According to AllThingsD, a not-yet-public comScore mobile audience measurement report reveals that in the month of August Instagram passed Twitter for the first time to claim the title of  leader in mobile daily engagement. During the month, Instagram is said to average 7.3 million daily active users, topping Twitter’s 6.9 million DAUs. Those instagram mobile users reportedly spent 257 minutes on average accessing the in August, compared to 169.9 for the average Twitter user. Instagram managed these feats with 7 million less unique visitors, 22 million to 29 million. Conclusoin: Twitter has more users, but Instagram is getting better engagement. [Source AllThingsD]