Species with Most Block Gains
Top 30 species with the greatest percent increase in number of priority blocks reported from the First (1987–1995) to the Second (2007–2012) Colorado Breeding Bird Atlas.
| Species a | # of Atlas I Blocks | # of Atlas II Blocks | % Increase in Priority Blocks |
| Summer Tanager | 1 | 8 | 700% |
| Black Phoebe | 4 | 23 | 475% |
| Great-tailed Grackle | 27 | 127 | 370% |
| Least Flycatcher | 2 | 9 | 350% |
| Cattle Egret | 1 | 4 | 300% |
| Bald Eagle | 19 | 69 | 263% |
| Osprey | 16 | 54 | 238% |
| Columbian Sharp-tailed Grouse b | 9 | 25 | 178% |
| Gray Catbird | 68 | 184 | 171% |
| Willet | 3 | 8 | 167% |
| Dickcissel | 59 | 157 | 166% |
| Cedar Waxwing | 70 | 171 | 144% |
| Double-crested Cormorant | 27 | 59 | 119% |
| Sandhill Crane | 23 | 48 | 109% |
| Western Grebe | 19 | 39 | 105% |
| Black-necked Stilt | 5 | 10 | 100% |
| Great Blue Heron | 105 | 205 | 95% |
| Peregrine Falcon | 36 | 70 | 94% |
| Long-eared Owl | 37 | 70 | 89% |
| Green Heron | 7 | 13 | 86% |
| Ovenbird | 7 | 13 | 86% |
| Grace’s Warbler | 22 | 41 | 86% |
| Barn Owl | 75 | 137 | 83% |
| American Three-toed Woodpecker | 118 | 216 | 83% |
| Northern Saw-whet Owl | 72 | 129 | 79% |
| Snowy Egret | 9 | 16 | 78% |
| Wild Turkey | 142 | 249 | 75% |
| Northern Pygmy-Owl | 37 | 64 | 73% |
| Gray Vireo | 45 | 78 | 73% |
| Eastern Phoebe | 23 | 39 | 70% |
a Omits species with zero priority blocks in Atlas I.
b Sharp-tailed Grouse subspecies (Columbian and Plains) analyzed separately.
Species with Most Block Losses
Top 30 species with the greatest percent decrease in number of priority blocks reported from the First (1987–1995) to the Second (2007–2012) Colorado Breeding Bird Atlas.
| Species a | # of Atlas I Blocks | # of Atlas II Blocks | % Decrease in Priority Blocks |
| Red-eyed Vireo | 16 | 2 | −88% |
| Black Tern | 11 | 2 | −82% |
| Chestnut-sided Warbler | 4 | 1 | −75% |
| Short-eared Owl | 16 | 5 | −69% |
| Western Screech-Owl | 37 | 13 | −65% |
| Chestnut-collared Longspur | 14 | 5 | −64% |
| Field Sparrow | 5 | 2 | −60% |
| Lesser Prairie-Chicken | 9 | 4 | −56% |
| Greater Roadrunner | 52 | 23 | −56% |
| Barrow’s Goldeneye | 4 | 2 | −50% |
| Least Tern | 4 | 2 | −50% |
| Northern Pintail | 97 | 50 | −48% |
| Black Swift | 25 | 13 | −48% |
| Lewis’s Woodpecker | 167 | 88 | −47% |
| Canvasback | 7 | 4 | −43% |
| Veery | 22 | 13 | −41% |
| Mountain Plover | 116 | 71 | −39% |
| Yellow-billed Cuckoo | 53 | 33 | −38% |
| Northern Bobwhite | 67 | 42 | −37% |
| Long-billed Curlew | 78 | 51 | −35% |
| Piping Plover | 3 | 2 | −33% |
| Forster’s Tern | 6 | 4 | −33% |
| American Redstart | 9 | 6 | −33% |
| Green-winged Teal | 247 | 167 | −32% |
| Scaled Quail | 139 | 94 | −32% |
| Belted Kingfisher | 284 | 202 | −29% |
| Indigo Bunting | 62 | 44 | −29% |
| Evening Grosbeak | 254 | 181 | −29% |
| American Dipper | 251 | 183 | −27% |
| Canyon Towhee | 77 | 56 | −27% |
a Omits species with zero priority blocks in Atlas II.