A Silent Invasion is Slowly Changing Our Landscape and our Birdscape

The invasion I'm talking about is not all the people moving here to eastern Pennsylvania from New Jersey to escape huge property taxes.  No, that is definitely not a silent invasion.  And I'll talk about that invasion in a future blog post about community planning and smart growth.  I'm talking here about invasive plants – non-native plants that crowd out native plants.  So the obvious question would be, "What do invasive plants have to do with the birdscape (birdscape, in this case, refers to the variety and number of birds we see in our backyards, parks, and open spaces).  Fair question.

There is a synergy in backyard ecosystems just as in natural ecosystems miles from human interference.  I sometimes hear casual birdwatchers lamenting the lack of diversity of backyard songbirds now compared with 20 or 30 years ago.  Similar to humans from different cultures eating different types of food, different species of songbirds also eat different types of food.  Birds that are primarily insectivores, like martins, wrens, and tanagers, will have no interest in sunflower seeds in your birdfeeder.  Warblers, in particular, rely on caterpillars for up to 60 percent of their diets.  So those birds and others like them will go wherever they can find the insects on which they depend.  Many birds rely on both bugs and berries to feed themselves and their young.  They won’t build nests where they don’t have suitable food sources nearby.

So, how do the invasive plants come into play?  Most casual birders realize that eliminating herbicides and pesticides from there home landscapes is crucial to encouraging diversity of insects in their backyard habitats.   But eliminating toxins from our backyard environments is only the first step to creating an inviting and diverse habitat that will attract a diversity of birds.   Native trees and bushes like serviceberry, dogwood, elderberry, spicebush, holly, blueberry, and beautyberry will provide ample food for bird species that eat fruit.  But for the full-time or part-time insectivores, we have to remember that many of the insects they eat are looking for plants that provide both food and shelter for them and their larva.

Butterfly house among purple coneflowers (Echinacea purpurea)

Most people who are serious about creating a thriving butterfly garden probably know that they must select plants that provide the food and shelter preferred by various butterfly and moth species in both their larval and adult stages.   But invasive plant species tend to spread aggressively and crowd out native plants, stealthily diminishing the natural habitat for native wildlife.

My township’s Environmental Advisory Council (EAC) held an invasive plant removal event back in April of this year at an open space property owned by our township.  The property is along a planned Greenway trail that would roughly follow the Little Lehigh Creek as it snakes right though the center of our township.  Two years earlier, the township used some state grant money to hire the Natural Lands Trust to complete a natural areas stewardship report of this 86-acre property (it’s a great report – here’s a link to it: http://www.lowermac.com/library/file/main_bccc_eac/2010-04%20KratzerFarmStewReportLowRes.pdf).  One of the report’s recommendations was to try to control the invasive plants that are found throughout the property.

Garlic Mustard (Alliaria petiolata), an invasive plant

So this spring, the EAC enlisted the help of our local Boy Scout troop and spent a Saturday morning pulling and uprooting garlic mustard plants and Japanese honeysuckle bushes. At the advice of one of our EAC members with a botany background, we targeted these two invasives because they were in bloom or beginning to bloom in late April when we held the event, so they were easy for our group of about 24 botanical amateurs to identify.  We also applied for a mini-Greenways matching grant from the Keep Pennsylvania Beautiful foundation, which allowed us to purchase approxilmately $1,000 worth of native plants to take the place of the invasives that we removed.  It’s important to promptly replace the removed invasives with healthy native plants, because seeds from invasives will quickly try to take advantage of any disturbed soils to embed themselves and germinate.

New native plants waiting to be planted in place of invasives

We anticipate that this will be the first of many invasive removal events at this township property in the years to come.  Securing available grants and partnering with an enthusiastic Boy Scout troop were the keys to getting this project off the ground.  Yes, it’s a drop in the proverbial bucket, but we hope that a sustained and determined effort will pay off in noticeable increases of native vegetation (in place of invasive vegetation) by the time the Greenway trail is built in the next few years.

The health of the ecosystem starts with the smallest members of the food chain, in this case insects, and ripples upward to the creatures that we are more likely to notice, such as our feathered friends.  And really, this isn't just about insect diversity for the sake of birds.  Our food crops depend on bees for pollination.  A big, green, weedless lawn offers nothing at all for bees, and, arguably, is even detrimental to the bees along with hundreds of other insects.  On the other hand, gardens and herbicide-free lawns offer all kinds of nectar and pollen opportunities for bees … and birds.  After all, life is all about the birds and the bees, right?

A bee in my butterfly garden