The Texas Border Volunteers are simply back-up for U.S. Border Patrol. The goal of the volunteers is not to engage with the "criminal trespassers," as they call them, but alert border patrol of their findings.
In late June, as a border patrol drone zig-zagged across a ranch and patrollers on the ground searched for crossing immigrants, it was a volunteer who spotted a group of 10 immigrants running across a field. The volunteer called it into headquarters and helped border patrol apprehend five of the 10 immigrants.
"They catch a lot more because of what we do," Cottrell says.
Since 2008, when the volunteers began keeping logs, they have reported 2,142 illegal immigrants on ranch land in Brooks County. U.S. Border Patrol has been able to apprehend 1,180.
The number of immigrants passing through Brooks County is on the rise. The Rio Grande Valley saw a 65 percent increase in apprehensions in 2012. While border crossings appear to be decreasing nationwide, south Texas stands out.
Border patrol says it has dedicated historic levels of personnel, technology and resources to the border, but acknowledges they have seen an uptick in apprehensions in south Texas among immigrants from central America, including El Salvador, Guatemala and Honduras.
Border Patrol officials in the area say they work well with the border volunteers and appreciate the extra eyes and ears on the ground.
"The last month I was here, I spotted myself 33 [immigrants]," says Jean Swan, the only woman on patrol one weekend night. "Our nation is supposed to have a border and it is being breached constantly. The government is not doing anything about it and so some of us want to do it, anyway."