Discover the surprising gluttons of the animal world

Humans at Christmas are no match for these extreme eaters, like hummingbirds, who eat twice their body weight in a day.

By Liz Langley
Published 21 Nov 2018, 09:11 GMT
This male ruby-throated hummingbird is sipping from a mimosa flower, probably the first of many it ...
This male ruby-throated hummingbird is sipping from a mimosa flower, probably the first of many it will visit. Hummingbirds can eat up to twice their body weight each day.
Photograph by George Grall, Nat Geo Image Collection

With Christmas approaching, it's a time when we get together to appreciate what we have—and feel our waistlines expand like a puffer fish.

With the most food-centric holiday upon us, we wondered which non-human animals stuff themselves, and why?

No in-flight snacks

Many birds feast to sustain themselves before long non-stop flights over oceans or deserts, says Dan Roby, a wildlife ecologist at the U.S. Geological Survey and Oregon State University, by email. Scientists call these periods of intense feeding 'hyperphagy'.

With one of the world’s longest migrations, the blackpoll warbler has to seriously fuel up before its trip. The tiny birds breed as far north as Alaska, and each year fly to New England, where they “double their weight by storing an amount of fat equal to their lean body weight,” before an 80-hour nonstop flight over the Atlantic Ocean to Venezuela, Roby says.

Likewise, bar-tailed godwits double their weight by storing fat to make it through a 10-day non-stop flight from Alaska to New Zealand, the longest of any animal. (Related: Alaska bird makes longest nonstop migration ever measured.)

Chickadees and tits living above the Arctic circle consume mass quantities so they “have enough stored fat to keep their body temperature above freezing throughout the long winter night.”

The birds aren’t really overindulging like a human holiday eater, but putting on enough fat to get through a time of long fasts sometimes combined with intense exercise.

“In this context, 'over-eating' is a critical adaptation for many birds,” Roby says.

Globe-trotting bar-tailed godwits gorge to fuel a non-stop 10-day flight from Alaska to New Zealand.
Photograph by Saverio Gatto, Alamy

Whale of an appetite

Then there are animals that eat massive quantities on a regular basis.

The largest animal on earth, the blue whale, puts away four tons of krill a day. That’s sounds like a lot, but this animal has a 200-ton body to feed, so that’s not a high percentage of its body weight.

By contrast, Britain's pygmy shrew weighs less than an ounce, but can eat “one-and-a-quarter times its body weight,” says biologist Elmer Finck of Fort Hays State University in Oklahoma.

In general, he says, if you compare consumption to body size, “the small animals eat more than the large animals.”

Tiny hummingbirds, for example, have a fast metabolism requiring them to eat about twice their weight in nectar every day, Finck says. It takes a lot of energy to keep them moving as fast as they do; their hearts beat 1,200 times a minute while in flight.

Other animals, such as big cats, eat huge amounts but feed less often. “Big cats in the wild do not make kills every day, so there are days they will not eat,” says Susan Bass of Big Cat Rescue in Tampa, Florida. But then they will feed from a large kill for days, some guarding the meat so they can eat more later.

Tigers can go two weeks without eating and may gorge themselves when they make a kill, eating up to 40 kilograms in a day.
Photograph by Theo Allofs, Minden Pictures/Nat Geo Image Collection

“Leopards can climb trees carrying an animal more than twice their weight” to keep it from other predators, Bass says.

Afton Tasler, Big Cat Rescue’s media producer, says tigers can eat between 16 and 40 kilograms in a sitting, which is more than lions, who “share their kills with their pride.”

Snake snacks

Adult Burmese pythons eat once a month, sometimes less, but they make the most of it. (Related: See how a python can swallow a crocodile.)

A 2013 study of Burmese pythons’ genes found that during digestion, changes in their gene activity allow their metabolism to increase and some of their organs to grow radically in size — up to 150 percent in 24 to 48 hours — and then return to normal after digestion. This 'physical remodeling' allows the snakes to digest meals bigger than themselves.

In 2017 alone pythons of various species were caught on camera, devouring or regurgitating huge animals including a pregnant sheep and a monitor lizard. (Related: The python that swallowed a woman.)

Makes a little extra turkey and Christmas pudding seem like no big deal.

Tweet me, leave me a note in the comments, or find me on Facebook with your questions about the weird animal world.
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