Mortimer is the pet bird that belongs to Kelsey. He is always seen on top Kelsey's head. Kelsey has had many other pet budgerigars, as seen in the pet cemetery scene in the pilot episode. Mortimer is also called her 'trusty falcon' by Kelsey. Kelsey is Mortimer's owner and when Kelsey needs her trusty bird he know she can whistle to call him.
He is a Budgerigar, which is a species of parakeet. He is a male, because of the blue cere above his beak.
Mortimer is seen to be obedient to Kelsey, as seen in the first episode when Kelsey is teaching Mortimer to peck out the brains of her enemies, and Mortimer complied efficiently. And when Mortimer has to do something well, Kelsey gives him some bird seeds.
- Itch To Explore
- You're It
- Jessica Goes to the Creek
- Too Many Treasures
- The Final Book
- Sunday Clothes
- The Curse
- Dog Decider
|1. "Itch To Explore":||Appears||17. "The Invitation":||Absent|
|2. "You're It":||Appears||18. "Vulture's Nest":||Absent|
|3. "Jessica Goes to the Creek":||Appears||19. "Kelsey Quest":||Absent|
|4. "The Final Book":||Appears||20. "Jpony":||Absent|
|5. "Too Many Treasures":||Appears||21. "Ace of Squares":||Appears|
|6. "Wildernessa":||Appears||22. "Doorway to Helen":||Absent|
|7. "Sunday Clothes":||Appears||23. "The Last Kid in the Creek":||Appears|
|8. "Escape from Family Dinner":||Absent||24. "The Climb":||Appears|
|9. "Monster in the Garden":||Absent||25. "Big Pinchy":||Appears|
|10. "The Curse":||Appears||26. "The Kid from 3030":||Appears|
|11. "Dog Decider":||Absent||27. "Power Punchers":||Absent|
|12. "Bring Out Your Beast":||Absent||28. "Creek Cart Racers":||Appears|
|13. "Lost in the Sewer":||Absent||29. "Secret Book Club":||Appears|
|14. "The Future is Cardboard":||Absent|
|15. "The Brood":||Appears|
|16. "Under the Overpass":||Appears|
- The name Mortimer is of French origin. In French the meaning of the name Mortimer is: Dead sea (a stagnant lake).
- Kelsey mentions that she has had 47 Mortimers in her life, and visits a grave site with Craig and J.P. in the Pilot. She also says this one was the only one who understood her, in the episode Wildernessa.
- Sometimes, Mortimer hides in Kelsey´s hair bun, with his wings showing through her hair.