Browsing by Subject "Species Distribution"

The Northern Andes stands as a bastion of unique and narrowly distributed global biodiversity. However, it has also experienced rapid transformation of habitats, posing a serious threat to species in the wild by shrinking their ranges. In this dissertation, I aim to deepen our comprehension of how species react to global changes, pinpointing areas where conservation efforts are lacking and highlighting urgent conservation priorities. Moreover, I demonstrate tangible conservation strategies designed to safeguard vulnerable species, while also prioritizing potential exploration regions to confirm the extent of their ranges.In the first chapter, I assess elevational retreats of nearly 200 range-restricted birds from their lower and upper elevational ranges (Medina et al. 2023). Using abundant crowd-sourced data from the Cornell Lab of Ornithology database, eBird, and the Global Biodiversity Information Facility, I examine whether species shifted their elevational ranges over time by comparing observed versus expected occurrences below a low elevational threshold and above a high elevational threshold for two periods: before and after 2005. I also test for deforestation effects at lower elevations within each species’ distribution ranges. Species’ retreats from lower elevations are ubiquitous and involve a 23–40% decline in prevalence at the lowest elevations. Increases at higher elevations are not consistent. The retreats occur across a broad spectrum of species, from predominantly lowland to predominantly highland. Because deforestation show no relationship with species retreats, I contend that a warming climate is the most parsimonious explanation for such shifts. In the second chapter, I identify priority range-restricted bird species and their conservation hotspots in the Northern Andes (Medina et al. 2024). I employ updated maps of Area of Habitat (AOH), following a protocol I contributed along a set of experts from the Cornell Lab, Birdlife International, and American Bird Conservancy (Huang et al. 2021). In this protocol, I was tasked to build R and Python scripts capable to handle crowd-sourced data and batch-generate habitat maps for a thousand birds across the Americas. With the updated maps of species distribution, I estimate protection within each species’ AOH and for the cumulative distribution of birds. For the latter, I also calculate protection across the elevational gradient. I estimate how much additional protection community lands (Indigenous and Afro-Latin American lands) would contribute if they were conservation-focused. AOHs ranged from 8 to 141,000 km2. I identify four conservation priorities based on cumulative species richness. These priorities are high-resolution mapped representations of Endemic Bird Areas for the Tropical Andes that should be considered critically important. Protected areas cover only 31% of the cumulative AOH, but community lands could add 19% more protection. Sixty-two per cent of the 335 species have ranges smaller than their published estimates, yet IUCN designates only 23% of these as Threatened. Top 50 priority species concentrate in areas of low protection near community lands and at middle elevations where, on average, only 34% of the land is protected. I highlight the importance of collaborative efforts among stakeholders: governments should support private and community-based conservation practices to protect the region with the most range-restricted birds worldwide. Private reserves hold promise for the restoration of degraded landscapes and the protection of fragmented animal populations. In the third chapter, I advocate for the creation and implementation of private reserves as concluded in the previous chapter, drawing upon a case study from the Eastern Andes of Colombia to illustrate their potential. This study examines the rehabilitation efforts spanning four decades within Rogitama, aiming to assess their impact on mammal diversity and composition (Medina et al. 2021). Findings reveal the presence of 22 species, predominantly bats and rodents. These results mirror biodiversity levels akin to those observed in less disturbed areas of the Eastern Cordillera, indicating promising advances in ecosystem recovery within the reserve. I posit Rogitama, as a noteworthy case of successful plant rejuvenation, highlighting its significance in the broader context of biological conservation efforts. I firmly advocate for stakeholders to take heed of this case study as a blueprint for development in Northern Andean regions, where I have previously identified critical conservation gaps and priorities. In the last chapter, I identify species and areas that urgently need exploration to increase knowledge on distribution limits (Medina et al. in prep). I consider the AOH where there is less probability of finding a target species given its closeness to non-detection areas. These non-detection areas have checklists where a target species has yet to be reported. The proportion of species absent from an area over the species present will result in relatively uncertain areas. To define potential exploration sites, I mapped these areas along cumulative AOH for 281 species. I found priority exploration areas (high richness and high relative uncertainty) are relatively small compared to non-priority areas. Since 2000, human impact has penetrated 8% of priority areas and allowed 8% of the areas to be studied. Deforestation has progressively reduced, but some countries are still dealing with it. Protection along the priority regions is low. It is essential that governments devote more efforts to exploring biodiversity to better understand patterns in species distribution and thus develop accurate conservation and management plans.