The Uta Project's Journal

I have updated the range map for Uta stansburiana and the five continental subspecies based on some recent work in the field the past couple years. The map can be found as this observation. Some areas of these distributions are still poorly understood, such as much of the non-Baja distribution in Mexico (especially at the subspecific level) and where U.s.elegans, U.s.nevadensis, and U.s.stansburiana come together in the Great Basin Desert. Let me know if you have any questions.
—Pete Zani

It's been three weeks since the last review of the observed Uta, so I thought it a good time to consider the status of spring. During the past three weeks there were over 1300 observations of Uta, all of which were Uta stansburiana. These observations spanned the range of this species, but with a definite focus in the range of U.s.elegans in Southern California.

Males are in full breeding colors in all corners of Uta's distribution. Examples of colorful males include:

—this male by @erayner

—this male by @jmaughn

—this male by @tmessick

—this male by @sunbelt

There continue to be good observations of gravid females as the spring breeding season progresses. Many of which come from Southern California and some look about to pop which is good indicator of how close they are to laying their eggs. Examples of gravid females include:

—this female by @plascenciaivett

—this female by @jonrobson

—this female by @joseph92

—this female by @cjustus320

For observation of the week I have chose a pair of observations of Uta in the act of mating by @knight17 and @roadddog. Mating in Uta can be quick, lasting no more than a minute or so. Courtship involves circling behavior and lots of headbob displays by both male and female. The female will also use body postures like a raise as part of the courtship. Mating only occurs once females have ovulated and so will often reject courtship displays before or after that time in her cycle, which takes about 28 days early in the spring or as few as 16 days in the heat of summer. Once mating occurs, it can still take several weeks for the female to yolk and then shell the egg before laying, so mating is an important time point in the breeding season. Mating will continue from now until mid-to-late June with last clutches usually laid by mid-July most places.

As always, thank you to everyone who has observed a Side-blotched Lizards in the past few weeks. Your contributions are greatly appreciated.
—Pete Zani

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22 May, 2024

: first hatchling

5 May, 2024

: copulations

14 April, 2024

: nesting female

23 March, 2024

: copulating Uta

10 March, 2024

: colorful male

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Since the last observation of the week on May 5, there have been 683 observations added to The Uta Project. There were many notable observations including:

—this pretty female Uta stanburiana stejnegeri by @georgezimmer.

—this nice male-female pair by @zachary488. I've seen males do laps between attending and courting females. I've also see a single male just hang out with a single female for a while.

—this very gravid female by @scubabruin.

—this male whose colors show even more sitting in the shade like this by @daniel0910.

—even the northern side-blotched lizards have started laying eggs, like this female by @alexsowers6.

—there are continued mating attempts being observed, such as this one or this one by @raphaela_fb and @dustdevil.

—this example or this example by @robtea and @cellomaniac of interspecific basking between a Fence Lizard and Side-blotched Lizard. These two species are surprisingly tolerant of one another.

Despite all of these observations, I am choosing as observation of the week this observation of a hatchling Uta by @lagardilla. This is amongst the very first hatchlings of the year and will not be the last. These can be hard to ID, so it's nice to note the even dark-light-dark stripes behind the eye. These stripes can be one of the only ways to tell these since their blotch often doesn't show until they sexually mature at age 10 months. Right now, the southern latitude/low elevation females are probably working on their third clutches, mid-latitudes/elevations on their 2nd clutches, and the northern latitude/higher elevation populations working on their 1st clutches still. The breeding season will usually continue into July, rain permitting. However, the monsoons can induce late-season clutches in some locations.

As always, thank you to everyone who has observed a Side-blotched Lizards in the past few weeks. Your contributions are greatly appreciated.
—Pete Zani

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