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They should hatch at around 14 days. But only when you start counting the time after the last egg is laid and when mom finch starts sitting on them. The countdown of when they will hatch does not commence at laying but at the beginning of incubation. After five days incubation, you can candle them and look for veins. If the eggs don't show veining or spidery lines, they are not viable or dead eggs.
Source: Here is an excellent resource regarding finch eggs and their care.
By Robyn 
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Here are questions related to Breeding Zebra Finches.
I have been keeping a pair of zebra finches for the last year. They are provided with nest boxes and stuffing. They keep on laying eggs, about 2-3 at a time, but none of them have hatched. I think some of them are not fertile. What could be the reason? Should I provide them additional food supplements?
By heather inwood04/01/2013
Often first timers go through the cycles of laying eggs & not following through - sometimes they need a few times to get it right Also are you sure that they are a male & a female? - as females will still lay eggs and go through the motions of sitting on them. Have you seen them mating? Google breeding finches for some good tips.
My zebra finches laid four eggs and I have now two newly hatched babies. Next to them are two unhatched eggs. Will they hatch still?
Our finches had two babies. At about 16 days old both died, over two days. We are devastated. Any ideas why?
By Ralph from Surrey
I was recently given two zebra finches (1 female, and 1 male) as a gift from my parents. I have only had them for about a month and a half and noticed them mating the last week or so. I have a basic cage that measures 18 X 13 X 10.5 inches with a small bed/nest hanging from the top.
I honestly never expected them to lay an egg, as my parents have had theirs for months and they never had and was told it probably wouldn't happen. Well sure enough, I came home today after work and noticed both the parents in the bed/nest which they have never once used before. When they left the bed/nest I shined a flash light in the bed/nest and noticed an egg. I couldn't believe it!
I have been researching finches and egg laying and have read that they usually lay one egg a day and can lay up to 8! I understand that many times the female will lay an egg, but it may not be fertile and will not hatch - therefore it can be removed after 20 days if nothing has happened.
My concern is that if they do hatch, my cage is just not large enough for more than two finches, but they have already started laying eggs and I have read you should not move them or the eggs until after the baby birds leave the nest and can be on their own. I just want to make sure that information is correct.
My other question is, can I still clean the cage even though they started laying eggs? I normally let the birds out of the cage in the bathroom to fly around while I clean the cage and I normally take the entire cage apart. But with there being eggs in there now, should I just leave the birds in there and only remove the bottom part of the cage that slides out and clean that part off or what? Thank you for any help and advice you can give. I am very new to this and never expected it to happen. Thank you!
By Ariana G
By heather inwood11/16/2013
Personally, if you are going to move them into a more comfortable size cage (which the bigger the better) then do it now - then you may only sacrifice the one egg. The move will likely upset them, but only for the moment - they will lay again. I would still leave the egg in the nest.
Also, the less you disturb the birds the better once they've been rehoused- so the cleaning of the cage is as you have suggested. Best by just removing the bottom tray and refreshing their water. It will be ok to be a "little" dirty as it's only for a short time.
Once they have been hatched & fully feathered and flying you could move them into the smaller cage , give the big cage a good scrub - with soap and water [and without the use of disinfectant] Then return them to the big cage - I suggest that once the babies are fully weaned that you separate them from their parents as they will likely want to breed again & the babies may get harassed. Good luck! Bird breeding is a joy.
How long do zebra finches take to fully changes their colors to the adult coloration?
I have 10 finches and all have eggs. Can I put all the males in another cage to stop the breeding? Will the babies be fed by mom alone? And if I put all the males in another cage will they kill each other? Help please.
By heather inwood10/01/2013
It's too late now - you could throw all the eggs away. If you want to stop them breeding try taking out all the nest boxes. If you want to get only a few babies just put the one pair in with a nest box and keep all other birds in a separate aviary. It would be a bit cruel to separate the males from the females as they are pairs, after all.
I have four finches, I have one zebra finch (male), two white zebra finches (females), and one fawn finch (female). Will they breed and also when they will start laying eggs?
When will my zebra finches lay eggs after building a nest and what material should I use?
I have two zebra finches, a male and a female. The female won't allow the male to mate. They had many clutches of eggs in 2010 and had 1 brood. Then they of course pecked it. I was quite devastated. I wanted to see new life, but it wasn't meant to be. They are only 3 and I told my uncle (an expert in zebra finches), but he didn't have a clue what was wrong with them. So that's it, I do not know what's wrong with them. :(
I just got 2 finches from Petsmart. One is a solid white zebra finch and the other one is a classic zebra male. Now I know that with females they have a lighter colored beak so I'm pretty sure it's a female, but they haven't touched their nest or the stuff to make a nest that I put in their cage. They sit on the nest and sleep.
