title: Visual Depth Perception via Motion Parallax by Chickens (Gallus Gallus) in an Operant Chamber

authors: Ellis, Haylee Maree

subjects: perception

abstract: There are multiple cues animals use to infer depth from the two-dimensional information that passes across the retina. Differential motion of objects across the retina, or motion parallax, has been extensively studied in humans and primates, but little information is available on avian species. This set of experiments utilised an operant chamber and computer-generated stimuli to investigate the parallax discrimination abilities of domestic chickens (Gallus gallus). The birds were able to discriminate between a single stationary and a single moving object, but performance dropped to chance, and biased responding developed when parallax stimuli were introduced. A second operant chamber that forced the animals to view stimuli from a distance also resulted in chance performance. Birds may require motion across both eyes to discriminate depth when displayed on a screen.

text: Visual Depth Perception via Motion Parallax by Chickens (Gallus Gallus) in an Operant Chamber There are multiple cues animals use to infer depth from the two-dimensional information that passes across the retina. Differential motion of objects across the retina, or motion parallax, has been extensively studied in humans and primates, but little information is available on avian species. This set of experiments utilised an operant chamber and computer-generated stimuli to investigate the parallax discrimination abilities of domestic chickens (Gallus gallus). The birds were able to discriminate between a single stationary and a single moving object, but performance dropped to chance, and biased responding developed when parallax stimuli were introduced. A second operant chamber that forced the animals to view stimuli from a distance also resulted in chance performance. Birds may require motion across both eyes to discriminate depth when displayed on a screen.

year: 2015

title: Large leaves in warm, moist environments confer an advantage in seedling light interception efficiency.

authors: Lusk, Christopher H.

subjects: Yplant

abstract: Leaf size varies conspicuously along environmental gradients. Small leaves help plants cope with drought and frost, because of the effect of leaf size on boundary layer conductance; it is less clear what advantage large leaves confer in benign environments. We asked if large leaves give species of warm climates an advantage in seedling light interception efficiency over small-leaved species from colder environments. We measured seedling leaf, architectural and biomass distribution traits of 18 New Zealand temperate rainforest evergreens; we then used a 3-D digitiser and the Yplant program to model leaf area display and light interception. Species associated with mild climates on average had larger leaves and larger specific leaf areas (SLA) than those from cold climates, and displayed larger effective foliage areas per unit of aboveground biomass, indicating higher light interception efficiency at whole-plant level. This reflected differences in total foliage area, rather than in self-shading. Our findings advance the understanding of leaf size by showing that large leaves enable seedlings of species with highly conductive (but frost-sensitive) xylem to deploy large foliage areas without increasing self-shading. Leaf size variation along temperature gradients in humid forests may therefore reflect a trade-off between seedling light interception efficiency and susceptibility to frost.

text: Large leaves in warm, moist environments confer an advantage in seedling light interception efficiency. Leaf size varies conspicuously along environmental gradients. Small leaves help plants cope with drought and frost, because of the effect of leaf size on boundary layer conductance; it is less clear what advantage large leaves confer in benign environments. We asked if large leaves give species of warm climates an advantage in seedling light interception efficiency over small-leaved species from colder environments. We measured seedling leaf, architectural and biomass distribution traits of 18 New Zealand temperate rainforest evergreens; we then used a 3-D digitiser and the Yplant program to model leaf area display and light interception. Species associated with mild climates on average had larger leaves and larger specific leaf areas (SLA) than those from cold climates, and displayed larger effective foliage areas per unit of aboveground biomass, indicating higher light interception efficiency at whole-plant level. This reflected differences in total foliage area, rather than in self-shading. Our findings advance the understanding of leaf size by showing that large leaves enable seedlings of species with highly conductive (but frost-sensitive) xylem to deploy large foliage areas without increasing self-shading. Leaf size variation along temperature gradients in humid forests may therefore reflect a trade-off between seedling light interception efficiency and susceptibility to frost.

year: 2019

title: The environmental and social impact of Kaivolution's services

authors: Paymani, Kesian Serous

subjects: food insecurity

abstract: Food insecurity and food waste are two significant issues within New Zealand. In order to address these two issues organisations like Kaivolution rescue and redistribute food to community groups who help those in need. Kaivolution rescues edible food from food retailers that would otherwise be thrown away, and redistributes this rescued food to community groups who assist whanau who are food insecure. The purpose of this thesis is to examine the social and environmental impact of Kaivolution’s food redistribution service. Three of Kaivolution’s stakeholders were chosen to participate; Kaivolution volunteers, community groups who receive the rescued food, and whanau who receive the food from the community groups. Semi-structured interviews were used in order to gather data. The key findings showed that for Kaivolution volunteers there was an increase in awareness of social issues like poverty, food insecurity, and homelessness. The findings also showed that the participants volunteering with Kaivolution had increased feelings of belonging, and increased social networks, both contributing to a heightened sense of wellbeing. The key findings from both the community groups and the whanau had significant overlap. Key findings from these participants illustrated how the process of colonisation has negatively impacted Māori who are more prone to food insecurity within Aotearoa. Other groups vulnerable to food insecurity included university students and children from various ethnicities. The findings also highlight the failings of our current social welfare system to provide enough resources for basic living. Community groups often step in to assist food insecure whanau in a culturally and social sensitive community approach to food redistribution. Such an approach promotes a sense of community, builds social relationships, and enhances whanau sense of self-worth and belonging.

text: The environmental and social impact of Kaivolution's services Food insecurity and food waste are two significant issues within New Zealand. In order to address these two issues organisations like Kaivolution rescue and redistribute food to community groups who help those in need. Kaivolution rescues edible food from food retailers that would otherwise be thrown away, and redistributes this rescued food to community groups who assist whanau who are food insecure. The purpose of this thesis is to examine the social and environmental impact of Kaivolution’s food redistribution service. Three of Kaivolution’s stakeholders were chosen to participate; Kaivolution volunteers, community groups who receive the rescued food, and whanau who receive the food from the community groups. Semi-structured interviews were used in order to gather data. The key findings showed that for Kaivolution volunteers there was an increase in awareness of social issues like poverty, food insecurity, and homelessness. The findings also showed that the participants volunteering with Kaivolution had increased feelings of belonging, and increased social networks, both contributing to a heightened sense of wellbeing. The key findings from both the community groups and the whanau had significant overlap. Key findings from these participants illustrated how the process of colonisation has negatively impacted Māori who are more prone to food insecurity within Aotearoa. Other groups vulnerable to food insecurity included university students and children from various ethnicities. The findings also highlight the failings of our current social welfare system to provide enough resources for basic living. Community groups often step in to assist food insecure whanau in a culturally and social sensitive community approach to food redistribution. Such an approach promotes a sense of community, builds social relationships, and enhances whanau sense of self-worth and belonging.

year: 2019