With apologies for in any way reprising those tasteless jokes which reference  the alleged paucity of stray dogs in areas abutting budget priced chinese restaurants, I offer for the canny investor a convenient metric by which to know in advance that global warming's grip on the throat of humanity has inexorably tightened beyond repair.  A leading indicator, if you will, of the food price apocalypse prophesied in the latest government climate change report.

The amateur anthropologists among us have from time to time turned an amused glance at the culinary habits of rural americans, who not infrequently hunt and dine upon small mammals (some from the class rodentiae,) viz: squirrel, racoon, possum, rabbit, etc.

There are even several festivals at which Southern politicians gather annually to demonstrate their readiness to consume small mammals.

Likewise, rural Americans are willing, even eager, to spend a day catching fish which they promtly and enthusiastically ingest (toxic pollution of the local freshwater habitats notwithstanding).  In immigrant communicties near San Francisco Bay, and New York City, it is common to note the consumption of species which have earned from public authorities a warning that they are not fit to eat.

The common element: need.

When you are hungry, and have not the wherewithal to shop at Safeway, you eat what you can catch.

I propose to you that a time will come when "urban foraging" will become so widespread and intense that a particularly ubiquitous (if noxious) urban mammal will be transformed from pest to food source.

When this happens, the expenditures by municipal governments to exterminate this species will be unnecessary, and budgets for the same will shrink, leading to layoffs.

So it will be said, "First they came for the dogcatchers, but I was a ratcatcher, so I did not speak up...and soon they came for me"