I noticed when I got the white one from the store the back of her neck was missing a few feathers and you could tell right where her beak is there is a tiny hole. I don't know where that's from, but they will be sitting on the nest and he will start grooming her at the back of the head and neck. I noticed he had plucked out a feather. She would just sit there then get a little agitated. Is he being mean? That's the only time they get a little irritated with each other. Will they breed?
Also I noticed when I was choosing my birds at the pet store that they pant with their beaks open. The first set of birds I had a few years ago didn't do that, but these 2 do. Also the male will sorta pant and squeak. Is he sick? I have only had them 2 days. I'm starting to think Petsmart needs to take better care of their animals.
By Sierra S
My zebras have had 3 chicks and I know that once they start feeding on their own and become independent I should remove them because the mother and father will want to start a new family again. How long shall I separate them for until I can let them go back into the main aviary again with the other birds? Or if my aviary is big enough can I just leave them in there?
My zebra finches have start building a nest, but I have just noticed that the female finch was doing most of the nest building instead of the male.They started putting feathers in the nest. Will my zebra finches lay eggs soon?
By Amy Louise
Sometimes the female will help build the nest so its just the way she wants it, and you can expect eggs within the next week give or take a few days.
I have 2 finches and she has laid a clutch of 7. I was not expecting this and this clutch was laid in a very small hut. I (have) want to put the babies and eggs (whole nest) in a bigger hut (house). Should I not touch the nest? If I do will she not feed them and not hatch the remaining eggs? What will happen if I change this?
I have 5 babies in a small basket nest. Can I move them to a box nest and will the parents go and feed them if I do?
By David from Paducah, KY
By heather inwood06/04/2013
I breed cockatiels on a casual basis, & was told never to change the nest box once the eggs were laid or babies were born as the parents would never return. I've never tested the theory though - maybe you could Google finch breeders & ask them.
I have had a male and female Zebra finch for about two months, but they are not laying eggs. They have a cuttlebone, nest box, water, and food. Please Help
By Tutu Y.
One of my finches tossed out an egg and it broke. Is this normal and why would it happen?
I have 4 babies that are 2 weeks old. I have 3 that came out of the nest in the last few days. Is it okay to remove the nest when the 4th comes out? The nest is really messy of course and I wondered if it would be best to get it out of the cage.
By heather inwood04/25/2013
Yes - I would remove the nest & start again - cleanliness is the key to healthy birds.
I had a pair of finches, that laid 6 eggs. It has been 20 days and none of them hatched. Can I assume that they will not hatch or is it because the temperature is very high in our state?
By Arun Kumar
I have a pair of zebra finches. Two weeks ago they laid 9 eggs in a period of 4-5 days out of which 5 were fertile. Yesterday two of the eggs hatched, but the parents didn't seem to be feeding them properly so I hand fed them this morning. Should I separate the chicks and raise them by hand or should I leave them in the box with the eggs. I am worried that the parents won't be able to care for the chicks and incubate the remaining eggs at the same time.This is their first clutch. Please help me.
By Neil from IN
By william giltrap08/19/2013
It might be the best if you try not to disturb the male and female, since I made my birds kill the scald from disturbing them. You could try giving them a tiny tiny little bowl or saucer with milk and tiny little parts of bread. If your scalds die it could be of being disturbed or the male getting jealous of the female spending so much time with the scalds. I hope you enjoyed this few helpful tips!
What are the foods I need to feed the finch while they are nesting and after the eggs have hatched?
By heather inwood04/09/2013
Try Googling "breeding finches " on the internet - I'm sure you will find heaps of very important imfo.
I have two zebra finches one male (Micky) and one female (Minny). I recently learned that they have babies in the nest. They have laid eggs before and the babies died and also they have lost eggs. Now I have at least two babies in the nest. What can I do to ensure that the babies survive this time? The babies are maybe a few days old.
By heather inwood03/30/2013
Congratulations - it is thrilling to have your birds breed sucessfully - but most importantly - do not handle them - leave the parents to care for them - google finches on the internet & read all about the breeding of finches . Keep the parents diet healthy & plentiful - this is a great interest but do your homework.
