Pouch Stores Seed

a light gray bird holds a seed in its mouth on a snowy branch

Biological Strategy

Clark's nutcracker

AskNature Team

Image: Keith Roper / Flickr / CC BY - Creative Commons Attribution alone

Store Solids

Living systems, especially organisms, must sometimes store solids, often pieces of material (such as mud, seeds, stones, or leaf fragments). They use these solids for building structures, feeding during periods of low food availability, or other purposes. To be effective, the storage strategy must be appropriate to the sizes of solids and to the media in which they exist, whether air, water, or other solids like soil. It must also safely arrange the solids for storage in a location appropriate to either short- or long-term storage. An example is the Clark’s nutcracker, a forest bird that can collect up to 150 pine seeds and temporarily hold them in an expandable pouch under its head, where it doesn’t interfere with the bird’s daily activities.

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Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

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Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

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The throat of the Clark's nutcracker can temporarily store up to 150 small seeds thanks to an expandable pouch.

Expand and collapse: Many of life’s containers are flexible, like the throat pouch of the Clark’s nutcracker that expands to hold 150 pine-nut-sized seeds, or the pelican pouch that scoops 3 gallons of seawater, then returns to shape. What if we could design a juice bottle that would fill up like a sturdy balloon, then collapse to a small disk when its liquid is gone? You could store it in your pocket as a go-cup, or send hundreds back to the manufacturer in a single envelope.

Last Updated November 30, 2018

References

“Technically a diverticulum, or sacklike extension, of the floor of the mouth, the sublingual (‘under the tongue’) pouch is carry-on luggage for birds traveling with pine nuts. Each nut to be pouched is brought into the oral cavity, and dropped into the pouch through an opening at the base of the tongue. The pouch wall is thin, wrinkled, and elastic, and stretches as seeds are added, swelling almost to the size of a walnut when fully packed (Figure 5.3). The capacity of a pouch stuffed with twenty-eight singleleaf pinyon nuts is about 28.5 milliliters, sufficiently capacious for ninety seeds of Colorado pinyon. A Clark’s Nutcracker sacrificed for science a century ago in Montana had eight-two whitebark pine seeds in its pouch.” (Lanner 2006: 42-43)

Book

Made for Each Other: A Symbiosis of Birds and Pines

29/08/1996 | Ronald M. Lanner

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