The enclosures will now be surrounded by electric fences, Christopher Landsberg, head of the Cologne Zoo told the Express newspaper.
“But we will only turn them on when we close in the evenings,” he said, adding that they were only a provisional measure.
“We are working on a concept of how to secure the zoo boundaries so that the foxes can't enter in the first place,” he said.
A wall which runs along the Riehler Strasse is impossible for foxes to get over, he said, but admitted that a side entrance and the entry to the food yard presented opportunities for foxes to get in.
“One cannot blame the foxes, the table is laid out with goodies for them,” said Theo Pagel, Landsberg's predecessor in charge of the zoo, back in 2006 when foxes first broke in to feast on exotic birds.
The flamingos are also targeted by local crows, who steal the pink birds' eggs, said Landsberg.
“Electric fences cannot help us there,” he admitted.
Keepers collect the eggs as soon as they are laid, and they are kept in incubators until the chicks hatch.