On September 1, 1914, the last passenger pigeon in the world, Martha, died in the Cincinnati Zoo; her death cemented the extinction of the passenger pigeon species, whose population numbers were in the billions, and remains a solemn reminder of the impact humans have in their surrounding ecosystem.

The demise of the passenger pigeon was a shocking one. Early colonists documented flocks of pigeons so dense they could blot out the sun. Estimates of the pigeon population were qualified as humanly incalculable (though scientists, in their hubris, estimate a rough population of between 3 – 5 billion pigeons at their peak population.

While migrating across the continent, passenger pigeons “make waste whole forest in a short time, and leave a famine behind them for most other creatures,” noted colonial historian Robert Beverly, in 1722. “They have never been observed to return to the northern countries in the same way they came from thence, but take quite another route, suppose for their better subsistence.”

However, as colonization and the rapid expansion of America swept across the continent, the timber felled restricted food resources, which in turn limited the species’ population growth. Instead of breeding twice a year, pigeons began to reproduce only once annually. To compound the problem, commercial hunting of the passenger pigeon was a popular sport. By the time the population dwindled into the millions, the species was already doomed.

Although one of the most memorable species extinctions and a blemish on the industrialization of America, Martha and her species helped give rise to the modern conservation movement. Besides allotting protected wildlife refuges, imposing hunting restrictions on endangered species, new techniques are becoming commonplace in the fight against extinction:

Genome resource banking allows for scientists to store vast amounts of genetic variations that occur in individuals throughout a species population, which can be utilized to increase biodiversity in small or isolated populations of endangered animals.

Assisted reproduction can overcome the barriers that may pop up when attempting to breed species in captivity. Scientists now are able to monitor cyclic ovarian activity, collect spermotazoa samples, artificially inseminate and produce embryos in vitro, as well as transfer them to the host mother.

Scientists also employ various other techniques to monitor specie population and evaluate its well-being. Camera traps are a successful technique in the wild, especially remote areas. Over the past few years, numerous animals thought to be extinct have been “re-discovered” after the deployment of camera traps (the hairy-nosed otter was rediscovered after 100 years without contact with the human world).

Other non-invasive techniques such as monitoring hormone levels and performing genetic analysis on animals can clue scientists into the health and diversity of an animal population.