Shrubbier Parks Can Help Migratory Birds
By Georgia Silvera Seamans
Spring brings more than showers and flowers. Birds arrive in New York in the hundreds and thousands starting in April. They don’t pack lunch for their flights. When these neotropical birds stopover in the city, they have to make do with whatever resources are available in our savanna-like urban landscapes. One of the best ways to help birds is to make our parks function more like native forests.
A temperate forest is composed of several layers: canopy, mid-story, understory, and forest floor. The mid-story canopy layer is composed of shrubs and small trees. These small trees are either short-statured tree species or young individuals of large-statured trees. In New York, our forests’ mid-story canopy layers are composed of native shrubs and small trees like Black Cherry (Prunus serotina), Pinxter Azalea (Rhododendron periclymenoides), serviceberry (Amelanchier spp.), and Spicebush (Lindera benzoin). Notably, tree and shrub regeneration is not allowed to progress in the city’s thousands of acres of landscaped parks. This management regime further hinders the formation of a native mid-story.
One third of bird species in the U.S. are in decline across all habitats according to the 2025 State of Birds Report. Millions of birds migrate through the city each year with some stopping over and even breeding in all boroughs. Refueling and nesting sites are primarily located in areas of the city with more intact forest layers. Many New York City parks don’t even feature a mid-story layer of vegetation. The dominant layers are a ground cover of lawn grass, ornamental annuals, and introduced perennials and a canopy layer. In other parks, there are shrubs and small trees, but they’re mostly non-native species. Many birds rely on the spatial niche provided by a native mid-story layer. We could help birds by expanding this layer. Native plants provide food for adult birds and chicks. Native fruit is more nutritious than the fruits of introduced plant species.
Additionally, forest fruits can be a cultural resource. Fruit picking, gleaning, and foraging are important practices in Afro-descendant communities. After the Civil War, southern legislatures passed criminal trespass laws to deter African Americans from foraging on previously accessible land. Here in New York City, a 1740 “slave code” enacted by the Common Council prohibited Black New Yorkers from selling their own produce including fruits. But a growing number of Afro-descendent people are once again connecting with our urban forests.
While adult birds are omnivorous, chicks are insectivorous. Insects like caterpillars are the main component of their diet. Caterpillars have evolutionary relationships with native plants. In the absence of these plants, caterpillar populations decline. Without sufficient caterpillar populations, breeding bird reproduction is compromised. Doug Tallamy, professor of entomology and wildlife ecology at the University of Delaware, notes that a clutch of Carolina Chickadee chicks requires up to 9,000 caterpillars for successful development. Desiree Narango, a conservation biologist, and her colleagues have identified that having more than 70% of native plants in a residential yard is a crucial threshold, below which a breeding pair might not be able to replace themselves,
Shrubs and small trees are also nesting sites. Introduced plant species provide suboptimal nesting structure. Research shows that birds experience more nest predation when they locate their nests in introduced species. Moreover, research shows that future nesting site re-occupation is reduced when birds experience reproductive failure.
Finally, birds provide what are known as “invisible” ecosystem services such as pollination, seed dispersal, and predation on harmful insects including disease vectors.
One of the joys of spending time with wild birds is listening to the diversifying chorus of songs and seeing the bevy of colorful plumage as migratory birds arrive in the city. Tuning into bird song on spring days is like a spa treatment for your brain. Noticing all the field marks–cheek patches, eyelines, caps, rumps, and tails–is directed attention, yet it is not fatiguing work. It is a restorative experience.
Our parks can be transformed into more robust havens for birds. Add clusters of native shrubs and small trees to capital projects. Call it a mid-layer retrofit. Each time a small tree or shrub needs to be replaced in a landscaped park, choose a native species alternative. Let’s ensure we can hear the songs of the birds who have migrated here for millenia (and that New Yorkers have more opportunities to experience biodiversity).
Georgia Silvera Seamans has managed street tree planting contracts and community forestry programs. She teaches environmental studies at two universities in NYC.
