There is some way to massively collect DNA samples from the environment. https://www.newscientist.com/article/2375624-air-pollution-monitors-have-been-accident

There is some way to massively collect DNA samples from the environment. https://www.newscientist.com/article/2375624-air-pollution-monitors-have-been-accidentally-harvesting-wildlife-dna/ https://www.newscientist.com/article/2375624-air-pollution-m... https://www.bbc.com/future/article/20230606-how-air-pollution-sensors-can-find-wildlife https://www.bbc.com/future/article/20230606-how-air-pollutio... https://www.sciencedirect.com/science/article/pii/S0960982221016900 https://www.sciencedirect.com/science/article/pii/S096098222... these can be deployed at great density in an array providing granularity made to order.