Concern for native birds and small mammals which are a keystone part of our ecosystems is not futile. They support literally everything required for human survival (carbon cycle, water, cycle, nitrogen cycle, pollination, sea dispersal, pollution control, etc) directly, and indirectly by their behaviors which have coevolved for millions of years. Invasive, feral cats, just like humans have only been here for a very short window of time, and while there are still native birds and mammals and plants left to care for, we can and should support them by minimizing the wonton carnage and death which we unleash each year. You’re probably aware that in North America alone feral cats kill between 10 and 30 billion native birds and small mammals a year. Euthanasia instead of trap neuter release is not a sailed ship. Planting native (human intervention) and undoing the lawns (human intervention) that have destroyed our native ecosystems is not a sailed ship. There is hope and it is exciting to work towards this in your own community and I hope you come to see that. The results (insects return, the soil enriches and traps carbon, and birds you've never seen before sing on your back porch in the morning) are nearly immediate and heartwarming
Edit: typo