Great Tame. They lay special eggs which are used to make the best kibble in the game, extraordinary kibble. I found the best place to tame them is around the green obelisk. Follow the river out to the ocean and you should find some along the way. The river also has lots of Sabertooth Salmon and piranhas which the Hesperornis love. The process is still lengthy as they need lots of fish to tame, but finding those fish and paying attention to sizes (around 1.0 the larger the better) will make it much faster