Make America Native Again

By Melissa Brown-Grieco

Our very own backyards can become part of a vast, interlocking sanctuary for native insects, plants, and wildlife stretching across the continental United States and linking otherwise isolated national and state parks. This is the vision laid out to an enthusiastic crowd of over 125 individuals who packed into the Jay Heritage Center on a recent Friday morning.

All were gathered to hear Doug Tallamy, professor and chair of the Department of Entomology and Wildlife Ecology at the University of Delaware, speak about restoring nature’s relationships. The event was co-sponsored by the Rye Sustainability Committee and made possible by a grant from Con Edison.

Tallamy, who is considered a veritable rock star in the world of ecology, has authored 92 research publications and taught Insect Taxonomy, Behavioral Ecology, Insect Ecology, and other related courses for 37 years. He tackles such serious topics as the loss of biodiversity and extinction occurring in our urbanized habitats. Thankfully, he also offers accessible remedies that any property owner can adopt. 

The key lies in supporting the intimate evolutionary relationships, evolved over eons, between native plants and insects. These relationships keep systems thriving but are vulnerable to disruption and breakdown when those plants are no longer abundantly available. Tallamy illustrated this point perfectly with the relationship between numerous caterpillars and the specific food sources that they have evolved to depend on for survival. 

Plants defend themselves from insect predation by secreting toxic enzymes and other chemicals, but certain insects have adapted. For example, it has become an evolutionary advantage for caterpillars, which depend on plants for food, to develop physiological mechanisms such as immunity and other means of withstanding and bypassing particular plant poisons.

Perhaps the best-known example of this relationship is that of the Monarch butterflies’ dependence on milkweed plants for survival. Female Monarchs lay their eggs on the underside of milkweed leaves. When the caterpillar hatches from the egg, it relies solely on the milkweed for food, as it is the only plant these caterpillars can eat. The milkweed delivers carotenoids and other important vitamins to the caterpillar as it matures and turns itself into a chrysalis.

These perfectly harmonious – but delicate – relationships are easily disrupted by rapid urbanization and development. Not only do we lose natural spaces, but we also see a widespread replacement of native plants with exotic, foreign ornamentals. Native insects haven’t developed ways to evade the defenses of these alien – and often invasive – plant species that we have introduced into our yards, so caterpillars can’t rely on them for food. They don’t share the necessary evolutionary history with the new plant arrivals.

When popular, ornamental suburban trees, such as the ubiquitous Callery Pear and Crepe Myrtle, replace and crowd out native species like oak, sugar maple, and wild black cherry, the caterpillar population plummets. Insects are not the only species that are negatively affected; the impacts echo up the food chain. As caterpillar numbers drop, so, in turn, do the many bird species that rely on caterpillars to feed their young. Tallamy explained that, just as caterpillars have evolved with specialized diets to feed on certain plants, so birds have also evolved to feed on certain caterpillar species.

While many residents like to think that keeping their feeders filled with seed year-round will provide enough nourishment for birds, it is caterpillars that are the vital link in their food web. Caterpillars are crucial to maintaining bird populations because the preferred diet of most baby birds (fledglings) is caterpillars. Unlike bird seed, caterpillars are soft making them easy for the parents to push down fledgling throats. They are also rich in nutrients such as fat, protein, and carotenoids which are crucial to the healthy development and adult virility of the baby birds.

When planning a landscape, we should be sure to choose native plant species over the easy fallbacks of the decorative varietal (which are often invasive Asian imports). In Tallamy’s studies, he has found that oak trees in particular support the greatest number and diversity of caterpillars. He gives us encouragement by sharing that oaks are not, in fact, so slow growing that you won’t live long enough to enjoy them, as popular folklore would have you believe. To demonstrate his point, he showed us a photo he took of a healthy-sized oak tree standing at least 30 feet tall that he’d planted on his property as an acorn only a handful of years ago.

If every property owner across the United States were to reduce the amount of grass/turf in their yards to the areas that they actually use to walk or play on and, in its place, plant more native trees, shrubs, and flowers, we could transform our yards into corridors connecting otherwise isolated natural areas. This would create a vast interlocking network of wildlife sanctuaries. It would be one small step for each Rye homeowner, but one giant leap for our native insect population and the beneficial wildlife that relies on it for survival. Tallamy says it best: Make America Native Again!

Footnote: Enter Rye’s zip code into the National Wildlife Federation’s ‘Native Plant Finder’ atwww.nwf.org/NativePlantFinder for a list of plants that are specifically adapted to and naturally occurring in our region.