Birth Control — Long-tailed Macaques in Phana

The first stage of the birth control programme for the long-tailed macaques in Phana took place at the end of August and beginning of September 2016. Stage two is likely to begin soon, so it is time that we look back on the initial stage.

The original idea was to perform vasectomies on about 100 adult males and sterilisation of a much smaller number of females. However, a total of 114 males underwent the operation but no females were sterilised although everyone agreed that female sterilisation was an important and necessary step to take. Two females were operated on in the sense that they were anaesthetised and opened, but the vets found that the operation as performed with the equipment they had available to them at that time would take too long, resulting in a need for longer under anaesthetic and a longer recovery time and overall a longer time away from their female-bonded families , all of which would be a traumatic for the monkeys involved, including those family members which would be missing one of their number.

Monkeys were accustomed to open capture cages for several days and they moved in and out to feed without much initial hesitation.


Male monkeys dominated the feeding groups inside the capture cages. When capture began, monkeys were moved in smaller transport cages to the operating centre based in rooms at the OPT Phana (Phana sub-district administration offices).


This was the base for the whole operation. There was a covered but open area for pre-op procedures, an operating room, a food storage area and a recovery area.


The pre-op area

The first step then was to administer the anaesthetic by injection, which was achieved by enticing the monkey to the side of the small cage and grabbing a leg.

dsc02814When the anaesthetic had taken full effect, the monkeys were tattooed on the face. dsc02760The position of the tattoo or tattoos on the face are coded. Here is the code they were working with. dsc02816 This monkey has two, one representing 10 and the other 1, so he was monkey number 11.

dsc02752bFinally, the monkeys were weighed and their information recorded.

dsc02752 This was the biggest monkey recorded.

The monkeys were moved to the operating room as vets became available to operate on them. Vets worked in pairs or small groups as not all of them had had previous experience, and there was a limit to the equipment available.

The monkeys’ heart rate was monitored throughout the operation, which took about 15 minutes.dsc02766

Monkeys were then moved to recovery cages to await their return to full consciousness.dsc02781

Most were returned the following day to the forest close to where they had been captured.

About isantraveller

I have been in and around North-East Thailand for more years than I can recall. I now live here permanently. I have travelled in 32 countries on 3 continents (Europe, Asia, Africa) so I am a bit of a traveller.
This entry was posted in Long-tailed Macaques, Monkey birth control, Monkey population, Wildlife conservation and tagged , , , , , . Bookmark the permalink.

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