title: Sequencing the New Zealand dawn chorus: can song playback alter the timing of song initiation?

authors: MacDougall, Mark

subjects: Dawn chorus

abstract: The dawn chorus of songbirds is a behavioural phenomenon occurring prior to sunrise; birds of many different species sing simultaneously at rapid rates. Avian physiology, social behaviours and local environment all influence the onset of dawn song. The influence of social cues on dawn chorus singing is poorly delineated relative to the effect of environmental or physiological factors; in particular, our knowledge of the role of heterospecific cues is limited. In this study, I aimed to determine if New Zealand songbirds would chorus in a distinct order, like those seen in other countries. I investigated whether the timing of song onset relative to sunrise would change as the breeding season progressed. I also assessed if conspecific and heterospecific acoustic cues influence a species’ start time. Finally, I explored the influence of acoustic cues from an early singer, the Tui (Prosthemadera novaeseelandiae) and a late singer, the Riroriro (Grey Warbler; Gerygone igata) on start time. I recorded the dawn chorus at nine sites at the Maungatautari reserve between September and November 2016, using arrays of time-synchronised autonomous recording devices. I broadcast different playback stimuli at three arrays per morning; an early singer, a late singer, and noise.  My results suggest that New Zealand dawn choruses follow an order and that the timing of chorus start time changes over time as the breeding season progresses. Tui began singing earliest, and their start time shifted much earlier as the breeding season progressed. Most species joined the chorus in a highly interchangeable order within the same 12 minute window, while Pōpokatea (Whitehead; Mohoua albicilla) sang last. Start time was not found to shift in response to any playback stimuli for any species. The onset of Tui or Riroriro song is unlikely to be used as a cue by either con- or heterospecific neighbours to initiate their own dawn song.

text: Sequencing the New Zealand dawn chorus: can song playback alter the timing of song initiation? The dawn chorus of songbirds is a behavioural phenomenon occurring prior to sunrise; birds of many different species sing simultaneously at rapid rates. Avian physiology, social behaviours and local environment all influence the onset of dawn song. The influence of social cues on dawn chorus singing is poorly delineated relative to the effect of environmental or physiological factors; in particular, our knowledge of the role of heterospecific cues is limited. In this study, I aimed to determine if New Zealand songbirds would chorus in a distinct order, like those seen in other countries. I investigated whether the timing of song onset relative to sunrise would change as the breeding season progressed. I also assessed if conspecific and heterospecific acoustic cues influence a species’ start time. Finally, I explored the influence of acoustic cues from an early singer, the Tui (Prosthemadera novaeseelandiae) and a late singer, the Riroriro (Grey Warbler; Gerygone igata) on start time. I recorded the dawn chorus at nine sites at the Maungatautari reserve between September and November 2016, using arrays of time-synchronised autonomous recording devices. I broadcast different playback stimuli at three arrays per morning; an early singer, a late singer, and noise.  My results suggest that New Zealand dawn choruses follow an order and that the timing of chorus start time changes over time as the breeding season progresses. Tui began singing earliest, and their start time shifted much earlier as the breeding season progressed. Most species joined the chorus in a highly interchangeable order within the same 12 minute window, while Pōpokatea (Whitehead; Mohoua albicilla) sang last. Start time was not found to shift in response to any playback stimuli for any species. The onset of Tui or Riroriro song is unlikely to be used as a cue by either con- or heterospecific neighbours to initiate their own dawn song.

