Humphrey has become something of an internet celebrity.
Videos of his exploits have gone viral. The zoo has released videos showing the cub taking its first steps, getting his first bath and exploring his outdoor habitat — each has proven to be click magnets for the zoo.
In a contest to name Humphrey, more than 14,000 fans cast votes to land on his given name in March of this year.
The zoo is inviting fans of Humphrey to its polar bear exhibit for cupcakes at 12 p.m. on Sunday. Humphrey will get his own special birthday treat, according to the zoo.