"Mexico, the US and Canada have many species that don't know our political borders, that cross the borders freely," Jewell said.
The goal, she said, 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."
The number of butterflies has dropped by 90 percent in the last 25 years.
The butterflies travel 4,000 kilometers (2,500 miles) from Canada to spend the winter in a mountain reserve straddling the states of Mexico and Michoacan.
They usually arrive at their nesting ground between late October and early November and head back north in March.
While the Mexican government has announced arrests of illegal loggers in recent months, the World Wildlife Fund (WWF) reported in August a drastic increase in clandestine tree cutting in some reserves.
In the Michoacan community of San Felipe de los Alzati, 19.13 hectares were affected by illegal logging in the 2014-2015 monarch butterfly season.
This was four times higher than the 5.18 hectares that were hit by such illegal activities in the communities in the 2013-2014 season.
The arrival of monarch butterflies means jobs for 250 families at the Piedra Herrada sanctuary.
Miguel Dominguez, 52, has worked as a guide there for more than 15 years.
"Tourism falls year after year," Dominguez lamented as he pulled a horse that took visitors up the mountain. "It's good for us that the governments are working together and not fumigating the milkweed, so that more butterflies arrive in Mexico."