Male and female Cackling Geese look very similar, with the main difference being size; males are typically larger than females. Both sexes share the same overall plumage, featuring a black head and neck, white cheek patches, a white chin strap, and a mottled brown body. They also have black legs and feet, and a black tail with a white band on the rump. The bill is short and stubby, meeting the forehead at a steep angle.
Detailed Description:

• Size and Shape: Cackling Geese are small and compact, with a short neck and a rounded head. They are smaller than Canada Geese, with a wingspan of about 42.5 to 43.7 inches.
• Plumage: Both males and females have a dark brown to pale brown mottled body, a black neck and head, and white cheek patches divided by a black chin stripe. They also have a white band on the rump and a white chin strap extending from ear to ear.
• Bill and Legs: The bill is short and black, and the legs and feet are also black.
• Sexual Dimorphism: The primary difference between males and females is size, with males being larger. However, this difference can be subtle, especially among some subspecies.
• Vocalizations: Both sexes make a variety of calls, but females tend to have a softer, less incisive flight call according to All About Birds.
• Subspecies Variation: There are several subspecies of Cackling Goose, with varying sizes. The smallest subspecies is only about one-quarter the size of the largest Canada Goose subspecies.