I honestly did not know that my finches had eggs! When I saw, they had three eggs. The female bird immediately came out and was flapping her wings everywhere. I saw that they did not have food so I refilled their tube and the female comes out and was scared. It has been 18 hrs since the incident and I don't think the finch eggs survived or anything since the female finch hasn't been in the nest in a while. What should I do? Please help me :( (p.s. I had 4 finches one of them died a while ago now it is 2 females and one male).
Hi well I have 4 male finches and 4 female finches lately I have just been checking them every so often and today my mum walked in there thinking that there was just eggs in there but instead there where baby finches I think that there are around 4 or 5 babies.
What do I feed them. I need this question answered in the next 24 hours please. At the moment I have just given them some meal worms.
I have 3 males and 1 female zebra finch. The female bird laid some 20-25 eggs in the last 6 months, but not a single one has hatched to date. All the eggs were thrown out by the bird after few weeks. Please let me know what should be done so that the eggs can be hatched.
I find that if you have more females than you do males, the fertilization seems to be better, and have many nesting places for them available. They seem very picky to me. All I give them for nexting material is soft dried grass and cut up soft cotton, from an old tshirt, cut into 5 inch strips by about 1/4 inch wide... they love it.
My Zebra finch laid 5 eggs. The male and female are both sitting on them. What do I need to do? Help me.
My male zebra will not let the female in the nest. Can anyone tell me why he's being very possessive? He chases her around the cage. Do I need to separate them? They have one egg in the nest and he's the one that sits on it. He won't let her in at all. Please help!
I have a male and one female zebra finch. Now they have laid 2 eggs in the breeding box which I had attached from outside the cage. I have read somewhere that they can lay more than 7 eggs. Then what must be the reason behind laying just two eggs? The female finch sits on the eggs regularly. but will the 2 eggs hatch? I want at least one cute baby zebra finch. How many days will it take for the eggs to hatch?
What other than the seeds can I feed the mummy zebra finch. Please help me out of this.
By Arpita G
My bird laid eggs in the food dish, I have moved the egg to a manmade nest. What do I do now?
By Tess Vowels08/27/2012
It's been 30 years since I raised Zebra Finches... loved them. They use to lay eggs in their food dish, too. But my memory doesn't hold like it use to. I suggest you Google raising Zebra Finches. I had a great book, too... and my local pet store took babies, after hatched, to sell!
My pair of finches, mom and dad, had 3 males and 1 female. They are 2months old they are separated from mom and dad. Can my 3 male finches and female be together? Can brother and sister breed? Should I separate them in pairs? Should I separate the female from the 3 males? What should I do?
By Rosa M.
I would like to buy 2 zebra finches (female+male) for my birthday, but I don't know how much they cost. Can you tell me?
By Marie H.
By Janace Lynn M.07/25/2012
Call Petsmart: Zebra Finch
Ideal for children 14 & up Makes soothing sounds Lives approximately 5 years Note: Pet availability is seasonal. State and local regulations may vary. Pricing may vary by store location. PetSmart stores cannot match the price below for this pet. Ask a store associate for details. Very messy with food.
I think my baby zebra finch is undersized. I have a baby zebra finch in the nest, it is fully feathered, but looks tiny and I am not sure how old the baby is. Can anybody help me?
By Kayla from Wollongong, Australia
I might have the answer to your problems. if you think it is to small it might just be it's first layer of feathers. finches have 2 layers. if it has still got a bit of a black beak it is 4 weeks or younger. if it is orange then it is more than 5 weeks. I would take it out of the nest put it in a cage separate from the others and make sure the feed and water are on the bottom of the cage and it will get fatter and look more healthy in around 2 weeks. if beak is still black then don't remove the bird.
I have two finches (male and female), the male is gray and the female is white. I have seen that the male has been missing a few feathers. Then the next day I saw that the female has been chasing the male and the male keeps running away from her. And then when she caught him she got on his back and pecked him! And now his back and neck have no feathers at all. At first I thought she was a witch, but now I think that maybe, just maybe, they do that on purpose?
Can you please help me.
By Matthew from Western Cape, CapeTown
By Lisa Denton G.05/21/2013
I actually just had the same problem with my finches. I called my local pet store and they informed me that it was probably the females way of telling the male that she was ready to mate, and was using his feathers as bedding for a nest. So I went out and got them a nest, and a few weeks later, we have four eggs in the next!
How many days would it take for zebra finches to be paired with each other? They are new to each other.
I want to know more about finches, like how many eggs they lay, how many days they take to hatch, and how many times these birds lay eggs in a year. Can someone help?
