Migration timing

In most of Colorado, hummingbirds arrive in April and most are gone by the end of September. The two species that nest here, the Broad-tailed and the Black-chinned, show up first, in April (later in the mountains). The busiest stretch is July and August, when Rufous and Calliope hummingbirds come through on their way south. Males arrive first in spring and leave first in late summer.

Colorado's hummingbird calendar

  • March: a few early Broad-tailed reach the Front Range foothills in some years. Most of Colorado is still waiting.

  • April: Broad-tailed and Black-chinned arrive at lower elevations, males first. Time to have feeders up.

  • May: Broad-tailed reach the high mountains. Females are building nests.

  • June: nesting season. Females are sitting on eggs and raising chicks.

  • July: Rufous start arriving from the north, and Calliope begin passing through. Young birds are out of the nest.

  • August: peak feeder activity and the most fights. Adult males start heading south. Black-chinned begin leaving.

  • September: most birds leave. Females and young of the year are the last ones at the feeder.

  • October: mostly gone. A late straggler is possible, which is why feeders stay up a while after the last sighting.

Spring arrival

  • Black-chinned: typically arrive in April. They stick to lower elevations, below about 6,000 feet.

  • Broad-tailed: males reach the lower foothills around the end of April, and the species fills in across Colorado from late April into early May. In the high mountains, May is more typical. Evergreen Audubon has reported Broad-tailed in the foothills as early as mid-March in recent years.

  • Males come first: males arrive ahead of the females to claim territories, often in the same spot as the year before.

  • When to put feeders out: Denver Audubon suggests hanging feeders from mid-April to mid-September. If you want to catch the early birds, have them up a week or so before you expect the first arrival. In bear country, read the bear note on the Feeders and Nectar page first.

Summer

Broad-tailed nesting runs from late April to late July. The female lays 2 eggs and sits on them for 16 to 19 days, and the young leave the nest 21 to 26 days after hatching.

A climate note: a University of Colorado Boulder study near Crested Butte found that Broad-tailed hummingbirds still arrive on the same schedule as decades ago, but early flowers like glacier lily now bloom about 17 days earlier than in the 1970s. The birds are increasingly arriving after their first food source has peaked.

The late-summer rush

July and August are the best time of year to watch a Colorado feeder.

  • Rufous: Rufous hummingbirds make a big clockwise loop each year: north up the Pacific Coast in spring, then south through the Rocky Mountains in late summer. They can start south as early as July and show up in Colorado from early July on.

  • Calliope: the smallest bird in the United States takes a similar route and turns up in the foothills and mountains in July and August.

  • More birds, more fights: migrants stop to refuel, and Rufous are famously aggressive. All ages and both sexes defend feeders, even on stopovers of just 1 to 2 weeks. If one orange bird is chasing everything else away in August, it's probably a Rufous.

Fall departure

  • Adult males leave first: often starting in August. Females and young birds stay longer, so the birds you see in September are mostly green-backed females and juveniles.

  • Black-chinned: leave in August or early September.

  • Broad-tailed: head south from August through September.

  • Day length triggers migration, not food: shortening days tell hummingbirds when to go. Leaving your feeder up won't keep a bird from migrating, and it can help a late straggler refuel. More on that on the When They Leave page.

My season log

I watch the feeders from my porch in southern Denver. Here's my 2026 season.

  • Feeders up: last week of March / first week of April

  • First bird: April (a Rufous)

  • Busiest stretch: mid-August into September

  • Last bird: September 30

I put my feeders up in the last week of March or the first week of April. That's a bit early, but it doesn't hurt in case some birds come early.

I don't know the exact date of my first visitor, since I was probably away when it showed up. The first one I did catch was a Rufous heading north, which surprised me, since most Rufous take the Pacific Coast north in spring and come through Colorado on the way south. This likely is a misidentification, but if it was a Rufous, poor little guy was lost.

The busiest stretch was mid-August into September, when migration was really kicking in, and Rufous and Calliopes were passing through along with the Broad-tailed and Black-chinned that nest here.

The last bird I saw, and the last one my camera feeder caught, was on September 30.

Sources

From the Journal

Journal
Update 1 - Learning

This is the first update since starting and creating this website. A lot has happened since, and I would like to take the time today to do so with this first blog post.

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