Breeding Bosc Monitors in Captivity
by Dan Tupper

I have had my adult female Bosc for four years now. When I got her she was around six inches long. She is now around three feet long. Early on this year I re-homed another Bosc through PRAS. I keep my Bosc’s in a six foot by two foot by 18 inch vivarium they are fine if I could give them more space I would, but at the moment it just isn’t possible.

At first I was unsure as to how my female would react to having another Bosc in with her, but as I let them meet for the first time they were fine and didn’t seam bothered by each other at all.
They were fine for around two month’s; I would always take one of them out for feeding just to be on the safe side.

Then after around two month’s I found them mating, this lasted for around five and a half hours, during this time my male would change sides, I would think that this was to change hemi peen. At this point I dug out my Bosc books to check out how long it would be before I had eggs. The book said eggs would be laid around 8 weeks after breeding, great I thought lots of time. This was in fact wrong as most breeding information for Bosc’s is in fact written about White Thought Monitors. I had 21 eggs laid on the floor of the vivarium after four weeks, what a panic!

As my book was wrong I decided to try the Internet to get the incubation temperature. The best site I found was www.mampam.com This site is great for all monitor lizard information, as well as Bosc’s. The information I found gave me two different temperatures. The first was 29 degrees C and an incubation time of six to seven months. The second was 32 degrees C and an incubation time of four months. I set up a second incubator at 32 degrees C and placed my Bosc eggs in. I checked the eggs often and removed the lid to change the air.

Around two weeks before the four months incubation time was up I checked my eggs and found an egg slit with a dead baby Bosc inside. This little guy had an egg sack as large as him still attached. This left me in a panic as it happened over night and I was about to go away on holiday for the weekend! I left instructions for the eggs to be checked every few hours and an empty viv if any hatched. Lucky for me no other eggs hatched. I didn’t get another one hatch for a week and a half and the same thing happened, it slit the egg over night and died before absorbing the egg sack. Now I didn’t know what to do was this going to happen to all the eggs? A few days later a third Bosc hatched over night and died. At this point I lowered the temperature in the incubator to 29 degrees C. I then spent the next night getting up every two hours to check the eggs! This was not a good move as I didn’t have any hatch and then spent all the next day over tied. My next master plan was to get up once in the night at 4am. After a few nights of this it paid off I checked the eggs and found a little head looking at me not moving, my first thought was not another dead Bosc, so I went to touch him and a then there was a little bit of movement from him!
At this point I decided to remove the egg from the incubator and place in a plastic box with lots of kitchen roll and place it in the empty viv. I them went back to sleep.

In the morning the Bosc was still sat in the egg looking at me. He left the egg in the afternoon and is doing fine. As I write this he is now two days old and doing great, I still have not had anymore hatch yet and I an still getting up in the middle of the night to check Bosc eggs. I have taken some pictures of the baby Bosc and they will soon be posted on the PRAS website. I look forward to another week of getting up in the night to check eggs. As for next year if my adult Bosc’s breed again I will incubate them at 29 degrees C over six to seven months and hopefully I wont have to get up every two hours to check Bosc eggs.
After a few weeks no more Bosc’s hatched out. So this year I only had the one hatchling, I will aim to breed my Bosc’s again next year and I hope to have a better success rate. In total four eggs hatch but three of the babies died soon afterwards.

The surviving Bosc is doing very well and has a great appetite. He has around 10 – 15 3rd crickets a day and is now coming up for his first shed. One of the best things I can say about captive breed Bosc’s is they have a very good attitude and can be handled with ease. As most people who keep Bosc’s know when they are juveniles they can be a bit of a hand full defecating every time you pick them up, if they don’t do that they will hiss and whip their tails. These characteristics have not been show at all in my little hatchling; I think the reason for this is because he has been handled since he hatched out of the egg.
On a final not I can only say I look forward to breeding my Bosc’s next year and I hope to have a much better survival rate for the hatchlings.