Do Hummingbirds Actually Sleep?

George Fox University
Newberg, Oregon
DOI: 10.18258/8929
Funded on 3/27/17
Successfully Funded
  • $4,010
  • 114%
  • Funded
    on 3/27/17

About This Project

When hummingbirds use more energy than they consume, they use deep hypothermia (torpor) at night to lower energy costs. Torpor is not restorative like sleep so extended use can have physiological consequences. Our field work suggests hummingbirds might be capable of controlled shallow hypothermia. This would be a novel tool for periods of low energy intake. We will use thermal imaging to track nighttime body temperature to see if hummingbirds use the more restorative shallow hypothermia.

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What is the context of this research?

We have measured hummingbird metabolic rates of both torpid and non-torpid hummingbirds the past two years in Arizona and Ecuador. One striking result was that in both locations some hummingbirds exhibited metabolic rates that were intermediate between torpor and non-torpor. Since nighttime metabolic rate and body temperature are connected, we viewed this as evidence that hummingbirds might be capable of regulating their body temperature a few degrees below their normal body temperature. If true then shallow hypothermia could be used for short periods of time to "sleep" and engage in physiological restoration. During deep torpor, body temperature is so low that this physiological restoration likely does not occur.

What is the significance of this project?

Extensive deep torpor use by hummingbirds has consequences. Torpor is not restorative, so its use for several consecutive nights could disrupt normal physiology resulting in poor condition. In mammals, torpor includes periodic arousals necessary for restorative sleep. Periodic arousals are not an option for hummingbirds because torpor is short-term (night only), and rewarming costs of an arousal would negate overnight energy savings. Use of controlled shallow hypothermia is more compatible with normal sleep, devoid of the rewarming costs of deep torpor, and still provides some energy saving. Broader importance includes understanding hummingbird energy management in response to increasing temperature due to climate change.

What are the goals of the project?

We will measure body-temperature regulation by hummingbirds at night to determine if they are able use shallow hypothermia in addition to deep torpor. While our experiment will involve captive hummingbirds in large cages, the measurements involve non-invasive thermal imaging of individual birds throughout the night. Measurements will be made outdoors so that hummingbirds will experience normal light and temperature variation. This is critical because previous highly controlled laboratory studies of hummingbird torpor might have masked any shallow hypothermic response. Our field site is in Arizona where we can study both territorial and non-territorial species to see if foraging strategy plays a role in how hypothermia is used to manage energy.


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Equipment, travel, and lodging are already funded for this project through external and institutional internal grants. Even so, no funding has been provided for student stipends, so sadly this project will not happen if stipend funding is not found. There are few funding sources that are willing to provide stipend funding specifically for undergraduates, which is unfortunate considering that these students represent the future of science in our country. Collaborator Isabelle Cisneros, the undergraduate student that will work on this project, will devote her entire summer to data collection and analysis so is in need of some compensation.

