Regardless of the poll results, the scientific consensus is that birds ARE a group of theropod dinosaurs that evolved during the Mesozoic Era. A close relationship between birds and dinosaurs was first proposed in the nineteenth century after the discovery of the primitive bird Archaeopteryx in Germany.
The Berlin specimen of Archaeopteryx lithographica
Birds share many unique skeletal features with dinosaurs.
Moreover, fossils of more than twenty species of dinosaur have been collected with preserved feathers. There are even very small dinosaurs, such as Microraptor and Anchiornis, which have long, vaned, arm and leg feathers forming wings.
Close up of Anchiornis wings
Fossil evidence also demonstrates that birds and dinosaurs shared features such as hollow, pneumatized bones, gastroliths in the digestive system, nest-building and brooding behaviors.
The ground-breaking discovery of fossilized Tyrannosaurus rex soft tissue allowed a molecular comparison of cellular anatomy and protein sequencing of collagen tissue, both of which demonstrated that T. rex and birds are more closely related to each other than either is to Alligator.
Even then, you can compare the legs and feet of birds like Emus... to that of Ornithomimus...
Emu leg and feet
In fact, if you remove all the feathers from an Emu, you basically have a naked avian (bird) dinosaur.