The honeydew that crystallizes into a lerp is a sugary substance produced from the sap of the eucalyptus tree. These sugar pills have proven to be an extraordinary energy source for migratory birds. Maybe, maybe not. To understand the possible problem, you need to know a bit of California's history. In the early 1980s, scientists documented that waterfowl in marshy areas of California's San Joaquin Valley were producing offspring that were stillborn or deformed.
Selenium is an essential trace element that occurs naturally in the environment.
Although small amounts of selenium are important for both wildlife and people, too much is toxic. Selenium poisoning in animals results when they eat selenium-tainted insects, plants or animals. In parts of the western United States, the soils contain rather high levels of selenium. The Valley is a broad basin perfect for collecting the sediment carried down from the mountains by streams and rivers. Over tens of thousands of years, large amounts of sediments containing trace elements and salt have been deposited in the Valley.