In what country might a large flamboyance of flamingos have set a new record, following the animals' annual migration to feed?

Kenya

Explanation:

The most likely place that this record would be set would be in the East African country of Kenya. That is because Kenya is where the largest population of flamingo's exist in the world. This population also migrates together once a year to feed, which is why is is rightfully named the "Flamingo City" by tourists.