The dead birds, found across the north east of the city, had toxic levels of rat killer in their system.
Officers are investigating whether the birds died after eating animals that have been poisoned legitimately, or whether there is a more sinister explanation.
The West Yorkshire Police Wildlife and Rural Crime unit specialises in the policing of wildlife crime across the region.
In a statement posted on Facebook, the unit said: "Police are currently looking at cases of deceased raptors that have been located around the North East Leeds area which have been found to contain significant amounts of rodenticide variants.
"At this time we are looking into whether or not these raptors have died due to consuming animals that have been poisoned legitimately and due to the amount the raptor has consumed has proved fatal or if there is another line of enquiry."
Officers urged the public not to touch or handle dead birds of prey, but to report it immediately by calling police on 101, and Natural England on 0800 321 600, using the mobile app What3Words to pinpoint a location.
Anyone with information is asked to email [email protected]
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