Herbivores play an important role in determining the structure and function of tropical savannahs. Here, we (i) outline a framework for how interactions among large mammalian herbivores, carnivores and environmental variation influence herbivore habitat occupancy in tropical savannahs. We then (ii) use a Bayesian hierarchical model to analyse camera trap data to quantify spatial patterns of habitat occupancy for lions and eight common ungulates of varying body size across an approximately 1100 km 2 landscape in the Serengeti ecosystem. Our results reveal strong positive associations among herbivores at the scale of the entire landscape. Lions were positively associated with migratory ungulates but negatively associated with residents. Herbivore habitat occupancy differed with body size and migratory strategy: large-bodied migrants, at less risk of predation and able to tolerate lower quality food, were associated with high NDVI, while smaller residents, constrained to higher quality forage, avoided these areas. Small herbivores were strongly associated with fires, likely due to the subsequent high-quality regrowth, while larger herbivores avoided burned areas. Body mass was strongly related to herbivore habitat use, with larger species more strongly associated with riverine and woodlands than smaller species. Large-bodied migrants displayed diffuse habitat occupancy, whereas smaller species demonstrated fine-scale occupancy reflecting use of smaller patches of high-quality habitat. Our results demonstrate the emergence of strong positive spatial associations among a diverse group of savannah herbivores, while highlighting species-specific habitat selection strongly determined by herbivore body size. This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.

In carnivores, securing suitable den sites with associated early maternal home ranges is important for successful reproduction, and understanding natal den site selection is essential to ensure that these habitats are protected from human disturbance. This study investigated Eurasian lynx Lynx lynx natal den site selection across multiple use landscapes in Norway and explores whether the selection of early maternal home ranges across southern Norway involved a trade-off of security for access to their preferred prey species, roe deer Capreolus capreolus. The characteristics of natal dens and home ranges from 33 reproductive events were quantified across south-eastern and northern Norway. Natal dens were located in terrain further from the most accessible and disturbed areas (public roads) and in terrain more rugged than generally available. Early maternal home ranges were characterized by low human and low road density in rugged terrain and a selection for areas associated with higher or lower roe deer densities was not important in our analysis. Humans are the dominant cause of lynx mortality throughout Norway and our findings suggest that female lynx primarily chose areas that limited their interaction with people during the denning period.

Ollier disease is a rare disorder characterized by the presence of multiple enchondromas and a propensity to develop malignancies. We report the case of a 7-year-old Caucasian male with Ollier disease who developed acute myelogenous leukemia (AML). This report describes a patient with Ollier disease and AML and may offer a clue into the genetic pathogenesis of these disorders.