Posted: July 14, 2017

During the summer months, we see a number of shrubs with beautiful fragrant flowers, that attract bees and other pollinators, and whose berries often attract a diversity of birds and other wildlife. Unfortunately, some of those shrubs are non-native and invasive, and although they may seem attractive, they can actually be quite detrimental.

Fruits of the Bush Honeysuckles (Lonicera spp.)  Photo by Chris Evans, University of Illinois, Bugwood.org

Fruits of the Bush Honeysuckles (Lonicera spp.) Photo by Chris Evans, University of Illinois, Bugwood.org

Honeysuckle is one example of a non-native invasive shrub that fits that description. Although there is one honeysuckle native to the area, the majority of the honeysuckles we see these days are non-native and invasive. The non-native varieties include tartarian honeysuckle, Morrow's honeysuckle, and amur honeysuckle. They can be distinguished from the native species by breaking the stems - the non-native species have hollow stems. These honeysuckles begin producing flowers in late May, which fully blossom in June. Amur and Morrow's honeysuckle produce white flowers, and tartarian honeysuckle is bright pink. Berry production starts in mid-summer, which then ripen to an attractive bright red color in late summer through early fall.

While it is common to see many birds flock to honeysuckle for nesting and forage, several recent studies have actually found that these non-native invasive shrubs have some negative consequences for the birds. In fact, the nutritional content of berries from these and many other non-native shrubs are significantly lower than from native shrubs…making them the equivalent of bird fast food. The berries of non-native honeysuckles have fewer carotenoid pigments than native berries, which help to strengthen the bright red feathers of cardinals. In addition to being a less adequate food source, many non-native invasive shrubs also have negative impacts on chick survival. Many non-native invasive shrubs, including honeysuckles and buckthorns, leaf out several weeks and even up to a month before native shrubs and vegetation. Bird nests found in these non-native shrubs have been reported to have less brood survival, which was attributed to higher predation levels. Because the non-native shrubs leaf out earlier than all the surrounding native vegetation, the nests lose the protection of a more closed canopy with a majority leafed out; the nests were more visible and exposed to predators such as raccoons and hawks. If you are interested in reading more about the impact of honeysuckle on birds, the National Wildlife Federation has a very interesting article featuring this topic, which is online.

In conclusion, removing non-native shrubs and planting native species will significantly improve habitat for both native plants and wildlife. Small honeysuckle plants pull easily, but for larger infestations herbicides may be applied either to the foliage in mid-summer (before berry production) or to the base of cut stems. Native species to replant in these locations include anything from your basic raspberry and blackberries to dogwoods and chokeberries.

James C. Finley Center for Private Forests

Address

416 Forest Resources Building
University Park, PA 16802

James C. Finley Center for Private Forests

Address

416 Forest Resources Building
University Park, PA 16802