Photoperiod and your tegu (or any other reptile)

[tupinambis]

I've read in a few posts where people were talking about their tegu's photoperiod, and some of the photoperiods I came across rather shocked me. For pretty much any of the tegus (some T.rufescens may be exempt), anything less than 11 hours of light and you'll likely be seriously messing with the animal's indigenous biorhythms via its pineal body. Probably making its physiology think it should be hibernating, or at least sleeping all the time.

In nature, for most T.teguixin, they pretty much have a standard 12hr day:12 hr night all year round. For most T.merianae, depending on where they are from, can range anywhere from 12hL:12hD all year round to 14-15hL in the summer, 9-10hL in the winter. For T.rufescens, it ranges from 13-15hL in the summer, to 9-11hL in the winter.

However, for those of you who want to be a little more serious about photoperiod with your tegus (or any other reptile for that matter, any can benefit), I'll point you in the direction to where you can not only EXACTLY pinpoint how many hours of light and darkness your tegu should have, but if you've got the wherewithall, the means to duplicate their natural timing for every day of the year! All courtesy of the United States Naval Observatory (and you thought the military doesn't want to help your pets :wink: ).

First, you go to their site at http://aa.usno.navy.mil/, on the left hand column click on Data Services, and in the new window select Table of Sunrise/Sunset. From there, fill out the chart. All you need to enter is the geographic coordinates of where the animal is from, and voila, instant sunrise/sunset chart for an entire year (if you look around the site, there are some other possibly useful functions you might be interested in). So, if you're lucky enough to know exactly where your tegu is from, you can duplicate its precise natural photoperiod. If you're unsure, I'd suggest entering in mid-range values for the geographic coordinates.

For those of you unsure of the coordinates, here's some general values I've looked up for you:

T. teguixin ranges from 11degrees N to 14degrees S lattitude, and from 75degrees W to 44degrees W longitude.

T.merianae ranges from 7degrees S to 38degrees S lattitude, and from 63degrees W to 35degrees W longitude.

T.rufescens ranges from 18degrees S to 40degrees S lattitude, and from 66degrees W to 58degrees W longitude.

Happy timer programming.

[Rick]

Very good post. I have known about that site (my wife was in the Navy) but I never gave it a thought as a tool for tegu timer setting.

Bravo for supplying another useful tool.

Rick

[tupinambis]

Well, for the average person, it is probably more data than they could really use, other than looking up the average summer and winter daylengths. However, for the serious herpetoculturalist, I've found there are some devices and software you can get where you can program your computer to precisely control the turning on and off of electrical devices, and presto, you're simulating the animal's natural environment as well as anyone can indoors (plus, it allows you to find a use for those old clunker computers you have in the basement).

I've found there are some devices and software you can get where you can program your computer to precisely control the turning on and off of electrical devices

Could you please elaborate? I'm interested in such software.

[Johelian]

Hmm...I havent varied my tegus photo period at any point as so far, though when we reach winter I may reduce hours to see if he will hibernate (he gave up last year when I got him home). My timers are set to allow for a 14 hour day period - eternal summer. Do you have any info on animals that have been kept on this continuous photoperiod? I know the effects it has on breeding, but anything else?

[tupinambis]

For devices and software to add to a computer to control electrical equipment, probably the cheapest and most convenient is to go with the X10 Firecracker system using their Fuse software (go to www.X10.com). It's relatively cheap and straightforward to use. There are better, more customizable and versatile systems out there, however, we're talking about a readily available product that has an initial investment of less than $100 (not including the computer), to something that you cannot just buy off the shelf or order online and starts in the range of several thousand dollars.

As far as info on studies looking at the impact of photoperiod on tegus, I don't know of any. All I know is of my own experience, and that is tegus kept indoors under constant photoperiod routines do not enter hibernation and do not tend to reproduce at all. Many of the tegus endogenous biorhythms are modified by input received by the pineal body in the brain. The pineal organ is what is often referred to as the "third eye" in a lot of reptiles. Whether or not it has a surface structure, it still receives illumination (yes, even if it is wholly encased under the skull) and interprets this to advise the brain as to seasonality, daytime, etc. A lack of feedback from this system is likely to place reproductive processes into dormancy. A lack of reproductive cycles often leads to impacts in other aspects of the animals' lives. These may or may not be deleterious.