THE DAILY HUMIDITY CYCLE

As harsh as their desert habitat is, T. kleinmanni finds it mitigated somewhat by the fact that their range is restricted to the first 120 km or so inland from the coast. This coastal strip lies heavily under the marine influence of the Mediterranean Sea, including the marine layers of low to mid-level fog through the harshest part of the year, the most intense heat of summer. This marine layer blanket creates a daily humidity cycle for the kleinmanni of which they take full advantage. Day-by-day in mid summer, the humidity at a known kleinmanni site will range from 95% relative humidity at midnight, to 78% at 4:00 a.m., to 63% at 8:00 a.m., to 38% at 2:00 p.m. This is pretty much a typical daily cycle (as recorded on July 7, 2003) reflecting the coastal marine layer of the Mediterranean.

The influence of this cooling marine layer on the temperature in this coastal zone is such that morning temperatures especially are quite moderate and provide the tortoises optimum time for grazing and foraging. The high humidity cycle at night leaves quantities of dew on desert grasses and low lying broadleaf plants, providing moisture for the tortoises on a daily basis as well. In captivity, my own collection of kleinmanni will take the morning's opportunity if placed on the Bermuda grass lawn to browse slowly through the grass licking the moisture off its blades in long, casual gliding motions of the tongue, a habit that is clearly a native or instinctual technique.

The Weather Magnet at the bottom of the next column displays current weather information for the Sallum Plateau on the northwest coast of Egypt, one of the sites where kleinmanni were last seen in the wild. For another look at what is happening today in the coastal weather that has affected these creatures over the millennia, go to and enter Giza, or Alexandria, or Port Said, Egypt in the www.weather.com search box to get today's temperature, relative humidity, and dew point statistics for these former kleinmanni habitats.

Knowing where a tortoise is from and how its climate and weather patterns unfold through the year in its annual cycle is a critical part of learning to care for that tortoise. Only with this data in hand can we begin to approximate its needs and begin to accommodate its genetic memory of how life works.

The Egyptian Tortoise: its natural history, its captive care, its beauty, its lore. . .
Climate and weather in kleinmanni life and ecology
kleinmanni home | golden beauties | desert life | climate's role | captive needs | unique diet | Captive Habitat 1: basics | Captive Habitat 2: habitat development | Breeding | hatchling care | when something goes wrong | natural and un-natural history | All in the family | captive behaviors | tortoise links | references

Kleinmannis' welfare in captivity depends on their keeper's understanding of their ecology as it evolved over the millennia in their particular environmental and adaptive niche. Our best understanding of that ecology must include a careful study of the climate in which they live, attention to how that climate influences their behaviors, and how the cycles of the days and seasons impact the survival of the tortoises.

SUMMER SUN AT AN OASIS NEAR WADI NATRUN
oasis.jpg
Photo by W.G. Dever

THE ANNUAL COASTAL DESERT CLIMATE CYCLE

The circannual rhythms of this tortoise depend directly on the coastal weather patterns of Mediterranean Egypt. Winter is kleinmanni's prime time, after the autumn rains to provide some relief and the initiation of early winter vegetation. The winter temperatures also provide kleinmanni's best comfort zone for activity in the wild. Summer dry periods in kleinmanni habitat extend from May through September, and regularly log temperatures between 90 and 100 Fahrenheit, depending on the location. Average weather data for a location once known to be frequented by Testudo kleinmanni is provided in the chart below.

The dry season, May through September, is highlighted in bold print on the chart. As can be seen, virtually no rain or other precipitation is available during these times. For some animals, proximity to the coast and the daily cycle of humidity will provide some relief (see the sidebar to the left). But for most tortoises, the high daytime temperatures combined with the scarcity of water and graze resources lead into a period of aestivation and rest during this hottest period of the year. This conserves much-needed resources and energy in much the same way that hibernation does in cold climate species.

With the autumn rains in October, daytime temperatures take a more significant drop. Studies have shown that kleinmanni are at their most active around 85F. With the cooler autumn and winter temperatures, as well as the return of the rains and the renewal of plant life for grazing, the tortoises are able to return to a more active pattern of morning basking and foraging.

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IMPLICATIONS FOR CAPTIVE CARE

The climate and weather patterns that have shaped the ecology of Testudo kleinmanni in the wild are built permanently into the genetics of the animal. They have shaped its diet and the niche of high fiber plants to which it has accommodated in its own evolution. They have shaped the pattern of summer rest and winter activity that is its norm and in some measure its need. They have shaped its need for arid rather than subtropical landscape, and its sensitivity to too much continual moisture exposure.

For these reasons, an understanding of its climate can help shape a wise captive care regimen. In order to imitate the rocky, sandy plains on which kleinmanni once thrived, and to assist in drawing as much moisture out of the habitat as possible, I keep my adult kleinmanni (and hatchlings over the age of 6 months) on a crushed oyster shell substrate. In consequence, the ambient relative humidity in my kleinmanni habitat is always between 20% and 25%. The high fiber mix of greens, orchard grass hay, weeds, flowers, and leaves which mine are fed is my best strike at an imitation of the sort of things they eat in the wild (see the diet page for more info).

The summer aestivation is something that even my adults, two generations removed from their Egyptian homeland, have built into their system. When the summer temperatures here get high enough, they grow sluggish, slow down, and will often crawl into a hide pot and sleep for days if I do not disturb them. Or, if I do disturb them, they will return to their rest post haste when I let them.

PARALLEL CLIMATE ZONES

My kleinmanni are lucky to live in a coastal desert that proximates the conditions in Mediterranean Egypt day-by-day, season by season, all year long. The temperature and humidity parallel that of the Sallum Plateau almost exactly. So I watch the tortoises carefully, having studied their setting, to see what they are going to teach me about their need.

The annual climate rhythm on the Sallum Plateau, a site once frequented by Testudo kleinmanni

MONTH

AVERAGE
HIGH

AVERAGE
LOW

AVERAGE
PRECIPITATION

January

65F

49F

0.80 inches

February

68F

50F

0.60 inches

March

73F

54F

0.30 inches

April

82F

59F

0.20 inches

May

89F

64F

0.10 inches

June

93F

70F

0.00

July

93F

72F

0.00

August

92F

72F

0.00

September

90F

69F

0.00

October

85F

65F

0.50 inches

November

75F

58F

0.40 inches

December

67F

51F

0.70 inches

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"You can't trample infidelswhen you're a tortoise.I mean, all you could do isgive them a meaningful look."

-- Terry Pratchett, "Small Gods"

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The Egyptian Tortoise: its natural history, its captive care, its beauty, its lore. . .
Fred L. Erwin, Jr., 2004 - 2005 C.E.