Anza Borrego – Circle of life

20 03 2016

Swainson’s Hawk – Luke Tiller

This weekend I led an awesome trip for Pasadena Audubon Society to Borrego Springs in San Diego County. The trip was ostensibly to visit the Borrego Valley Hawkwatch but also just to enjoy some of the great flora and fauna that call this desert area home. Part of the Colorado Desert the nearby Anza Borrego State Park, at 600,000 acres, is the second largest State Park in the county behind the Adirondacks (more about the park here).

We started out our morning adventure pre-sunrise at the area that is commonly known locally as the mesquite sink or mesquite bosque. Here we picked up a host of regular desert species that are not commonly found in Pasadena: Verdin, White-winged Dove, Black-throated Sparrow and Black-tailed Gnatcatcher as well as one that is found almost solely in this little corner of California: Crissal Thrasher. Thrashers are difficult to see at most times of the year, but at least in the breeding season they tend to be relatively vocal. We stumbled upon at least two birds in this little breeding enclave thanks partly to the sharp eyes of Grace Wong who first spotted a bird while it perched low in a bush below a Sage Thrasher that we had been looking at.

We then endured a cat and mouse game of hide and seek with at least two birds while we tried to work a way to get clear views of the Crissals in good light. In the end most of the group enjoyed good views but unfortunately without a chance for good photos. We weren’t so lucky with Lucy’s Warbler though, another species that is hanging on in this rapidly dying mesquite bosque (thanks to water being pumped from the aquifer).


Desert Sand Verbena – Luke Tiller

With at least one target bird under our belt and the sun starting to rise in the sky we headed out to the Borrego Valley hawkwatch with hopes that the Swainson’s Hawks that make up the bulk of the flight at the watch were starting to get active. With a brief stop to check out some Swainson’s that were lounging in a field en route (or maybe hunting some ubiquitous caterpillars) we got to the hawkwatch just in time to enjoy watching distant, but large numbers of Swainson’s Hawks kettling from out of their nearby roosts. You can read more about the watch, and check out the great photo opps provided by roosting Swainson’s, on their blog (here). You can check out daily migrant counts on their hawkcount page too (here).

Though the hawks always come through Borrego Springs in migration ,this year they were taking advantage of the caterpillars that were busily devouring an impressive desert wildflower show.  Millions of mainly White-lined Sphinx caterpillars (more on those attractive moths here) were eating everything in sight and were so thick in many areas it was all one could do to not to step on them. I’m sure the myriad of beetles and a impressive Northern Desert Iguana (useful CA herp info here) we found near the watch were making the most of this bounteous food supply too.


White-lined Sphinx Caterpillar – Luke Tiller

After enjoying the watch for a while we headed off to grab some refreshments, but a fortuitous stop to check out a couple of Swainson’s Hawks kettling by the roadside turned up a rather exciting and unexpected addition to the day’s sightings: a juvenile Zone-tailed Hawk (photographed by Darren Dowell). It put on quite the show and allowed for good views of it’s ability to mimic Turkey Vultures both in plumage and in flight style. There had been one juvenile reported in the area over two weeks ago but it wasn’t clear if this was the same bird (hard to believe the experts at the hawkwatch had missed if for over two weeks).

After a stop at the Roadrunner Club for a break we were on to our next couple of stops. With temperatures rising it was starting to become hard to find birds. There was however much to entertain including Costa’s Hummingbirds and lightning quick Western Zebra-tailed Lizards. We were also indebted to Rick Fisher for a wonderful introduction to desert wildflowers to keep us entertained. Even in the midday heat of a 94 degree day our intrepid group were still finding good birds (what is it they say about Mad Dogs and Englishmen…) and though stops weren’t exactly ‘birdy’ we were turning up some highly desirous species including both resident Le Conte’s and migrant Sage Thrashers inhabiting an incredibly bleak little portion of desert. Along with the thrashers we also turned up a rather neat, and endangered, Colorado Desert Fringe-toed Lizard too (photo).


Costa’s Hummingbird – Luke Tiller

After a welcome stop for lunch and an obligatory visit to the gift shop we headed to our last desert stop of the day: Tamarisk Grove Campground. The greenery of the campground and nearby Yaqui Wells seep (more here) offer a welcome respite for migrant birds in this rocky and desertlike environment as well as some shade to rapidly overheating birders. During the peak of migration who knows what you might find at these productive migrant trap sites? Previous years have yielded everything from Xantus’s Hummingbird, Kentucky Warbler and Red Phalarope!!!!!!

As it was mid-afternoon we avoided the hot hike out to the seep and birded the campground where we enjoyed a few nice desert specialties: Ladder-backed Woodpecker, Cactus and Rock Wren. Even more excitingly we managed to turn up a nice migrant of our own in the shape of a young male Vermilion Flycatcher. Best of all though we got to share that sighting with a young San Diego Birder and his parents.

The other highlight here was Rick again sharing his knowledge of the local succulents, and we enjoyed a variety of them in bloom including Beavertail Cactus, Hedgehog Cactus, Barrel Cactus and Ocotillo.


Beavertail Cactus – Luke Tiller

We ended our day wending our way back towards Pasadena. A final couple of roadside stops provided us with a number of nice birds including Tricolored Blackbirds (sadly declining precipitously in the state) and fittingly a bunch more raptors including White-tailed Kite, Bald Eagle, Northern Harrier and American Kestrel.

I think we can safely consider this inaugural Pasadena Audubon Society trip to Borrego Springs a success and I look forward to running it again next year. Thanks to everyone who came and made it such a fun and successful trip. If you want to see what other trips I have coming up locally and beyond check out my Trips and Tours Page (here). A couple more pics from the day are on my Flickr page (here).



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