Crows & Dogs

The Gray Crows and Red Dogs are the greatest fear of unregistered individuals and criminals alike. Surveillance drones capable of violence, where they are, crimes are hard to hide. They patrol the borders of slums, to make sure no unregistered sneak past. They also patrol other areas with randomized patrol routes, meaning criminals always have to be wary.
The government has been using these drones for decades, heavily improving their designs over time. The Gray Crow hoverdrones either fly or perch, scanning all individuals to detect suspicious situations and wanted criminals. While capable of combat if needed, they primarily are spies. When the need for a fight arises, they cry havoc and let slip the red dogs of war, vicious combat drones which use guns and metal teeth to kill.

Gray Crows

Hover-drones with eight small engines, capable of flying, hovering, and even perching on ledges to spy on people. Due to their dull colouring and soft engine noise, they are near-impossible to detect in busy areas. They even have sharp extensions that they can use to aim for eyes and throats.
Facial recognition has always been their weakness. There is a significant error-margin at a larger distance, causing the occasional false positive. While they can offload their footage to central servers, the sheer amount of Crows flying around means only a few at any time can validate their checks. Even in high-security areas, this causes a small delay.
Masks, however, the Crows can easily recognise. Some criminals have started using masks when they go out, both to hide their real identity and to make a name for themselves. The downside is that because the masks are near-instantly recognised, they guarantee a quick response and vicious crackdown.

Red Dogs

Walking drones the size of large dogs, capable of running at a top speed of 43 km/h, and a speed of 28 km/h while actively firing. They do poorly at rapid corners, however. They are coloured bright red, as a warning sign for everyone to get out of their way, and have sharp spikes protruding from their shoulders that will injure anyone they brush past.
The Dogs have sharp claws and teeth, have a bite strength of approximately 2,000 psi, and an internal shotgun capable of firing out of their throat. Where their Crow companions use cameras aimed at facial recognition, the Dogs use thermographic cameras focused on high-speed chases and following. They also are equipped with olfactory sensors, to track by smell and detect explosives.
The Dogs are weak at corners and tight spaces, forcing them to stay out of alleyways. Furthermore, without Crows to initially identify their targets, they are aimless and at worst might attack indiscriminately.