Abbott’s Lagoon with Organismal Biology

Today I returned to Abbott’s Lagoon in Point Reyes, this time with my Organismal Biology students. I was hoping for shorebirds and – if we were lucky – river otters. We got both, and the otters gave us a field trip to remember.

As folks arrived, we headed down the upland trail, which was quieter than I’d expected. I did see a few species of birds – and some great plants – but mostly we were focused on getting down to the beach and lagoon.

At the bridge, we saw a gorgeous Great Blue Heron, but sadly, nothing but otter footprints (not the otters themselves). As I approached the lagoon, at first it looked pretty uninhabited as well, especially after the large flock of pelicans and gulls I’d seen here on my first visit. However, as I got closer to the mudflat, I realized there were hundreds of small shorebirds. Western Sandpipers foraged alongside Dunlin, Black-bellied Plovers, Semipalmated Plovers, and Least Sandpipers. Later, a larger flock of Sanderlings joined the gathering. It was fun to pick the different species out of the crowd.

As I headed toward the ocean, we saw a handful of Snowy Plover, and watched a Black-bellied Plover catch and eat a worm (possible a Pile Worm). At the ocean end of the lagoon, I found a few more shorebirds, including a particularly cooperative Short-billed Dowitcher who supplied its own identification clue: as it flew off, it gave a three-part “chew-chew-chew,” which allowed me to make the otherwise difficult ID (as these birds look very similar to the Long-billed Dowitcher).

I continued on to the actual beach, where the crashing waves were huge and beautiful. A few Brown Pelicans flew past (but nowhere near the number I’d seen on my previous visit).

Speaking of pelicans, one of the unusual things today was a number of dead Brown Pelicans on the ground, mostly just feathers and denuded bone. Turns out that this may be due to a very interesting dynamic: researchers have documented River Otters attacking and drowning pelicans before feeding on them at Abbott’s Lagoon (and a few other California locations)! Pelican remains also provide food for Coyotes and other scavengers, and there are hints that pelicans may be beginning to respond to the danger. Researchers have observed resting birds taking flight when an otter approached, which suggests possible avoidance behavior.

When it was time to start heading back to the trailhead (which I knew would take a while, with as often as I stop to look at things again), as we walked along the lagoon, we saw more Snowy Plovers and Least Sandpipers resting in small depressions in the sand. So tiny and adorable!

Two of the plovers wore leg bands, and I reported the bands in the hope learning more about these individual. And I’ve already heard back about one of them! (The one with the orange/violet/orange band).

According to the fellow who messaged me, “The bottom bird is o/v/o:o (orange/violet/orange:orange) – it was banded at North Tahkenitch Douglas Co., Oregon on 7/21/2019. We know of one individual with this combo and it is a male, and he is known to breed at North Tahkenitch.”

Of course I also stopped near the mudflat to see if anyone new had shown up. Mostly, I found the same species, except for a large flock of Sanderling and sever Black-bellied Plovers, along with a lone California Gull resting in the water nearby. Along the route back to the bridge, I found plants such as Coyote Brush, Coastal Bush Lupine, Marsh Jaumea, and Beach Suncup.

The day’s highlight came as we reached the bridge. Students on the other side of the bridge had spotted North American River Otters, and some enthusiastic improvised sign language got the rest of us looking in the right direction. Two otters swam along the cattails, climbed onto the sand to wrestle, and passed right beneath the bridge. A few minutes later, the two original otters returned with a third, which we could see on the shore near the rocks. One returned to the water, caught something, and ate it while we watched, which one of my students captured on video.

I was so happy to see the otters – this was by far the closest and longest river otter encounter I’ve ever had, and everyone who saw them seemed delighted. (To be honest, how could you not be charmed by these adorable friends).

Heading back through the upland habitat we saw a good variety of birds, including some new ones of for the day: California Quail, Northern Harriers, a California Scrub-Jay, and a Western Meadowlark. It was a fantastic day, and I’m already looking forward to me next trip to the lagoon.