Communication and time - activity budgets in the New Zealand fur seal Arctocephalus forsteri (Lesson)

Abstract

Communication and time activity budgets of the New Zealand fur seal Arctocephalus forsteri (Lesson) were investigated (at irregular intervals) from 18 March 1993 to 18 February 1994, with preliminary feasibility studies from 27 March 1992 to 15 December 1992. Data were collected from two study sites; Cape Palliser on the southern coast of the Wairarapa (communication and time budget data), and Turakirae Head on the north east Wellington coast (time budget data only). Recordings of fur seal calls were analysed and the frequency of call and posture in relation to age and sex was investigated. Use of calls and postures varied according to social context and status. Time activity budgets were observed and recorded using focal animal sampling technique (Altmann 1974). Time budgets exhibited seasonal variation and classification and regression trees were used to analyse patterns of time budget behaviour with respect to abiotic conditions. Time budgets differed between Cape Palliser and Turakirae Head and these results were compared with previous studies carried out at Taumaka (Open Bay Islands, Westland). The present study shows there is variation between age and sex classes and with season in both time budget behaviour and - to a lesser extent communicatory behaviour - between different demes. It appeared likely that individuals display a considerable degree of behavioural plasticity according to abiotic (climatic) and biotic (population structure, social status, seasonal hormone levels) conditions.