Any decisions made on breeding will be restricted by available space - even Werribee isn’t infinite (in exhibit space or food bills). A herd of 35 elephants is going to bring in no more customers than a herd of 20, so I’d be surprised if we saw a complete end to artificial birth intervals at Werribee.
Having calves born together (a cohort) is beneficial from a management perspective and for the socialisation of the calves. The first cohort will be three calves as it was important to breed from all three cows ASAP - but I imagine we’ll see cohorts of two from there on (probably ever 3-5 years). If nothing else, it will lead to a healthier age structure of the herd long term - a baby boom now will become an ageing population later.
Elephants can be bred at 50 - but do they need to be? Is it a priority to breed this cow over others in the herd which NEED to breed to maintain their reproductive health? To use Thong Dee as an example. Thong Dee (1997) gave birth to calves at 12 and 19 years of age. Both calves have survived and one has now impregnated three cows. Assuming further success, breeding Thong Dee at 50 would be unjustifiable when you factor in the risks of a geriatric pregnancy and the fact other cows are less represented and are a higher priority to breed.
I recognise there is good relevance to sustainable population management in captivity, I was not contesting that. But given the current position at which the developping program is I would try to conform to the intergenerational normal life history criteria for the species to make one's management decisions and as it is I do find the ZAA program has potentially left opportunities to create a sustainable captive-breeding ex situ conservation program open and lost valuable time to do so. As it stands, I do think we have and the timeline it has taken to do the most obvious and sensible thing to have the open range zoos establish exhibits for breeding herds in larger acreages to address exactly the space issues in the city zoos that held/hold or are maintaining animals within the program.
Given the long generational time lengths between each and every potential birth and potential surviving offspring (no guarantee either) and the next birth and no guarantees existing that current breeding cows will remain reproductively healthy over time - which we have seen happen in the ZAA program is surely not always the case - it is imperative to early on proceed more rapidly with allowing all breeding cows to have at least 2 surviving calves and let nature takes its natural course early on according to natural parameters for the species and later on factor in discretions to allow for building a stable sustainable managed population and program. I assume you will agree that the Australasian program for Asiatic elephant may be far from that stage by far till date.
For ZAA sound population management, that is what you are clearly referring to some questions need asking about the current population and where it is going (or not):
a) Which over and above your above rough timeline for the cows you mentioned are current breeders within ZAA and whether these might breed and calve in the next few years or not?
b) Which (potential) breeders have we already lost and are currently part of the ZAA population?
c) What do we make of the few Sumateran elephants at Australia Zoo within this sustainable population management framework? Can the breeding program sustain this (even though privately I am a huge supporter and proponent of pure-bred ex situ breeding for this subspecies which has gone from threatened to endangered and the numbers in the wild continue to go down (I privately think there may already be more Sumateran elephants in captivity)?
d) What future outlook do we have for more than the current number of breeding facilities? What is to happen with the city facilities and breeding?
e) How do we factor in building bachelor herds close to breeding bulls? What about the expected surplus at sex ratio 1:1 in the species and births?
f) Are we as yet at a stable population level in number breeders, number of surviving offspring and stable sex ratio for the current program?
g) Looking at the wider picture and in situ conservation what support are we at ZAA providing for in situ conservation of Asiatic elephants where it is clearly needed (Sumatera, Kalimantan, Indochina, Malayan [Peninsula // I think Indian subcontinent can and should deal with that itself mostly with facilitation by US/European zoo collections and the Indian ex situ conservation breeding community at CZA zoos and aquaria)?
h) Ultimately, how can we for the love of global population management not create opportunities for providing captive-bred Asiatic elephants from known breeding lines to in situ sites for establishing or augmenting in situ populations? What opportunities for support to and for in situ conservation community in the regions mentioned in g)?
