Drivers of change and stability in the gut microbiota of an omnivorous avian migrant exposed to artificial food supplementation

Human activities shape resources available to wild animals, impacting diet and likely altering their microbiota and overall health. We examined drivers shaping microbiota profiles of common cranes (Grus grus) in agricultural habitats by comparing gut microbiota and crane movement patterns (GPS-tracking) over three periods of their migratory cycle, and by analyzing the effect of artificially-supplemented food provided as part of a crane-agriculture management program. We sampled fecal droppings in Russia (non-supplemented, pre-migration) and in Israel in late fall (non-supplemented, post-migration) and winter (supplemented and non-supplemented, wintering). As supplemented food is typically homogenous, we predicted lower microbiota diversity and different composition in birds relying on supplementary feeding. We did not observe changes in microbial diversity with food supplementation, as diversity differed only in samples from non-supplemented wintering sites. However, both food supplemen...