hunt_create_sighting_effect

hunt_create_sighting_effect = {
	if = {
        limit = { NOT = { exists = scope:sighting_county } }
        save_scope_as = sighting_county
    }
	# Track who can use the sighting
	set_variable = {
		name = animal_type
		years = 3
		value = $ANIMAL$
	}
	# Track who can use the sighting
	set_variable = {
		name = sighting_owner
		years = 3
		value = $OWNER$
	}
	# Stop sightings in the same place too regularly
	set_variable = {
		name = recent_sighting
		years = 10
	}
	# Add sighting modifier
	add_county_modifier = {
		modifier = hunt_sighting_$TYPE$_modifier
		years = 3
		desc = hunt_sighting_$TYPE$_modifier_custom_desc
	}
}

As written in game/common/scripted_effects/00_hunt_effects.txt.