Monarch butterflies making a comeback on the Peninsula. Here's why

Monarch butterflies are making a comeback in the Bay Area, thanks, in part to a warm winter, and also because they're adaptable. 

Last year, the population of the monarch butterfly hit an all-time low, but, during the winter heat wave, scientists say large populations delayed their usual migration, and kept mating instead

Now, thousands of butterflies and their eggs have been found in backyards across the Peninsula and at Google's Shoreline campus in Mountain View, according to research published in this month’s issue of the journal Insects.

Google planted nutritious milkweed as part of its ecology program.

The plants are seen as critical because the orange-and-black butterflies lay their eggs on them. Their caterpillars also eat them.

And on Nov. 13, scientists will begin the official monarch butterfly count.