There are several reasons for this. The first is that biologists have not closely tracked snake populations until recently. While many states have reported declines in specific species, there was no overall system to track the number of snakes in each state. This is true of most reptile species, who are considered “data deficient” in population studies.
The second reason is that snakes are extremely hard to find. They are nocturnal, secretive, and excellent at using camouflage. They are much harder to observe than other species, and attaching monitors to them is difficult.
Scientists are aware that snake populations are declining, however, and that is cause for concern. Snakes are integral to their ecosystems, and they are a primary means of controlling rodent populations. Developing ways to count their populations in the U.S. and elsewhere is critical to helping preserve these beautiful and often misunderstood animals.