Thank you for submitting your item for appraisal. This appears to be a chinese painting on canvas, oil paint directly applied on to the cotton canvas, depicting a sparrow on a branch. The painting is signed 張卢 and bears a hardly visible red artist´s seal. The painting was most likely painted in the 1980s when supply of artist materials was still difficult. I would advise you to remove the plywood on the back, as it leads to browing of the colours. There is no information on this artist available. Zhang is a very common name.
The estimate is based on similar items offered or sold at auction and condition.