Michael D Sumner

Australian Antarctic Division · Southern Ocean Ecosystems: Environmental Change and Conservation

A dominant Antarctic ecological paradigm suggests that winter sea ice is generally the main feeding ground for krill larvae. Observations from our winter cruise to the southwest Atlantic sector of the Southern Ocean contradict this view and present the first evidence that the pack-ice zone is a food-poor habitat for larval development. In contrast,...

Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species chan...

In recent years, marine predator and seabird tracking studies have become ever more popular. However, they are often conducted without first considering how many individuals should be tracked and for how long they should be tracked in order to make reliable predictions of a population's home-range area. Home-range area analysis of two seabird-track...

Many optimal foraging models for diving animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. Other models have considered the effect of patch quality and predict a net energetic benefit if dives where no prey is encountered early in the dive are abandoned. For...

Predictable sources of food underpin lifetime reproductive output in long lived animals. The most important foraging areas of top marine predators are therefore likely to be related to environmental features that enhance productivity in predictable spatial and temporal patterns. Even so, although productive areas within the marine environment are d...

The reliable estimation of animal location, and its associated error is fundamental to animal ecology. There are many existing techniques for handling location error, but these are often ad hoc or are used in isolation from each other. In this study we present a Bayesian framework for determining location that uses all the data available, is flexib...

Argos full path estimates with raw location track. Animation of full path estimates constructed from the posterior for z. The sequence consists of a rolling 2 day window for every 10 hour interval of the tagging period. The matching sequence of original raw Argos locations is overlaid as a line. (0.47 MB GIF)

Satellite tracking devices were used to examine the at sea movements of southern and northern giant petrels from Macquarie Island during the Austral summers of 2005–06 and 2006–07. Time spent at sea for nine northern giant petrels (four breeding adults, five recently fledged juveniles) and 10 southern giant petrels (three breeding adults, one non-b...

Foraging by adult male otariids, a demographic component that often interacts with commercial fisheries, are poorly known. To assess movement patterns and habitat use, nine adult male Australian fur seals (Arctocephalus pusillus doriferus Wood Jones, 1925) from Seal Rocks, in northern Bass Strait, southeastern Australia, were tracked for periods ra...

We studied the foraging behaviour of lactating female, adult male and juvenile New Zealand (NZ) fur seals to compare and contrast their foraging strategies and assess the degree of spa- tial separation of their foraging habitats. Adult male fur seals are longer and heavier than lactating females, which are longer and heavier than juveniles. Trip du...

In highly dynamic and unpredictable environments such as the Southern Ocean, species that have evolved behaviors that reduce the effects of intra-specific competition may have a selective advantage. This is particularly true when juveniles face disadvantages when foraging due to morphological or physiological limitation, which is the case for many...

Choices made by foraging animals should maximize energy intake, although ‘irrational’ short-term behaviours are common. One explanation for this is that environmental variation may lead to the evolution of behaviours that benefit individual reproductive output, but only over long timescales. Long-term (multiyear) fidelity to foraging regions in ext...

Hot-iron brands were used to mark permanently 14000 six-week-old southern elephant seal (Mirounga leonina L.) pups at Macquarie Island between 1993 and 2000. We assessed temporal changes in the quality of 4932 brands applied in 1998 and 1999 to determine the duration of the brand wound, and the relationships between brand healing, brand readability...

Summary • Numerical models that predict trophic structure require both accurate information on prey consumption rates and estimates of spatial and temporal variation. In the Southern Ocean little information exists on the spatial and temporal patterns of resource use by predators, so we attempted to examine these patterns for an important Antarctic...

Nineteen years of Advanced Very High Resolution Radiometer Multi-Channel Sea Surface Temperature (AVHRR MCSST) data were used to calculate monthly averages of sea surface temperatures (SSTs) for a large region of the Southern Ocean centred on Macquarie Island. Between October and February, the MCSST data were a reliable source of SSTs north of 60°S...

2002. The optimal spatial scale for the analysis of elephant seal foraging as determined by geo-location in relation to sea surface temperatures. – ICES Journal of Marine Science, 59: 770–781. There is increasing emphasis put on the correlation of marine predator behaviour and foraging performance with the bio-physical properties of the ocean envir...

Twenty-three juvenile (8-14 months of age) southern elephant seals (Mirounga leonina L.) from Macquarie Island were tracked during 1993 and 1995. Migratory tracks and ocean areas with concentrated activity, presumed to be foraging grounds, were established from location data gathered by attached geolocation-time depth recorders, The seals ranged wi...