A Little Bit More
Humans are lucky – when our clothing gets dirty or worn out, we either wash them or buy new, but animals can’t do this. So it shouldn’t be a surprise to learn that feathers do indeed wear out and are eventually replaced. Since feathers are totally non-living structures, once fully formed, they can’t be repaired as they wear out – they need to be totally replaced. As a result, they may show extensive wear over time until new ones grow in. The loss and replacement of new feathers is called molting and may occur once, twice or even more often each year, depending on the species. It should be pointed out that if a bird loses an entire feather, earlier than expected, that feather will be replaced fairly quickly and is not part of the periodic molting process.
As the unit poster points out, some birds rely on feather wear to signal their readiness to breed. The male House Sparrow looks very different in the winter months than it does in the spring and summer. As spring approaches, the lighter outer portion of the males’ breast feathers wear away and expose the darker, more central, dark coloration allowing the males’ black bib to become more and more obvious. Once the males molt at the end of the summer, they revert back to the winter look and their bibs are once again hidden by the newer, overlying feathers.
It’s also interesting to note that for those birds that rely on flight for survival, they don’t lose all of their flight feathers at one time but do so in stages. It’s typical for these birds to lose their flight feathers in pairs with one on the left wing being lost at the same time one on the right is lost; these birds are never left flightless and are always reasonably symmetrical, feather-wise too. For those birds that do lose most/all of their flight feathers at one time, like ducks and geese, these birds retire to “safe” locations during this period of flightlessness.
Activities
Science – Time to Change
Objectives: Graphic demonstration of how clothing wears out
Materials: Materials: student with new article of clothing and one with an old article
This activity is a graphic one that could be a bit embarrassing for some of your students so you be the judge of whether you want to try this or not.
After discussing or at least reading this unit on the wear and tear on feathers, it would be good for students to realize that this is happening to their clothing too. Ask in class if someone has a brand new article of clothing on that day. Then ask if someone else has the same article (shirt, pants, sweater, shoe, sock etc) but one that is considered “old”.
Have the two students exhibit their articles in class so all can see the new as compared with the old. It should be evident rather quickly that the old article has wear and tear on it, especially in places like at the cuffs or collar – not different than what’s happening to feathers.
Even though we don’t grow our own clothing, it does suffer from wear and must be replaced periodically.
Inquiry Activities you may want to pursue
Can you figure out why clothing wears in some areas and not in others? This might require checking many different articles of clothing to see if you can get a good idea of what is common to the wear areas and thus what may cause this uneven wear.
Can you find any differences in wear between natural fibers (cotton) and manmade ones (rayon, polyester, etc)? You’ll need to look at the labels to know which is which but you should be able to separate the two. Also, you may find that a combination of natural and manmade fibers may make a difference too.
Key Concepts
Behavior and Regulation, Identification, Structures and Functions
Questions
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