[Tweeters] Hummingbirds

[Gene Beall via Tweeters]

For those who don't have a subscription to the New York Times, the full 
text without photos is below.  For those who have a subscription to the 
NYT, here's the link to the article: 
https://www.nytimes.com/2025/02/14/science/hummingbirds-living-in-a-hive-found-for-the-first-time.html?unlocked_article_code=1.xE4.AvQI.4v4X26EQp3Jl&smid=url-share

Gene Beall
Sammamish, WA
gene.beall at gmail.com


*Hummingbirds Living in a Hive Found for the First Time In a remote 
mountain cave in Ecuador, hummingbirds were discovered sleeping and 
nesting together.*

Image:  A male Chimborazo hillstar, a subspecies of high-altitude 
hummingbird native to the Andes of Ecuador and far southern 
Colombia.Credit...Dusan Brinkhuizen

By Rachel Nuwer

Feb. 14, 2025

Hummingbirds are tiny and delicate, but don’t be fooled: They are among 
the most aggressive birds in the avian kingdom. Their territorial fury 
is especially aimed at other hummingbirds. Competition over a patch of 
flowers or a mate often results in high-speed aerial chases, divebombing 
and beak jousting.

So when Gustavo Cañas-Valle, an ornithologist and birding guide, 
stumbled across a cave full of hummingbirds nesting and roosting 
together in Ecuador’s High Andes, he could hardly believe it.

“I thought, ‘This looks like a colony,’” Mr. Cañas-Valle said. He added, 
“They were like bees.”

He documented 23 adult birds and four chicks,all of the subspecies 
Oreotrochilus chimborazo chimborazo, commonly known as the Chimborazo 
hillstar.

Mr. Cañas-Valle’s discovery, described in the journal Ornithology in 
November, may be the first documented example of hummingbirds that 
nested and roosted communally. It is also notable that he found the 
birds engaging in both these behaviors in the same space — something 
that even highly social species from other bird families tend not to do.

Juan Luis Bouzat, an evolutionary geneticist at Bowling Green State 
University in Ohio and another author of the study who is also Mr. 
Cañas-Valle’s former graduate adviser, said the finding raised 
fascinating questions about the role environmental factors can play in 
driving group living and in promoting the evolution of certain social 
traits.

Dr. Bouzat and Mr. Cañas-Valle at first hypothesized that harsh 
environmental conditions along the Chimborazo volcano where they found 
the nests had forced the birds together. The birds live more than 12,000 
feet above sea level on a sparsely vegetated slope where it is hard to 
come by nectar-providing flowers, water or shelter from freezing 
temperatures and biting winds.

“Either you aggregate or perish,” Dr. Bouzat said.

Image:  A view of a snow-topped mountain with a sparsely vegetated plain 
in the foreground.  The birds live more than 12,000 feet above sea level 
on a sparsely vegetated slope where it is hard to come by 
nectar-providing flowers, water or shelter from freezing temperatures 
and biting winds.Credit...Gustavo Cañas-Valle

The birds live more than 12,000 feet above sea level on a sparsely 
vegetated slope where it is hard to come by nectar-providing flowers, 
water or shelter from freezing temperatures and biting 
winds.Credit...Gustavo Cañas-Valle

But this may not be the full story. Mr. Cañas-Valle explored the region 
and found six other examples of hummingbirds nesting and roosting 
together. He and Dr. Bouzat also surveyed concrete drainage pipes 
scattered around the area. The pipes had similar environmental 
conditions to the cave but could fit only one or two nests. The 
researchers found that just 45 percent of the pipes were occupied by 
nesting females — significantly lower than the frequency expected by 
chance, according to computer simulations the authors conducted.

There were significantly more nests found in groups, on the other hand, 
than there would have been if randomly predicted. Of the 74 total nests 
Mr. Cañas-Valle documented, 82 percent were part of groups. Taken 
together, these findings implied that the birds were actively choosing 
group living over nesting alone.

Dr. Bouzat suspects that environmental factors originally caused the 
birds to aggregate but that once they bunched together, they evolved 
traits that made them more social, helping them adapt to their environment.

“I was very surprised to read about a truly colonial hummingbird, 
because most are aggressive and intolerant of others of the same 
species,” said Scott Robinson, an ornithologist at the Florida Museum of 
Natural History who was not involved in the work. “No one would have 
considered a hummingbird a candidate for coloniality.”

Image:  A hummingbird nestled on orange-flowering shrubs. The 
hummingbird's plumage is a dull gray and orange, faintly mimicking the 
surrounding flora.  A female Chimborazo hillstar. Researchers have 
discovered nesting patterns for this hummingbird subspecies that imply 
its members are actively choosing to live as a group rather than 
alone.Credit...Gustavo Cañas-Valle

A female Chimborazo hillstar. Researchers have discovered nesting 
patterns for this hummingbird subspecies that imply its members are 
actively choosing to live as a group rather than alone.Credit...Gustavo 
Cañas-Valle

Charles Brown, a behavioral ecologist at the University of Tulsa who 
also was not involved in the research, said he was not convinced, 
however, that the hummingbirds observed in the study actually qualified 
as being colonial.

Animals that live in true colonies often behave in ways that benefit 
their neighbors, Dr. Brown said, such as working together to find food 
or detect predators. While it was interesting to find hummingbirds in 
close quarters, “there was no evidence of any social behavior on the 
part of the animals nesting in these clusters,” he said.

Mr. Cañas-Valle pointed out, however, that he observed the hummingbirds 
from the cave departing and returning together, suggesting a cohesive 
social group. “It’s not that each one is doing their own thing,” Dr. 
Bouzat said.

But the authors agree that more research is needed. They hope to conduct 
behavioral studies to determine if the hummingbirds are merely 
tolerating each other or are actively cooperating.

They would also like to conduct surveys for other hummingbird species in 
similar High Andes environments to see if they are engaging in group 
living, too. “I’m sure there are other unknown caves in the mountains 
where hummingbirds live,” Mr. Cañas-Valle said. “I’m expecting to find 
other species, for sure.”



On 2/14/25 9:36 PM, via Tweeters wrote:

> This is just the beginning of an article published in The NY Times. 

>  Too long & too many pix to post the whole article

>

>

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