A Little Bit More
The mergansers, often known locally as sheldrakes, sawbills, fish ducks, or frog ducks, represent an interesting group of specialized birds. These atypical ducks may seem more grebe or loon-like to the casual observer but they’re true ducks.
Three species of mergansers commonly breed in North America: the Hooded, the Red-breasted, and the Common Mergansers. The Hooded is the smallest of the three and feeds upon aquatic insects, frogs, tadpoles, crustaceans, and small molluscs, as well as small fishes. The other two larger mergansers prey more heavily on fish than the Hooded although their diet varies depending upon available food. Although a merganser’s bill is much thinner than a typical duck’s bill, their serrations make up for lack of grasping area and are especially adept at holding on to slippery fish once they’re captured.
Merganser bill serrations
Fishermen and commercial fishing interests have advocated the reduction of mergansers from time to time, especially on salmon streams. Research has shown however, that merganser predation on smaller fish may actually improve fishing on the whole according to some studies but acceptance of these studies by many fishing interests is not wholesale. In any event, these are interesting and certainly beautiful birds. The next time you see a “funny looking” duck on the pond you can impress your friends by identifying this different duck as a merganser.
Activities
Science – Hold On Tight
Objectives: See how serrations improve holding ability
Materials: Pliers – one serrated, one not, plus assorted articles from room
- Obtain two pliers – one with serrations and one without.
- Assemble several different pairs of articles that can be experimentally grasped by the two pliers at the same time (pieces of paper, pencils, pieces of string, thin pieces of plastic, thin magazines, etc)
- Have one person hold both pliers in their hands (one right and one left)
- Take the first pair of items and place each in the pliers
- Once the pliers have a firm grip, ask the “pliers-holder” to maintain as similar a force on each tool (lots of strength is NOT necessary here)
- Have a second person pull on both materials at the same time with “identical” force from the two pliers
- Note which pliers (serrated or non-serrated) is able to hold on the longest with a similar force
The results of this exercise may vary but for the most part, the serrated pliers should be able to hold on to most objects longer than the smooth pliers. Serrations really do work and it’s easy to see why the mergansers’ bills have them with their fishy diet.
Key Concepts
Environmental Issues, Identification, Predator/Prey Relationships, Structures and Functions
Questions
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