What has made the wolf leave her home in Mexico to roam in the United States?

The wolf had crossed from Mexico into the United States after having seen her mate caught in a trap. She hadn't wanted to leave, but her mate had snapped and snarled, trying to chase her away from the danger. She'd been nearby when the men had come. Now she is ultimately careful, never returning to a kill, crossing roads in daylight, or going under a fence in the same place twice. Just west of Black Point, the wolf stops. She's scented the trap but it takes some time for her to figure out exactly what has happened.