The Danish History of Corruption and Anti-Corruption, 1660 - 1900
American mink (Neovison vison) kits are born altricial and fully dependent on maternal care, for which the kits’ vocalizations appear essential. We used auditory brainstem responses (ABRs) to determine: (1) hearing sensitivity of adult females from two breeding lines known to differ in maternal behaviour and (2) development of hearing in kits 8–52days of age. We also studied sound production in 20 kits throughout postnatal days 1 to 44. Adult female mink had a broad hearing range from 1kHz to above 70kHz, with peak sensitivity (threshold of 20dB SPL) at 8–10kHz, and no difference in sensitivity between the two breeding lines (P>0.22) to explain the difference in maternal care. Mink kits showed no signs of hearing up to postnatal day 24. From day 30, all kits had ABRs indicative of hearing. Hearing sensitivity increased with age, but was still below the adult level at postnatal day 52. When separated from their mothers, kits vocalized loudly. Until the age of 22days, 90% of all kits vocalized with no significant decline with age (P=0.27). From day 25, concurrent with the start of hearing, the number of vocalizing kits decreased with age (P<0.001), in particular in kits that were re-tested (P=0.004). Large numbers of mink are kept in fur industry farms, and our results are important to the understanding of sound communication, which is part of their natural behaviour. Our results also suggest mink as an interesting model for studying the development of mammalian hearing and its correlation to sound production.
Journal of Experimental Biology, 2013, Vol 216, Issue 18, p. 3542-3550
corruption; history of corruption; history of corruption and anti-corruption; auditory brainstem response; ABR; American mink; Hearing; maternal behaviour; Mustela vison syn; Neovison vison; social communication; vocalization