16 September 2012

Highlights of Field Season 4: The Final Release

Good evening lizard-lovers,
I hope you enjoyed the last post in which I got a little off-topic of summing up the field season with a tonne of baby pictures...
Anyway, this time I promise to actually write a concluding blog this time.

First off, as I may or may not have mentioned before, we decided to exclusively catch S. undulatus this time. The reasoning behind this was mainly that mark-recapture of the sort that measures natural selection requires one initial capture, and at least two more recaptures following. We already have this completed for H. maculata... May/June 2011, August 2012, and May/June 2012. Because we decided to add the second species, S. undulatus, May/June of this year we decided to focus on them this season (July/August) because we had under a month and needed to increase our sample size... (yes this also means we'll be going back next spring for our last recapture!)

Well, unfortunately, recapture-rates (from lizards marked in the spring of this year) weren't nearly as good as they were for H. maculata.

       The release of a little S. undulatus that certainly
got going as soon as we let him go!

Overall, of the over-200 lizards we caught, only ~10% showed elastomer marks from the spring. This is surprising since after the summer last year, we had a 60% recapture rate for H. maculata. We can think of two possible reasons behind this low recapture rate. The first is that perhaps the elastomer tags are falling out. Perhaps I am not tagging the lizards deep enough and they are shedding their tags with their skin. We thing this is unlikely because we'd see a number of lizards with some, but not all of their tags remaining- i.e. the ones that were not deep enough. This doesn't seem to be the case... either lizards had tags, or they didn't. We hope that with all the photographs, scans, and gps coordinates we took, we can match up the lizards determine if they really did lose their tags.

Our "field schedule" including person-hours, lizards-captured, and some other... interesting drawings that show up after four people have been living in close proximity for far too long.
Of course, it is also possible that the population size of S. undulatus is much larger than we had anticipated (this is what mark-recapture calculations should tell us)... and this species is far more elusive. Considering what we know about the fence lizards... they do seem to be elusive. They are more arboreal than the lesser-earless lizards, and hide extremely well in vegetation (such that we often have to wait for an hour for the little fellows to re-emerge).

Sometimes we mistake this species, the side-blotched lizard (Uta stansburiana) for S. undulatus when it flashes by through a bush. These little ones are only found on the very edge of White Sands... often only the first dune off the dark soil desert. As of yet, it's a mystery why the side-blotched lizard hasn't colonized and adapted to White Sands.
Regardless of the extra patience it required to catch S. undulatus and the lower recapture rate, the field season was a great success with an average of 13 lizards per day. We even got a chance to head over to the Jornata Long Term Ecological Research Site (one of our dark-soils sites) and take a look at some of the species there:

One of the cutest/fattest lizards of all- a Texas horned lizard (Phrynosoma cornutum)

Lizard food? Unlikely... in all the lizard guts I've dissected.. I've never seen evidence of them having eaten an Anisoptera.
Recognize this little guy? My supervisor likes to call them the "junk lizard" of the desert. I took this action shot just after we let this one go... 
Well with that I will finally sign off for this year. Hopefully soon I will be able to post some results regarding the direction and magnitude of natural selection on the two White Sands lizard species- the lesser-earless lizard (Holbrookia maculata) and the Eastern-fence lizard (Sceloporus undulatus). Is natural selection still acting? What form does it take? Is it similar in both species? What about the population dynamics? Is there a fifty-fifty sex ratio? What is juvenile recruitment? How far do lizards disperse and do both species overlap in habitat use?
So many questions... only one dissertation (for now!)

Thank you everyone for following! Thank you to my great field assistants (Jackie Howells, Isaiah Hoyer, and Michaela Brinkmeyer), and especially the lizards for their reluctant participation in the noosing, prodding, flattening, and injecting that is my project!
Until next time, good night herps and herpetologists of the world!
-S. Des Roches

Highlights of Field Season 4: White Sands the Nursery

Dear followers (including Dr. Losos' Harvard uni freshman class),

I have a legitimate excuse for not posting during the last field season. I finally broke down and purchased a new camera body. Unfortunately, because I shoot in RAW, and Nikon seems to change this format every few cameras, my old-2008-macbook's version of iPhoto could not seem to process my recent photos. After much chagrin, I found freeware online that allowed me to batch and convert a group of photos from RAW to jpeg all at once! Woohoo!

Anyways, I have been back from the field for nearly a month now and I am eager to show you some of my new sparkling photographs and do a little sum-up of the highlights of this year's field season.

When we came back to the field at the end of July, the desert was a nursery of scaly and feathered young. The barn swallows are always nesting around the White Sands visitor centre- very cute. Very inquisitive, and overwhelmed by instinct, likely to open their mouths in synchrony when you pass your hand in front of their nest.
Young barn swallows outside the WSNM visitor centre.

Momma (or poppa) black-throated sparrow making a racket
outside the nest.

Isaiah also happened to look down the right bush and see a black-throated sparrow nest just 1.5 feet from the ground!
Adorable hatchling black-throated sparrows. 
Enough of the feathered creatures, you say! Where are the tiny cute little lizards we're all waiting to see!? Fortunately, I have some for you. Last year, times were tough- little rain brought fewer delicious insects, larvae, and spiders and thus fewer offspring. As such, we noticed far fewer yearlings/juveniles this spring. This year, however, butterflies fluttered everywhere, it was greener (for a desert), and we saw babies of each of the three White Sands species!

Hatchling A. inornata. This little guy is 'dark' and when we nabbed him outside the visitor centre, the people there scolded us for handling the lizards- until we said we were Herpetologists! 

The cutest little H. maculata we decided to name "Drew." (mainly because I misheard when Jackie said, "It's true!")
Baby lizards getting into some mischief with Jackie and Mikki... and Drew clearly knows which spot to best show crypsis on my foot!

Tiny little S. undulatus in the heart of White Sands.
I'm going to sign off for now and continue the sum-up of this last field season with a new blog post. Stay tuned- for later this evening!

Until then!
-S. Des Roches