Date: 4/21/26 11:33 am From: basquebirder via groups.io <allaboutbirds...> Subject: [northbaybirds] 04/16 Marin County Biking Big Day
Hi all,
On April 16th, Josiah Clark and I embarked on a Marin biking big day, attempting to see as many species as possible while traversing across the varied habitats this county has to offer. The evening prior, we dropped off Josiah's truck in front of Jim White's house at Muir Beach, which greatly helped logistically (so thanks for that Jim!). The morning of, I picked up Jo and heading up to the Atherton park-and-ride by Rush Creek in Novato and began our journey at about 5:15 am.
We took the path hugging the creek in the dark, and heard our first bird of the morning, a few Least Sandpipers calling along the water's edge. A Great Horned Owl sounded off nearby, which we somehow missed entirely last year. We checked out the spot we lucked into a Western Screech-Owl last year, but alas no response. We arrived at Bahia Marsh just before dawn, and were greeted by pretty thick low tule fog. We couldn't see out more than 30-40 feet on the water. No matter... A couple Soras started calling from the reeds, a raucous group of Ridgway's Rails sounded off rather readily, and our more difficult target Black Rail took a little bit of effort, but eventually starting grrr-grrr-grrr ing for us to both hear. As we looped around in the early light, the expected land birds were making themselves known, a White-tailed Kite sat in an oak watching the day slowly get brighter, and we managed to catch up with a few Bufflehead and Greater Scaup lingering near shore out of the fog's engulfing embrace.
As we made our way back through the neighborhood towards the Bahia Trail, we lucked into a Hooded Oriole calling from a lone palm tree. Right at the trailhead, Josiah had scouted a Lincoln's Sparrow a few days before, which was happy to hear one of its kind calling and came out right where he had seen it before. The oak specialists were all present, with Acorn Woodpeckers, Oak Titmouse, and White-breasted Nuthatches all stoked to see us out there seizing the day. We ended up hearing a couple House Wrens singing, a couple American Goldfinches flew out of the oaks (our only ones of the day in the end), and a lucky Ash-throated Flycatcher called out distantly. As we approached the mudflats, the fog began clearing, revealing the large numbers of waterfowl and shorebirds out there. The vast majority of the ducks here were Green-winged Teals, and the shorebirds were mostly peeps and Dunlin.
We rounded a corner on the trail, and were overlooking the Cemetery Marsh. Josiah had scouted out a couple Kestrels on a dead snag visible from here, wondering if they maybe had a nest. We scanned around with no luck. The marsh itself had a bunch of American Wigeons, and many silent dowitchers (which we learned were Long-billed Dowitchers once we approached them). This was when Josiah pointed out this odd looking shorebird hanging out near the dows. Smaller, grayer and lighter overall, we couldn't figure out what it was. I thought maybe a yellowlegs, but we needed to get closer to figure this one out (in hindsight, we should have just busted out the scopes from there and gotten our answer right away). We got the other side of the marsh, much closer to this bird, and well it ended up being a Stilt Sandpiper! According to eBird anyways, this appears to be only the 4th Bay Area spring record, with the other 3 coming from the south bay in Santa Clara county. Thanks to Dominik Mosur for promptly getting the word out for us, and we were happy to learn other people connected with this bird before it took off and disappeared out in the mudflats. We watched it for about 10-15 min, but big days by bike have to stay moving if we wanted to complete our route, so off we went. We checked out the large span of water in the creek by the highway for any additional waterfowl, but all we got were some disgusting Mute Swans.
After swinging by the car one last time to drop off any unnecessary weight and refuel, the real ride began. We headed straight to Rowland Marsh, where we could hear the Great-tailed Grackles singing, and get some firsts like Virginia Rail and Pied-billed Grebe. We crossed to the east side of the 101, a from there it was basically a straight shot south to Pacheco Pond. We took the SMART Pathway, a very neat bike trail along the train tracks which makes biking in Marin such a kind experience. The Leveroni Basin sits just north of Pacheco Pond, on the other side of Bel Marin Keys Dr., and you get a good view of it from this bike path. We picked up several Greater White-fronted Geese, Ring-necked Ducks, and our first coots of the day here. We finally made it to Pacheco Pond, where we were met with a squad of American White Pelicans in the water, the Great Egret colony in full force, and Cinnamon Teals. We were also met with a concerningly loud airboat (like the ones from the Everglades) zipping around the pond. We couldn't figure out what they could possibly be doing with such a disturbing piece of machinery in this wetland in full breeding season, with Great Egrets flushing from the colony, and baby Mallards jostling around in the wake of the boat. We learned this was for mosquito surveys, I guess to access the shallow corners which are their breeding grounds. Given the time of year and significance of this location, this is highly overkill and we couldn't understand why surveying via kayak or rowboat or even a Jon Boat with the small tiller engine fishermen use to creep around ponds' edges, wouldn't work. Disappointing to see... Nonetheless, we managed to scrape up some new birds like Common Gallinule and the greatly desired Least Bittern.
Next up were the Hamilton Wetlands, our first real look at the shorebirds (the Bahia shorebirds were mostly all too distant to do much with). Semipalmated Plovers, Western Sandpipers, and Marbled Godwits were plentiful, with a few Willets in the mix. We looked closely for Snowy Plover, since this is where we saw some last year, but no luck. We got out to where we could the see deeper water better, where there were Canvasbacks and Ruddy Ducks floating around. We were approaching the end where we did some final hard scoping and Josiah picked out our only Long-billed Curlew of the day and I picked out our only American Kestrel of the day. Team work! We packed up the scopes and headed south towards Las Gallinas WTP. On our way down, there was an adult Bald Eagle causing a scene at one of last ponds we passed by before the WTP. Thanks to a tip from Jim White, we knew to keep our ears open for Horned Lark right around here as well, by the large field. And sure enough, we heard the tinkling song of a skylarking bird basically right on arrival. Love when that happens! We checked out this distant abandoned pier from the trail, in hopes for maybe a grebe or something, and Josiah spots to dark blobs on the pilings. Even in the scope they were just dark shapes in the heat haze, but that's all we needed to see to know these were our first Black Oystercatchers of the day.
