Why I am obsessed with hummingbird pee…and torpor

My two recent obsessions have been hummingbird pee and hummingbird torpor.

Video: Hummingbirds may be small, but their energy consumption is huge. Learn how they do this.

Hummingbirds are tiny (and I mean, tiny) birds.

They use up energy very quickly and barely store any fat, so they really don’t have a backup generator to rely on if they come close to running out of fuel. I’m really interested in how they manage this limited energy over short time scales.

Okay, so going back to my obsessions. We all know what pee is, but here’s a hummingbird peeing, just in case you were curious:

A Rivoli’s hummingbird peeing as it is released. Photo credit: Don Powers

We injected stable (non-radioactive) double isotopes of water (Deuterium + Oxygen-18) into hummingbirds, and collected their pee just after injection, then released them. Twenty-four hours later we would try capturing the same hummingbirds to collect another pee sample. The change in the levels of isotopes in their pee over 24 hours told us how much energy they’d used in the wild in that time! How cool is that? So I was (understandably, don’t you think?) excited when they peed for us. Sometimes, as you saw in this gif, they would pee as a goodbye token to us as they were released. This was often even more exciting, because sometimes it was the only pee sample we got from that bird–we would scramble to collect it from our hands!

And what is torpor? Daily torpor is an energy-saving mode, a form of hibernation, that some animals use. Like humans, hummingbirds are endotherms; they generate their own body heat to keep warm.

We use infrared cameras to measure hummingbirds’ surface temperatures at night. Here’s a hummingbird spending energy to keep its body temperature nice and high at about 41oC (though because of the insulation its feathers provide, its surface temperature maxes out at about 36oC):

A hummingbird maintaining a normal body temperature. Photo credit: Anusha Shankar, Isabelle Cisneros

We also use oxygen and carbon dioxide analyzers to measure a hummingbird’s breath at night and estimate how much energy it spends per second. A hummingbird at normal body temperature spends energy something like this for an hour at night:

By using torpor at night, some endotherms allow the outside air to decide their body temperatures, and allow some of the internal processes in their body–their metabolism–to slow down. These torpid animals can drop down to using just 5-30 percent of the energy they would normally use while awake and resting.

Hummingbirds, being tiny, speedy, flying machines, often use torpor overnight, when they don’t have access to their energy-packed sugary nectar. Somewhat dramatically, they do this to avoid speeding their way to death overnight. But as a result, hummingbirds in torpor are quite useless; a torpid hummingbird cannot respond to outside stimuli for between 10-20 minutes. Here’s what it looks like when a hummingbird enters torpor (black means the bird is at normal body temperature, and red means the bird is in torpor):

And when it is in torpor for a whole hour:

Hummingbird in Torpor

And this infrared image below is what a hummingbird in torpor looks like; you’ll notice that its body’s temperature is about the same as that of the air around it (~ 17oC)!

Imagine if you were on a cold mountain somewhere, running out of food, and you could turn your internal thermostat down and save energy–all without feeling terribly cold, because your body was itself cold! Hummingbirds can save 65-92 percent of their energy every hour that they use torpor. I was mindblown when I realized this. I am so happy that scientists before me invented ways of measuring the oxygen in a bird’s breath, and ways to measure the temperature of a surface with a camera. And that I was able to take this technology to the field and explore what hummingbirds in their natural habitats do to balance their crazy energetic needs!

Beautiful Places to Work

My field team and I have gone to a number of beautiful and beautifully different places to study how hummingbirds manage their energy on a daily basis. Here are some of our sites:

Patagonia Lake State Park, Arizona, USA. Photo credit: Anusha Shankar

A view from the Santa Lucia cloud forest in Ecuador (1900m). Photo credit: Anusha Shankar

Maquipucuna cloud forest, Ecuador (1400m). Photo credit: Anusha Shankar

A view from El Gullan, Universidad del Azuay, in the Ecuadorian Andes (3000m). Photo credit: Anusha Shankar

Our hummingbird headquarters at El Gullan, Universidad del Azuay, in the Ecuadorian Andes. Photo credit: Anusha Shankar

Mist nets we used at El Gullan, Ecuador, to catch hummingbirds. Photo credit: Anusha Shankar

In the video, a description of our site at El Gullan (owned by the Universidad del Azuay), near La Paz, Ecuador. We studied hummingbird physiology and ecology. Check out my blog page for more details! anushashankar.weebly.com/fieldwork-blog

Originally posted 2018-02-07 02:01:13.

