Avian Dinosaurs: Bald Eagles at the Sacramento National Wildlife Refuge

Sometimes I am reminded that the dinosaurs never actually went extinct. They were decimated certainly, and their present-day species don't look all that much like their ancient ancestors, but there are occasional clues to their dinosaurian past. The claws of a Bald Eagle (Haliaeetus leucocephalus), for instance. We were at the Sacramento National Wildlife Refuge just before Christmas, and saw several of birds at close quarters.

How close are the birds to the dinosaurs? Dinosaurs are classed as reptiles, but the reptiles we know today, the lizards, snakes, turtles, and crocodiles, were separate evolutionary lines in the Permian and early Triassic, before the dinosaurs even arose. The crocodilians are the closest of these ancient relatives, but they were already on their own evolutionary path during the Jurassic and Cretaceous periods when the dinosaurs were dominating the terrestrial habitats of the planet.

The birds on the other hand developed from the dinosaurs, descending from small theropod carnivores similar to the Velociraptor or Deinonychus, monsters made famous in the Jurassic Park movies. Evidence has emerged in recent decades that many dinosaurs may have in fact sported feathers (which are modified scales). Many bird embryos support teeth that are later resorbed during development.

In any case, that's what I was thinking about as we came across at least three Bald Eagles while traveling the auto tour route at the Sacramento Refuge. There were a couple of immature individuals and one adult. They were accustomed to automobiles passing by so they didn't retreat as we passed by, enabling me to get a zoomed view of their claws.

One juvenile was still hanging out with mom, while the other was on its own. They were a sight to see in the rain (that's why they all looked a little scruffy; they were generally soaked).