Las Gallinas quickly offered us our first Common Mergansers as we scanned the rocky edges for Spotted Sandpipers. We were also looking for Green Heron, always a challenging big day bird. To our surprise, Josiah spotted a Red-throated Loon in one of the ponds. As I look through eBird now as I write this, this wasn't a known bird and the first one here since March of 2024. Hmm... Anyways, the Green Heron appeared and we knew it was time to go. The water fountain at the parking lot here is a critical stop on bike. We downed a bunch of our water to rehydrate, refilled up the bottles, had a snack, and bye-bye bayside!
This was the beginning of the new and improved route from last year. Last year, we headed straight up Lucas Valley Rd. to Big Rock and Loma Alta OSP. Good birds and beautiful, but such a climb and energy expensive. Josiah remembered there was an access via the Mission Pass Path in Sleepy Hollow down Fawn Dr., which basically drops us off in Fairfax. As we biked west along Sir Francis Drake Blvd., we picked up some new birds like Warbling Vireo, Orange-crowned Warbler, and Great Blue Heron (our only one of the day!). We made it to the Cross Marin Trail, which is a walking/biking path that runs parallel to main road, but on the other side of the creek. So it's quieter, safer, and birdier! We have definitely entered a new habitat type at this point, with new birds like Brown Creeper, Pacific Wren, and Golden-crowned Kinglets calling around us. The east half of this trail I would say is dominated by redwoods and douglas-fir, and overall darker and colder. The west side opens up more and is dominated by willows and box elders, and much warmer in the sun. Right about at this transition zone, Josiah made the best spot of the day. We were flying down this bike path, listening more than looking. I was ahead, and all of a sudden I hear Josiah call out 'Wood Duck!'. He was biking as fast as I was, and happened to look into the creek during the maybe half a second window the vegetation opened up and noticed the striking male in the creek. It would have been so easy to miss. I backed up to him and sure enough there the male was, joined by a female. Nice to see this low-density species in prime habitat, hoping they are breeding and successful. We also added Allen's Hummingbird and Black-headed Grosbeaks to the day list on the west end where the trail ends.
The next chapter of our day takes us up the scenic Bolinas Ridge Trail. The lower north end of the trail is dominated by open grassland and patchy coastal scrub. Our first new bird here was a Purple Finch on the barbed wire fence out in the grassland, a funny visual indeed. We stopped many times in this habitat to listen for Grasshopper Sparrow and Lark Sparrow, a species Josiah says you didn't even need to try for back in the day, they would just be there singing. Perhaps the changes this habitat has underwent, different grazing regimes, or corvid abundance are to blame, but regardless we dipped hard. The trail is a fun ride with a mountain bike or at least something with burly tires, but our narrowly tired gravel/road bikes made this ride somewhat challenging. We ended up spending about 3h ascending the rolling hills to reach the Randall Trail. But we did add some new birds like Pileated Woodpecker, Red-breasted Nuthatch, some late winterers like Ruby-crowned Kinglet and Fox Sparrow, Steller's Jay, and Red Crossbill at the Eucalyptus spring! I also got charged at by a muscular steer which caused me to fall off my bike, which then required us to deal with some bike stuff, in the form of a broken bolt attaching the rack to the bike. But after a little bike surgery, we were off again.
It was already 6:15pm by the time we were at the top of the Randall Trail. We would've tried harder for Hermit Warbler if we had more time, but given we hadn't even looked at the ocean, it was time to jam! Down the Randall Trail we went, and south on the 1. We took Horseshoe Hill Rd. to arrive at the mouth of Bolinas Lagoon. Finally, we hadn't seen salt water since this morning. And a whole new slew of birds to find. A skein of Brant floated near the mouth, Whimbrels on the sandbars, Common Loons and a Herring Gull in the lagoon, and pelicans, Elegant Terns, both Aechmophorus grebes, Common Murres, and Surf Scoters in the ocean. With the little light we had left, we figured we should just double-down on the ocean birds and headed to the Duxberry Reef overlook. This was the right call, because we manage to eke out 3 new birds, in the form of Black Turnstone, Pelagic Cormorant, and Pacific Loon. And just like that, nighttime had taken over, and our birding was done by 8:30pm. Our birding was done but not our day, since we still have to bike south to Muir Beach. After a steady 1h30 ride along the 1, we arrived back at Jim's house at 10pm. The idea originally was to maybe do some owling at Muir Woods, but we arrived later than expected and still had to pick up my car in Novato and then drive back home to San Francisco, so no owls.
We ended up with the modest total of 157, and covered about 70 miles of riding. Considering the minimal scouting that we did, and only having ridden piecemeal sections of this route, I think we did good! This new route was certainly more sane than last year (where we crested Loma Alta OSP, Carson Ridge, and Mt. Tamalpais in a row), but the Bolinas Ridge section might have eaten up too much of our time. Nonetheless, it was fun day and something I look forward to doing each year.
Thanks to Josiah for crafting this route, and putting in more scouting effort than I, thanks to Jim White for offering us his driveway and giving some tips for certain keys birds, and thanks to all the friends stoking us to get out there and do it. And thanks to you the reader if you made it this far.
