The first monarch butterflies have appeared in the mountains of central Mexico where they spend the winter.

The first butterflies have been seen exploring the mountaintop reserves in the states of Mexico and Michoacan.

The monarchs did not show up for a few days. They usually arrive for the Day of the Dead in November. The orange and black butterflies were associated with the souls of the dead.

The butterflies were seen around their three largest traditional wintering grounds.

Depending on the weather, the main group of butterflies is expected to arrive in the coming weeks.

It's too early to say how big this year's migration will be from the US and Canada. The counts are usually done in January when the butterflies have settled into the trees.

When butterflies clump together, the number of acres they cover is more important than the number of butterflies.

More monarch butterflies arrived last year. The butterflies may be able to adapt to hotter weather by changing the date they leave Mexico.

monarchs migrate back to the US and Canada in March

Climate change, pesticides and habitat loss north of the border are some of the threats to the monarchs migration. There are illegal logging and loss of tree cover in Mexico.

The monarch butterfly was added to the "red list" of threatened species and categorized as "endangered" two steps from extinction.

The population of monarch butterflies in North America has fallen between 22% and 72% over the last 10 years according to the group.

The monarch's migration is the longest of its kind.

The butterflies travel thousands of miles after wintering in Mexico. At the end of summer, the offspring return to Mexico.