Chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is a fungal disease only fatal to some amphibian species. Among the vulnerable species is the Nectophrynoides asperginis, endemic to the Kihansi Gorge spray wetlands in Tanzania’s Udzungwa Mountains. By 2009, chytridiomycosis had driven N. asperginis to extinction in the wild, though it survives in captivity. Reintroduction efforts have faced difficulties, underlining the importance of understanding Bd’s prevalence in the wild to guide re-introduction programs. We assessed Bd’s presence 20 years after its initial detection in Tanzania and determined whether it was responsible for the 98% mortality of 1000 captive-bred N. asperginis released in Feb 2022. In December 2022, time-constrained surveys were conducted across three spray wetlands covering N. asperginis habitats. Amphibians were skin-swabbed following a protocol developed by the University of California, resulting in two sets of 44 samples from seven species. These samples were analyzed for Bd presence using conventional and real-time quantitative polymerase chain reaction, followed by nucleotide sequencing of PCR products. Bd was detected in 32% of samples, affecting four species: Arthroleptides yakusini (14%), N. asperginis (9%), Ptychadena anchietae (7%) and Hyperolius substriatus (2%). Whereas N. asperginis was severely affected, the other species were healthy carriers. Bd-CAPE was confirmed as the cause of the mass deaths of the released toads. The continuing presence of Bd-CAPE in the spray wetlands remains a barrier to the successful re-introduction of N. asperginis, necessitating further experimentation to develop strategies for coexistence.

To conserve wide-ranging species in human-modified landscapes, it is essential to understand how the behavior of animals changes in relation to the degree and composition of modification. Evidence suggests that large inter-individual variation exists in the propensity for use of human-modified areas and may be driven by both behavioral and landscape factors. The use of agriculture lands by wildlife is of particular interest, given the importance of reducing human-wildlife conflicts and understanding how such areas can function as biodiversity buffers. African elephant space use can be highly influenced by human activity and the degree to which individuals crop-raid. We analyzed GPS data from 56 free-ranging elephants in the Serengeti-Mara Ecosystem using resource selection functions (RSFs) to assess how crop use may drive patterns of resource selection and space use within a population. We quantified drivers of similarity in resource selection across individuals using proximity analysis of individual RSF coefficients derived from random forest models. We found wide variation in RSF coefficient values between individuals indicating strongly differentiated resource selection strategies. Proximity assessment indicated the degree of crop use in the dry season, individual repeatability, and time spent in unprotected areas drove similarity in resource selection patterns. Crop selection was also spatially structured in relation to agricultural fragmentation. In areas with high fragmentation, elephants spent more time in crops and selected most strongly for crops in areas close to the protected area boundary, but in areas with low fragmentation elephants spent half as much time in crops and selected most strongly for crops further from protected area boundaries. Our results highlight how individual differences and landscape structure can both shape use of agricultural landscapes. We discuss our results in respect to the conservation challenges of human-elephant conflict and incorporating behavioral variation into human-wildlife coexistence efforts.