This weekend (April 25-28), New Yorkers are invited to record the wild plants and animals in their area as part of the annual City Nature Challenge (CNC).

Organized by the nature observation app iNaturalist, the CNC collects data about urban biodiversity that can be used for scientific research.

This will be New York City’s ninth year participating in the global event that now spans over 600 cities. Last year, New Yorkers across all five boroughs uploaded 25,719 observations of plants, animals, fungi, seaweed, bacteria, and beyond. Over 10% of those observations came from one person: Bronx resident Melissa Rosenthal, who logged an incredible 2,587 nature sightings over four days of dawn-to-dusk exploration. 

Rosenthal approaches nature spotting with the dedication of a professional athlete. “I come [to the CNC] really prepared,” she says. “I pre-bake sweet potatoes and have snacks with me so I don’t have to worry about stopping and eating. I bring chargeable batteries so I can charge my phone, and two sets of headphones in case one of them dies…I’m really determined.”

Competitive spirit aside, she sees the CNC as a fun opportunity for any city dweller to observe and appreciate the nature around them. Here are her top tips for getting out into the Greenpoint and Williamsburg area:

You don’t need a fancy camera or a degree in biology to contribute to this weekend’s mass biodiversity survey, or “bioblitz.” 

The CNC is an example of participatory science (essentially, science for non-scientists). To take part, all you need to do is download the iNaturalist app on your cell phone, head outside, and snap a picture of anything wild you see. 

“You don’t have to venture deep into the woods,” says Rosenthal. “Look at a street tree; there’s probably going to be lichen or moss on it. Or you’re probably going to find a fern coming out of a city sidewalk or along a rockface.”

City staples like pigeons, squirrels, and weeds are all fair game to photograph. Just avoid things like pets or potted plants, as the point is to record the city’s naturally occurring life. 

Once you take your picture, the app will prompt you to provide some information about what’s in it (and help you ID it if you’re not sure). Once you press upload, your geotagged photo will be reviewed by a community of scientists and naturalists. It can then be published as “research-grade” data that goes on to fuel future urban nature science. 

You don’t need to travel far to make your sightings. The CNC can be a chance to explore local Williamsburg and Greenpoint parks with a new level of awareness, attention, and appreciation. 

“I feel very in awe of nature, even in urban spaces,” says Rosenthal.

Stroll over to McGolrick Park at 11 a.m. – 12 p.m. on Saturday for an official CNC walking tour led by the Brooklyn Public Library. You’re sure to spot park staples like dandelions, oyster mushrooms, and plenty of milkweed. Keep your eyes peeled for less common visitors like the black-and-white warbler bird, identifiable by its bold zebra stripes. 

Or, head over to the Naval Cemetery Landscape at the edge of Williamsburg for CNC programming from 10 a.m. to 12:30 p.m. on Saturday, plus street tree stewardship, trash pickup, and a chance to see the work of local climate-focused artist Jessica Dalrymple. The memorial park’s native plant meadow is a popular habitat for pollinators of all kinds, and it’s officially recognized as a Monarch Waystation.

For more ideas on where to head, you can open up iNaturalist to see where your favorite plants, animals, or critters have been sighted around Newtown Creek, Transmitter Park, or Bushwick Inlet. Cherry blossom groupies, assemble!

Even in a city setting, “leave no trace” rules still apply. If you head out this weekend, remember to stay on marked trails, throw away your trash in marked bins, and leave your surroundings the way you found them. Be sure to look out for poison ivy as you crouch down to get the perfect shot, too.

If your CNC outing inspires you to get more involved in protecting the city’s biodiversity, check out the Natural Areas Conservancy’s Super Steward Trail Maintainer Program (which Rosenthal helps lead), sign up for NYC Parks’ Street Tree Care Program, or look into volunteering with local greening groups like the Brooklyn Greenway Initiative, North Brooklyn Parks Alliance, McCarren Park Demonstration Garden, or North Brooklyn Stewards.