On a pleasant July morning, a group of 10 volunteers met at Warm Springs Park, spread out into an open field, and began diligently filling up large, black trash bags. Dozens of people who were walking and biking by on the Boise River Greenbelt stopped to ask the group, “What are you doing? What’s going into the bags?” The volunteers weren’t picking up trash or gold (as one onlooker joked) but the invasive plant Puncturevine a.k.a. Goathead.
Most of us in the Treasure Valley are familiar with Puncturevine (Tribulus terrestris) as its sharp nutlets puncture our bike tires and get stuck in our dogs’ paws. It is designated as a noxious weed by the state of Idaho, which means it is a non-native plant that can “colonize a variety of habitats, reproduce rapidly with a variety of mechanisms, and aggressively out-compete native species … it is considered to be injurious to public health, agriculture, recreation, wildlife, or property.” This plant is quite the nuisance but why would Golden Eagle Audubon Society be organizing volunteer efforts to remove it? Why should bird lovers be concerned about invasive plants?
One way invasive plant species can negatively affect birds is they displace native plants that birds rely on for food. Southwest Idaho birds have coexisted with the native plants in this ecosystem for centuries and are accustomed to eating their seeds, fruit, or the pollinators they support. While birds can often digest the seeds and fruit of invasive plants, they typically provide much lower nutritional value as compared to native plants. Invasives can also be unpalatable and even toxic to insects and pollinators, thereby decreasing an important food source for many native birds.
Invasive plants also displace native trees and shrubs, thereby decreasing important shelter and nesting opportunities for birds. One study found that certain bird species are lost to predation at a higher rate when they nest in nonnative shrubs as compared to the native ones with which they have coevolved. Additionally, the decrease of biodiversity associated with invasive species means there is a lower variety of plants for birds to find shelter and nesting opportunities.
So, as you can see, there are a lot of reasons to care about managing invasive plants if you are someone who loves birds. But what can you do about it? Here are some simple actions you can take to lessen the negative impacts of invasives:
Clean your boots, clothes, and binoculars after every time you go out birding. This can greatly lessen the spread of invasive seeds.
Manage invasive plants in your yard. Late summer is a good time to remove common invasives like cheatgrass and goathead before they go to seed.
Watch this great video from GEAS volunteer Kellie Smith to learn about how to safely remove cheatgrass:
Plant native Southwest Idaho plants in your yard. More natives in our valley means more viable habitat for birds. Landscaping with Native Plants of the Intermountain Region and the Native Garden Guide of Southwest Idaho are great resources to get you started.
Attend an invasive removal volunteer event. Removing invasives from our natural spaces will improve habitat for birds. Find an event with GEAS or the City of Boise Weed Warriors.
Invasive Species of Idaho Website http://invasivespecies.idaho.gov/plant
Randall, Johnny. “Invasive Plants are NOT for the Birds.” New Hope Audubon Website. https://www.newhopeaudubon.org/blog/invasive-plants-are-not-for-the-birds/
K.A. Rawlins. 2013. Why should I care? Series: I am a bird watcher, why should I care about invasive species? The University of Georgia Center for Invasive Species and Ecosystem Health, Tifton GA, BW-2013-113. 2 p
Schmidt, K.A. and C.J. Whelan. 1999. Effects of exotic Lonicera and Rhamnus on songbird nest predation. Conservation Biology 13 (6). pp 1502-1506.