What is the correct food to feed my Zebra finches, they have now laid 4 eggs?
By Maggie J
My Zebra couple have laid 5 eggs. One is already hatched, but my female has laid 4 more new eggs, one as late as today! Is this normal and should I just leave the new baby and the new eggs alone? I am just confused about one hatched egg and yet four new white eggs. Please give me any info that might put my mind at ease or help me ensure the safety of both the parents and the eggs and hatchlings!
By Daniel T.
I have two males and a female zebra finch. She laid 7 or 8 eggs and I don't know the first thing about raising birds. What do the chicks eat? How will they survive in the cage? I know the alpha male seems to be the daddy and already he's territorial. I have no idea what to do. Help please.
Well, I don't know anything about Zebra Finches specifically, but I do know a few things about birds (do an online search on Zebra Finches to find out specifics). The mother birds usually feeds the babies, you don't worry about that.
The daddy bird usually stays out of it, but not always, so find that out. Some daddy birds kill the babies, also find that out, you may need to separate mother and babies from him until they are quite a bit larger. In fact this information pretty well covers the whole spectrum of "nature". Hope this helps, kinda :).
I have 2 zebra finches. A male and a female. My female zebra finch laid eggs and everything was fine, until one day the male zebra finch found a hole in the cage and escaped outside.
The female is still sitting on the eggs, but I don't know if she can raise them alone, because this is her 1st nesting. So can she raise them alone with out a daddy?
My finch eggs have hatched. Yey! I am very happy with this as we have had eggs before, but all were infertile as we had two females and weren't very clued up about birds!
Since then my white female sadly died from egg binding. I now have done some very intensive research on finches. Since my girl past my other female was depressed so I made the choice to get her a male and now we have eggs that have finally hatched. The babies are about 1 week old now and are making lots of noise even though I have yet to see them. And I am wondering if there is anything I can do to help mum and dad to give them a better chance of survival? I have yet to find any information about how I can help?
I have 2 female zebra finches. I want to get a male so they can have babies, but I'm scared the 2 females would fight, they are kinda like sisters. One is a little smaller and the other one is fat (always eats xD). So if I got 1 male would the females fight and I would have to get 2 males, 1 for each? Also, would I have to get 2 nests or 1 nest would be okay, and they would take turns breeding? Also my cage's length is 25 inches how many finches could I fit in there? Once the babies are older do I separate the youngsters so they don't breed?
By Olivia from Ontario
Hi there. I just went to my zebra finch cage this morning to find one egg in the food bowl. Mum and dad are still in the cage. They chucked out all the seed I put in on floor, and she laid one egg. They're new parents, but we put in a finch nest made of wicker. The female is interested, but the male chases her out of nest. Why? I don't want to take him out of cage, since I've only got one available cage, but I'm frightened he's going to reject her and the baby chick once hatched. Any advice? I'mnew to this hatching lark and breeding.
My zebra finch has laid eggs. When they hatch will all of the birds be able to live in the same cage as their parents when they are mature?
By Robyn Fed03/15/2012
The mother will lay about eight eggs, which will hatch in about two weeks.
Be sure to count the amount of eggs laid and without disturbing the nest too much or at all.
If after three weeks has passed and the eggs have not hatched, they are not ever going to hatch and must be removed quickly as the mother will lay more eggs, and then it will be hard to tell which ones are going to hatch and which ones are not going to hatch.
It is necessary to separate the pair between egg layings in order to rest before breeding again.
After 21 days the baby birds will leave the nest to the cage and start to eat on their own.
After 6 weeks they will develop their adult coloration and feathers.
Separate the little finches from their parents after 6 weeks.
They should be moved to a separate cage at this time.
Talk to your local bird store about selling or trading them for seed and supplies.
For more information go to:
Have fun, these are beautiful birds!
I had 7 finch eggs; 5 hatched, but 2 didn't. Should I take them out?
MsHawklet is right. Leave the eggs in there for a while. Eventually the parents will push the unhatched eggs out of the nest, then it'll be safe for you to remove them.
I had a pair of zebra finches several years ago that quickly became 7 (5 hatched eggs). This happened a couple of times with them.
I now have two more zebra finches. I didn't want them to breed this time though, so I got two males. They have a grand time together and I don't have to worry about nests or eggs or hatchlings.
I have a male and female zebra finch. In the cage there are 2 open half shell-shaped nests and one enclosed peep-hole type nest. Usually every other day I remove the eggs, but recently I couldn't get to the ones in the enclosed nest. Then I noticed they were each in that nest more often, together at night, and usually at least one was always there during the day.
