author Published:22 May 2019https://doi.org/10.1098/rspb.2019.1006This article corrects the followingResearch ArticleThe demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed slothshttps://doi.org/10.1098/rspb.2018.2206 Mario F. Garcés-Restrepo, M. Zachariah Peery and Jonathan N. Pauli volume 286issue 1894Proceedings of the Royal Society B: Biological Sciences16 January 2019Proc. R. Soc. B286, 20182206. (Published Online 16 January 2019). (doi:10.1098/rspb.2018.2206)Purpose for correction:A figure and table depicting a population model in the article ‘The demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths’ (doi.org/10.1098/rspb.2018.2206) had editing errors. Our original table 1 depicting the matrix model incorrectly represented a reproductive element for 2- to 3-year-old juveniles as non-zero (first row, third column in matrix) and added (rather than multiplied) fecundity (m) with adult survival (ϕ3+). Additionally, there was incorrect symbology presented in figure 4: we have corrected the reproductive element (m × ϕ3+); shown that fecundity (m) was divided by 2 (because the model was female based); and added a negative sign to the exponent. We have updated table 1 and figure 4 below to correctly illustrate the projection we conducted that match the results and conclusions presented in the article. Reference numbers are as in the original main text. Table 1. Matrix model used to estimate annual population growth rates for three-toed sloths in northeastern Costa Rica (m, fecundity; ϕ0–1, annual juvenile 0- to 1-year-old survival rate; ϕ1–2, annual juvenile 1- to 2-year-old survival rate; ϕ2–3, annual juvenile 2- to 3-year-old survival rate; ϕ3+, annual adult survival rate). Collapse 000m × ϕ3+ϕ0–10000ϕ1–20000ϕ2–3ϕ3+Figure 4. Influence of Cecropia obtusifolia density on the population growth rate (λ) of three-toed sloths (Bradypus variegatus). Density of C. obtusifolia (coloured dots) was based on previous estimates of C. obtusifolia in different habitat types (see the electronic supplementary material for details). Filled colours represent the range of expected population growth in different habitat types. Inset graph illustrates a four-stage life-history diagram including the relationship between C. obtusifolia density and adult survival and reproductive output (m, fecundity; 3+, adults; ϕ0–1, annual juvenile 0- to 1-year-old survival rate; ϕ1–2, annual juveniles 1- to 2-year-old survival rate; ϕ2–3, juveniles 2- to 3-year-old survival rate; ϕ3+, annual adult survival rate) used to derive the estimated population growth rate.Download figureOpen in new tabDownload PowerPoint Previous Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesThe demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths16 January 2019Proceedings of the Royal Society B: Biological Sciences This IssueMay 29, 2019Volume 286Issue 1903 Article InformationDOI:https://doi.org/10.1098/rspb.2019.1006PubMed:31113324Published by:Royal SocietyOnline ISSN:1471-2954History: Published online22/05/2019Published in print29/05/2019 License:© 2019 The Author(s)Published by the Royal Society. All rights reserved. Citations and impact Subjectsecology Large datasets are available through Proceedings B's partnership with Dryad

Description of the Female ofAmi bladesiPérez-Miles, Gabriel & Gallon, 2008 (Araneae: Theraphosidae), with Notes on Its Distribution, Ecology, and Behaviour

The female sex of Ami bladesiPerez-Miles et al., 2008 is described, based on three specimens from northeastern Costa Rica and one specimen from the type locality in Panama. It is the first record of this species and genus from Costa Rica. In addition to the modified urticating hairs of type I, urticating hairs of type III were found in both females and males from Costa Rica and Panama. Notes on the distribution, ecology, and behaviour of A.bladesi are included.

Regional Groundwater and Storms Are Hydrologic Controls on the Quality and Export of Dissolved Organic Matter in Two Tropical Rainforest Streams, Costa Rica

