as an endling, and offers of a $1,000 reward for finding a mate for her brought even more visitors to see her. During her last four years in solitude (her cage was ), Martha became steadily slower and more immobile; visitors would throw sand at her to make her move, and her cage was roped off in response. Martha died of old age on September 1, 1914, and was found lifeless on the floor of her cage. It was claimed that she died at 1 p.m., but other sources suggest she died some hours later. Depending on the source, Martha was between 17 and 29 years old at the time of her death, although 29 is the generally accepted figure. At the time, it was suggested that Martha might have died from an apoplectic stroke, as she had suffered one a few weeks before dying. Her body was frozen into a block of ice and sent to the Smithsonian Institution in Washington, where it was skinned, dissected, photographed, and mounted. As she was molting when she died, she proved difficult to stuff, and previously shed feathers were added to the skin. Martha was on display for many years, but after a period in the museum vaults, she was put back on display at the Smithsonian's National Museum of Natural History in 2015. A memorial statue of Martha stands on the grounds of the Cincinnati Zoo, in front of the "Passenger Pigeon Memorial Hut", formerly the aviary wherein Martha lived, now a National Historic Landmark. Incidentally, the last specimen of the extinct Carolina parakeet, named "Incus," died in Martha's cage in 1918; the stuffed remains of that bird are exhibited in the "Memorial Hut". Extinction causes The main reasons for the extinction of the passenger pigeon were the massive scale of hunting, the rapid loss of habitat, and the extremely social lifestyle of the bird, which made it highly vulnerable to the former factors. Deforestation was driven by the need to free land for agriculture and expanding towns, but also due to the demand for lumber and fuel. About 728,000 km2 (180 million acres) were cleared for farming between 1850 and 1910. Though there are still large woodland areas in eastern North America, which support a variety of wildlife, it was not enough to support the vast number of passenger pigeons needed to sustain the population. In contrast, very small populations