The age that Emeralds reach sexual maturity is stated to be between 3-5 years, although this may be true for males, I have found that the female needs to be somewhat older. All my females were in the region of 7-8 years old before they started to breed successfully.
As they get older and more experienced the clutch size and neonate size greatly increases. The neonates heads of my second clutch from the same females were almost twice that of the previous breeding season.
Having said this, there are exceptions as I have heard of females breeding at three years of age, but this I'm sure is not commonplace.
This may be stating the obvious, but proper sexing of animals is recommended before pairing animals off. This should be done by probing. The table below shows the probe depth in subcaudal scales for both male and female Emerald tree boas.
| Sex |
Probe depth (Subcaudal
scales)
|
|---|---|
| Male |
13
- 15
|
| Female |
3
|
Just checking for enlarged spurs or hemipene bulges is insufficient , as I have encountered experienced herpetologists making these mistakes, not least myself.
One of my early Emerald purchases (a wild caught individual) from a reputable dealer/importer, assured me that I was getting a large adult male. After a couple of months of unsuccessfully attempting to feed him, having tried everything, I woke up one morning to find that 'he' had given birth to 3 babies and several slugs, much to my surprise.
Soon afterwards she started to feed well and has since become my most successful breeding female.
In their native country, wild Emerald Tree boas breed between the months of January and March, which is their rainy season. The trigger for breeding seems to be the small drop in air temperature of approximately 39-41 degrees Fahrenheit (4-5 degrees Centigrade) and the increased humidity that is brought about by the rains.
These conditions are essential and need to be reproduced in captivity to ensure successful mating of this species.
Three months prior to the cooling off period, the females are fed more regularly, about every two weeks and sometimes more frequently. This is done so that they can gain a little extra body weight, needed to see them through the months of fasting during pregnancy.
This extra body weight is also necessary to encourage breeding activity in the female. I have noted that underweight females will still ovulate but refuse to breed and drop unfertilized ovum (slugs) at full term.
The feeding regularity of the males remains much the same as the rest of the year, even though during the cooler breeding months they will refuse to eat as regularly. This may last up to four months.
In mid November,cooling begins. The day time high temperature is maintained, but the night time low temperature is gradually dropped to a low of 68 degrees Fahrenheit (20 degrees Centigrade). See the Winter Breeding tables in the Breeding Records section for more details.
This night time drop promotes an increase in humidity to 85% and higher. During the day the subrate of the vivarium is sprayed several times to achieve the higher humidity requirement, essential for breeding.
Throughout this period, the feeding regime is as normal.
No artificial lighting is used to control photoperiods during this time, and I rely entirely on the seasonal changes in this country (Oxford, England), which are very variable with the summer sunset as late as 10:00pm and dawn at 5:00 am to the winter sunset as early as 4:00 pm and dawn at 7:30 am. In their country, photoperiods are much more even and do not vary much. So lighting probably does not have much bearing in their mating rituals.
In January, the mating pairs of snakes are introduced to one another.
I introduce my males by placing them into the females enclosure and not the other way around as mostly stated. There was no particular reason for this, it was just the way that I started, and being successful I maintain this routine. I believe it makes little difference which way round it is done.
Mating is observed almost immediately.
On introduction of the male to the female, he will encircle her, flicking his tongue rapidly over her and at the same time stimulating her with his spurs. This he does by scratching at her dorsal scales. He attempts to align his tail with hers to bring their cloaca together. Within a short time the female becomes receptive to the males advances by everting her cloaca and elevating her tail. The male immediately wraps his tail tightly around the females cloaca and copulation takes place. This is followed by several matings over the first week. These matings may last from just a few minutes to several hours.
The second week the matings are less frequent, until no matings are observed late into the second week. This is rarely due to the males constant advances, but it seems that the females get bored and will reject their advances after some time.
This is the time to remove the male for a week or so before reintroducing them again. This tends to spark of renewed interest in each other. I also swap males around around to stir interest back into the females.
This procedure is followed throughout the months of January, through to March. Several feeding attempts are made when the snakes are separated, with the females ready to feed in between periods of copulation but the males are much more recalcitrant to do so.
In the past I have experimented with multiple males to promote sexual activity in both males and females. I have found that there has never been any animosity between competing males for dominance and hence no further increase in sexual activity in the female. This technique it seems is not apparent nor required to promote sexual activity in Emeralds.
By early March, sexual activity has become quite rare and I have found that the females have become quite irritable by the middle of the month, possibly seeking a warmer spot to gestate. This is the stimulus to start the warming process. Over the next three weeks, the night time low temperature is steadily increased back to normal.
The snakes are separated and offered food, which they normally take.
In early May, I have found that the female will begin to refuse food, the first sign of her possibly being gravid. By the end of May, she will have shed her skin and food is offered again, but refused.
By early July a large increase in girth is obvious, with more time being spent near the the heat source of 89 degrees Fahrenheit (31 degrees Centigrade). At this time I remove the night time drop facility to provide a constant temperature both day and night, together with a small increase to the overall temperature within the vivarium (from 28 to 30 degrees Centigrade). With this the female finds a spot in the vivarium in which they are comfortable and remain there most of the time, with very little nocturnal activity. This spot is not usually near the heat source.
As their girth increases, they tend to get a little untidy in their resting position and are unable to coil up in their characteristic position as they adapt to their increasing girth.
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Gravid
Female #1
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Gravid
Female #2, click to enlarge
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Throughout July and August, the girth further increases and the interstitial skin between the scales becomes clearly visible. By late August, early September the gravid female tends to move to a slightly cooler spot within the vivarium. This process seems to be similar to the slight cooling of incubating eggs seen with species such as Chondros.
As birth approaches, the area around the cloaca becomes swollen as the unborn young move to a more posterior position in the oviduct.
On several occasions just prior to giving birth (one week), I have noted that females come down to the ground foraging around as though they are looking for a suitable spot to give birth. In the wild, one would assume that they descent from the canopy to lower elevations in which to drop the babies or possibly even on the ground or in a tree hollow.
The total gestation period in Emeralds is between 6 - 7 months, depending on the number of degree days. This is the number of degree temperature provided per twenty-four hour day multiplied by the number of days of gestation (The Reproductive Husbandry of Pythons and Boas by Richard A. Ross and Gerald Marzec).
Birth of the young takes place in late August to early September.
On two of the occasions that my Emeralds have given birth, I have been fortunate enough to witness the spectacle. Both occurred in the early afternoon, whilst I happened to be cleaning out my collection. The first occasion, 13 babies were born within a period on one hour with the last one being stillborn. The cause of stillborn babies is not entirely understood. Some say that its due to when the female was last fed, causing the developing embryos to be compressed by the space taken by the food item. It is usually one of the last ones to be born and I put it down to possible suffocation whilst traveling down the oviduct.
The babies on this occasion weighed an average of 1.32 oz (37.5 g) and measured approximately 18" (46 cm).
The following breeding season the same female gave birth to 19 young of which two were stillborn. This occurred in the early hours of the morning and I was unable to witness the birth. This time the babies were considerably bigger than the previous time. Their average weight was 1.76 oz (50 g) and measured slightly longer at 20" (51 cm)
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These stillborn Emerald tree boas, show the difference in size of the neonates, between the two breeding seasons of the same female. Though not much difference in length, the girth and head size is significantly larger. |
The following week, my second female gave birth whilst I was again cleaning out vivariums. She had 3 babies of which one was stillborn and several unfertilized ovum.
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Female
#2's stillborn baby and slugs
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Close
up of the unfertilized ovum
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Within two weeks of parturition, all females then resumed feeding.