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"Variability in length of lactation and maternal association allows otariids flexibility to\r\nbuffer their young against changes in nutrition. It also increases the chance of their young\r\nsurviving to sexual maturity, which is particularly important in a declining species such\r\nas Steller sea lions {Eumetopias jubatus). Timing of weaning is a critically important\r\nevent in mammalian development that can affect subsequent aspects of an animal's adult\r\nlife, and may hold the key to understanding the population dynamics of Steller sea lions.\r\nUnfortunately no studies have yet fully documented the behavioural ecology of Steller\r\nsea lions outside of the breeding season.\r\nThe goal of my study was to document suckling behaviour over 13 consecutive\r\nmonths to determine the timing of weaning for male and female Steller sea lions under\r\nthree years of age at Southwest Brothers Island, Southeast Alaska (July 2004 - July\r\n2005). I also wanted to ascertain the haulout patterns and activity levels of the colony in\r\nrelation to season, prey availability, time of day, and weather. Finally, I sought to\r\nevaluate the feasibility of using an automated, time-lapse camera system to monitor sea\r\nlions and its potential for future use.\r\nMale Steller sea lions were found to suckle longer than females, with a greater\r\nproportion of males than females suckling at one year. Time spent suckling declined with\r\nage suggesting that the animals became more independent as they grew older, most likely\r\nas they increased their ability to forage successfully on their own. Male sea lions that\r\nremained with their mother for longer than one year may have had reduced exposure to\r\npredation, and obtained more calories with less energy expenditure from milk, compared\r\nto females that became nutritionally independent sooner. As a result, this may provide\r\nmales with a chance to grow as big as possible, as fast as possible, and increase their\r\nability to hold a territory and have access to mates later in life.\r\nThe number of sea lions onshore at Southwest Brothers Island was influenced by\r\nweather on a daily time-scale, but also displayed seasonal changes that may have been\r\nrelated to prey availability and the timing of breeding. The colony abandoned the island\r\nmid-March to mid-April, coinciding with the herring spawn and eulachon runs, which are\r\nhigh-fat species and spatio-temporally predictable prey. High daily variability in numbers of animals at Southwest Brothers likely reflected movement of animals to and from other\r\nnearby haulouts. Activity levels varied throughout the year, with proportionally more\r\nanimals resting in the summer and more animals engaged in low activities in the winter.\r\nThis suggests a higher behavioural expenditure of energy in the winter, contributing to\r\ntheir need for high quality nutrition.\r\nJune and July is an optimum time to assess sea lion numbers due to the high number\r\nof animals onshore at that time and a greater predictability in sea lion behaviour. The\r\ncounts obtained from the automated time-lapse camera system's digital images correlated\r\nwith counts obtained from direct observation (r\u00B2 = 0.99). The direct counts were on\r\naverage 22% greater than the digital images. While direct observation is the best method\r\nfor obtaining a greater variety of data, the camera systems have a good potential to be\r\nused to monitor Steller sea lions and other species when researchers cannot be physically\r\npresent."@en
<https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0074897>