Saturday, July 14, 2018

Monitoring a Common Poorwill Nest Site

Male Common Poorwill Wasatch Mountains Utah County, Utah

An endeavor to locate and and photograph Great Basin Collared Lizards on June 8th resulted in a series of visits to a Common Poorwill nest site.

It all started as I was exploring prime habitat for collared lizards--a rocky desert hillside with sparse vegetation. That particular hillside was punctuated with scattered sagebrush and junipers. I was coursing along a south-facing rocky outcrop when a Common Poorwill, an elusive nocturnal bird, flushed from its daytime roost. I wondered if I had stumbled upon a nest site, but when I checked the base of the bush from which the bird flushed I noticed only a single feather. Perhaps it was just the bird's roost for the day, but I captured an image with my phone to preserve a GPS location in case I wanted to return a week or so later to check for evidence of nesting.

My search for collared lizards was quite productive and resulted in some nice photos. My friend Eric enjoyed the photos and asked if I'd take him out to the same location since he'd never photographed collared lizards. We made that trip the next day, June 9th.

I mentioned my encounter with the Poorwills as we hiked up the hillside and suggested we check the previous roosting site. As we approached that site two birds flushed, not from the previous bush, but from a nook of the rocky outcrop. Both birds flew quite a distance, without any attempt to do a distraction display so I could tell that they had no eggs nor chicks to protect. There was no evidence of nesting in nor around that nook so we moved along the hillside. After covering about fifty more yards I was surprised when a third poorwill flushed from the base of a bush to my left. That bird landed a short distance away and did a distraction display, which clued me in to that fact that it had flushed from a nest site. I immediately realized that the poorwill was doing what nature had programmed it to do--protect its offspring. The bird appeared to be a female because it lacked the white corners that males have in their tail feathers. Since both sexes are known to incubate it can't be taken for granted that a bird flushing from a nest site is a female.

Common Poorwill Distraction Display Near Nest Site Great Basin Desert Utah
Rather than follow the bird after it flushed I inspected the base of the bush from which the bird had flown.  I beamed with excitement when I observed two white eggs and promptly alerted Eric so he could observe the eggs as well.

Common Poorwill Nest Site Great Basin Desert Utah

Common Poorwill Nest Site Great Basin Desert Utah

The previous images illustrate typical nesting behavior for Common Poorwills--laying their eggs in gravelly areas next to bushes that provides a fair amount of shade. These two eggs were on the south side of a bush on a south-facing hillside. They were situated in a way that allowed morning sun followed by shade from mid-morning through evening. Because I am fascinated by nature and the cycle of life, and because it is quite rare to find a poorwill nest site, I shared with Eric my desire to carefully and briefly revisit the site every few days to document the progress.

Several days later on June 13th we returned to the site and observed that an adult was still incubating the eggs.

Common Poorwill Incubating Eggs Great Basin Desert Utah

Common Poorwill Incubating Eggs Great Basin Desert Utah

I returned to the site by myself on June 17th to discover that one chick had just hatched and the second was in the process of hatching.

Common Poorwill Hatchling and Egg Great Basin Desert Utah

The upper right edge of the remaining egg shows evidence of a breach, evidence that the second chick was in the process of hatching. The tiny beak, nostrils, and eyelids were the only distinguishing features among the messy fluff of down feathers.

Common Poorwill Hatchling and Egg Great Basin Desert Utah

Common Poorwill Egg Shell Being Breached By Chick Great Basin Desert Utah

I made another quick visit to the site on June 19th, ten days after initially discovering the two eggs, with hopes of confirming that the second chick had successfully hatched. Sure enough the adult had two chicks tucked under its chest. The down feathers of one chick can be seen slightly protruding from beneath the bird's left side, the right side from our perspective.

Common Poorwill on Chicks at Nest Site Great Basin Desert Utah

Common Poorwill on Chicks at Nest Site Great Basin Desert Utah

The adult moved away and began its distraction display as I slowly approached. I quickly captured images of the chicks for documentation purposes and left the site.

Common Poorwill Hatchlings at Nest Site Great Basin Desert Utah

Common Poorwill Hatchlings at Nest Site Great Basin Desert Utah

When I returned on the 23rd, just under a week after the chicks had hatched, down feathers were being replaced by pin feathers on both chicks.

Common Poorwill Hatchlings at Nest Site Great Basin Desert Utah

On the 27th, about ten days after hatching, both chicks were still at their hatch site and were beginning to show signs of typical cryptic plumage.

Common Poorwill Chicks at Nest Site Great Basin Desert Utah

Common Poorwill Chicks at Nest Site Great Basin Desert Utah

Common Poorwill Chicks at Nest Site Great Basin Desert Utah

As I was leaving the area after this afternoon visit I noticed that my truck was registering a temperature of 101 degrees Fahrenheit. It was a reminder of some of the harsh conditions that are endured by creatures that live in our local desert.

