SEASONAL DIFFERENCES AT TONGA ISLAND

By On Thursday, September 26th, 2013 Categories : Review

There was also a decrease in the number of seals swimming at Tonga Island. Early in the season (Nov-Dec), the majority of the seals swimming were bulls moving between territories to challenge for the territory. There were few seals in the water at anyone time in comparison to later in the season. After pupping and re-mating, the males will begin to leave and, as the pups become older, the cows begin to move into the sea for thermoregulation. On 8 of 13 occasions, the number of cows “loafing”, on the West side of the island exceeded 20 with maximum numbers at anyone time ranging from 26-47 (approximately 34% of all seals visible in the scan).
Given that habituation occurs over a period of time, it will be likely to influence seal behaviour over time as was observed at Tonga Island and Kaikoura. At Tonga Island more resting was observed in the 2000/2001 field season. With increasing tourist traffic the seals are becoming more accustomed to the tourists and continuing with more normal behavioural patterns.
The following season this behaviour decreased dramatically. Only twice out of 32 scanS did numbers of cows swimming reach 20, the maximum numbers on those two occasions were 20 and 21 (25.5% of all seals visible). The other reason relates to the increase in boat and kayak traffic, which may increase the chance of a swimming seal getting bumped into or frightened by a boat while in the water. Swimming is another behaviour that warrants more investigation along with mother/pup interactions and should be compared to numbers of vessels around a focal group throughout the day. At Kaikoura, differences between seasons were only observed at Ohau Point, where there was a decrease in comfort and mother/pup interactions and an increase in swimming. The decrease in mother/pup interactions may also relate to the time at which the scans were carried out.

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