Bertha is an American Kestrel, North America’s smallest falcon. They are colorful raptors (specifically the males) with spotted plumage, including two eye-like black spots on the back of their heads that may confuse predators. If you ever hear these sounds, you may be able to spot one on a telephone pole or wires, or perhaps on a fence post nearby.
American Kestrels can see in the ultraviolet light range, allowing them to easily track voles, mice, and other small mammal prey by their urine trails. They also have super head stabilization skills, making it look locked in one position in the air. From Talons and Teeth:
Watch this next: The Brown Owl’s remarkable head stability.
Many bird species readily display their natural ability to stabilize their heads, but the kestrel seems to do it most frequently. Complex neck movements let them keep their eyes completely focussed on what they are looking at when perched on a branch or wire that is swaying in the breeze!
via The Awesomer.