The generality of cryptic dietary niche differences in diverse large-herbivore assemblages.

Ecological niche differences are necessary for stable species coexistence but are often difficult to discern. Models of dietary niche differentiation in large mammalian herbivores invoke the quality, quantity, and spatiotemporal distribution of plant tissues and growth forms but are agnostic toward food plant species identity. Empirical support for these models is variable, suggesting that additional mechanisms of resource partitioning may be important in sustaining large-herbivore diversity in African savannas. We used DNA metabarcoding to conduct a taxonomically explicit analysis of large-herbivore diets across southeastern Africa, analyzing ∼4,000 fecal samples of 30 species from 10 sites in seven countries over 6 y. We detected 893 food plant taxa from 124 families, but just two families-grasses and legumes-accounted for the majority of herbivore diets. Nonetheless, herbivore species almost invariably partitioned food plant taxa; diet composition differed significantly in 97% of pairwise comparisons between sympatric species, and dissimilarity was pronounced even between the strictest grazers (grass eaters), strictest browsers (nongrass eaters), and closest relatives at each site. Niche differentiation was weakest in an ecosystem recovering from catastrophic defaunation, indicating that food plant partitioning is driven by species interactions, and was stronger at low rainfall, as expected if interspecific competition is a predominant driver. Diets differed more between browsers than grazers, which predictably shaped community organization: Grazer-dominated trophic networks had higher nestedness and lower modularity. That dietary differentiation is structured along taxonomic lines complements prior work on how herbivores partition plant parts and patches and suggests that common mechanisms govern herbivore coexistence and community assembly in savannas.

Plant-frugivore networks are robust to species loss even in highly built-up urban ecosystems.

Animal seed dispersal processes are an important aspect of ecosystem services, as they shape the survival of seed dispersers and the balanced distribution of propagules for many plant communities. Several studies within tropical wild ecosystems have generally shown that seed dispersal processes are highly generalised and robust to extinction. Studies examining seed dispersal networks in highly built-up urban ecosystems and their robustness to species loss or extinction are rare. We examined avian seed dispersal networks across an urban ecosystem characterised by a high human settlement and infrastructure of the built environment in Zambia to determine their network specialisation, interaction evenness and interaction diversity, as these three parameters are critical in driving the resilience of these mutualisms' interactions against extinction. A total of 405 individuals representing 11 species of birds were observed and recorded feeding on a total of 11 focal fleshy-fruiting plant species. Network specialisation was generally low and remained similar across study areas. Interaction evenness and interaction diversity were not only high but also remained similar across study areas. Low specialisation and high interaction evenness and diversity show that mutualistic interactions in these networks are equally highly generalised, suggesting a stable and robust coexistence of species in plant-frugivore communities within urban ecosystems. Generally, our results seem to broadly suggest that opportunities for conservation still exist in these ecosystems provided urbanisation is accompanied by promoting either the management of remnant fruiting plants or the cultivation of new ones to support the avian communities existing in these areas.

Food Quality in Lusaka National Park: Tracking Mortality in Black Lechwe Antelopes.

Translocation is one of the fundamental tools in wildlife management but only if appropriately undertaken. In 2009, 30 black lechwe antelopes were suddenly translocated from the State House Habitat (STH) into the newly established Lusaka National Park (LNP). However, within 4 months of being translocated to LNP, 28 black lechwes (93%) died. A pathological report produced by veterinarians following a postmortem examination suggested no disease incidence affected the antelopes. The food quality of LNP was tested and compared to that in the STH and the antelopes' native habitat of the Bangweulu wetlands (BGW) to establish if variations in food quality were responsible for the antelopes' mortality. The findings suggest that the food quality in LNP was greatly inferior to that in STH, which could explain the observed high mortality of the antelopes in LNP. Further, the quality of food in LNP did not widely differ from that in the BGW, suggesting that the antelopes might not have survived had they been translocated to their native habitat, as they had already adapted to feeding on highly nutritious supplementary feed at the STH.