Yellow-billed Magpies on the West Campus

One of the few birds that are truly endemic to California, the Yellow-billed Magpies (Pica nuttalli) are an elegant looking species. They have been showing up in larger and larger flocks on our west campus in the last few weeks, and making their presence known in a number of ways. Their squawking has been a nice welcome when I arrive on the campus just after sunrise. One landed this afternoon outside the window of my geology lab.

The Magpies used to flock together in the hundreds, but they were decimated a decade or so ago when the West Nile Virus arrived in California. They were especially vulnerable to the disease, and their flocking nature meant that it was easily passed from bird to bird. The population crashed in just a few years by 50%. Luckily, some birds possessed some resistance to the virus, and their numbers are beginning to recover. It's been obvious to me that the flocks near my house number in the dozens rather than only a dozen, which was the case just two years ago.