No abstract

The high plains native savanna landscape (HPNSL) northeast of the Orinoco River is the habitat of 50% of the wild ungulate species (WUS) reported for Colombia. Over the last 20 years, this high species diversity has been strongly threatened by the accelerated human transformation of the natural land cover causing connectivity loss of the habitats. Despite this situation, the region lacks a biological connectivity analysis with a multi-species approach involving species groups that are representative of the savanna ecosystem such as the WUS. Understanding the spatial distributions of suitable habitats and the main habitats that act as primary habitats for ungulate focal species (UFS) in these landscapes is fundamental for the design of effective conservation strategies. Here, we use an occurrence dataset for Tapirus terrestris, Odocoileus virginianus, and Tayassu pecari in the development of species' potential distribution models, the binarization process, and morphological spatial pattern analysis. This information was used for the modelling of dispersal corridors connecting the core habitats of the UFS using the randomized shortest path algorithm and quantifying the weighted global connectivity metrics. Our results suggest an integral corridor with potential least-cost dispersal routes between the HPNSL on the middle and lower-middle basins of the savanna rivers and, to a lesser extent, the lower basin of the Meta River. These areas associated with the fluvial dendritic systems are connected, while the core habitats in the eastern part of the savanna landscape are largely disconnected. We discuss how the application of such knowledge on the spatial ecology of ungulate species might improve management of the metapopulations in the Colombian HPNSL.

Unsustainable fisheries practices carried out in large parts of the Amazon, Tocantins, and Orinoco basins have contributed to the decline in the populations of the Amazon River dolphins (Inia spp.), considered Endangered by the International Union for Conservation of Nature (IUCN). Amazon River dolphin byproducts are often obtained through unregulated fisheries and from stranded and incidentally caught individuals that are traded for the flesh and blubber used for Calophysus macropterus fisheries, traditional and other medicinal purposes, and more recently for human consumption. To identify localities of use of Amazon River dolphins, we conducted a systematic review of the related literature published since 1980, complemented with structured surveys of researchers that allowed the identification of 57 localities for uses of Inia (33 in the Amazon, two in the Tocantins, and 22 in the Orinoco basins), and two more on the Brazilian Atlantic coast, with recent reports of targeted consumption in the upper Orinoco River. Subsequently, the localities of use or bushmeat markets where Amazon River dolphin byproducts are trafficked were identified. This information was integrated with a kernel density analysis of the distribution of the Inia spp. populations establishing core areas. Our spatial analysis indicated that the use of Inia spp. is geographically widespread in the evaluated basins. It is urgent that decision-makers direct policies towards mitigating the socioeconomic and cultural circumstances associated with illegal practices affecting Amazon River dolphin populations in South America.

Context: Identifying the heterogeneity in the habitat use and hotspots of Amazon River dolphin activity is essential to design effective strategies for the management and conservation of these cetaceans and their habitats in the Colombian Amazonas River and Orinoco basin.Objectives: Quantify the differential use of habitat that Amazon River dolphins exhibit and to identify hotspot activity during seasons of rising waters in the Colombian Amazonas River and other major rivers in the Orinoco basin.Methods: Based on processed satellite images Landsat 8 (2018-2022), we classified habitat types used by I. geoffrensis and reported in the literature: (1) main river, (2) confluences, (3) tributaries, (4) channels, (5) islands, (6) bays, and (7) lagoons. We combined this dataset with GPS location data obtained from 17 tagged Amazon River dolphins to quantify the proportion of habitat types used, and we used GAMLSS to explore the relationship between the number of locations per habitat as the predictor variable and nine response variables. Kernel density estimate (KDE) analysis was used to identify both areas used (K95) and hotspot activity associated with core areas (K50) in the habitat types for the individuals monitored in the Amazonas River and Orinoco basin. Results: Satellite tracking of I. geoffrensis individuals reported 16.098 locations (Amazonas River, n = 2.934 locations and Orinoco basin, n = 13.164 locations) classified into seven habitat types. For the analyzed period (rising waters) main habitat types used were as follow: in the Amazonas River (1) main river (n = 1.346, 46%), and (2) lagoons (n = 1.158, 39%); and in the Orinoco basin (1) main river (n = 7.798, 59.2%), and (2) channels (n = 1.535, 11.7%). The best fitting GAMLSS for the I. geoffrensis monitored individuals in the Amazonas River showed that body length, sex, and habitat types (lagoons and main river) were significant predictors of Amazon River dolphins; and in the Orinoco basin they showed that body length, longest distance, K50, and habitat types (confluences, lagoons, main river, and tributaries) were significant. Individuals monitored in the areas evaluated in the Amazonas River reported K95 ranged: 30.7–105.5 km2 (mean = 62 ± 32), and the K50 or hotspots of activity were recorded in the main river, confluences, lagoons, and tributaries. In the five rivers of the Orinoco basin, monitored individuals registered K95 ranged: 6–116 km2 (mean = 32.8 ± 31.53), and hotspots of activity were recorded in the main river, islands, channels, confluences, bays, tributaries, and lagoons.Conclusions: Evaluation of differences in habitat type use and identification of hotspot activity will contribute to improving management and conservation efforts for the populations of these cetaceans in the Colombian Amazonas and Orinoco basins.