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August Species Spotlight: Autumn-Olive and American Robin
August 16, 2021
by Robin Kuehn
Autumn-Olive, Elaeagnus umbellata
Autumn-olive is a resilient shrub that has been widely cherished for having beautiful silvery green foliage, sweet-smelling cream-colored flowers, and bountiful clusters of berries that are edible to wildlife and people alike. Also known as Japanese Silverberry, it was first introduced to the United States from Asia in the early 1800s; during the 1950s, this hardy shrub was planted across the continent to serve as erosion control that would also provide habitat and food for wildlife. As the story tends to go with invasive species, it was successful! TOO successful.
Monstrous Autumn-Olive shrubs on the lower area of Joppenbergh, photographed by Tess Hogan
As you can see in the photo to the left taken on the trail in Joppenbergh, when Autumn-Olive moves onto a landscape, everything else moves out. They can easily reach twenty feet high and thirty feet in diameter, and create enough shade to make it hard for other plants to compete. In addition, the bushes also change the chemistry of the soil around them which makes it difficult for nearby plants to grow. This adaptation of a plant influencing neighboring plants chemically is called allelopathy. Garlic Mustard is another commonly known invasive plant that uses this strategy.
Another way this shrub is similar to other plants that have invaded the United States is that it can handle infertle, dry soils, as well as those with extreme pH, high salinity, or heavy metal contamination. The roots house nitrogen-fixing bacteria that help it get the nutrients it needs to grow, and to recover if the upper part of the plant is chopped down or burned. In addition to being drought-tolerant, the quick-growing shoots help this plant be the first one to sprout and take over after a forest fire. All of these attributes will make it easier for the Autumn-Olive to spread in habitats affected by climate change.
Autumn-Olive’s clustered flowers, photo by author.
Autumn-Olive’s silvery foliage, photo by author.
This photo was taken in early August. The berries will be fully ripe in September.
Not only has Autumn-Olive been spread extensively by humans enamored with the amazingly aromatic clusters of bell-shaped flowers (which even I can’t dispute, smell wonderful) the silver-mottled, bright-red berries are attractive to both people and wildlife. Autumn-Olive’s biggest group of unintentional allies in sending its progeny to new places are BIRDS!
American Robin, Turdus migratorius
Photo 118616207, (c) by arianeg on iNaturalist, some rights reserved (CC BY-NC-ND)Ah
The ubiquitous robin, well known for its orange belly feathers and striking yellow beak against their dark head and wings, plus their penchant for nesting in extremely obvious places near human houses. Robins like a lot of the same spaces we do, big yards with a few trees and shrubs nearby. They are quite common, and because of this, we tend to not pay them enough attention. Many are familiar with the robin’s spring migration and excitedly point out the arrival of the first flocks, but who stops to think about their journey in the other direction?
Many songbirds in the northeast migrate to warmer regions for the winter. One of the main reasons is to follow food resources; while some fruits and seeds can be found in winter by titmice and chickadees, many of the larger songbirds need insect or worm proteins to round out their diet. In the summertime, a careful observer can spot a robin plucking worms from the lawn and flying off to feed their hungry babies, but this activity is impossible with a blanket of snow on the ground. A handful of adult robins will stick around New York and make do with whatever leftover fruits they can find such as crabapples and sumac berries, but the majority of the flock will travel south, covering distances as far as 4,500 km, or roughly 2800 miles!
All songbirds that migrate must spend the short window between the summer exhaustion of raising young to be self-sufficient and the long and perilous autumn journey eating, eating, eating. They need to build up enough fat to fly all the way to safety, or in some cases to their stopover points along the way. Imagine training for an ultra-marathon by having to spend all of your time jogging to different restaurants to pig out on takeout, while all of your neighbors are doing the same thing. Now imagine if during that training, all you could get was low-nutrition junk food! This is what many songbirds in New York are experiencing today.
It’s easy to believe that any shrubs with a lot of berries are great choices for wildlife. The Autumn-Olive, for instance, can produce upwards of 200,000 berries on a single bush. While these tasty fruits are eaten by many birds, they have low amounts of protein and fat and high carbs– the unfortunate birds fill up on somewhat empty calories, much like a person gobbling down french fries. While the human may only spoil their dinner, the birds lose valuable time and energy that they need to build up as much fat and muscle as possible before their journey. And even worse, once they’ve eaten those berries, they poop out the seeds and disperse them across the landscape!
(c) Seymore Gulls on iNaturalist, some rights reserved (CC BY-NC)
Many invasive shrubs that have utilized this unfair relationship include the Japanese Barberry, Multiflora Rose, Buckthorn, Burning Bush, Asian Honeysuckles, and Asian (Oriental) Bittersweet. Luckily, a recent study has shown that given the choice, songbirds will choose nutritious native berries over invasive options.
So what does that mean for you and I?
It’s imperative that we make sure these birds have good choices available! When we allow invasive plants to take over a landscape, we are inadvertently creating food deserts for our wildlife. By removing the invasive plants and planting native plants, you are helping to provide both fruits and insects (that feed on the native plants) for both the snowbirds and the year-round residents.
American pokeweed “planted” by birds at the author’s house. The bees and butterflies love the flowers, so it’s a win-win to leave a couple around the yard!
For a full list of native plants that birds prefer (and suggestions on where to find them), check out https://www.audubon.org/native-plants. Some of the plants I have around my yard that birds benefit from include staghorn sumac, black chokeberry, raspberries, blackberries, elderberries, pokeweed, and even poison ivy. (Yes, birds love the berries!) North American Songbird SAFE has plenty of other information on their page on how to help our feathered friends thrive. See also #birdslovenativeplants for ideas.
One of the best ways to combat invasive plants is by eating them! Check out this page for more information and a recipe for an Autumn-Olive Berry Tart:
https://northernwoodlands.org/knots_and_bolts/autumn-olive
Please be careful with how you dispose of the seeds to reduce the chance of spreading the plant, and as with any harvesting, know the land you’re gathering from. These berries can be contaminated with heavy metals from polluted soils.
And if you’re interested in learning more about invasive plants and helping the Wallkill Valley Land Trust evict them from the lands we steward, join us on our next volunteer days! Check our website for more information, or email us to be added to the volunteer list at info@wallkillvalleylt.org
Resources:
https://www.wnyprism.org/invasive_species/autumn-olive/
https://extension.psu.edu/autumn-olive
https://wildlife.org/migrating-birds-choose-native-fruits-over-invasive-berries/
https://www.allaboutbirds.org/guide/American_Robin/overview
https://www.jstor.org/stable/43287103
https://www.audubon.org/news/migratory-birds-native-berries-best