An endangered bird and rare reptile were among the travellers disrupted by the volcanic ash last week.
A giant Madagascan gecko and a critically endangered Bali starling were due to arrive at Belfast zoo but were stranded by the flight ban, zoo authorities said.
The gecko was to be one of the final touches to the renovations of the reptile house and the starling was to join an existing pair to promote a flock by the end of the year.
Two Belfast zoo keepers were also affected.
Manager Mark Challis said: “Whilst it’s sad that our animal moves had to be postponed, it was even more concerning having our valuable zoo staff scattered across Europe and not at work. We’re glad that they are back now and working as hard as ever.”
Zoo keeper Tracey McWilliams was left at Twycross Zoo, Leicestershire, without a flight home. She had accompanied the zoo’s male silver back gorilla Boulas to his new home to help him settle in. She arrived home a few days late after a coach and ferry back.
Allan Galway, the new European studbook keeper for the marbled polecat, was in Hungary at a small mammals meeting. All flights to return home at the end of the conference were cancelled.
However after two days on a coach to London, a train to Liverpool and an eight hour ferry, Allan finally returned to Belfast.