Mexican environmental authorities said Thursday that the iconic monarch butterfly's population may quadruple this year, citing joint efforts by Mexico, Canada and the US.

"We estimate that the butterfly population that arrives at the reserve is as much as three and could reach four times the surface area it occupied last season," Mexican Environment Secretary Rafael Pacchiano said at a press conference at the Piedra Herrada monarch reserve.

Monarch populations have witnessed a steady plunge of nearly 90 percent since their peak, hitting roughly 35 million between 2013 and 2014, a stark contrast to around one billion in the mid-1990s.

US Interior Secretary Sally Jewell, who addressed reporters alongside Pacchiano, said that the North American countries are making concerted efforts to impede illegal logging and plant more milkweeds, which the monarch butterflies use to produce offspring.

Experts have also said that pesticides significantly damage monarch populations, prompting environmental authorities to create pesticide-free zones.

'Returning'

"Mexico, the US and Canada have many species that don't know our political borders, that cross the borders freely," said Jewell.

The goal is "225 million monarch butterflies returning right here to Mexico every year. We believe we can get there by working together and it sounds like we may be on our way, we hope," Jewell added.

The delicate insects travel nearly 4,000 kilometers (2,500 miles) as they migrate from Canada to Mexico.

However, scientists have yet to discover how the butterflies are able to make their annual path since not a single butterfly makes the full round-trip.

ls/jm (Reuters, AFP, AP)