Endorsed by

This work represents an important contribution to physiological ecology that will clarify expected climate change responses of a key indicator species. Such research is necessary to effectively manage and protect ecosystems under continued environmental change. Having worked with Dr. Powers as both a former undergraduate research assistant and an academic colleague, I can state with confidence that this work will provide a high-quality contribution to physiological ecology along with an extremely valuable undergraduate training experience.
Having the opportunity to participate in undergraduate research in the Powers Lab has been instrumental in my career as a scientist. Dr. Powers's strong commitment to training undergraduate scientists is reflected in the quality of the work produced by the lab as well as the ongoing success of former lab members. Not only is this important work for furthering understanding of hummingbird energetics, but I can say with confidence that it will prepare undergraduates to make significant contributions to science in their future.
Dr. Powers is an established expert on the subject of hummingbird thermoenergetics and this project aims to address important questions regarding how these birds use torpor under natural conditions. I'm excited to see this group develop creative tools for quantifying torpor use. I would make use of such tools! I also highly endorse this project as a great opportunity for the training of young scientists (including the co-investigator here).
I have known Dr. Don Powers since he was an undergraduate student. I have watched his scientific and teaching career for over 30 years. His is a world renowned hummingbird physiological ecologist. He is also a master teacher! His passion for involving undergraduates in the process of becoming literate and competent scientists is practically innate. His commitment to teaching at a smaller liberal arts university deserves the support of the broader scientific community.
Don Powers is a world-renowned researcher on both hummingbirds and energetics. I have collaborated with him for several years now on energetics and mating behavior in our garter snake system in Manitoba, Canada. In that work, Don has always brought along one or two of his really bright undergraduate research students. Don's science is exceptional, he publishes his research regularly and widely, and most importantly, he is an excellent mentor to his students. Torpor is a really important physiological process that is still poorly understood.
The project is physiological ecology at its finest: probing a crucial factor of an organism's physiology that has far-reaching implications for how small bird species adapt and survive in the complex world around them. Having worked with Dr. Powers and collaborators before, I have total confidence in their techniques, equipment and technical skill used to collect the data, and am interested to learn more about how they incorporate field-collected measures of metabolism and heat to determine whether hummingbirds do use intermediate torpor.
Hummingbirds are famous for their ability to enter torpor, yet we know surprisingly little about how they use torpor in the wild. This project will expand what we know about these charming creatures.
I am looking forward with great anticipation to the results of this work, and I can think of no better place for it to be done!
We need to understand how our precious natural resources will respond to climate change. How organisms manage their energy budget is a key determinate of the habitats they occupy and whether they will thrive or go extinct. Hummingbirds are 'canaries' in the coal mine due to their high-energy lifestyle; they constantly live on the edge. Therefore, any effects of climate that affects their energy budget, may push them over the edge. Prof. Powers is an outstanding researcher and dedicated mentor to his students. This money will be well spent.

Flag iconProject Timeline

Feb 25, 2017

Project Launched

Apr 03, 2017

Lab planning session to schedule training, weekly lab meetings, and prepare for field work.

Jun 05, 2017

Travel to the Chiricahua Mountains, SE Arizona, to begin field work.

Jun 21, 2017

Complete field work in the Chiricahua Mountains.

Meet the Team

Donald R Powers
Donald R Powers
Professor of Biology


George Fox University
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Isabelle Cisneros
Isabelle Cisneros
Undergraduate Research Student


George Fox University
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Donald R Powers

I am a Professor of Biology at George Fox University, and have studied various aspects of hummingbird physiology/ecology/biomechanics for more than 30 years. My work on the energetics and biomechanics of hummingbird hovering, published in Nature in 2005, revealed important insights into the mechanics and evolution of this key hummingbird adaptation. In addition I have published numerous works that have added to our understanding of hummingbird energy management, flight metabolism, water regulation, evaporative water loss, and torpor. I am currently wrapping up a NASA-funded study of hummingbirds in both Arizona and Ecuador in which I explored how they will physiologically respond to increases in global temperature resulting from climate change. I received my B.S. degree in biology from Biola University, an M.S. in ecology from San Diego State University (advisor: Dr. George Cox), and a Ph.D. in physiological ecology from the University of California, Davis (Advisor: Dr. Wesley Weathers).

Isabelle Cisneros

I am a junior Biology major at George Fox University. Research interests me because it involves hands-on learning and critical thinking, each of which is critical preparation for my post-graduate education. I plan to attend medical school, but experiences such as this are necessary if I am to become a scholarly physician.

In addition to my interest in research and the medical field, I have a great love for the outdoors. Growing up between the mountains and the coast, much of my lifetime has been spent embracing nature. Field research, therefore, intrigues me because it is an opportunity to combine my love of both nature and science.

Additional Information

If funded this project will provide a critical research experience for a talented undergraduate student wishing to gain an experience that will prepare them for graduate school. Since practical research experience has become an expectation for undergraduates, supporting these types of opportunities is essential for shaping the future generation of scientist! Undergraduate students that work on my projects frequently have the opportunity to cap their experience with authorship on resulting peer-reviewed publications. Here is a link to one example publication Heat dissipation during hovering and forward flight in hummingbirds that is relevant to this proposed study. This study was featured as a Science Shot in the online version of Science! Below are some images of a past study on hummingbird heat dissipation at high temperature (currently being prepared for publication) as part of our broader effort to understand how hummingbirds might respond to climate change.

Former undergraduate student Katie Langland recording infrared images of Arizona hummingbirds for an upcoming paper on heat dissipation at high temperatures.
A typical infrared image taken of an Arizona hummingbird coming into a feeder.

Project Backers

  • 31Backers
  • 114%Funded
  • $4,010Total Donations
  • $129.35Average Donation
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