Am I religiously obligated to do anything after unintentionally running over a pigeon with my car on my way back from Umrah?

It is forbidden to kill pigeons in the Haram, whether the killing is intentional or accidental. The majority of scholars hold that the killer is obligated to offer expiation, even if the act was mistaken or forgotten; only the sin is lifted from him.

The expiation for killing a pigeon is a sheep, based on what the Companions ruled. The killer is given a choice of three options: 1. Slaughter a sheep and distribute its meat to the poor of the Haram. 2. Appraise the sheep in monetary value, then purchase food with its equivalent value and distribute it to the poor of the Haram. 3. Fast for a number of days equivalent to the value of the sheep, such that each mudd of food corresponds to one day of fasting.