Fostering is the deliberate introduction of chicks or eggs into another birds nest.  There are many reasons for fostering and as was related in part one of this post, aviary birds occasionally and probably mistakenly do it to  when they attempt to take over an existing nest. Fostering is most commonly done to as a way to increase the productivity of more expensive or difficult species and sometimes it is the only way to raise young in the case of birds that have lost their instincts or as is the case of achromatic gouldians, whihc because of the mutation the young do not exhibit the correct feeding stimulus for their parents to feed them  (see picture from Finch Lovers Paradise and William Astor’s website).  

Fostering is also used to save abandoned  babies or nests with excessive babies with too wider age spread.  The latter is quite common if birds start incubating before they have completed laying thier clutch.  It must also be stated that egg smugglers also typically use this method of introducing new species or bloodlines but new DNA based identification proceedures have made this a risky proposition in more developed countries. Of course you can hand-rear birds but that is an extremely time consuming and the mixes and impliments aren’t easy to come by in the Philippines.  If you want to read up on hand-rearing then a good place to start is the Queensland Environmental Protection Authority site but there are others if you search the web.

 

While I’m against interspecific fostering as a way of life in aviculture I have used intra-specific fostering to save chicks from poor parents.  Earlier this year I found it necessary to move cut-throat chicks between nests as I have one very productive pair and a new pair that, which after three consecutive nests, I know barely manages get their chicks through the first week before the hatchlings starve to death.  Luckily last time, both nested synchonously and each started off with 6 chicks, however because they started incubating after the third egg the developmental difference in their chicks ages doomed the youngest hatchlings from both nests from the outset.  Although I gradually transferred all the chicks to the good parents when it was apparent that the pair in my second aviary couldn’t cope they eventually fledged 4 young.  For the ”good pair” I’m pleased with the result as that equals the maximum they have ever raised but since this was one more than survived from the original hatching it’s a very good result.  For the “bad-pair” you might just see them at Cartimar after Christmas as I would rather breed from birds that can look after themselves.

Interspecic fostering

As you may have gathered from part 1 you can use star finches to foster gouldian’s however in my experience Gouldians are much better parents than stars.  The most common choice of foster parents for Estrillid finches however are either zebra or society finches and there are pluses and minuses for both species.  A big plus for both species is that they are prolific breeders and so their price is relatively cheap.  According to Zann (1996) the zebra finch is a much more attentive parent than the society finch, however they aren’t as easily induced to accept a eggs or young.  According to a study by Care (1982) the stronger interactions that young suggests that imprinting is likely to be stronger when using zebras. 

Society finches are basically a GMO, selected for breeding insticts so strong that that some birds, regardless of sex or previous conditioning will accept eggs or young. I had an interesting case of inter-familial fostering occurred in my aviary when I was a kid between a pair of female diamond doves and a young red-browed finch that I acquired (from the wild).  The young finch’s incessent begging to any birds willing to come close eventually paid off with the doves coughing up.  With the right birds any fostering combination appears possible.  According to the Finch Information Center (and thanks for the sociey photo), societies will also hyridise with other Lonchura species as will as genera (Amandina, Erythrura, Poephila, Uraeginthus) so they are best not kept in mixed collections.  

Societies, like any other foster species are best at their job when their reproduction is synchonised to that of the dononors and according to Garrie Landry you need 4 pairs of fosters for every donor pair in order to ensure synchronisation.  Another good site with specific fostering instructions is Kathy Landry’s (- I don’t know if these two Landry’s are related).  A very detailed account of how to foster Gouldians has been posed on Gouldian Finch Info if you want really detailed information for that species. 

So where does this leave my view on fostering?  I’m still against interspecific fostering but even nature conspires to create such things so I can’t afford to be too critical of those that practice it.  For those that have the time and inclination to manage banks of society finch cages this is certainly a way to increase productivity. Now that I’ve got foundation birds capable to raising their own young  I will endeavour to keep those lines alive and doing what they are supposed to do – sustaining themselves.