The length of gestation in alpacas has a huge variable. With over 1000 cria having been born on our property, there is still no absolute pattern to offer owners.
I have seen cria born at 10.5 months gestation who are average size, normally active and with teeth erupted, while others with almost a 12 month gestation display some signs of dysmaturity, such as down on the pasterns and may need extra care. Gestation lengths of in excess of 12 months have also been recorded with babies still not excessively large.
Even animals mated on the same day have remarkable differences in gestation. For example, three females mated at Benleigh by three different males on the 5 May 1999, resulted in birth dates of 30 March, 3 April, and 20 April!
Just to add to the 'guess work', occasionally a female will surprise an owner with an unexpected delivery, and a cria which is active, has teeth erupted and is clearly not a premature baby. On checking mating dates, it is obvious she had conceived earlier, but allowed herself to be mated again. (This tends to happen more often with young females)
If you know your alpacas, you are sure to recognize behavioural changes. Body language (ears back, sitting on one hip, arching back etc.) is a great indicator.
It is practical to move animals to a paddock where observation is easy during the last 6 weeks prior to anticipated birthing. This is also the time when increased nutrition is wise.
Towards the end of gestation, the progesterone levels in the female decreases. It is unwise to have males running with late stage pregnant females as mating could occur with potentially serious results for the unborn foetus.
Any previous progeny should not be with the expectant mother at this stage, as it has there have been a number of reports of previous offspring taking the precious colostrum (first milk) leaving the new cria in a potentially life threatening situation.
Whilst we cannot alter the period from conception to birth, knowing the last mating date gives a guide as to when to be prepared, so good advice is to keep good records.
Benleigh Alpaca Stud