Nest boxes made by park wardens and put up around Daventry Country Park for the benefit of breeding birds have been pulled down off trees by vandals.
Walkers have reported finding nest boxes lying on the ground to park wardens, who have also found several themselves.
With spring now upon us and birds preparing for the nesting season walkers using the park have expressed concern and anger at the nest boxes being pulled down.
Apparently someone is going around the park, probably under cover of darkness or early in the morning, pushing the boxes from the trees with a long stick then smashing them as they fall.
Walkers have counted up to ten nest boxes at the side of the paths and park wardens have stepped up their patrols in the hope of catching the perpetrators in the act.
Visitors to the park have been asked to report anything suspicious to the park wardens or police.