Journey North Hummingbird Spring 2006

Discussion of Challenge Questions #3 and #4

Photo: S. Sorenson

Two weeks ago, we reported on a rufous hummingbird that wintered in Indiana. Then we shared some hummer facts and asked you these questions:

#3: What factors can you list that could explain this Rufous sighting in Indiana?
#4: What factors could explain the overall increase in Rufous sightings?

What Students Said
Seventh grade students at Iselin Middle School in New Jersey thought about the conditions hummingbirds need to survive.

“Our group agrees maybe the Rufous hummingbirds saw a big patch of flowers and came down to eat. They stayed there because conditions were favorable.” (Anthony M., Vaho, Gurpreet, Vanessa)

“Unlike other states, Indiana probably has favorable limiting factors, such as
shelter, blooming flowers that contain food, and water for bathing. Last, but
not least, excellent breeding grounds in this environment are acceptable to the birds.” (Anthony, Kara , Sophie, Zaheen)

Good thinking! Now let’s dig deeper. Remember, scientists always question data. For instance, many asked, “Are there really more rufous hummers in Indiana than before, or is something else at work?”

What Hummingbird Researchers Say
Nobody knows for sure why rufous hummingbirds have been sighted out of their range more often in recent winters than in the past. Researchers collect data on sightings over many years. That way, they can can look for patterns and better explain what’s happening. Here are some theories from hummingbird specialists:

Maybe people are just noticing them more . . .

More rufous hummingbirds are being reported out of their range simply because more people are aware of them (for instance, through Internet projects like Journey North and Operation Migration).
Because of such projects, people are also more aware of the scientific value of reporting unusual sightings.
Because more people are watching hummingbirds, more hummers are likely to be spotted in the winter. (But the numbers may not have changed!)

Changing conditions might influence rufous hummingbirds' winter travels . . .
Hummingbird feeding has become more popular over the years. More people are putting out feeders. More are also leaving them up into the winter.
Rufous hummingbirds overwinter in much cooler regions that ruby-throated hummers do. They might be able to survive mild winters out of their range.
Mild weather during the past several winters has allowed some hummingbirds to wander further than normal. (Global warming might play a role.)
Habitat destruction in the traditional wintering grounds or along migratory paths could influence more hummers to wander.

How might school and community observers affect data in Journey North's Hummingbird study? See Citizen Science and Journey North.