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

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

An example of acoustic features of boat noise used in controlled noise experiments on Kanowna Island.

<p>Top Panel is motor boat noise showing the amplitude of the boat noise and Lower Panel is the spectrogram of motor boat noise, spectrogram parameters: 256-point FFT, 256-point Hanning window with 50% overlap.</p

Mean and SE values for the acoustic parameters of male Australian fur seal bark calls during the playback experiments.

<p>Mean and SE values for the acoustic parameters of male Australian fur seal bark calls during the playback experiments.</p

Fitted multinomial probabilities from the maximum likelihood of the proportional odds model from the ordinal logistic analysis.

<p>Where 0 = no response; 1 = eye movements towards the sound source; 2 = body movement towards the sound source; and 3 = move away from the sound source. The four shaded areas of the stacked bar chart represent the fitted probabilities of the four responses (0, 1, 2 & 3) for each treatment. 0 is represented in white, 1 in light grey and these represent minimal or no responses, 2 is represented by dark grey and 3 in Black and these represent the stronger responses of seals hearing the boat noise.</p

Description of evaluation methods to analyse the response of Australian fur seals during the noise playback experiments.

<p>Description of evaluation methods to analyse the response of Australian fur seals during the noise playback experiments.</p

Ethogram of Australian fur seal behaviours on Kanowna Island during playback study.

<p>Ethogram of Australian fur seal behaviours on Kanowna Island during playback study.</p

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