[oliviababy]

As an aunt can I file for temporary custody of my niece if her mother has abandon her?

[N0help4u]

Where did she abandon her? And how long ago?

[N0help4u]

For a while abandonment meant left without any supervision. Meaning that leaving a child with a trusted adult was not abandonment. But it looks like they may have changed the law again to any of these, but probably depending on state law.
Leaving a child with another person without provision for the child's support and without meaningful communication with the child for a period of three months;
Making only minimal efforts to support and communicate with a child
Failing for a period of at least six months to maintain regular visitation with a child;
Failed to participate in a suitable plan or program designed to reunite the parent or guardian with a child;
Leaving an infant on a doorstep, in trash cans and dumpsters, and on the side of the road
Being absent from the home for a period that created a substantial risk of serious harm to a child left in the home
Failing to respond to notice of child protective proceedings; or
Being unwilling to provide care, support, or supervision for the child

[ScottGem]

You need to define what happened. What do you mean by abandoned? Where is the child now? How old is the child?