Nature Notebook, September 12, 2019


The full moon of Friday, Sept. 13 is followed by the autumnal equinox—a day with equal amounts of daylight and darkness—on Monday, Sept. 23. Traditionally, the equinox marks the calendar beginning of fall, though we have seen many seasonal changes already, with acorn-laden oaks and buckeye leaves dropping. The latest reminder of fall, besides the crispy cool mornings, is the carpet of caramel-colored bay leaves dropping along the Earthquake Trail.

A new set of oval-shaped badger holes has appeared along the trail to Kule Loklo. Badgers typically dig several holes near foraging areas, such as one sees with the pocket gopher colonies around Bear Valley; they usually occupy one hole for a few days while feeding, then dig a new one. They do not hibernate, but they may rest for a month or so in a sleep state during winter.

This year has been special for viewing humpback whales. Typically seen in the fall, the whales were seen throughout much of August in Drakes Bay. Unlike the Pacific gray whales that are on the move, humpbacks linger in an area while they feed on krill or small fish. New research on humpback “singing” indicates they learn a unique song from where they were born but can learn new songs as they travel and hear the songs of other humpbacks. Scientists believe the males sing to attract females and possibly communicate with other males.