Birds Need Caterpillars

If you’ve observed fewer birds, particularly songbirds, over the years, there’s an important connection you should know: healthy bird populations rely on healthy caterpillar populations. Surprisingly, gardening for caterpillars is essential if you care about birds.

Many people love having birds in their gardens but may unintentionally make their yards unsuitable for them. According to entomologist Doug Tallamy, birds need a large supply of caterpillars to rear their young. For example, raising a single brood of chickadees can require between 6,000 and 9,000 caterpillars. In fact, about 96% of songbirds depend on caterpillars to feed their chicks. The abundance of these nutritious caterpillars determines where birds chose to nest.

To truly support birds, you must begin by supporting the caterpillars. Without caterpillars, most songbirds cannot successfully nest or flourish. Native plants are key because they host a wide variety of caterpillars, but not all native plants are equal in this regard. Just 14% of native plant species support 90% of caterpillar populations—these vital species are called keystone plants.

Caterpillars, which are the immature life cycle of butterflies and moths, play a central role in sustaining ecosystems. Tallamy’s research highlights that birds, especially during breeding season, rely on caterpillars as the main food source for their young. Caterpillars offer high levels of protein and fat crucial for the fast growth of nestlings, so birds spend much of their time searching for these larvae to keep their chicks healthy.

It’s clear from Tallamy’s findings and other ornithologists’ work that native plants are indispensable for maintaining robust caterpillar populations. Native plants serve as abundant food sources for indigenous caterpillar populations, while numerous non-native species frequently fail to sustain local caterpillars.

Areas rich in native plant diversity will have more caterpillars and these habitats will draw more bird species and foster thriving communities. Native plants not only fuel caterpillar populations but also supply birds with shelter, nesting spots, and other resources for their survival.

A single native tree can support hundreds of different species of moths and butterflies. Importantly, birds go to native trees where the caterpillars are. A yard or landscape with a diversity of plants is important, so bring back the natives and along with them the caterpillars…the birds will follow.