Thanks to invasive shrubs, birds need a nutrition makeover

It has not been easy to work outdoors this winter thanks to the rain and melting snow. I am spending more time on social media, which I am not proud to admit, and have found several Facebook Groups – rather Facebook found them for me - that share information on native and invasive plants. The algorithm did good this time. I am rather hooked.

These groups include ‘Native plants of the Northeast’, ‘Native and Invasive Plants of the Eastern US’, ‘Propagating Native Plants’, ‘Invasive Plants ID and Removal in the US and Canada’,

‘Connecticut Native Plants’ and ‘New England Native Plant Seed Share/Trade’. Many within the communities are fierce advocates of native plants. They identify species almost competitively, the way someone might with the New York Times Spelling Bee, and offer suggestions on ridding invasive plants, propagating and planting native substitutes.

Recently, a community member shared a chart that put some data around a serious issue.

Berries of invasive plants do not offer the nutrition required by migrating songbirds. For birds that migrate south for the winter, a lot of fat is needed in their food to sustain them through their journeys. The research study behind this chart comes from a 2013 paper published in the scientific journal Northeastern Naturalist. Even though the study is now 10 years old the findings remain relevant and the issue it informs is more acute than when the study was published.

In addition to migrating birds, those that over-winter in our area require food with a high fat content to nourish them through the winter and into spring when they can rely on caterpillars (and, for the caterpillars to survive we need to plant the native plant they eat.) Sadly, birds in the wild are being malnourished due to the proliferation of non-native and invasive plants and their berries. Birdfeeders can only do so much.

According to the study, Japanese honeysuckle, Lonicera japonica thunbergii berries have less than 1% fat content. Compare this to northern bayberry, Myrica pensylvanica, a native shrub, at 50% fat. Remember tasting the sweet nectar from honeysuckle flowers as a kid? Perhaps the berry is similarly tasty to birds, but don’t eat a berry to find out; although the flowers are fine for human consumption, the berries are toxic to us. Japanese honeysuckle is basically junk food for birds.

The avian candy store includes berries from multiflora rose and buckthorn, with less than 1% fat, and autumn olive and oriental bittersweet at less than 3% fat. Compare with the native plants that co-evolved with local birdlife over millenia: gray dogwood has 35% fat, virginia creeper 34%, arrowwood viburnum and spicebush at 48%. These plants have been largely replaced in our backyards, fields and woodlands with non-natives and invasives, adding to the decline of our bird life.

When a bird ingests a berry it also ingests the hard seed or seeds inside the berry. The bird’s digestive system removes the outer part of the seed and excretes it coated in poop fertilizer, greatly increasing the seed’s chances for germination. This helps to explain the rapid spread of invasive species.

Some of the berries of invasive plants have healthful benefits, providing a few useful nutrients for the birds, and even for humans. Invasive Barberry, Berberis Thunbergii, is a relative of the Barberry, Berberis vulgaris, that is used in Persian cooking. Both types of plants have sour-tasting berries that contain berberine, an antioxidant phytonutrient that has been shown to lower cholesterol and help control blood sugar in humans.

Autumn olive, Elaegnus umbellate, which comes to us from Asia, is a shrub or small tree that can produce as much as 30 pounds of fruit from a single mature specimen. The fruit contains many more times the lycopene levels than our main food source of this carotenoid — tomatoes.

Lycopene has been shown to inhibit certain cancers and protects against diabetes among other benefits of its anti-oxidant rich pulp. Harvesting the prolific number of berries from the autumn olive will help to reduce seed dispersal by birds so, if you decide not to remove the plant it is a good idea to collect as many berries as possible when they are ripe. There are many recipes for autumn olive condiments and dishes to be found online.

The berries of the Amelachier genus are being touted as a superfood in Canada, where the tree is called saskatoon (here we know it as shadblow or serviceberry). According to Web MD and a few other sources I have checked, the berries have plenty of vitamins and minerals as well as the kind of flavonoids that can help prevent blockages in our blood vessels and can protect our heart and liver. They are ripe when purple; not red, or they will be too sour.

There’s only so far a bird feeder will go to solving this life and death issue for the birds in our area; still, it can’t hurt. Planting more native shrubs that produce fat-containing berries is the only long-term solution to the winter nutrition issue. A health food pantry to replace the existing sweet shops in our backyards.

Dee Salomon “ungardens” in Litchfield County.