Initial Observation

An initial observation is that hummingbirds drink.

Preliminary Conditions

There are two theories posed to explain how hummingbirds drink:

A₁: Capillary Action Theory. The water is drawn up small capillaries in the tongue due to the attraction of water molecules to each other.
A₂: Micropump Theory. The theory says: "Instead, bird bills squash the tongue and its grooves flat. When the tongue tip touches nectar, the grooves spring open, pulling up a column of nectar as they expand."

Assume these theories have merit, satisfying at least half of the criteria for a scientific theory (it will be required to show this starting with the next set of examples). Also, each of the theories could explain the initial observation (as described above).

Data (From the Science News article.)

D₁: Hummingbirds do this tongue dipping fast.
D₂: Hummingbird tongues don't have muscles.
D₃: Capillary suction is important in drawing nectar up the grooves.
D₄: When tongue met nectar, the fluid moved fast — averaging nearly 1 meter per second as it rose up the tongue. Even under ideal conditions, a simple capillary rise would draw in nectar much slower, only about 36 centimeters per second, the new paper reports.
D₅: A bird bumped one side of its tongue against a feeding tube and the tongue’s compressed groove opened prematurely before touching the nectar. In this instance, nectar did a typical capillary rise — but moved more slowly than nectar in the groove on the opposite side of the tongue that sprang open later.
D₆: Mathematical models agreed with the micropump theory.

Evaluation Chart

	Capillary Action	Micropump
D1	no	yes
D2	yes	no
D3	yes	yes
D4	no	yes
D5	no	yes
D6	no	yes

Result

From this data (Capillary Action - 2, Micropump - 5), it would seem that hummingbirds drinking by using micropumps is the best theory!