Targeting the TNR method mainly at feeding groups in urban residential neighbourhoods may result in increased group size, as a consequence of 2 major changes in group dynamics: sexually intact cats immigrate into the neutered groups more readily and neutered cats reduce their emigration rates, possibly because of a reduction in reproductive and competitive pressures. To maintain a high proportion of neutered cats in such cat groups, persistent TNR campaigns are therefore necessary.
Significance
Although popular companion animals, domestic cats pose numerous problems when free-roaming, including predation of wildlife, hazards to humans, impaired sanitation, and a decrease in their welfare. Thus, managing their populations is essential. The trap–neuter–return method (TNR; capturing, sterilizing, returning/releasing) is widely employed for managing cat populations. However, there is a lack of long-term controlled evidence for its effectiveness. We examined the outcomes of high-intensity TNR by performing a 12-y controlled field experiment. Neutering over 70% of the cats caused population decline when applied over contiguous areas. However, it was limited by a rebound increase in reproduction and survival. These findings provide a robust quantification of the limitations and the long-term effectiveness of TNR.
Less aggression was observed in the neutered groups, specifically, fewer agonistic neutered-neutered male encounters occurred. This reduced agonistic behavior of neutered males resulted in reduced fighting and vocalizations, potentially leading to fewer injuries and reduced transmission of fight-related infectious diseases and reduced noise disturbance from a human perspective. Regarding food delivery, the feeding groups were time-and-place dependent, exhibiting context-related social interactions. When competing for food resources, as neutered cats time their arrival in accordance with food delivery, they thereby gain access to the choicest items.
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