AbstractA paired‐watershed approach was used to compare the quality and fluxes of dissolved organic matter (DOM) during stormflow and baseflow in two lowland tropical rainforest streams located in northeastern Costa Rica. The Arboleda stream received regional groundwater (RGW) flow, whereas the Taconazo stream did not. DOM quality was assessed with absorbance and fluorescence and stable carbon isotope (δ13C‐DOC) values. RGW DOM lacked detectable fluorescence and had specific ultraviolet absorption (SUVA254) and absorbance slope ratio (SR) values consistent with low aromaticity and low molecular weight material, respectively. We attributed these properties to microbial degradation and sorption of humic DOM to mineral surfaces during transport through bedrock. SUVA254 values were lower and SR values were higher in the Arboleda stream during baseflow compared to the Taconazo stream, presumably due to dilution by RGW. However, no significant difference in SUVA254 or SR occurred between the streams during stormflow. SUVA254 was negatively correlated to δ13C‐DOC (r2 = 0.61, P < 0.001), demonstrating a strong linkage between stream DOM characteristics and the relative amounts of RGW flow and local watershed runoff containing soil and throughfall C sources. Mean DOC export from the Taconazo stream during the study period was 2.62 ± 0.39 g C m−2 year−1, consistent with other tropical streams, yet mean DOC export from the Arboleda stream was 13.79 ± 2.07 g C m−2 year−1, one of the highest exports reported and demonstrating a substantial impact of old RGW from outside the watershed boundary can have on surface water carbon cycling.

New observations of frog and lizard predation by wandering and orb-weaver spiders in Costa Rica

Studies have suggested that predation by spiders may be an important force regulating life history in neotropical frogs and lizards, but detailed descriptions of predator-prey relationships are few. Here we describe novel observations where spiders contributed to the mortality of frogs and lizards in northeastern Costa Rica, and we corrected or clarified three identification errors of spiders from the literature. The most frequently observed predators were wandering spiders (Ctenidae), which seem to be generalist predators on frogs and lizards. An orb-weaver spider (Araneidae) also contributed to frog mortality, likely after the frog became entangled in the spider’s web. More detailed studies are needed to elucidate the role that spider predation contributes to frog and lizard demography in neotropical forests.

Camera traps provide valuable data to assess the occurrence of the Great Curassow Crax rubra in northeastern Costa Rica

The Great Curassow (Crax rubra) is an endangered species in Costa Rica due to habitat loss and hunting pressure. Little is known about the spatial ecology of cracids and there is a need to assess their distribution to establish efficient conservation strategies. In this study, we integrated camera trapping data with occupancy models to examine landscape factors that affect the distribution of the Great Curassow in the San Juan-La Selva Biological Corridor in Northeastern Costa Rica. We established remote camera traps at 38 sites within the corridor between July 2009 and July 2011. The Great Curassow was detected on 56 occasions at 19 of the 38 sites. Eight of the 19 occupancy models contained plausible support to predict Great Curassow occurrence, but distance to villages and forest cover were the most important factors positively related to their occurrence. These results suggest the distribution of the Great Curassow is largely susceptible to forest loss and human disturbance in the corridor. Both camera traps and occupancy analyses are useful tools to study medium to large terrestrial birds in the Neotropics.

Integrating feeding behavior, ecological data, and DNA barcoding to identify developmental differences in invertebrate foraging strategies in wild white-faced capuchins (Cebus capucinus).

Invertebrate foraging strategies in nonhuman primates often require complex extractive foraging or prey detection techniques. As these skills take time to master, juveniles may have reduced foraging efficiency or concentrate their foraging efforts on easier to acquire prey than adults. We use DNA barcoding, behavioral observations, and ecological data to assess age-based differences in invertebrate prey foraging strategies in a group of white-faced capuchins (Cebus capucinus) in northeastern Costa Rica. Invertebrate availability was monitored using canopy traps and sweep netting. Fecal samples were collected from adult female, adult male, and juvenile white-faced capuchins (n = 225). COI mtDNA sequences were compared with known sequences in GenBank and the Barcode of Life Database. Frequencies of Lepidoptera and Hymenoptera consumption were higher in juveniles than in adults. A significantly smaller proportion of juvenile fecal samples contained Gryllidae and Cercopidae sequences, compared with adults (0% and 4.2% vs. 4.6% and 12.5%), and a significantly larger proportion contained Tenthredinidae, Culicidae, and Crambidae (5.6%, 9.7%, and 5.6% vs. 1.3%, 0.7%, and 1.3%). Juveniles spent significantly more time feeding and foraging than adults, and focused their foraging efforts on prey that require different skills to capture or extract. Arthropod availability was not correlated with foraging efficiency, and the rate of consumption of specific orders of invertebrates was not correlated with the availability of those same taxa. Our data support the hypothesis that juveniles are concentrating their foraging efforts on different prey than adults, potentially focusing their foraging efforts on more easily acquired types of prey.

Tropical amphibians in shifting thermal landscapes under land-use and climate change.

