Predicting wildlife corridors for multiple species in an East African ungulate community

Abstract

Wildlife corridors are typically designed for single species, yet holistic conservation approaches require corridors suitable for multiple species. Modelling habitat linkages for wildlife is based on several modelling steps (each involving multiple choices), and in the case of multi-species corridors, an approach to optimize single species corridors to few or a single functional corridor for multiple species. To model robust corridors for multiple species and simultaneously evaluate the impact of methodological choices, we develop a multi-method approach to delineate corridors that effectively capture movement of multiple wildlife species, while limiting the area required. Using wildlife presence data collected along ground-based line transects between Lake Manyara and Tarangire National Parks, Tanzania, we assessed species-habitat association in both ensemble and stacked species distribution frameworks and used these to estimate linearly and non-linearly scaled landscape resistances for seven ungulate species. We evaluated habitat suitability and least-cost and circuit theory-based connectivity models for each species individually and generated a multi-species corridor. Our results revealed that species-habitat relationships and subsequent corridors differed across species, but the pattern of predicted landscape connectivity across the study area was similar for all seven species regardless of method (circuit theory or least-cost) and scaling of the habitat suitability-based cost surface (linear or non-linear). Stacked species distribution models were highly correlated with the seven species for all model outputs (r = 0.79 to 0.97), while having the greatest overlap with the individual species least-cost corridors (linear model: 61.6%; non-linear model: 60.2%). Zebra was the best single-species proxy for landscape connectivity. Overall, we show that multi-species corridors based on stacked species distribution models achieve relatively low cumulative costs for savanna ungulates as compared to their respective single-species corridors. Given the challenges and costs involved in acquiring data and parameterizing corridor models for multiple species, zebra may act as a suitable proxy species for ungulate corridor conservation in this system.

Wildlife corridor degradation and human‐wildlife conflict: A case study from Tanzania

“…While elephants are known to be highly adaptable, for instance, changing their behaviours when using human-dominated landscapes (Graham et 2009), the evidence we collected from both interviews and ground tracking shows that their use of the Katavi-Mahale wildlife corridor has substantially declined. This apparent sensitivity to corridor degradation is in accordance with the findings of another study carried out in an area between Lake Manyara and Tarangire National Parks in Tanzania (Riggio et al, 2022). However, we found that other species of large mammals were still using the degraded areas between the Katavi and Mahale National Parks.…”

Using density surface models to assess the ecological effectiveness of a protected area network in Tanzania

“…Although the target species appear widely distributed across the core PCAs in the ecosystem, they were mostly absent from the UAs (Figure 3a–f). Because large‐scale connectivity is pivotal, especially for large and wide‐ranging mammals (Cisneros‐Araujo et al, 2021; Riggio et al, 2022), we recommend targeted efforts in areas outside of protected areas to ensure functional connectivity to adjacent ecosystems in order to support the persistence of wildlife populations over the long term.…”

Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania

“…However, overall wildlife movements within Tanzania have been constricted by rapid expansion of agriculture and human settlements (Caro & Davenport, 2016;Jones et al, 2009;Lamprey, 1964;Riggio et al, 2022;Riggio & Caro, 2017). Although savannah elephants are known to cross the GRE (Douglas-Hamilton, 1973;Lohay et al, 2020;Prins et al, 1994), most other wildlife movements eastwest or around the formidable cliffs of the GRE are rare (Baker et al, 1972;Scoon, 2018).…”

“…By contrast Masai giraffe populations in the Serengeti Ecosystem west of the GRE are dispersed over a large single, protected landscape mostly free of human settlements and agriculture, although whether giraffes move between dispersed populations in the Serengeti Ecosystem is unknown. However, overall wildlife movements within Tanzania have been constricted by rapid expansion of agriculture and human settlements (Caro & Davenport, 2016 ; Jones et al, 2009 ; Lamprey, 1964 ; Riggio et al, 2022 ; Riggio & Caro, 2017 ). Although savannah elephants are known to cross the GRE (Douglas‐Hamilton, 1973 ; Lohay et al, 2020 ; Prins et al, 1994 ), most other wildlife movements east–west or around the formidable cliffs of the GRE are rare (Baker et al, 1972 ; Scoon, 2018 ).…”