Overexploitation or overkill results from hunting at a rate above the maximum sustained yield. The number of individuals that are hunted are higher than the number of individuals that will be born, so that the population cannot recover and will decline. Animals with a low intrinsic rates of increase, such as whales, elephants, and rhinos, are the most susceptible species, because of their limited ability to recover quickly. They reproduce too slow! Animals are even more vulnerable if they are valued either as food or as an easily marketable commodity. 

Photo: American Bison skulls, mid-1870s, waiting to be ground into fertilizer. Courtesy of the Burton Historical Collection, Detroit Public Library.

Overexploitation is not only a problem of the past, even now is overexploitation becoming a greater problem on our planet, with a fast growing human population! Many animals cannot cope with the amount we harvest for consumption or other use (e.g. Chinese medicine). Overexploitation and bycatch by commercial fisheries is such a recent problem, which causes the decline of several fish species, such as the Northern Cod. Modern fishing technology and expanding markets for seafood have caused the world's fish population to decline. Boats could now fish year round, day and night, even in ice and at great depths. There was no place the fish could hide. Along with the desirable species, such as cod and haddock, the nets also swept up many non-commercial species, or commercial fish so young they should be left in the ocean to reproduce. 

Photo: The photograph surfaced amongst the papers of the hunter who shot it in 1925. Little more is known.

Photo: A pair of thylacines that lived at the US National Zoological Park in Washington DC from 1902 to 1905.

In the early 19th century, anyone claiming that the Passenger Pigeon would become extinct would have been branded a fool. These pigeons were ones called the most numerous birds in the world. Due to the extremely large number of birds, they could cause great damage to the gardens and cornfields of settlers from Europe, killing them seemed to be justified. On the other hand, the meat of the Passenger Pigeon was tasty food for the people, who captured them in large numbers with nets. 

The major decline occurred in the 1870's. From this time on, there was no point in destroying them ruthlessly, neither would this have been economic. Within ten years, flock size dropped dramatically and at the end of the decade only small groups were reported. By 1896 there were only 250.000 Passenger Pigeons remaining in one single flock, but still they were not safe. The newly erected telegraph lines allowed a large group of hunters to communicate with each other. On a spring day in April they descended on the flock. At the end of the day the carnage was devastating: 200.000 carcasses, 40.000 mutilated, thousands of chicks destroyed or left to predators. Less than 5.000 Passenger Pigeons survived. The last reported individuals in the wild were shot at Babcock, Wisconsin in 1899, and in Pike County, Ohio on March 24, 1900. Some individuals, however, remained in Captivity. The very last Passenger Pigeon died alone at the Cincinnati Zoological Gardens at about 1:00 PM on September 1, 1914.

The Passenger Pigeon is probably the most common extinct bird species in museum collections. More than 1500 skins and skeletons have been preserved.

Photo: a passenger pigeon pair in the Rosensteinmuseum in Stuttgart, Germany. Copyright and courtesy by Sordes.