The right of possession is in the mortgagor unless agreed otherwise though by the common law it was in the mortgagee.
Who shall have the right of possession depends upon the contract of the parties but if there is no express provision in the contract the mortgagor has the right of possession until breach occurs on his part. By the common law the mortgagee had a right of possession but now in most of the states the mortgagor has this right and cannot be deprived of it at least until breach.
The duty of the mortgagor is not to impair the value of the property. The duty of the mortgagee in possession is to treat the property as a prudent owner.
The general duty of the mortgagor is not to decrease the value of the security by pulling down buildings or other acts of destruction, though he can hardly be said to have any duty to keep the place at its original value. When a mortgagee goes into possession he must give that care to the land that a prudent owner would give. He must see that it is insured, that taxes are paid, etc., though he may add expenses of this sort to the debt. He also must allow a reasonable rental for the value of the premises while in his possession to go to reduce the debt, and whatever rents and profits there may be from the land he is not entitled to except in payment of the debt.