The Behavioural Response of Australian Fur Seals to Motor Boat Noise

Australian fur seals breed on thirteen islands located in the Bass Strait, Australia. Land access to these islands is restricted, minimising human presence but boat access is still permissible with limitations on approach distances. Thirty-two controlled noise exposure experiments were conducted on breeding Australian fur seals to determine their behavioural response to controlled in-air motor boat noise on Kanowna Island (39°10′S, 146°18′E). Our results show there were significant differences in the seals' behaviour at low (64–70 dB) versus high (75–85 dB) sound levels, with seals orientating themselves towards or physically moving away from the louder boat noise at three different sound levels. Furthermore, seals responded more aggressively with one another and were more alert when they heard louder boat noise. Australian fur seals demonstrated plasticity in their vocal responses to boat noise with calls being significantly different between the various sound intensities and barks tending to get faster as the boat noise got louder. These results suggest that Australian fur seals on Kanowna Island show behavioural disturbance to high level boat noise. Consequently, it is recommended that an appropriate level of received boat sound emissions at breeding fur seal colonies be below 74 dB and that these findings be taken into account when evaluating appropriate approach distances and speed limits for boats

Temporal segregation of the Australian and Antarctic blue whale call types (Balaenoptera musculus spp.)

We examined recordings from a 15-month (May 2009–July 2010) continuous acoustic data set collected from a bottom-mounted passive acoustic recorder at a sample frequency of 6kHz off Portland, Victoria, Australia (38°33′01″S, 141°15′13″E) off southern Australia. Analysis revealed that calls from both subspecies were recorded at this site, and general additive modeling revealed that the number of calls varied significantly across seasons. Antarctic blue whales were detected more frequently from July to October 2009 and June to July 2010, corresponding to the suspected breeding season, while Australian blue whales were recorded more frequently from March to June 2010, coinciding with the feeding season. In both subspecies, the number of calls varied with time of day; Antarctic blue whale calls were more prevalent in the night to early morning, while Australian blue whale calls were detected more often from midday to early evening. Using passive acoustic monitoring, we show that each subspecies adopts different seasonal and daily call patterns which may be related to the ecological strategies of these subspecies. This study demonstrates the importance of passive acoustics in enabling us to understand and monitor subtle differences in the behavior and ecology of cryptic sympatric marine mammals.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Oxford University Press on behalf of American Society of Mammalogists. The published article can be found at: http://jmammal.oxfordjournals.org/content/96/3/603Keywords: cryptic sympatric marine mammals, seasonal, diel, Australia, calls, Balaenoptera musculus intermedia, Balaenoptera musculus brevicauda, ecology, vocalizationsKeywords: cryptic sympatric marine mammals, seasonal, diel, Australia, calls, Balaenoptera musculus intermedia, Balaenoptera musculus brevicauda, ecology, vocalization

Perception of Male Caller Identity in Koalas (Phascolarctos cinereus): Acoustic Analysis and Playback Experiments

The ability to signal individual identity using vocal signals and distinguish between conspecifics based on vocal cues is important in several mammal species. Furthermore, it can be important for receivers to differentiate between callers in reproductive contexts. In this study, we used acoustic analyses to determine whether male koala bellows are individually distinctive and to investigate the relative importance of different acoustic features for coding individuality. We then used a habituation-discrimination paradigm to investigate whether koalas discriminate between the bellow vocalisations of different male callers. Our results show that male koala bellows are highly individualized, and indicate that cues related to vocal tract filtering contribute the most to vocal identity. In addition, we found that male and female koalas habituated to the bellows of a specific male showed a significant dishabituation when they were presented with bellows from a novel male. The significant reduction in behavioural response to a final rehabituation playback shows this was not a chance rebound in response levels. Our findings indicate that male koala bellows are highly individually distinctive and that the identity of male callers is functionally relevant to male and female koalas during the breeding season. We go on to discuss the biological relevance of signalling identity in this species' sexual communication and the potential practical implications of our findings for acoustic monitoring of male population levels

