Hummingbirds typically leave Colorado in the last week of September or early October. Due to Colorado's high altitude, they migrate before frost destroys their food sources, such as flowering plants and insects. Most hummingbirds stay in Colorado from late April to early September or mid-October, with some variation depending on the species. For example, Broad-tailed Hummingbirds often depart in mid-October, while Black-chinned Hummingbirds tend to leave by the first week of October. Overall, you can expect hummingbirds to start their migration southwards from late September through early October.