My last observation of the two chicks took place on the 30th, nearly two weeks after the chicks had hatched. Eric joined me on this trip. We discovered that the birds had fledged and moved to a new roosting site about 20 yards up the hill from their hatch site. Knowing that it might be my last observation since the birds had ventured from their hatch site I took the opportunity to capture detailed images of their plumage and features.

Common Poorwill Fledglings Near Original Hatch Site Great Basin Desert Utah

Common Poorwill Fledgling Beak and Nostril Detail

Common Poorwill Fledgling Crown Feather Development

Common Poorwill Fledgling Feather Development

Common Poorwill Fledgling Feather Development

Common Poorwill Fledgling Feather Development

This image was captured to remind me of where the eggs were laid and where I last saw the chicks because I was unable to locate them several days later when I made my last attempt to observe their development. I feel grateful for the opportunity to watch those chicks develop. I'm also grateful to have a desert playground to explore so close to home.

Tuesday, July 10, 2018

Up Close With Horns and Collars

The morning sun was warming up the eastern edge of the Great Basin Desert as I turned off the pavement and onto a dusty gravel road that would lead me several miles to the base of a rocky hillside with sparse vegetation.  I had studied Google Maps to pinpoint an area that looked promising for Great Basin Collared Lizards and was on my way to check it out. I was anxious to begin my search so I was moving along at a steady clip.  A a cloud of dust was trailing behind me until I caught a glimpse of a tiny anomaly on the surface of the path ahead. I recognized the shape as a Desert Horned Lizard just in time to ensure that my tires straddled it as I passed over and attempted an abrupt, but safe, stop. After the cloud of dust dissipated a glance at the rear view mirror confirmed that the lizard was still safe and sound in its original position. A spontaneous expression of "Happy day!" escaped my lips as I approached the tiny, modern-day dinosaur. It's always a good day when you encounter a horned lizard.

I moved the lizard to a safer place and captured some images with both the Nikkor 200-500mm and the Micro Nikkor 105mm (macro) lenses. The armor of these guys is fascinating if you really take the time to examine it.

The macro lens allowed me to capture some of the finer details of its natural body armor. The images that result from the macro lens give the five-inch lizard the appearance of a larger and fierce creature. In reality, they are small and quite docile, even sluggish. When threatened they may attempt to lay low and blend in with their surroundings, sometimes half burying themselves in sand, or make a quick but short dash to nearby vegetation where they remain motionless, again hoping to blend in with their surroundings.

Here is detail of one of the two longest occipital  horns.

And another head shot, this time from beneath the blunt snout. If you were an ant, the primary component of the horned lizard diet, you'd be concerned if you looked up and had this in your view.

The shapes of thorns, warts, and granular scales mix with varied colors in this image of the left side of the lizard's back. The colors often vary from one individual to another as they tend to match the common colors of their local environment.

The image below shows the keeled scales protecting the forearm and the lateral row of shark-tooth-like scales that are found on both sides of the lizard.

Shortly after leaving the Desert Horned Lizard I arrived at the base of the rocky hillside I pinpointed on Google Earth. I've been told by a paleontologist friend that these rocks are from the Middle Cambrian period so they are believed to be over 500 million years old.

Here is another image I captured later that morning at another location I explored. Both of these images show typical habitat for the Great Basin Collared Lizard in northern Utah.

The first collared lizard of the day was small and blended in quite well with its limestone surroundings. A small cluster of tiny red mites can be seen between the base of the tail and the left hind leg. I later came to understand that it is common for mites to ride along on these lizards.

This female, the most striking lizard of the morning, displayed some nice orange striping as it basked on the top of a small mound of lichen-covered rocks. Typically, the females are less colorful than their male counterparts, but they develop the bright orange stripes during breeding season.

She was quite cooperative even after eventually moving to the top of another rock.

This male's collars were accentuated with white/creamy contrasting lines and a bluish tint on the neck, shoulders, and back.

The males varied in appearance. This one lacked the bluish coloring and had a couple of dark lines on the upper back and more fine white spotting than the one above, which appeared to have more of darker spots on a light base. Many males show the faint vertical line that can barely be seen running down the top of part of the tail.

This image provides a nice look at the large head and strong jaw structure of the collared lizard.

Several clumps of mites were seen on the should of this guy, along with a small group in the ear.

I really enjoyed see the results of these head shots. So much detail in the eye and and face were captured, including my faint reflection in the pupil.

I captured the following images when I realized that this individual was shedding old skin for a newer, brighter look.

These collared lizards are about 4 1/2 inches from snout to vent and their tails can add another 7 or more inches to their total length. They tolerate higher temperatures than most lizards in their territories. They use their speed to secure prey that primarily consists of arthropods but also includes some vegetation and even smaller lizards.

I eventually made several trips to various locations to document Great Basin Collared Lizards. During that process I enjoyed the accidental discovery of some unique bird nests. One of those nests was occupied by an elusive nocturnal bird, a Common Poorwill. I'll be putting together a post to share progressive images of the Poorwill nest site in the next few days. It was a rare opportunity to follow and document that progression with images from eggs to hatchlings to fledglings.