Tuesday, 18 October 2011

Some personal notes on rearing Sand Lizards for reintroduction to the wild


In June 2010 I was asked to join the captive sand lizard breeding program. It was felt the amount of Merseyside animals being bred for release needed to be raised due to the large number of receptor sites.
During the summer months I monitored the levels and positions of the sun in my back garden to establish the best position to build an outdoor vivarium. Ideally this would be a south / southeast facing part of the garden with the maximum hours of sunshine available. The best spot was found but the surrounding vegetation needed a bit of a   haircut.
The enclosure was built to mimic as closely as possible an existing vivarium being used by a current member of the program. Based in the Lake District he has a great success rate working within the guidelines of the Captive Husbandry manual.

The next consideration after location is the size, biggest is best. The largest size possible was 12 ft. long x 5 ft. deep by 4 ft. high with a further 2 ft. being below ground level.
I started building the vivarium in February 2011and dug a hole to the above dimensions 2 ft. deep. This was filled with gravel 6 “ deep and then a breeze block wall was built to 4 ft. above ground level on 3 sides with the front being 1 ft. above ground level. Hard-core was then added to a general depth of 12” and additional contours were made to enable sand banks to be created. Sand was taken from the dunes at Blackpool airport along with marram and lyme-grass and habitat was created as close as possible to that found in a dune system. 8” wide plastic cladding was added to the top section inside the walls to prevent the animals escaping and the top and front of the enclosure was made safe from predators with 1“ x ½ “ mesh, there is a door at the front for access.

Four females and 2 males were introduced to the vivarium on 09.05.11 (about 2 weeks later than I had hoped). The animals were taken under licence from the frontal dunes at Southport. They were a nice mix of ages and all 4 females were gravid. They settled in well and after a few days seemed to loose all desire to escape.

The weather was really good in early spring but was pretty poor after 12.05.11 for most of the summer.  

All the females were showing egg bulges and were put into a Perspex enclosure within the main vivarium on 17.05.11 so that the eggs could be harvested after laying.
In hindsight this was too soon with the first female not laying the first eggs until 24.06, she laid 6 eggs of which 2 were infertile, a second female laid 10 eggs on 26.06, these were all fertile.
Probably due to the stress of being taken from the wild the 2 younger females re- absorbed their eggs. All 4 females were returned to the main vivarium as soon as they either layed their eggs or it became apparent they were no longer gravid.   

As soon as the females were back in the vivarium the males took an immediate interest in them and would probably have mated again if the females had laid a few weeks earlier and the weather had improved. Although it is felt it may happen in the wild but is difficult to prove, females kept in captivity will often lay 2 clutches of eggs in a season and it has been known in exceptional years with good weather, that a small percentage of animals may lay a third clutch. It is felt this is mainly due to the females getting back to their ideal weight very quickly after being fed with wild caught food as often as the weather will allow.  

The eggs were found to be about 3 “deep in the sand and were removed as soon as possible. They were put into small clear plastic boxes with 1” of damp sand in the base. The eggs were dug up very carefully and placed into the box in the same orientation that they were found. The boxes were placed into an incubating chamber.
This is in the form of an insulated wooden box where the temperature is maintained at 24 degs. The Husbandry manual says to repeat the best conditions likely to be encountered in a very good summer within the UK. This will result in the eggs hatching in about 40 days.

The eggs started to hatch on 07.08.11 and all 14 eggs hatched within 36 hours.
The babies were graded for size and put equally into 2 plastic containers, these  had sand in the base to a depth of 3 “, a heat lamp, a UV lamp, cool spots, water container and cardboard / slate to hide under and bask on. The lighting and heat is controlled by a timer it came on at 06.30 and off at 20.00 with 2 breaks during the day. They were fed 2 / 3 times a day on black crickets and buffalo worms, their favourite commercial food, these were dusted with vitamin powder. I also fed them on spiders of all types along with caterpillars and red flying ants. They more than doubled in size in the 3 weeks before they were released being around 100mm long, on occasion, when possible they were put outside to get natural sunlight.     

On 01.09 all 14 of my animals were released at Ynyslas North West Wales along with 29 from Chester zoo a further 17 were kept back by the zoo to be released later.

A normal release schedule will be 50 babies released per year over a 3 year period, by the third year the first release of animals should be mature enough to start breeding and so this new established colony should be self- sustaining, though it can be a further 5 years before it can be established if the release has been a success.    

The adults fed well during the summer when the weather allowed. When they were caught 1 male and 1 female had lost their tails prior to capture, although they had regrown their tails to about ¾ length they have not grown in overall size as the other animals have. They stopped feeding around the middle of August and by 18.09 the 3 older animals had gone down for hibernation and by 25.09 all six were no longer seen, this was pleasing to see as this copies the normal behaviour in the wild.
The 2 younger females did re-appear but by 15.10 they had also gone into hibernation.

My initial response to the first year on the program was that of disappointment, I was hoping to have released in excess of 25 animals but with only 2 females laying eggs this was not possible.
On reflection I have learnt a lot over this initial period and assuming the construction of the vivarium is correct and all the animals re-emerge next spring all should be set for a successful year in 2012, especially with the additional bonus of the animals possibly being released on the dunes north of the Ribble.  


  1. Looks so nice everyone pictures. I appreciate of your work. reptile live food
    Thanks a lot!

  2. Fantastic animals - look at the colours on those males!



  3. Very Nice Article, Can you add more images of the inside of the vivaria?