Tuesday, January 3, 2017

Atascosa Highlands CBC – Arivaca Lake and Chimney Canyon

I participated in the Atascosa Highlands Christmas Bird Count yesterday. It was a blissful 13-hours of reconnecting with one of my favorite places to bird in the US. You might know that I was compiler for this CBC for the five years from 2008 to 2012. The compiler is now Jake Mohlmann, but this year he was out of the country during the whole season, so John Yerger filled in as he did for me in 2011.

As in past years, I camped the night before in order to get some sleep and do early morning owling. I borrowed my friend Keith’s car and departed home less than 19 hours after I had returned home from Oaxaca. Here's a screen grab of Google Earth showing the Atascosa Highlands CBC circle and the route that I hiked.

It had rained about 1/2 inch that day, so small sections of some roads were a bit slippery, but it created a layer of that horrible gumbo-type mud that quickly packs into tire tread, reducing traction to a physics-defying lack of friction. So I chose a camping spot before I became hopelessly trapped on the side road into Papago Tanks, and with my condensed breath freezing into tiny droplets on my tent walls I managed 6 1/2 hours of sleep in my toasty sleeping bag before my 3:00 a.m. alarm (I think I dreamt a screech of a Barn Owl sometime after midnight.)

I walked 1 1/2 miles on foot, getting just one Western Screech-Owl, then just like last year was met by Bill Lisowsky to continue owling for another 2 1/2 hours. We heard two more Western Screech, one Whiskered Screech, and two Great Horneds before it got too light. Bill dropped me off at the edge of the area I was to cover, Arivaca Lake and Chimney Canyon, and I soon met up with my neighbor and landlord Paul Sheppard for a paddle around Arivaca Lake.

It was cold, but calm with dry air, so the rock bottom temperature of 27°F (-3.33°C) began to rebound quickly after sunrise, and we had a beautiful and mostly peaceful ride up the several arms of the reservoir. This Great Egret changed perches as it moved around the lake in the direction we covered it.

This landscape of eroded welded tuff is usually home to Rock Wren, but their numbers might be down this year. I missed it entirely this day, which seems strange for a CBC that gets the national high every year with no close contenders.

We got out and birded below the dam where we got this House Wren, from its call and pale plumage a northern bird here for the winter.

We got out at the Cedar Canyon inlet (the largest drainage feeding into the reservoir), where this wet grass delta would seem to be the ideal place for a megararity (sparrow, shorebird).

Maybe next year. All we found this time was a huge number of Savannah Sparrows – I estimated 75, which is more than the total number this entire count usually gets.

Paul’s ability to steer the canoe was impressive, and he spotted all the non-vocalizing birds before I did. I’m an ear birder to a fault.

As Paul departed, I commenced my hike up Chimney Canyon to return to Keith’s car on the road to Papago Tanks, and the first bird I looked at as the canoe disappeared was a Lazuli Bunting, the only one for the count. It was an easy hike, which might be 3 1/2 miles if done as a direct route (much on a dirt road). It began at 3800 feet in elevation and ended at 4045 feet, so it was nearly flat. But I turned it into 6 1/2 miles by bouncing back and forth across the broad drainage, venturing up into the hillsides a few times to check some patches of oak woodland. Here's a closeup of my zigzagging track.

Early on the wash was dry and broad. In this dry grass I flushed a sparrow.

I was pleased to nail it as a Grasshopper Sparrow, normally found only in the far eastern edge of the circle where there are some large, flat grassy areas where the species is a resident.

Chipping Sparrow on the other hand is an abundant winter visitor in the region. They are very adaptable, moving to areas where their preferred grass is in seed, so some areas of the circle had very few while I had a lot – 339 was my estimate.

Bewick's Wrens were evenly spread throughout my area, and I tallied a total of 41.

As I worked up the canyon, concentrations of oaks increased.

I was surprised to flush a Woodhouse's Scrub-Jay, and with playback discovered that there were four in this group.

How each bird species chooses its ideal habitat is unique to itself, combining many factors which may include the climate as well as features of the plant community and physical landscape (such as elevation, soil type, slope, and aspect). Crissal Thrasher has a one of the most curious matrices of habitat choice factors for a non-migratory bird, obvious if you look at a  precise range map of its occurrence. Any biologist intricately familiar with their needs in the Salton Sea area (flat and below sea level) would be baffled by their presence in this topography, elevation, and mix of plant species. My guess is that the shape and distribution of shrubs are crucial factors.

As I worked my way up Chimney Canyon it became narrower, and water from the recent rains was apparent.

Gray Flycatchers became more obvious as I worked my way up, and I tallied 12 for the day.

One open grassy area hosted a small group of Western Meadowlarks, which I identified based on the yellow intruding into the malar feather tract.

My biggest surprise was a pair of Black-capped Gnatcatchers, as this canyon does not have the plant density and diversity as other areas in SE Arizona that host this Mexican species. I managed to get recordings of the calls as well as perhaps the best photos I’ve gotten of this species in Arizona.

Much more widespread in Arizona but not very common in this area were Black-tailed Gnatcatchers. Note the shorter bill and the more pronounced black brow in the male’s winter plumage. The outer two pairs of tail feathers aren’t  completely white either, and the voice was clearly different.

Farther up the canyon, the north slopes of side drainages were covered in oaks – Emory and Mexican Blue Oaks.

Here near the end of my hike I finally found a couple groups of Bridled Titmouses.

I had two Hepatic Tanagers here as well.

Red-naped Sapsuckers winter here in their greatest density in the U.S., but only where there are lots of Emory Oaks. I found a total of 8.

Townsend's Solitaire needs the fruits of Juniperus coahuilensis, Redberry Juniper, which is common in this part of the circle.

Also feeding on the juniper but preferring the mistletoe in ash trees were these Western Bluebirds, a female and a male.

I finished the day with 77 species.


  1. Great pics Rich and a great day as always. No rock wrens here either. Sounds like I need to get up earlier for screech owls--just 4 GHOW.

    1. Thanks Brett! I think the screech-owls were just very quiet this time – maybe they needed to hunt instead of sing after that weather passed through. I'm very curious how many Rock Wrens were tallied in total.

  2. Wonderful natural history notes and route description. Lovely photos.