Vocal characteristics of pygmy blue whales and their change over time

Vocal characteristics of pygmy blue whales of the eastern Indian Ocean population were analyzed using data from a hydroacoustic station deployed off Cape Leeuwin in Western Australia as part of the Comprehensive Nuclear-Test-Ban Treaty monitoring network, from two acoustic observatories of the Australian Integrated Marine Observing System, and from individual sea noise loggers deployed in the Perth Canyon. These data have been collected from 2002 to 2010, inclusively. It is shown that the themes of pygmy blue whale songs consist of ether three or two repeating tonal sounds with harmonics. The most intense sound of the tonal theme was estimated to correspond to a source level of 179 ± 2 dB re 1 μPa at 1 m measured for 120 calls from seven different animals. Short-duration calls of impulsive downswept sound from pygmy blue whales were weaker with the source level estimated to vary between 168 to 176 dB. A gradual decrease in the call frequency with a mean rate estimated to be 0.35 ± 0.3 Hz/year was observed over nine years in the frequency of the third harmonic of tonal sound 2 in the whale song theme, which corresponds to a negative trend of about 0.12 Hz/year in the call fundamental frequency

Click-Evoked Auditory Brainstem Responses in an Australian Sea Lion (Neophoca cinerea)

This otariid species, endemic to Australia, is listed as vulnerable under the Australian Environmental Protection and Biodiversity Conservation Act 1999 (Australian Government, 1999) and as endangered by the International Union for Conservation of Nature (IUCN) (Goldsworthy & Gales, 2015). Breeding colonies of the Australian sea lion can only be found on the south and west coasts of Australia, and numbers are declining. Mother-pup recognition in large breeding colonies is mediated primarily through acoustic cues. Any auditory impairment of a breeding sea lion could have knock-on effects in terms of nursing and, ultimately, breeding success. While by-catch in gill-net and trap fisheries is suspected to be the main threat (Goldsworthy & Gales, 2008), effects induced by excessive exposure to anthropogenic underwater sound (such as seismic exploration, underwater explosions, and pile driving for port construction; see Wyatt, 2008) might also cause changes in the distribution or abundance of this species

Policy implications for protecting health from the hazards of fire smoke. A panel discussion report from the workshop landscape fire smoke : Protecting health in an era of escalating fire risk

Globally, and nationally in Australia, bushfires are expected to increase in frequency and intensity due to climate change. To date, protection of human health from fire smoke has largely relied on individual-level actions. Recent bushfires experienced during the Australian summer of 2019–2020 occurred over a prolonged period and encompassed far larger geographical areas than previously experienced, resulting in extreme levels of smoke for extended periods of time. This particular bushfire season resulted in highly challenging conditions, where many people were unable to protect themselves from smoke exposures. The Centre for Air pollution, energy and health Research (CAR), an Australian research centre, hosted a two-day symposium, Landscape Fire Smoke: Protecting health in an era of escalating fire risk, on 8 and 9 October 2020. One component of the symposium was a dedicated panel discussion where invited experts were asked to examine alternative policy settings for protecting health from fire smoke hazards with specific reference to interventions to minimise exposure, protection of outdoor workers, and current systems for communicating health risk. This paper documents the proceedings of the expert panel and participant discussion held during the workshop

Blue whale songs worldwide: an update

Blue whales produce regionally-distinct songs. In over a decade since McDonald and colleagues published a summary of biogeographic differences in blue whale songs worldwide, multiple new publications have explored the seasonality and distribution of those songs. We review the spatial and temporal occurrence of previously-defined song types and report several new blue whale song types. At least thirteen songs believed to be produced by blue whales are now known worldwide, five more than reported in the previous review. In the North Pacific Ocean there are three blue whale songs: the well-studied Northeast Pacific song, the Central North Pacific (previously called Northwest and North Pacific) song, and a new song recorded off Hokkaido, Japan. There is spatial overlap of the Northeast Pacific and Central North Pacific songs in the Gulf of Alaska. Similarly, the new song co-occurs with the Central North Pacific song off Hokkaido. Only one blue whale song occurs in the North Atlantic. At least nine songs are present in the Southern Hemisphere. The Antarctic blue whale song is the most widely distributed, occurring in the Southern Ocean as well as seasonally extending into the other oceans of the Southern Hemisphere. The Indian Ocean has the largest variety of blue whale songs, with new data suggesting the Southwest Indian Ocean song should have type locality Madagascar, with Diego Garcia possibly another song-type. Southeast Pacific contains two distinct, co-occurring songs. We report a new song in the South Atlantic, near South Georgia Island, that also occurs seasonally off Ascension Island. Occasionally blue whale songs were recorded outside of their reported range, indicating individuals at times roam more broadly. However, this is not a common occurrence. This new information and finer details of occurrence will enable further development of hypotheses for blue whale population structure based on acoustics