MEXICO CITY - Mexico, Canada and the United States have agreed to work together to protect the monarch butterfly, threatened in Mexico by illegal logging destroying its winter nesting grounds.

Meeting in the central Mexican state Michoacan, where millions of butterflies spend the winter months, the three-country Commission for Environmental Co-operation, or CEC, formally pledged Wednesday to support conservation initiatives for the monarch, a commission statement said.

The monarch butterfly is not listed as endangered but scientists said deforestation could threaten its existence.

The monarchs' annual 5,500-kilometre journey from the forests of eastern Canada and parts of the United States to the central Mexican mountains is considered an aesthetic and scientific wonder.

The countries also agreed to joint efforts to aid the vaquita marina, a grey porpoise native to the Gulf of California. They are sometimes caught in fishing nets and their habitat is damaged by shrimp boats that trawl the sea floor.

Only 500 of the porpoises are thought to exist, environmentalists say.

The CEC -- a panel set up by Mexico, the United States and Canada under the North American Free Trade Agreement -- also said it has launched a Google Earth mapping tool that lets users explore pollution data from more than 30,000 industrial facilities in the three countries.