The Siberian customs department said two men, one from the United Arab Emirates and the other from Bangladesh, brought 29 falcons into Russia saying they wanted to keep them in more comfortable conditions during the UAE's hot summer and would return the birds to the UAE in autumn.
Authorities examined the birds, which were being kept in an enclosure near the Siberian city of Chernogorsk.
Two months later a second examination found the birds' identification rings gave different ages and genders from the first exam and some even "changed" their species, as gyrfalcons had turned into Peregrine and Saker falcons, the Siberian customs department said.
Department officials said it was clear the birds owners replaced some that were too old and unfit for falconry with younger ones caught by Russian poachers.
The birds were seized and temporarily taken to a sanctuary for rare birds. The two men were charged with attempted smuggling and face up to seven years in prison if found guilty, RIA Novosti reported.