Every evening from June through September, something quietly spectacular happens just ten miles west of Sacramento. As the sky shifts from gold to gray, hundreds of thousands of Mexican free-tailed bats pour out from beneath the Yolo Causeway in a dark, undulating ribbon — one of the most unusual natural spectacles within easy reach of the city.
Most Sacramento residents have never seen it. That’s about to change.
California’s Largest Urban Bat Colony
The Yolo Causeway is home to the largest urban colony of Mexican free-tailed bats in California, according to the Yolo Basin Foundation, the nonprofit that manages educational programming at the site. The bats take up residence under the bridge each spring, give birth in late June, and raise their pups through the summer before migrating south in the fall.
By mid-summer, the pups — each born to a single mother — are old enough to fly on their own, swelling the nightly emergence into a spectacle that can stretch for several minutes. The bats feed heavily on agricultural insects in the Yolo Bypass and surrounding farmland, making them both ecologically valuable and genuinely mesmerizing to watch.
Late September is the tail end of the season. The colony is still here, but not for much longer. If you’ve been meaning to go, this is the week to do it.
The Official Bat Talk and Tour
The Yolo Basin Foundation runs a structured “Bat Talk and Tour” program each season out of the Yolo Bypass Wildlife Area. The experience runs roughly three hours and includes an educational presentation with live ambassador bats — animals that live permanently with the foundation and are used for public programs — followed by a caravan tour through the wetlands and rice fields to the Flyway Pavilion, where guests watch the colony emerge at dusk.
Admission for the guided tour is $17 for adults, $5 for youth ages 6–17, and free for children 5 and under.
The program sells out quickly every year, and the 2026 season is no exception: all 2026 Bat Talk and Tour events are completely sold out as of late September. If you missed it this year, the Yolo Basin Foundation offers two ways to get ahead of the rush for 2027. Joining the waitlist or subscribing to the foundation’s newsletter at yolobasin.org gets you notified when tickets open. Becoming a Friend of the Yolo Basin Foundation unlocks early-bird registration access, meaning you’ll have a chance to book before tickets go on sale to the general public.
Visiting the Yolo Bypass Wildlife Area Independently
The Yolo Bypass Wildlife Area, managed by the California Department of Fish and Wildlife, is open to the public daily from sunrise to sunset at no charge. The wildlife area spans approximately 16,600 acres of wetlands, rice fields, and seasonal marshes — and it sits directly in the middle of the Pacific Flyway, making it exceptional for birding and wildlife watching well beyond the bat season.
The main access point is off County Road 32B, roughly a 20-minute drive from downtown Sacramento. Unpaved access roads lead to dirt and gravel parking throughout the property. Note that swing gates at the western levee access close at sunset, so plan your arrival accordingly if you’re hoping to catch the dusk emergence.
For anyone looking to combine this with other free fall outings in the Sacramento region, the Nimbus Fish Hatchery salmon run is happening right now in Rancho Cordova. The best fall hikes in Sacramento cover trails that also pass through wetland corridors worth exploring this time of year.
The Details
- Location: Yolo Bypass Wildlife Area, 45211 County Road 32B, Davis, CA 95618 (approximately 10 miles west of Sacramento)
- Wildlife area hours: Open daily, sunrise to sunset (closed Christmas Day)
- Wildlife area admission: Free
- Guided tour admission: Adults $17 | Youth 6–17 $5 | Children 5 and under free
- Bat season: June through September
- 2026 guided tours: Sold out — join the waitlist at yolobasin.org
- Early access for 2027: Become a Friend of the Yolo Basin Foundation at yolobasin.org
- Wildlife area phone: (530) 757-2461
- More information: yolobasin.org
Bottom Line
Sacramento is full of underrated fall experiences, but the Yolo Causeway bat colony might be the most overlooked. The guided Bat Talk and Tour offers the best version of the experience — live bats, expert interpretation, and a caravan through the wetlands — but it requires planning ahead. For 2026, the tours are gone. Get on the waitlist now, or plan a self-guided visit to the wildlife area this week before the colony heads south for winter. Either way, this is the kind of thing that makes you glad you live here.
If you’re building a full fall calendar for the Sacramento area, don’t miss the Sacramento Zoo’s fall guide for more wildlife-focused outings close to home.