I stuck my finger in the opening to check for eggs, it had been a couple of weeks and felt a live baby bird, to my surprise. I called the pet store and they basically said to leave it alone, the parents will care for it. I can see it moving in the nest and I can hear it's attempt at "trumpeting". I'm guessing it is a male. I can see grey fluff, but it hasn't come out yet.
What are the stages of egg laying to hatching and the stages of development and growth for these birds? (How old do you think it is and how does it grow week by week?) I've read both to separate and not to separate them "at the right time", please explain. What can you tell me that I would not think to ask? I've had 2 pairs (in separate cages) for 8 months now, but I am still new at this. I really do not want any more babies.
I would suggest putting the finches in seperate cages or not putting in a nest for them. They don't really need to have one to sleep in.
I have a male and a female finch that both live in the same cage. They recently laid 5 eggs in their cage, but they decided to lay their eggs in their food bowl that had all their food in there. I put a new food bowl with new food in the cage.
Yesterday I found that 2 eggs were hatched, but three still need to hatch. With the parents going in and out of the food bowl, and sitting on the eggs, the food dish has poop and old pieces of cotton all on the side. I don't want to mess with the birds until all the eggs have hatched. But I want to be able to clean their area and make it more comfortable for both the parents and for the babies to grow up.
When the babies are fully hatched out if their shell, can I clean the food dish and make it cleaner? Or should I just leave it alone. I also don't want them to suffocate the babies with the old stringy cotton. Can someone help me please. Thanks. I also want some tips on food the mother and father can feed them.
You didn't mention whether or not there is a nesting basket in the cage. Did they just ignore it or was there not one in the cage?
I never had the problem you do but i would not mess with the birds or babies.
If there is no finch nesting basket in the cage, get one and line it with new nesting material. Maybe the parents will check it out. If they start using it, maybe you could put the babies in there when they start feathering. Or not. You might want to check with an avian vet.
I feed my finches raw veggies and fruit all the time along with their seed. Mine love broccoli and apple best. Oh and corn on the cob (not cooked). I also make up a small batch of rice with mixed veggies in it. They munch on this all day.
Also for breakfast I make them scrambled eggs (use water not milk) I leave in the shells (crushed) this is good calcium. Just remember not to use salt. When they have babies I also have put in a dish of baby food mixed with baby rice cereal. Sometimes they eat it and some times they don't. Might be worth a try.
Hope this helps somewhat with your problem. Please keep us posted. At one time i had 13 birds of various varieties large and small. They are a joy (work yes, but worth it).
I have 2 male finches and one female finch (all Zebras). I have tried to add a pure white finch before, but they wouldn't play with her or be very nice and she died.
This morning, I went to clean their cage and found a egg in their seed bowl. I have never put in a breeding nest and am now unsure if the egg will hatch or if this is just something that happens every now and again. I'm rather confused because I was told they wouldn't breed without privacy.
What should I do to look after a baby finch? Will they lay another egg? I'm assuming no, but thought I should ask anyway. Will it be a issue that there is two males?
Thanks to all that help. Lana :)
By Alanah from Brisbane
By Kathy Lam02/10/2011
I had Finch's that also laid an egg in their food bowl. I placed a nest in their cage. One that hangs. It wasn't long before eggs started appearing. I would place shredded news papers, cat fur and other soft items in the cage for them to build their nest with. Before you new it, I was the owner of 16 babies. It is truly fascinating to watch. They pretty much will take turns in caring for their young. However when they got older (Showing their colors) I would separate the males and females. I kept the breeders together. I am not sure how two males would react to the babies since both parents have an active role in raising their young. You may want to call a pet store and get an expert opinion. But if you could possibly figure out which is the father, it would be an experience you would want to see first hand.
I have Zebra finches and they just hatched an egg. What kind of food,etc. should I feed them to ensure a healthy offspring?
By Sherry from Hickory, NC
If you dont put a nest in the cage they will not have babies or lay eggs.
I had to take my male zebra finch out of the cage while the female was laying eggs, because she was fighting with him. Now the babies are hatching and I want to know if I should put him in again.
By bird lover from ME
By ed robertson05/18/2010
Make sure you have plenty of room. Your cage is going to get crowded.
Trade some young birds to promote genetic variety.
A calcium source and lots of good food should help divert his attention. Don't rush the reintroduction. She has her own agenda until she notices that he is really cute and then it will start all over again.
