She neglected the birds until they died – has she committed a sin?
Question

                We used to raise birds, and my mother used to feed them, but she heard that it was wrong to go near the birds during her period, so she told me to feed them. But I was scared of them because sometimes they bite. I used to forget sometimes, until I forgot them altogether and they died. How can we expiate for what we did?.
Praise be to Allah.
      Firstly: 

    There is no basis for the belief that it is not permissible 
    for a woman to go near the birds during her period. There is no connection 
    between the two matters. What you must do is give up such beliefs. There are 
    certain rulings which apply to the menstruating woman but such matters are 
    not among them and are not at all connected to them. 

    The scholars are unanimously agreed that it is permissible 
    for a woman to slaughter animals (for food) when she is menstruating. See 
    al-Mughni, 13/311. 

    Secondly: 
Everyone who keeps these 
    birds or any other creatures is obliged to take good care of them. If he is 
    not able to do that then he should not keep them, and he should sell them or 
    slaughter them if they are the kinds of animals or birds that can be eaten. 
    There is a stern warning issued to the one who keeps an animal and does not 
    feed it or give it water until it dies. 

    Ibn Qudaamah al-Maqdisi (may Allaah have mercy on him) said: 

    Whoever owns an animal must take care of it and spend on 
    whatever it needs of food or appoint someone else to look after it, because 
    of the report narrated by Ibn ‘Umar, who said that the Prophet  (peace 
    and blessings of Allaah be upon him) said: “A woman was punished because of 
    a cat which she detained until it died of starvation, because she did not 
    feed it or let it go and eat of the vermin of the earth.” Agreed upon. If he 
    refuses to spend on it, he should be forced to do so; if he refuses or is 
    unable to do that, he should be forced to sell it or to slaughter it if it 
    is an animal that may be slaughtered (for food). End quote.

    Al-Mughni, 8/205 

    Al-Shawkaani said, commenting on the hadeeth about the woman 
    who detained the cat: 
It is understood from 
    this hadeeth that it is haraam to detain cats and similar animals without 
    giving them food and water, because this is tormenting the creation of 
    Allaah, which has been forbidden by the Lawgiver… al-Nawawi said: It seems 
    that she (this woman) was a Muslim, but she entered the Fire because of this 
    sin. End quote. 

    Nayl al-Awtaar, 7/7 

    It says in al-Mawsoo’ah al-Fiqhiyyah (5/119, 120): 
It is permissible to keep 
    animals for beneficial purposes, such as guarding (property etc), listening 
    to their voices and enjoying looking at them, but the one who keeps them is 
    obliged to give them food and drink, because of the sanctity of life. End 
    quote. 

    In the answer to question no. 48008 it says: 

    It is permissible to keep birds and similar creatures in 
    cages for pleasure, especially if that is because of their appearance or 
    their voices, subject to the condition that one feeds them and gives them 
    water. End quote.   

    See question no. 48008 for more detailed information. 

    Thirdly: 

    If your excuse for not feeding these birds until they died is 
    that you forgot and did not do it deliberately, then this is an excuse which 
    is acceptable according to sharee’ah. We ask Allaah to forgive you for that. 
    Allaah says (interpretation of the meaning): 

    “Allaah burdens not a person beyond his scope. He gets 
    reward for that (good) which he has earned, and he is punished for that 
    (evil) which he has earned. ‘Our Lord! Punish us not if we forget or fall 
    into error…’”

    [al-Baqarah 2:286]
And Allaah has answered 
    this prayer of the believers and says, “I have done that,” as was narrated 
    by Muslim (126) from the hadeeth of Ibn ‘Abbaas (may Allaah be pleased with 
    him). 

    And Allaah says (interpretation of the meaning): 

    “And there is no sin on you concerning that in which you 
    made a mistake, except in regard to what your hearts deliberately intend”

    [al-Ahzaab 33:5]

    Since you did not deliberately intend to kill them, there is 
    no sin on you, in sha Allaah. 

    And Allaah knows best.