Verifiable Sundarbans tiger weights are not found in any scientific literature. Forest Department records list weight measurements, but all are guesstimates and not verifiable. There are also reports of head and body lengths, some of which are listed as over 366 cm (144 in). More recently, researchers from the University of Minnesota and the Bangladesh Forest Department carried out a study for the US Fish and Wildlife Service and weighed three Sundarbans tigresses from Bangladesh. Two of them were captured and sedated for radio-collaring, the other one had been killed by local villagers. The two collared tigresses were weighed using 150 kg (330 lb) scales, and the tigress killed by villagers was weighed using a balance scale and weights. The three tigresses had a mean weight of 76. 7 kg (169 lb). One of the two older female's weight 75 kg (165 lb) weighed slightly less than the mean because of her old age and relatively poor condition at the time of capture. The teeth wear of the two radio-collared females indicated that they were between 12 and 14 years old. The tigress killed by the villagers was a young adult, probably between 3 and 4 years old, and she was likely a pre-territorial transient. Skulls and body weights of Sundarbans tigers were found to be distinct from tigers in other habitats, indicating that they may have adapted to the unique conditions of the mangrove habitat. Their small sizes are probably due to a combination of intense intraspecific competition and small size of prey available to tigers in the Sundarbans, compared to the larger deer and other prey available to tigers in other parts.