Land-cover and climate change are both expected to alter species distributions and contribute to future biodiversity loss. However, the combined effects of land-cover and climate change on assemblages, especially at the landscape scale, remain understudied. Lowland tropical amphibians may be particularly susceptible to changes in land cover and climate warming because many species have narrow thermal safety margins resulting from air and body temperatures that are close to their critical thermal maxima (CTmax ). We examined how changing thermal landscapes may alter the area of thermally suitable habitat (TSH) for tropical amphibians. We measured microclimates in 6 land-cover types and CTmax of 16 frog species in lowland northeastern Costa Rica. We used a biophysical model to estimate core body temperatures of frogs exposed to habitat-specific microclimates while accounting for evaporative cooling and behavior. Thermally suitable habitat area was estimated as the portion of the landscape where species CTmax exceeded their habitat-specific maximum body temperatures. We projected changes in TSH area 80 years into the future as a function of land-cover change only, climate change only, and combinations of land-cover and climate-change scenarios representing low and moderate rates of change. Projected decreases in TSH area ranged from 16% under low emissions and reduced forest loss to 30% under moderate emissions and business-as-usual land-cover change. Under a moderate emissions scenario (A1B), climate change alone contributed to 1.7- to 4.5-fold greater losses in TSH area than land-cover change only, suggesting that future decreases in TSH from climate change may outpace structural habitat loss. Forest-restricted species had lower mean CTmax than species that occurred in altered habitats, indicating that thermal tolerances will likely shape assemblages in changing thermal landscapes. In the face of ongoing land-cover and climate change, it will be critical to consider changing thermal landscapes in strategies to conserve ectotherm species.

Targeted reforestation could reverse declines in connectivity for understory birds in a tropical habitat corridor.

Re-establishing connectivity between protected areas isolated by habitat clearing is a key conservation goal in the humid tropics. In northeastern Costa Rica, payments for environmental services (PES) and a government ban on deforestation have subsidized forest protection and reforestation in the San Juan-La Selva Biological Corridor (SJLSBC), resulting in a decline in mature forest loss and the expansion of tree plantations. We use field studies and graph models to assess how conservation efforts have altered functional connectivity over the last 25years for four species of insectivorous understory birds. Field playback studies assessed how reforestation habitat quality affected the willingness of Myrmeciza exsul, Henicorhina leucosticta, Thamnophilus atrinucha, and Glyphorynchus spirurus to travel outside forest habitat for territorial defense. Observed travel distances were greatest in nonnative and native tree plantations with high understory stem density, regardless of overstory composition. In contrast, tree plantations with low stem density had travel responses comparable to open pasture for three of the four bird species. We modeled landscape connectivity for each species using graph models based on varying possible travel distances in tree plantations, gallery forests, and pastures. From 1986 to 2011, connectivity for all species declined in the SJLSBC landscape (5825km2 ) by 14% to 21% despite only a 4.9% net loss in forest area and the rapid expansion of tree plantations over 2% of the landscape. Plantation placement in the landscape limited their potential facilitation of connectivity because they were located either far from forest cover or within already contiguous forest areas. We mapped current connectivity bottlenecks and identified priority areas for future reforestation. We estimate that reforestation of priority areas could improve connectivity by 2% with only a 1% gain in forest cover, an impressive gain given the small area reforested. Results indicate key locations where spatial targeting of PES within the SJLSBC study region would protect existing forest connectivity and enhance the connectivity benefits of reforestation.

Mapping Species Composition of Forests and Tree Plantations in Northeastern Costa Rica with an Integration of Hyperspectral and Multitemporal Landsat Imagery

An efficient means to map tree plantations is needed to detect tropical land use change and evaluate reforestation projects. To analyze recent tree plantation expansion in northeastern Costa Rica, we examined the potential of combining moderate-resolution hyperspectral imagery (2005 HyMap mosaic) with multitemporal, multispectral data (Landsat) to accurately classify (1) general forest types and (2) tree plantations by species composition. Following a linear discriminant analysis to reduce data dimensionality, we compared four Random Forest classification models: hyperspectral data (HD) alone; HD plus interannual spectral metrics; HD plus a multitemporal forest regrowth classification; and all three models combined. The fourth, combined model achieved overall accuracy of 88.5%. Adding multitemporal data significantly improved classification accuracy (p < 0.0001) of all forest types, although the effect on tree plantation accuracy was modest. The hyperspectral data alone classified six species of tree plantations with 75% to 93% producer’s accuracy; adding multitemporal spectral data increased accuracy only for two species with dense canopies. Non-native tree species had higher classification accuracy overall and made up the majority of tree plantations in this landscape. Our results indicate that combining occasionally acquired hyperspectral data with widely available multitemporal satellite imagery enhances mapping and monitoring of reforestation in tropical landscapes.