Birds that are common to Colorado Springs year-round, and are considered invasive species or at least are not native to North America. These birds adapt well to living near humans, and live almost anywhere that people do (or are trending in that direction).

https://www.flickr.com/photos/19598613@N00/447649984/sizes/m/
Author: Author: Trisha Shears. Creative  Commons Attribution-Noncommercial 2.0

• Aggressive bird that displaces our native species
• Related to mynahs; song includes squeaky imitations of other birds and human-related sounds
• Breeding adults have iridescent plumage
• Immature and winter birds show heavy speckling
• A large flock of starlings is called a “murmuration”

https://www.flickr.com/photos/hisgett/4215602681/sizes/m/
Author: ahisgett. Creative Commons Attribution 2.0 Generic

• Has spread rapidly across North America since the 1960s
• Distinguished from Mourning Dove by chunkier pigeon-like body and smallish head, dark collar, light stone color,  squared-off tail.   
• Song is repetition of 3 cooed notes; call is a single harsh high-pitched “growl”, often given during display flight

https://www.flickr.com/photos/yeliseev/3402321180/
Author: Sergey Yeliseev. Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 Generic

• Old-world species that aggressively displaces native birds.
• Chirps monotonously.
• Male shown: female slightly smaller, drab all over, with brown beak.
• Often seen picking up crumbs underneath tables and chairs at restaurants with outdoor seating.

https://www.geograph.org.uk/photo/1309587
Copyright Christine Matthews. Creative Commons Attribution-Share Alike-2.0 Generic

• Natural habitat is cliffs; pigeons flourish among human structures such as skyscrapers
• Vocalization is a repetitive, throaty coo
• Pigeons in North America are a mix of the original wild bird and domesticated breeds