Keeper timer setting
T5 UVB: one hour later on, one hour earlier off
ON: 1 hour after the daylight lights come on.
OFF: 1 hour before the daylight lights go off.
October: daylight 11 h 45 m; T5 UVB 9 h 45 m per day.
The T5 runs for two hours less than the total photoperiod. Example: daylight 08:00-20:00 means UVB 09:00-19:00. Keep the monthly UVI strength as listed beneath the tube. Existing care values are preserved.
UVI beneath the optional T5 tube
Working exposure targetOctober target at normal back height
UVI 3-4directly under the tube when it is on
The retained range remains a provisional captive working target. No new species-specific result was found that clearly requires a numerical change. Retaining it is not certification of an experimentally established optimum.
Your measuring point
Measure at the animal's normal back height directly beneath the brightest accessible part of the T5 strip, positioned toward the middle/back. The animal can enter and leave this area freely.
Keep a lower-UVI gradient and fully covered refuges near UVI 0. This is the optional exposure area, not the average across the cage.
Use a UV Index meter, such as a Solarmeter 6.5/6.5R. Warm the tube for about 30 minutes; keep reflector, guards and mesh in place. Raise or lower the fixture within its manufacturer's minimum-distance guidance, then recheck the reading and every higher accessible surface.
Evidence level: Provisional retention. These are working recommendations, often inferred; exact species optima and seasonal UV dose usually have not been measured. Log lamp-on time and animal behaviour as well as UVI.
Baines et al. (2016), UV-Tool ยท Muryn, Baines and Dishman (2026), Reptile Lighting Guide V10
October management
Selected automatically using the Netherlands date
Rains taper
Seasonally dry lowland forest, woodland edge, thorn scrub, rocky sites and farms - southern Mexico through Central America
26-29 CDay ambient
20-22 CNight
41-43 CBasking
3-4T5 UVI*
11 h 45 mPhotoperiod
9 h 45 mT5 UVB duration
55-70 / 70-85%RH day / night*
2-3 rain/mist events/wkSpray / rain
3-4Food offers*
Annual schedule
Scroll sideways on smaller screens
| Month | Day ambient | Night | Basking | T5 UVI* | Photoperiod | T5 UVB duration | RH day / night* | Spray / rain | Food offers* | Status / breeding |
|---|---|---|---|---|---|---|---|---|---|---|
| January | 25-29 C | 18-21 C | 41-44 C | 3-4 | 11 h 20 m | 9 h 20 m | 40-55 / 55-70% | Light local spray 1-2x/wk | 4 | Courtship / mating |
| February | 26-30 C | 19-22 C | 42-45 C | 4 | 11 h 40 m | 9 h 40 m | 40-55 / 55-70% | Light local spray 1-2x/wk | 4-5 | Peak ovulation / mating |
| March | 28-31 C | 20-23 C | 43-45 C | 4-5 | 12 h | 10 h | 35-50 / 50-65% | Minimal; water always | 4-5 | Gravid / nesting prep |
| April | 29-32 C | 21-24 C | 43-45 C | 4-5 | 12 h 25 m | 10 h 25 m | 35-50 / 50-65% | Minimal + moist lay chamber | 4-5 | Main laying window |
| May | 29-32 C | 21-24 C | 43-45 C | 4-5 | 12 h 45 m | 10 h 45 m | 50-65 / 65-80% | 2-3 rain/mist events/wk | 4-5 | Early wet season / incubation |
| June | 28-31 C | 21-24 C | 42-44 C | 4 | 13 h | 11 h | 60-75 / 75-90% | 3-5 rain/mist events/wk | 4-5 | Hatching begins |
| July | 28-31 C | 21-24 C | 42-44 C | 4 | 12 h 55 m | 10 h 55 m | 60-75 / 75-90% | 3-5 rain/mist events/wk | 4-5 | Peak hatch / juvenile feeding |
| August | 28-31 C | 21-24 C | 42-44 C | 4 | 12 h 35 m | 10 h 35 m | 60-75 / 75-90% | 3-5 rain/mist events/wk | 4-5 | Wet-season activity |
| September | 27-30 C | 20-23 C | 41-43 C | 3-4 | 12 h 10 m | 10 h 10 m | 60-75 / 75-90% | 3-5 rain/mist events/wk | 4-5 | Wet-season maintenance |
| October | 26-29 C | 20-22 C | 41-43 C | 3-4 | 11 h 45 m | 9 h 45 m | 55-70 / 70-85% | 2-3 rain/mist events/wk | 3-4 | Rains taper |
| November | 25-28 C | 18-21 C | 40-42 C | 3 | 11 h 25 m | 9 h 25 m | 45-60 / 60-75% | Light local spray 1-2x/wk | 3-4 | Dry-season conditioning |
| December | 24-28 C | 18-20 C | 40-42 C | 3 | 11 h 15 m | 9 h 15 m | 40-55 / 55-70% | Light local spray 1-2x/wk | 3-4 | Breeding begins / male display |
Keeper notes
Use measured gradients and animal behaviour, not single thermostat readings
T5 UVI measurement
Measure UVI at normal back height directly beneath the brightest accessible part of the optional T5 strip. Place the strip toward the middle/back with free access to and away from it; preserve a gradient into fully covered refuges near UVI 0. These numbers describe the exposure area, not the whole enclosure or a daily average.
UVI review
The retained range remains a provisional captive working target. No new species-specific result was found that clearly requires a numerical change. Retaining it is not certification of an experimentally established optimum.
Identity and habitat
Ctenosaura similis ranges from southern Mexico through Central America. It is characteristic of open seasonally dry lowlands, woodland and forest edge, rocky sites and farms, using burrows, roots, stones and tree hollows as refuges.
Thermal biology
Field and captive data place preferred body temperature around 36-37 C. Animals bask heavily in the morning and seek shade or burrows as environmental heat rises. Use intense local basking while maintaining a real cool zone.
Humidity and rain
Pacific dry-forest populations experience a marked dry season followed by a May-November/December rainy season. Keep dry-season surfaces mostly dry with limited localized spray; increase short rain/mist events and overnight RH in the wet season while retaining strong ventilation.
Diet
Juveniles are proportionally more insectivorous. Adults feed mainly on foliage, flowers and fruit but remain opportunistically omnivorous, taking insects, eggs and small vertebrates. Shift feeding progressively toward plant dominance with age.
Reproduction
Classic field work found ovulation around mid-February, laying about five weeks later, clutch size 12-88 eggs with a mean around 43, and hatchlings appearing around May-July. Locality can shift timing by several weeks.
Social warning
Adult males are strongly territorial and should be housed separately. Do not assume female compatibility in confined enclosures. Separate for persistent pursuit, biting, cornering, refuge exclusion, suppressed feeding or weight loss.