The incident is being investigated as a matter of urgency by the Countdown chain of supermarkets, operated by the Australian-owned Progressive Enterprises Ltd.
The woman, who asked to remain anonymous, discovered the bird after eating a few salad leaves from the $4.49 bag of Fresh Zone value family mix salad.
She bought the 300g pack on Sunday but did not notice the dead bird inside until preparing dinner for her family on Wednesday night.
The bird was whole and was about 10cm long.
"Grossed out" by the discovery, the woman rang an 0800 telephone number printed on the plastic salad packaging.
She received an immediate apology and yesterday was told a supermarket staff member would collect the salad pack from her home in order to investigate how a dead bird came to be sealed inside.
The woman said she was happy with Countdown's handling of the situation, but would think twice about buying packaged salad for a while.
Countdown national communications and public affairs manager Luke Schepen said the incident was believed to be a one-off occurrence.
The product batch had an expiry date of September 1, 2012, and so it was unlikely any further stock from the order was on sale, he said.
"Food safety and quality is of the utmost importance and this investigation is now under way as a matter of urgency."
The salad was packaged by a Countdown supplier at a South Island facility, which did not produce stock for retail in the North Island, Mr Schepen said.
