"The first pilgrims they encountered trekking north with their loaded burros"

A burro is a type of small donkey, especially one used as a pack animal.

Although the word burro is often used interchangeably in the western United States with the word donkey, it usually refers to the smaller donkey descended from Mexican stock.

 

Burros carrying fodder for horses, Peru, 1923
Public DomainBurros carrying fodder for horses (Peru, 1923) - Credit: J. Francis Macbride
Zuni man and loaded burro
Public DomainZuni man and loaded burro - Credit: Edward S. Curtis (Library of Congress)