How can giant petrels catch young penguins on land?

Giant petrels are uniquely capable among the order Procellariiformes of hunting on land, where they act as predators of young or weak penguins.12

Because they are sufficiently agile on land, giant petrels target penguin chicks that are inadequately guarded by their parents at nesting grounds. While many other seabirds in the region feed on unguarded eggs, the giant petrel is specifically noted for its ability to actively attack and kill the young of other species. This predatory behavior is a significant source of mortality for penguin chicks in coastal colonies.123