Citizen scientists document nearly 200 species at Homestead Valley bioblitz

A team of ecologists, park rangers and local volunteers gathered April 29 off Marin County’s scenic Panoramic Highway in the foothills of Mount Tamalpais to take part in the Homestead Valley Bioblitz. The group’s task: to document every living species they could find in three hours.

To record their discoveries, participants took snapshots with their smartphones and uploaded them to an app called iNaturalist, which stamps each photo with a date, time and geolocation tag. The identification of species is then crowdsourced through the app’s vast network of scientists and naturalists.

Some of Saturday’s confirmed sightings included Silver Lupine, Bull Thistle, Anna’s Hummingbird and the Northern Alligator Lizard.

Bioblitzes engage ordinary citizens in the practice of science. The data collected by iNaturalist can be used by biologists and land managers to monitor the health and biodiversity of natural ecosystems.

By the end of the event, 29 citizen scientists had made a total of 947 field observations and identified nearly 200 distinct species. Their findings can be viewed at

Saturday’s bioblitz was sponsored by One Tam, a community-based organization dedicated to the preservation of the Mount Tamalpais wilderness, in partnership with the National Park Service.

In addition to the scientific mission, citizen science programs — like the one at Homestead Valley — offer the public a chance to get outdoors and gain a deeper appreciation for the environment.

“I think that the more we can bring people out to care about the environment, the more we’re going to have some power to make sure that it’s protected,” said volunteer Cathy Steirhoff.


Scroll to Top