Tiger sharkHONOLULU (HAWAII)- Traditionally they say in Hawaii that in the fall it is more dangerous to swim in the ocean. Chances are bigger of getting bitten by a shark. A recent study shows that there could be something behind this folk wisdom.

In the fall, an increased number of tiger sharks make their way to the islands, likely to give birth. Both the timing of this migration and tiger shark pupping season coincide with Hawaiian oral traditions suggesting that late summer and fall, when the wiliwili tree blooms, are a period of increased risk of shark bites.

But authors Carl Meyer and lead author Yannis Papastamatiou, of the Florida Museum of Natural History, told NBC News that people shouldn’t jump to the conclusion that this migration is directly related to recent shark bites near the islands.

Extremely rare
That’s because shark bites are extremely rare — claiming only an average of 15 lives per year globally, according to The International Shark Attack File — and so they’re difficult to study and to understand the reasons behind them. There are only two to four shark bites in Hawaiian waters every year.

The study that found the potential link involved tagging tiger sharks over a seven-year period, and included more than 100 animals, most of them female. About 25 percent of the female sharks are expected to return to the main Hawaiian Islands every year, according to the study, to be published in the November issue of the journal Ecology.

Stick around
While some tiger sharks arrive and depart the islands each year, a larger percentage sticks around, the study found. That agrees with recent research on other animals showing that migrations typically don’t involve every member of an animal population, and — counter to popular belief — a large number of individuals typically stay behind during migrations.

read more at NBC News.