Mallard – 1/20/10
Observer: Paul Lauenstein
Observation Date: 1/20/10
Observation Time: 3:55 p.m.
Observation Location: Knifeshop Pond, Ames Street
Common Name: Mallard
Scientific Name: Anas platyrhynchos
Comments: The Mallard is a rare example of both Allen’s Rule and Bergmann’s Rule in birds. Bergmann’s Rule, which states that polar forms tend to be larger than related ones from warmer climates, has numerous examples in birds. Allen’s Rule says that appendages like ears tend to be smaller in polar forms to minimize heat loss, and larger in tropical and desert equivalents to facilitate heat diffusion, and that the polar taxa are stockier overall. Examples of this rule in birds are rare, as they lack external ears. However, the bill of ducks is very well supplied with blood vessels and is vulnerable to cold.
The size of the Mallard varies clinally, and birds from Greenland, although larger than birds further south, have smaller bills and are stockier. It is sometimes separated as subspecies Greenland Mallard.
More Information: All About Birds