Gorilla BreedingA

S

Shorts

Well-Known Member
15+ year member
Apologies if similar thread has been started before (possible, but can't see one).

Just been reviewing Gorilla holding on ISIS. Looking at the births this year it would seem that a majority of them relate to zoos holding larger numbers of animals (i.e. >4).

This seems to imply that the larger the group held the more chance of breeding (I realise this might seem like a statistical truism from some perspectives). Is this correct or is it more complex than that?
 
Shorts said:
Apologies if similar thread has been started before (possible, but can't see one).

Just been reviewing Gorilla holding on ISIS. Looking at the births this year it would seem that a majority of them relate to zoos holding larger numbers of animals (i.e. >4).

This seems to imply that the larger the group held the more chance of breeding (I realise this might seem like a statistical truism from some perspectives). Is this correct or is it more complex than that?
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Basically you are correct: but gorillas are all individuals, and so there are exceptions to every rule about them (and I'm sure that the same thing applies to all the apes and many other species of birds and higher mammals to some extent). Howletts and Port Lympne are the perhaps the most experienced collection(s) in managing gorilla breeding groups. They usually start with half a dozen females and one male - but I imagine that introduction process is quite long and complicated, and requires keepers to know and observe the animals very fully.

Alan
 
Shorts said:
Apologies if similar thread has been started before (possible, but can't see one).

Just been reviewing Gorilla holding on ISIS. Looking at the births this year it would seem that a majority of them relate to zoos holding larger numbers of animals (i.e. >4).

This seems to imply that the larger the group held the more chance of breeding (I realise this might seem like a statistical truism from some perspectives). Is this correct or is it more complex than that?
Click to expand...

Actually, a gorilla must have a breeding recommendation from the EEP or SSP to breed. The zoos that generally get these recommendations are very experienced breeders (US - Columbus, Bronx, Atlanta / Europe - Port Lympne, Howletts), have genetically valuable gorillas, and have large quantities of gorillas. It just so happens the experienced breeders have larger quantities. And male to female ratio doesn't matter considering the recommendation is for one male gorilla and one female gorilla.

However, in the wild, the male to female ratio would play a significant factor in quantity of reproduction, in addition to factors such as age of gorillas (breeding age) and survival rate of offspring due to environmental factors and quantity of predators.
 
ColumbusZoo001 said:
And male to female ratio doesn't matter considering the recommendation is for one male gorilla and one female gorilla.
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Really? I would of thought any zoo keeping Gorilla's would be recommended to keep more than just the one female? Or is this to avoid situation of lots of unwanted silverbacks?
 
ColumbusZoo001 said:
And male to female ratio doesn't matter considering the recommendation is for one male gorilla and one female gorilla.
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What is meant by this is that the breeding recommendation is for the male and any one female within a group, not that they be kept as pairs.

Example; Chessington were recommended to breed from Damisi & Buu but not currently from the other adult females- probably due to space restrictions.

But I don't know if EEP make recommendations of this nature to Howletts, I rather doubt it...;)
 
Pertinax said:
Chessington were recommended to breed from Damisi & Buu but not currently from the other adult females- probably due to space restrictions.
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How do they prevent breeding with the other females? Are they all on contraceptives?
 
These are the pairings for 2009 that I know of

Atlanta: Taz X Kudzoo
Aubodon: Casey X Jamani
Buffalo: Koga X Kwizera
Busch Gardens Tampa: Simsim X Mary
Brookfield: Ramar X Binti
Brookfield: Ramar X Koola
Lincoln Park: Jojo or Kwan X Rollie or Kowali
Cincinatti: Jomo X Bana
Columbus: Anakka X Casade
Denver: Jim X Angel
DAK: Gino X Hope
DAK: Gino X Kashata
Fort Worth: Elmo X Shani or Johari
Los Angeles: Kelly X Alafia
Louisville: Mshindi X Mia Moja
Memphis: Mwelu X Mary-Sydney
Miami: Jimmy X Kumbuka
Oklahoma: Bombom X Kakamo
Pittsburgh: Mrithi X Moka
Rio Grande: Marcus X Matadi
SDWAP: Winston X Jessica

Also, Toronto has a prenant female "Ngozi who is due at the end of August and Toldeo wants to breed there gorillas (not sure which ones)
 
Pygathrix said:
Why is Bronx not on the list? Will they not be breeding for a while?
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All of their recommendations have resulted in births in the last few years (1 in 2005 and 4 in 2006) so the SSP will wait a few years for the babies to mature before handing them more recommendations.
 
Thanks for all you information and insights.

I'm still trying to get my head around the fact that if they do breed better in larger groups does this mean those facilities holding small numbers are basically on a "wing and a prayer".

Does anyone have an opinion on whether regional breeding would be better if the smaller groups were amalgamated? I realise, because of politics, this is extremely unlikely even it was considered for the best -I'm just interested in opinions on the hypotheticals.
 
Shorts said:
Does anyone have an opinion on whether regional breeding would be better if the smaller groups were amalgamated? I realise, because of politics, this is extremely unlikely even it was considered for the best.
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Its only fifty years or so since Zoos were falling over themselves to be the first to breed Gorillas, both in the US and in Europe. In those days many zoos still had only singles and some luckier ones had pairs or the odd trio. In those days too, many zoos failed to breed them because they didn't realise that because their pairs had grown up together from infancy, they had became 'platonic' rather than breeding pairs. Had more zoos engineered swaps or amalgamated two or more pairs into small groups in those early days, it would undoubtedly have increased the breeding rate by stimulating mating/breeding between new, unfamiliar partners, where none took place before. However breeding loans and moves were rare as most zoos just preferred to keep what animals they had, not take any risks and hope something would happen breeding- wise. But in the late 60's as more zoos began to form proper social groups, the breeding rate increased too, indicating the advantages of this system over the old 'pairs' one.

Nowadays the situation is almost reversed with only selected pairings of animals being encouraged to breed(see above) in many zoos. So there is no real advantage in amalgamating animals into larger groups than they live in now(except in the case of singles or pairs of course) in order to encourage more breeding-though it would no doubt have had a beneficial effect in the past.
 
Shorts said:
Thanks for all you information and insights.

I'm still trying to get my head around the fact that if they do breed better in larger groups does this mean those facilities holding small numbers are basically on a "wing and a prayer".

Does anyone have an opinion on whether regional breeding would be better if the smaller groups were amalgamated? I realise, because of politics, this is extremely unlikely even it was considered for the best -I'm just interested in opinions on the hypotheticals.
Click to expand...

Yes it's complicated. Gorillas generally 'do' better in larger groups which resemble the groups found in the wild. But smaller groups can work, depending on the individuals involved, the accommodation available and so on. Of course not every female in a group needs to breed - which is where the contraception comes in.
It's not just politics, genetics and economics matter too. If the population is to stay healthy over the long term, males and females must be moved around to maintain as much genetic diversity as possible. In other words, individuals with few relatives in the breeding population should be given every chance to breed, while individuals with more relatives need have fewer chances (or none at all for some unlucky males whose full brothers have already sired infants). Likewise, if a zoo is added to the breeding program, after designing and building suitable accommodation and meeting the conditions required, it needs stock, so extra breeding may be permitted in some collections and the opposite is true if a zoo decides to stop keeping gorillas, so that their animals must be rehoused.

Alan
 
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