Giant reed (Arundo donax) is one of the most infamous streamside weeds. Imported from Asia and once planted as an ornamental (who doesn't love the look of bamboo?), it proved to be well-adapted to streams and flooding. Plant fragments washed downstream during a flood develop roots and quickly grow new plants, making it difficult and expensive to control. Fun Fact: Giant reed does not produce viable seed in North America and only spreads by sprouting from stem fragments and rhizomes (underground stems).
Have you seen these iridescent beauties around? One hundred European Starlings were introduced in New York in 1890-1891 (thanks, Eugene Schieffelin!) and today they are one of the most widespread birds in North America. They are common along Putah Creek, but many folks don't like them - European Starlings compete with native cavity-nesting birds for nest spaces and can cause significant crop damage. But they're quite pretty, fun to watch, and earn some grudging respect for their tenacity!
Did you have a red-eared slider as a pet when you were a kid? It is the most popular pet turtle in the United States, and is a popular pet world-wide. It gets its name from the small red stripe around its ears, and because it easily slides off logs into the water when startled. Red-eared sliders are native to the southern Great Lakes area, west to Indiana, and south into southern U.S. and northern Mexico. You may have seen them basking on logs or rocks along Putah Creek, as they are fairly common. Unfortunately they out-compete our native western pond turtles, which tend to be shy and reclusive, and reproduce much more slowly. Red-eared sliders make great pets, but please don't "liberate" your little visitor into our local streams or ponds.
Tree-of-heaven (Ailanthus altissima): not so heavenly for Putah Creek. So named for its ability to rapidly grow towards the heavens, this native of Asia also produces copious seeds and vigorously sucker sprouts. In short, tree-of-heaven is a formidable competitor to native vegetation. It can resemble the native California black walnut - both have similar looking pinnately compound leaves - but the leaflets of tree-of-heaven have a small lobe at the base and are foul-smelling when crushed.
To cap off National Invasive Species Week, here’s one of our most formidable aquatic invasive species: New Zealand Mudsnails (NZMS). NZMS were first observed in Putah Creek in the fall of 2003 at Fishing Access #3 below Monticello Dam. They spread somewhat slowly at first, but with this winter’s high flows, they may have spread widely. NZMS disrupt the food chain by competing for algae with native benthic (bottom-dwelling) macro-invertebrates like caddisflies and mayflies – excellent fish food and bird food. Help prevent the spread of NZMS in Putah Creek by ALWAYS cleaning and thoroughly drying your boots before entering other areas of the creek or other waterways. Photo courtesy of Ken Davis.