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 40 m; T5 UVB 9 h 40 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
Late wet season
Seasonally dry tropical forest, thorn scrub, limestone rock fields and hollow-tree refuges - Yucatan Peninsula and northern Guatemala
26-29 CDay ambient
21-23 CNight
37-39 CBasking
3-4T5 UVI*
11 h 40 mPhotoperiod
9 h 40 mT5 UVB duration
65-78 / 78-88%RH day / night*
3-4 rain/mist events/wkSpray / rain
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 | 24-27 C | 19-21 C | 36-38 C | 3 | 11 h 10 m | 9 h 10 m | 55-65 / 65-80% | Light local spray 1-2x/wk | 3-4 | Dry season / courtship |
| February | 25-28 C | 19-22 C | 37-39 C | 3-4 | 11 h 30 m | 9 h 30 m | 50-65 / 65-80% | Light local spray 1-2x/wk | 3-4 | Mating / gravid development |
| March | 27-30 C | 20-23 C | 38-40 C | 3-4 | 12 h | 10 h | 50-65 / 65-80% | Minimal main cage + moist nest cavity | 4 | Main laying window |
| April | 28-31 C | 21-24 C | 38-40 C | 3-4 | 12 h 30 m | 10 h 30 m | 50-65 / 65-80% | Light local spray 1-2x/wk | 4 | Incubation / late laying possible |
| May | 29-32 C | 22-24 C | 39-40 C | 4 | 13 h | 11 h | 55-70 / 70-85% | 2-3 light rain events/wk | 4 | Pre-rains / incubation |
| June | 28-31 C | 22-24 C | 38-40 C | 4 | 13 h 15 m | 11 h 15 m | 65-80 / 80-90% | 4-5 rain/mist events/wk | 4-5 | Wet season / hatching likely |
| July | 28-31 C | 22-24 C | 38-40 C | 4 | 13 h | 11 h | 65-80 / 80-90% | 4-5 rain/mist events/wk | 4-5 | Wet-season activity |
| August | 28-31 C | 22-24 C | 38-40 C | 4 | 12 h 40 m | 10 h 40 m | 65-80 / 80-90% | 4-5 rain/mist events/wk | 4-5 | Wet-season activity |
| September | 27-30 C | 22-24 C | 38-40 C | 3-4 | 12 h 10 m | 10 h 10 m | 68-80 / 80-90% | 4-5 rain/mist events/wk | 4-5 | Peak rains |
| October | 26-29 C | 21-23 C | 37-39 C | 3-4 | 11 h 40 m | 9 h 40 m | 65-78 / 78-88% | 3-4 rain/mist events/wk | 4 | Late wet season |
| November | 25-28 C | 20-22 C | 36-39 C | 3 | 11 h 15 m | 9 h 15 m | 60-70 / 70-82% | Light local spray 1-2x/wk | 3-4 | Dry-down begins |
| December | 24-27 C | 19-21 C | 36-38 C | 3 | 11 h | 9 h | 55-65 / 65-80% | Light local spray 1-2x/wk | 3-4 | Dry season / conditioning |
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.
Taxonomy
Current taxonomy recognizes Cachryx defensor; Ctenosaura defensor is a homotypic synonym. Cachryx was resurrected in 2017 for the Yucatan lineage.
Habitat
C. defensor occupies seasonally dry forest and thorn scrub across the Yucatan Peninsula and northern Guatemala. Many populations use limestone rock holes, while recent records also show tight hollow-tree refuges.
Humidity and rain
Do not treat the dry season as desert-dry air. Keep moderate atmospheric RH but markedly reduce rainfall/surface wetting from November-May. From June-October, increase rain/misting strongly while keeping excellent ventilation.
Diet
Field fecal analysis found a predominantly leaf-based diet. Offer varied leafy greens, browse, flowers and tender shoots, with controlled fruit and only occasional invertebrates.
Reproduction
Wild clutch size is very small: historic reports 2-3 eggs and a 2022 wild nest contained three freshly laid eggs on 22 March. Modern captive-breeding reviews give 2-8 eggs. Captive incubation reports suggest roughly 70-90 days around 29-31 C.
Nest-zone warning
A recent wild clutch was deposited inside a hollow tree trunk on decomposed wood debris about 1 m above ground. Provide a warm humid cavity-style nest plus a small diggable moist pocket; do not rely only on an open sand box.
Social warning
Detailed social biology is sparse. Individual housing outside breeding is safest. Separate for persistent pursuit, bites, refuge exclusion, suppressed feeding or weight loss.