The Best of the Top 25: Part 2

This week we continue our flash back on some of the best Top 25 photographs of the last year. Of the thousands of pictures submitted and the hundreds selected for the Top 25 blogs, these are considered the best of the best! Thank you to all the photographers who have submitted pictures over the last year. Your pictures allows us to a tell a story about the wonderful birdlife that exists on our planet. Keep up the good work!

To recap even more of our Top 25 images you can visit our youtube channel. You can find even more bird photography highlights on our Twitter, Instagram and Facebook pages!

This beautiful Anna’s Hummingbird can be found on the west coast of North America (Sutapa Karmakar)The pet trade is one of the factors driving Bali Mynas to extinction (Arun Samak)The Black-throated Trogon can be found in the humid forests of South America. This one was photographed in Panama by Owen DeutschIn winter Brown-headed Gulls can be found on the coastlines of India and south-east Asia. Here they associate with fishing vessels, eating any scraps from the ship (Mukesh Mishra)The Brown-hooded Kingfisher of southern Africa rarely fishes, in fact they eat mainly insects (Rodnick Clifton Biljon)A Handsome Burchell’s Starling photographed in Botswana by Owen DeutschThe Collared Kingfisher is widespread across south-east Asia. Taxonomists have divided the species into 50 different sub-species! Although the species as a whole is widespread some of the sub-species have very small populations which are threatened (Kishore Debnath)The Common Kingfisher eats mainly fish and insects. Several times a day they will regurgitate a pellet with the indigestible remains of their prey (Kuntal Das)The Daurain Redstart was previously known to only breed in China, Mongolia and Russia. Recently a new breeding population was discovered in Japan (Vinayak Joshi)The Demoiselle Crane breeds aross central Eurasia. Those from the west of the breeding range then migrate to Africa for the winter and the others migrate to India (Anirban Roychowdhury)An endangered Egyptian Vulture photographed in Haryana, India by Vishal MonakarThe Eurasian Jay is a woodland species, they collect acorns and bury them to eat later. However they store far more than they need and many of them will start to grow into oak trees (Asim Haldar)The breeding success of European Bee-eaters is strongly linked to weather conditions. A study in Germany found breeding success to be twice as good in warm, dry years, compared to wet and cold years (Carlo Galliani)This European Starling is in fresh plumage, once the feathers start the wear, the pale spots become less visible (Donald Bauman)Male Great Bustards are known to eat poisonous blister beetles in the mating season. These contain cantharidin, a known aphrodisiac. It is suspected that this helps makes the males more willing to court females (Lennart Hessel)A yellow morph of the Green-winged Pytilia photographed in Kimberley, South Africa. Normally the face would be red in this species (Brian Culver)Between 1985 and 2004 the population of Grey Crowned-cranes halved, they are now considered endangered (Wasif Yaqeen)A striking portrait of an Indian Eagle-owl (Prasad Sonawane)The Northern Long-eared Owl has excellent hearing, it is thought that they locate their prey mainly from sound (Zafer Tekin)A male Calliope Hummingbird showing his colourful display feathers (Jola Charlton)A Mountain Bulbul photographed in the Himalayas by Vishal MonakarA pair of Atlantic Puffins on Skomer Island, Wales (Suranjan Mukherjee)Even thought Steppe Eagles are endangered, they are still one of the most common large eagles in the world (Tauseef Zafer)Violet-backed Starlings are important dispersers of mistletoes. They eat the fruit and then regurgitate the seed which then grows into a new plant (Shantharam Holla)The White-throated Bee-eater breeds along the edges of the Saharan desert, before wintering in central Africa (Caroline Muchekehu)

Our mission is to build a global community around the freedom and beauty of birds in the wild as ambassadors for the natural ecosystems that they depend upon. They are the music, decoration, and character of every terrestrial habitat on the planet and have been around since the dinosaurs. They are the witnesses and ambassadors of the awesome power of nature. The wide availability of good, cheap optics has opened their world to us for the last few decades. Amazing, affordable DSLR cameras with long lenses are delivering brilliant digital bird imagery to online communities.

We are in a day-and-age during which more bird species are threatened with extinction than ever before. The Wild Birds! Revolution aims to publish the “Top 25 Wild Bird Photographs of the Week” to 1 million people every week by the end of the year. That is a revolution that will change the world! Join thousands of other weekend naturalists, photographers, birders, experts, hikers, nature-lovers, guides, scientists, conservationists and artists that share the thousands of wild bird photographs submitted to the Wild Bird Trust website and Facebook page. Thousands of wild bird enthusiasts are going out every day to photograph our planet’s beautiful birdlife. Pick up your camera, fill your bird feeder, open your heart, and join the Wild Birds! Revolution!!

Edited by Christie Craig, Campaign Manager

The Best of the Top 25: Part 1

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