There has been a great deal of argument as to whether light cycles affect
reproductive success in snakes. I believe the only essential criteria to
initiate reproductive activity is a cooling followed by a warming period.
For the purposes of not excluding anything, however, the following is a
list of light-cycle methods that have been successful:
- On March 1st, 13 hours of cage or room light per day increasing 20
minutes per week thereafter ending at 16 hours of cage or room light per
day on April 30th. No sunlight is allowed into the room.
- Natural sunlight allowed into the room on a year-round basis with
incandescent light or heat tape used when heat is required to maintain
- Twenty-four hours of light per day all year round even during the
However, it has yet to be proven conclusively that light cycles influence
reproduction in these genera although breeders still use artificial light
Aside from lighting, between March 1st and August 1st is the time to
concentrate on captive breeding. The best feeding response of the entire
year usually takes place throughout March and into early April. This is
again an extremely important time for fattening of the breeding colony.
The snakes can begin feeding within 24 hours of their initial warming on
March 1st. It is important to raise the cage temperature to about 83°F at
some point each day but also allow it to drop to 75°F each day. This
allows for adequate food digestion and also the ability to get away from
prolonged heat. A constant, 24-hour per day cage temperature of 83°F or
above may cause sterility of males in certain species. A good behavioral
cue that the snakes are TOO warm TOO long is if most of the males
continually stay as far away from the heat source as possible (i.e., right
up against the glass). Providing a cage thermal gradient is the best way
of insuring adequate, but not excessive, heating. In this way the snakes
can select their own temperature preference.
Specimens that respond well to feeding will usually shed soon after March
1st. For Elaphe and Lampropeltis species, the first shed usually occurs
between March 20th-31st. For Pituophis, the first shed normally occurs
between March 23rd-April 4th.
Although these shed dates don't apply to every specimen, there seems to be
a trend toward this occurrence. The first shed gives the keeper an idea as
to how close the females are to full follicle (unfertilized egg)
development. Females appear to reach maximum reproductive receptivity from
3-14 days after this first shed. The easiest way to determine if a female
is reproductively active is to introduce her into the male's cage. If,
upon body contact with the male, the female violently flips her tail,
bunches up her body, or constantly tries to stay away from the male, she
probably is not ready. Under these circumstances, the male may try to
overpower the female or rapidly lose interest. However, if the female
responds by slowly crawling around the cage stretched out, allowing the
male to crawl on her back, and lifting her tail to expose the cloaca, she
is ready. To insure a viable mating to a female that responds positively,
it is best to reintroduce a male at least 2 more times, several days apart.
At some point in early egg development, the gravid female will begin to
show the negative response to the presence of the courting male.
Females will continue to feed for several weeks into pregnancy but
generally stop eating during the last 3 weeks before egg laying. Internal
development of the eggs after mating normally takes between 28 and 45 days,
depending on the individual and the mean cage temperature during this
period. Another shedding occurs toward the end of pregnancy. Females will
shed approximately 7-12 days prior to egg laying. This is an important cue
in preparing a suitable egg-laying location and also for knowing
approximately when the eggs will be laid.
Most of the egg laying will take place in the month of May with some
species ( i.e. L. t. sinaloae )laying slightly later. I will discuss-preparing for egg laying and
incubation of eggs in a future article. As soon as egg laying takes place,
most females will feed heavily to regain body weight. It is possible to
perform a second mating at this time. If a female has good body weight
after the first egg laying, she may rapidly develop new follicles. It is
apparently important to keep the male and female together constantly
immediately after the first egg laying to ensure a second reproductive
success. This is in contrast to the male-female introduction-separation
method for the first mating. If a female does produce a second clutch, she
will follow the same incubation-shed pattern as for her first clutch. Most
second clutches are smaller than the first, and laid in middle to late
In summary, the following is recommended:
I hope that this information offers a basic understanding of most
techniques now being used in captive breeding circles around the country.
I look forward to the answers that will be derived by studying these
concepts on the physiological level.
- Heavy feeding of females and males at all times of year except in the
cooling period and the latter part of pregnancy.
- A cooling period of approximately 3 months at temperatures between 55-65°F.
- Separation of the males and females during the cooling period.
- At all times except during the cooling period, maintain a cage or
substrate temperature of 75-83°F, allowing the temperature to rise and
fall within this range each day.
- Introduction of females into the male's cage when full follicle
development is suspected-watch for positive female reaction.
- Observation of shed dates in relation to follicle development or