New England birds prefer local cuisine

Richard B. Primack, Amanda Gallinat, and Trevor Lloyd-Evans

“Do not think that the fruits of New England are mean and insignificant, while those of some foreign land are noble and memorable. Our own, whatever they may be, are far more important to us than others may be. They educate us, and fit us to live in New England. Better for us the wild strawberry than the pineapple.” Henry David Thoreau.   

New England is famous for its regional cuisine of clam chowder, baked beans, and lobster. It turns out New England’s birds also prefer local food. In a recent study published in the journal Biological Conservation, we found that birds migrating through New England in the autumn, such as Gray Catbirds, Hermit Thrushes, and Baltimore Orioles, prefer high-quality native fruits, like blueberries, black cherries, and raspberries, even in late-autumn when non-nutritious but colorful fruits of invasive species like Asian bittersweet, Japanese barberry, and multiflora rose dominate the menu.

As they migrate later in autumn with climate change, birds like this Hermit Thrush will increasingly encounter invasive fruits like multiflora rose; however, our research shows that just because they encounter more invasive fruits doesn’t mean they will eat them. Image credit: Jeremiah Trimble.

This discovery was made by examining bird poop from over 450 birds captured in mist nets, placed in cloth bags, and later released after weighing and banding by bird banders at Manomet, on the coast southeast of Boston. Amanda and many BU undergrads sorted through the samples to identify seeds based on size, shape, and color. 

We used a reference collection of seeds from plants in the field at Manomet to identify seeds from over 450 bird poop samples. The seeds pictured are from (left to right, top to bottom) native blueberry (Vaccinium), black cherry (Prunus), raspberry (Rubus), and invasive Japanese barberry (Berberis). Image credit: Amanda Gallinat.

What we discovered was that the birds were almost exclusively eating the fruits of native species.   The low-quality invasive fruits are left behind for overwintering birds to eat when nothing more appetizing remains. 

Despite invasive plants dominating fruit availability in late-autumn, migratory birds like this Gray Catbird continue to prefer the fruits of native plants like pokeweed throughout the season. Image credit: Ann Stinely.

The article, “Can invasive species replace native species as a resource for birds under climate change? A case study on bird-fruit interactions”, can be accessed here.