I have a breeding pair of Zebra finches who have recently hatched a brood of 3 chicks. They are in a very confined small basket nest. Should I move them to a larger nest? They are about 8 days old and I'm afraid that as they grow one will fall from the nest or be accidentally pushed out.
Wanda from Calgary
By ed robertson05/18/2010
Hard call. Find a local breeder or bird club.
They need their combined body heat to keep each other warm until they get old enough.
If you change nests, handle them carefully. Make sure they don't get too much room and get separated from each other.
Use a larger nest for the next clutch. Make sure you have enough nesting material so that the mother can adjust the nest size to the brood size.
I am looking for someone in South Jersey that raises zebra finches. I can't seem to buy them locally.
Tom from NJ
By ed robertson05/18/2010
check your state department of agriculture or neighboring states.
Thrifty Fun has been around so long that many of our pages have been reset several times. Archives are older versions of the page and the feedback that was provided then.
I have two finch birds, a boy and a girl, they have laid eggs and I don't know if they are going to hatch.
I have a female and male Zebra finch. They have laid 4 eggs in the food dish and 1 on the bottom of the cage. They sat on them for about a week and then quit sitting on them. My husband noticed yesterday that there was 2 more eggs, and today there was another 1 in the dish.
We are wondering what to do because we think that the ones that were there at first might be no good, but we do not know which ones where just laid. Can you help us by telling us what we should do. Thanks.
Donna from Barrie, Ontario
You don't say if you have a nest in the cage. They sell small nests for finches. If they have a nest they will probably sit on the eggs and they will hatch. You really don't have to do much, they take care of them all by themselves. As for the eggs you have now that they haven't sat on, yes, I would get rid of them. But do get a nest and some nesting material, all can be found at any pet store. I only know because I have had finches in the past and they raised 3 sets of off springs, very cute.
But of course once the youngin's get of age they need to be put in a different cage. They can attack the mom (wanting to take over the "nest") once they get older and I'm sure you don't want that. Good luck. Tweet, tweet!
And, before I forget, I hope you also feed them more than bird seed. They love fresh veggies and fruit. Mine had a feddish for cucumbers and lettuce. Experiment and see what they like. (03/21/2009)
I have a pair of zebra finches and the male has been building the nest for a few weeks now with everything he finds (nesting material from the store, string I've given them, some price tab he found from the cage, and even ivy leaves from next to cage). Hes' making a great home for his family, but they haven't laid any eggs yet.
Yes, I've seen them mate, when he makes his "noises" and flaps up on top of her and does his thing and all, and then she does it to him which is weird but they do what they need to do, yet no eggs? Help?! Am I doing something wrong, or are they infertile or what's up?
Selah W from Spokane, WA
Mine had their eggs in the bird bath in which I let them dust themselves with corn pellets. Two weeks after the young were born, I put nesting material in and they made a nest for the young. The reason was because I thought the young were too weak to survive, so I continued to discourage them. The young are healthy and in a separate cage now because the original is too small for four birds. (08/15/2007)
I have two finches that have laid egg after egg, they have a total of 9 eggs. I just left the eggs alone because they are still sitting on them. They are taking turns sitting on them, but none have hatched yet. Please can you give me some information about them?
Finches sit on their eggs almost all of the time after laying them. Either one or the other bird will take turns to keep them warm until they hatch. Hatching usually takes about 2 weeks, but finches will lay on eggs forever, even if they never hatch. Because finches are very tiny, they do not lay them all the same day, so a good rule of thumb is to make sure 3 weeks has passed until you discard them.
Remember that the eggs must be in some sort of sheltered area inside the cage, so make it possible for them to be sat on. Finches are funny birds, so if you have more than one female laying eggs, and only one nesting spot, they will all squish inside it to "mother" the eggs and hatchlings. This can cause the babies to be crushed with too much weight. There can even be baby bird legs deformed from being bent or displaced due to over crowding.
I have added a pic of a standard finch nest, but you can make one out of cardboard. They do need a nesting material for the nest, fibre branches and rolls are sold (if you want to buy stuff) or Kleenex, toilet paper, etc, can be torn and stuck into the rungs of the cage. Just leave it there, the birds will take care of building their own nest.
I hope this helps. Right now I have 2 pair of coupled finches, and 6 eggs. I raised others for years just for fun.
Enjoy. Oh, don't forget to give your finches bird gravel, and a cuddle bone. This helps them to have strong eggs, so they harden. They also love pieces of apple, lettuce, etc. (05/19/2009)