year: 2017

title: Tube shape selection for heat recovery from particle-laden exhaust gas streams

authors: Walmsley, Timothy Gordon

abstract: Heat recovery from exhaust gas streams is applicable to a wide variety of industries. Two problems encountered in exhaust gas heat recovery are: the high heat transfer resistance of gases and the presence of entrained particulate matter, which can limit the use of extended surface area. Standard heat exchangers use round tube. This study uses Computational Fluid Dynamics (CFD) to investigate whether round or another shape is the best tube selection for exhaust heat recovery.
Tube shape rankings are based on taking into account heat transfer, gas flow resistance and foulability. Foulability is inferred from the average wall shear stress around the front or back of each shape. An estimated asymptotic fouling resistance is used to calculate an equivalent fouled j factor, jf. CFD results suggest the best tube for exhaust heat recovery is an elliptical tube. The ellipse shape produced j/f and jf/f ratios (where f is the tube bank friction factor) over 1.5 times larger than that of standard round tube. A flattened round tube is also promising and may be the practical and economic optimum.

text: Tube shape selection for heat recovery from particle-laden exhaust gas streams Heat recovery from exhaust gas streams is applicable to a wide variety of industries. Two problems encountered in exhaust gas heat recovery are: the high heat transfer resistance of gases and the presence of entrained particulate matter, which can limit the use of extended surface area. Standard heat exchangers use round tube. This study uses Computational Fluid Dynamics (CFD) to investigate whether round or another shape is the best tube selection for exhaust heat recovery.
Tube shape rankings are based on taking into account heat transfer, gas flow resistance and foulability. Foulability is inferred from the average wall shear stress around the front or back of each shape. An estimated asymptotic fouling resistance is used to calculate an equivalent fouled j factor, jf. CFD results suggest the best tube for exhaust heat recovery is an elliptical tube. The ellipse shape produced j/f and jf/f ratios (where f is the tube bank friction factor) over 1.5 times larger than that of standard round tube. A flattened round tube is also promising and may be the practical and economic optimum.

year: 2011-12-01

title: 'Freedom’s Ramparts on The Sea': The postcolonial New Zealand landscape and the quest for sustainability

authors: Morad, Munir

subjects: postcolonialism

abstract: New Zealand’s colonial legacy has had a major impact on the shape of its landscape. The European settlement of New Zealand transformed both the land itself as well as the tenure arrangements that had hitherto followed traditional Maori practices. The increasing political influence of the modem conservation movement in New Zealand has been mirrored by a parallel rise in Maori engagement with environmental issues. Land tenure claims brought by the Maori under the 1970’s Treaty of Waitangi Act have enabled an alliance of Maori and environmental interests to be forged. This linkage however is very recent, and if the current unsustainable land use practices are to be mitigated in New Zealand, a synthesis of the essential elements in both cultural traditions is necessary.
Culture shapes how people identify and evaluate elements of their environment, and influences their behaviour and experiences. At a more pragmatic level, culture provides the social infrastructure and institutions that determine how renewable land resources are used and managed. The authors highlight the links between postcolonial culture and landscape management in New Zealand, contrasting Pakeha-Maori points of view and attempting to mediate between these conflicting positions. These links are examined in the context of new social, economic and ecological forces that are shaping the country’s postcolonial landscape.

text: 'Freedom’s Ramparts on The Sea': The postcolonial New Zealand landscape and the quest for sustainability New Zealand’s colonial legacy has had a major impact on the shape of its landscape. The European settlement of New Zealand transformed both the land itself as well as the tenure arrangements that had hitherto followed traditional Maori practices. The increasing political influence of the modem conservation movement in New Zealand has been mirrored by a parallel rise in Maori engagement with environmental issues. Land tenure claims brought by the Maori under the 1970’s Treaty of Waitangi Act have enabled an alliance of Maori and environmental interests to be forged. This linkage however is very recent, and if the current unsustainable land use practices are to be mitigated in New Zealand, a synthesis of the essential elements in both cultural traditions is necessary.
Culture shapes how people identify and evaluate elements of their environment, and influences their behaviour and experiences. At a more pragmatic level, culture provides the social infrastructure and institutions that determine how renewable land resources are used and managed. The authors highlight the links between postcolonial culture and landscape management in New Zealand, contrasting Pakeha-Maori points of view and attempting to mediate between these conflicting positions. These links are examined in the context of new social, economic and ecological forces that are shaping the country’s postcolonial landscape.

year: 2003