Today’s guest, Anusha Shankar studies hummingbirds as a Rose Postdoctoral Fellow at the Cornell Lab of Ornithology. She has lived and worked on four continents and loves being an Indian woman in science. She is fascinated by hummingbirds’ ability to use a hibernation-like state called torpor to save energy at night. She is investigating how they can get cold (10°C / 50°F) and rewarm safely every night, without damaging organs like their hearts and brains. During her PhD, Anusha captured hummingbird nightlife with infrared video, and before that tracked king cobras and studied giant birds—hornbills—in India. Anusha is also a National Geographic Explorer and Young Leader and loves mentoring students, dancing salsa, bachata, and swing, and reading fiction.


1:30 Where are hummingbirds found?

Most diverse in Ecuador and Colombia.  330 species.  Smallest is Bee Hummingbird in Cuba– weighs 1.5 to 2 gms.  Largest Giant Hummingbird is 20 gms.  

3:38 What are attractive about hummingbirds? Why hummingbirds?

She is fascinated by how hummingbirds use energy, their metabolism. If they went 3 or 4 hours without food, they die.  Ruby-throated hummingbird migrates from Mexico to Florida. It is 3 gms.  Doubles its body weight to 6 grams before flying over the Gulf of Mexico

7:30 How do you classify hummingbirds?

Hermits, Mountain Gems, Giant, Bees are some of the nine clades. Go to Columbia if you want to see the most hummingbirds

8:00 Ancestor of the hummingbird migrated in Germany.  As the Andes were rising, it diversified its species.  Recolonized North America.

9:30 What is torpor?

Daily hibernation.  Get cold and then rewarm.  Humans get hypothermia with a lowering of 2 degrees.  Many hummingbird species go down to 10 degree Celsius (from 36 degree Celsius).  One species goes down to 3 degree Celsius.  All the organs cool down and rewarm.  

11:15 Why does torpor attract Anusha?

14:43: How do hummingbirds use their time and energy?

Their activity budget is very flexible.  The broad-billed hummingbird, 3.5 grams, in Arizona, expends daily energy in a variable way. Hovering for 3 hours a day up to 13 hours a day.  Post monsoon, flowers are clustered in one place so they don’t need too hover as much.  They can drink nectar and perch.

18:00 how did hummingbirds come up with hovering?

Flowers that they drink from are delicate so they cannot perch because the flower will break.

19:00 Interesting hummingbird species

Sword billed hummingbird has a beak-to-body ratio that is large.  Giant hummingbird has a capacity to live at high elevations– in South America.

Her work is in Arizona where some hummingbird species. Anna’s hummingbirds are expanding their range northwards.  Numbers are increasing.

21:00 She explains torpor in detail.  How they go into torpor.

23:00 Which other species use torpor?

Hummingbirds, nightjars and mousebirds of Africa can drop their body temperatures by more than 20 degree Celsius.  Pigeons, chickadees and a few other bird species can drop their temperature but not by much.

25:00 Interesting uses of torpor. Nesting females for instance, don’t use torpor. Torpor in migration.  They use it when their body fat is at 30 percent. When the bird tells itself, “Oh, you are getting low in your fat threshold so you better use torpor to get through the night but we have enough for you in the morning.”

27:00 Torpor in medical research and in surgeries.

28:00 she shows a 17 second videoo of a bird going into torpor.

29:00 Favourite bird species.

Booted racketail hummingbird, black-chinned hummingbird, quetzels, hornbills– Ratnagiri district

33:20: Other birds hovering in place: compare to pied kingfishers, white-shouldered kites and other birds.  Go backwards.  Figure of 8 hovering. 


Fun facts

Unlike most other birds that just poop, hummingbirds pee. A LOT. They need to do this because they drink so much nectar, or sugar water from flowers 2 to3 times their weight every day.

Hummingbirds use up energy so quickly that if an average human used energy as fast as they do, the human would need to eat 600 packets of potato chips a day to survive (when they’would normally need about 15).

Hummingbirds are the only birds in the world that can fly backwards, in addition to flying forwards and hovering in one place. Their wings are structured very differently from other birds, allowing them to hover by moving them in a figure-8 pattern.

Hummingbird wings can beat as fast as 80 times a second. Their hearts can beat more than 1000 times a minute. Your heart normally beats about 70 times a minute.

Time must seem very different to hummingbirds, compared to us. Their bodies (especially their heart, wings, and lungs) work so fast that their brains have to send signals for their wings to move backwards when the wings are only just starting to move forwards.

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