Loggerhead sea turtle used on every confirmed nest to prevent excavation by resident red foxes. A new concern with the steel cage technique is interference with the normal development of the nestlings' magnetic sense due to the use of ferrous wire, which may disrupt the turtles' ability to navigate properly. Efforts are underway to find a nonmagnetic material that will prevent predators gnawing through the barrier. Up to 40% of nesting females around the world have wounds believed to come from shark attacks. Infectious bacteria such as "Pseudomonas" and "Salmonella" attack loggerhead hatchlings and eggs. Fungi such as "Penicillium" infect loggerhead sea turtle
Varieties of Chinese increase, although there are also some sharp boundaries. However, the rate of change in mutual intelligibility varies immensely depending on region. For example, the varieties of Mandarin spoken in all three northeastern Chinese provinces are mutually intelligible, but in the province of Fujian, where Min varieties predominate, the speech of neighbouring counties or even villages may be mutually unintelligible. Classifications of Chinese varieties in the late 19th century and early 20th century were based on impressionistic criteria. They often followed river systems, which were historically the main routes of migration and communication in southern China. The first scientific classifications, based