Emily: Centuries ago a natural phenomenon unlike any other was responsible for periodically blacking out the skies of North America.  This overwhelming cloud of darkness often took hours and even days to pass overhead, and would leave destroyed crops and desiccated landscapes in its wake.  These events weren't tornadoes or rainstorms of the meteorological variety, they were caused by flocks of passenger pigeons, sometimes a few billion individuals in strength.  The incredible size of the species population was larger than what most people could comprehend.  When a flock of passenger pigeons approached a town many villagers thought the apocalypse was upon them.  It was a plague of Biblical proportions.

Emily (Reading dramatically): And then the dark cloud was over the city, day was turned to dusk, the thunder of wings made shouting necessary for human communication.  When the flock had finally passed, almost two hours later,  the town looked ghostly in the now bright sunlight that illuminated a world plated in pigeon ejecta.

Emily: Why do we care so much about the passenger pigeon?  With population so strong it seemed impossible that the birds would ever become eradicated. And yet, 2014 marks the 100 year anniversary of their extinction with the death of Martha, the last of her kind, who died in the Cincinnati Ohio Zoo in 1914, although the birds had been extinct in the wild since 1902.  It's been estimated that in 1860 there were 3.7 billion passenger pigeons in North America.  From the north-eastern states, to Texas, and up to the Southern tip of the Hudson Bay. They made up the greatest population of  any bird species in our planet's history, but within 40 years they would become extinct. Groups nested together in concentrations so thick that tree limbs were flattened to the ground against their weight.  And if the birds didn't kill the trees by snapping the limbs under their weight, then their excrement surely would.  It blanketed the ground beneath them so thick and toxic that the tree would soon die because of it; literally poisoned to death.  The pigeons were valuable, but loathed.  Occasionally they would turn up during droughts and food shortages as a blessing, but in the same breath would be resented because they'd dig up and eat any of the recently planted seeds for crops.  Farmers, hunters, and trappers were all looking to earn some additional money from the sale of pigeons.  Their feathers held some economic value, as they could be sold to stuff pillows and beds- but it took thousands of birds just to make one mattress.  With groups swarming in such large numbers it was relatively easy to string up huge nets to toss over congregations in fields.  In order to entice larger flocks to land near a trapper's hide, a Juda pigeon would be employed.  Its eyes would be sewn shut, as to blind the bird, preventing it from seeing incoming flocks and trying to fly too early.  Rope was tied around its feet and then the bird was tossed up into the air to flutter back down, catching the attention of the migrating pigeons and calling them to land.  One three man team brought in over 50,000 birds over the course of one year this way.  Land owners took much more drastic measures to kill pigeons.  Sometimes they would poison grains in their fields with strychnine, making them unfit for consumption.  Women were encouraged to assist in asphyxiating pigeons because the act was not too strenuous.  They just had lay a few ounces of sulfur at the base of a tree and then light it, suffocating the birds above.  And if that didn't work, thousands of acres of woods would be burned out of fear that the migrants would soon set up house and destroy viable farm land.   And while we typically think of food waste as a surplus issue only faced by the consumer driven world of today, passenger pigeons were hunted in such great abundance that hundreds at a time were tossed into the streets to rot.  By the 1870s, as weapon and firearm technology advanced, so did the lust for trap shooting.  And, you guessed it, they wanted to shoot pigeons.  Between 1874 and 1881 the New York State Sportsmen Association claimed around 90,000 birds for their tourneys.  It was around this time that a small minority began to speak out against the competitions, primarily because of the cruelty of the sport and not so much of fear that the birds were under any threat of extinction.  Henry Bergh founded the American Society for the Prevention of Cruelty to Animals, the ASPCA, in 1866, and used his position to create laws banning trap shooting in New York, but tourneys simply moved across the river to New Jersey instead.  It wasn't until 30 years later in 1897 that Michigan became the only state to outlaw and ban the killing of pigeons, after they had all but disappeared from the state.  Near the end of the 19th century Passenger pigeons had been hunted relentlessly and excessively without cessation for 300 solid years.  Over that time nesting sites were annihilated and adult birds abandoned their chicks before they had fledged.  Legislation encouraged land owners to drain swamps and turn them into viable farm land, in turn destroying historic roosting areas.  And conservation efforts weren't fueled with public support until someone made a call to action at the American Ornithologist Union meeting in 1909, 40 years too late when sightings of pigeons had been spotty at best for the last 10 years.  The 100 year anniversary of the last pigeon, Martha's, death is a solemn reminder of our destructive potential as a species.  But here's a question for you, if we were able to develop and manufacture the technology to revive the passenger pigeon from extinction, do we have an obligation to do so, especially since we wiped them out?  And if so, do we attempt to also match their historic population numbers?  Imagine the impact 3.7 billion pigeons would have on a city like Chicago today.  Like every form of life, the pigeons were not an inexhaustible resource.  Our eyes bulge at the idea of a few trappers bringing in over 50,000 birds in a single year, but consider the millions of tons of fish removed from our seas on an annual basis.  A lack of regulation on commercial fishing worldwide means unintended bycatch.  Those fish, turtles, dolphins, and sharks not intended to be caught are indiscriminately netted every year by the thousands.  And by the time we develop accurate ways of calculating the number of those species at risk, it may be too late.  And consider the other species- 30% of amphibians are at risk for extinction, 21% of mammals, reptiles, and fish, and 12% of all birds.  And by the time we develop accurate ways of calculating the numbers of those species at risk, it may be too late.  When it comes to conservation we need to be proactive, not reactive.  We can be outraged about the early demise of the passenger pigeon, but we can't forget about the waning populations of every ecosystem today.  Let Martha and the year of the passenger pigeon serve not only as a valuable warning, but as a motivation to change before it's too late.

(Brain Scoop music plays)

It still has brains on it.