Brianna Amingwa and Lamar Gore stopped in mid-conversation when their ears caught a trill above the marshland at John Heinz National Wildlife Refuge near the Philadelphia International Airport.
They quickly settled on the source: a warbling vireo, a tiny songbird with a big-throated sound that rises and dips as if asking the same question over and over.
While birding is a booming outdoor activity, Amingwa and Gore, both African-American, fit into a much smaller slice of it that they hope grows.
The experience of black birders came to the forefront last month after a white woman called police on Christian Cooper, a black man who had asked her to leash her dog in New York City's Central Park. Cooper was birding at the time.
While unrelated to his bird-watching, the experience motivated other black birders to unite and create an online community.
In response, a group of black scientists organized the first Black Birder Week, held May 31 to June 5. Within days, the group had 30,000 followers. Organizers encouraged participants to use the hashtag #BlackBirders Week to upload photos of birds they had spotted.
Amingwa, 27, an environmental education supervisor at Heinz Refuge, was one of the organizers of the national movement.
She said the goals were to make people aware there are black people actively involved in birding, as well as nature and science, and to start a conversation about what it's like for "nonwhite folks to go birding."