There has been a spate of dacoities and burglaries at night this winter particularly in Sangam Vihar, Ambedkar Nagar and Lakkarpur village in Faridabad. At around 1 a.m. today Sangam Vihar Station house Officer (SHO) Dhanvir Dutt was on patrol when he received a message about ``strange animal sounds and suppressed sounds of human movement'' emanating from the Pul Prahladpur area. Other patrol teams were alerted as there are certain tribes that use animal sounds to communicate with each other. The police reached there and arrested Rajbir and Sher Singh.