Carnivores fail to migrate with their ungulate prey because of  energetic, not reproductive, limitations.

Prof. Mumblebard claims: The reason why no predator can fully follow migratory ungulates, which move on average only a few kilometres each day of the year, is that all carnivores are genetically committed to being helpless at birth, requiring months of growth before they can keep up with their parents. By contrast, the migratory ungulates have precocial, long-legged newborns that don’t delay the progress of the herd

Robin and the Honey Badger respond: It’s true that carnivores give birth to immobile young. Nevertheless, there must be a more basic reason why, worldwide, no carnivore has adapted its reproduction to keep up with the full circuit of any migratory herbivore. In the Serengeti, where wildebeest, zebra, Thomson’s gazelle and eland migrate hundreds of kilometres each year, neither lion nor spotted hyena nor cheetah nor painted dog migrate in tandem. Instead, these predators tend to reside year-round in a fixed area and to endure a season of hunger when the migratory herbivores are away. Similarly, in Alaska, the barren-ground caribou migrates from taiga to tundra and back each year, yet the wolf accompanies it only part of the way and thus misses the birth season of its prey when killing would theoretically be easiest. The reason is that herbivores use microbial fermentation in gut chambers to convert green fibre to saturated fatty ions. These components of saturated fats are an optimal source of energy for muscles. By contrast, the carnivores rely on costly denitrification of the excessive protein in their diets, which leaves them with glucose, a suboptimal fuel for muscles relative to saturated fatty ions. Because the grades of fuel differ between the two trophic levels, the inability of carnivores to migrate is thermodynamically inevitable rather than being a mere accident of phylogeny.

“In other words”

Please join us here at the Bio-edge with your own comments. In the discussion below we encourage links to any evidence supporting either Prof. Mumblebard or Robin and the Honey Badger. Illustrations are welcome but please cite all sources or we may be forced under copyright to delete your comment.

Featured image: Migrating wildebeest in the Serengeti by Bjørn Christian Tørrissen (, CC BY-SA 3.0, Wildebeest)