title: An investigation into the persistence-strengthening effects of differential reinforcement of alternative (DRA) behaviour

authors: Layton, Karen Lorraine

subjects: differential reinforcement of alternative (DRA) behaviour

abstract: Ten experiments used hens to investigate the effects of different disruptive events and ways of introducing differential reinforcement of alternative behaviour (DRA), on the persistence of responding. Of interest was the persistencestrengthening effects of DRA on the target, or problem, behaviour, and whether this could be reduced by training an alternative behaviour in a separate context to that of the target behaviour. A DRA was compared to the effects of a procedure where the alternative and target behaviours were trained in the same context (traditional DRA). The different behaviours were pecking at different coloured keys, and responding was maintained by food reinforcement.
Baseline training involved a three-component multiple schedule; one component with two yellow keys available (DRA analogue using VI 37.5 s and 150 s) and the other two with one key available in each (analogous to target (blue and VI 150 s) and alternative (green and VI 37.5 s) behaviours trained separately). A disruptor test followed, also using three-component multiple schedules. This disruptor test included a component with the two yellow keys (Concurrent/DRA Component) and one which combined the, previously single, green and blue keys (Combined Component). In each experiment, the sequence of baseline followed by a disruptor test was repeated with different components in each test. Persistence was measured as the responses in the test as a proportion of baseline responses for that behaviour.
In Experiment 1 the disruptor was extinction and this showed that separate training reduced persistence of the target behaviour and extinction burst, as in previous research. Experiments 2 and 3 used the same procedures but the hens were exposed to a centre key alone (associated with one of VI 150 s (red centre key), 75 s (white centre key) or 37.5 s (pink centre key) schedule) prior to each baseline and this centre key then acted as the disruptor. Reinforcement was available on all keys in the tests. These found that the red key worked as a disruptor, and there were similar effects on persistence as in Experiment 1, regardless of the red key schedule. Experiment 4, using the same procedures but with no formal disruptor, also found the separate training gave reduced persistence of the target but not the alternative behaviour in the tests. Experiment 5 to 7 examined different disruptors (flashing light, sound, and a separate chamber), all with reinforcement continuing in tests. Target response persistence was reduced as a result of the separate training. Experiment 8 compared the effects on target persistence of separate training with the training schedule thinned prior combining and after combining. This found there was reduced target behaviour persistence when the schedules were thinned prior to being combined. Experiment 9 added a baseline with the target behaviour alone, prior to the previous procedure, and showed the same reduced target persistence even when both the target keys were initially presented alone. Experiment 10 showed the results were robust when each component was associated with a physically separate context. All experiments showed that training a target behaviour in a separate context to the alternative behaviour was successful at reducing the persistence-strengthening effects of DRA.

text: An investigation into the persistence-strengthening effects of differential reinforcement of alternative (DRA) behaviour Ten experiments used hens to investigate the effects of different disruptive events and ways of introducing differential reinforcement of alternative behaviour (DRA), on the persistence of responding. Of interest was the persistencestrengthening effects of DRA on the target, or problem, behaviour, and whether this could be reduced by training an alternative behaviour in a separate context to that of the target behaviour. A DRA was compared to the effects of a procedure where the alternative and target behaviours were trained in the same context (traditional DRA). The different behaviours were pecking at different coloured keys, and responding was maintained by food reinforcement.
Baseline training involved a three-component multiple schedule; one component with two yellow keys available (DRA analogue using VI 37.5 s and 150 s) and the other two with one key available in each (analogous to target (blue and VI 150 s) and alternative (green and VI 37.5 s) behaviours trained separately). A disruptor test followed, also using three-component multiple schedules. This disruptor test included a component with the two yellow keys (Concurrent/DRA Component) and one which combined the, previously single, green and blue keys (Combined Component). In each experiment, the sequence of baseline followed by a disruptor test was repeated with different components in each test. Persistence was measured as the responses in the test as a proportion of baseline responses for that behaviour.
In Experiment 1 the disruptor was extinction and this showed that separate training reduced persistence of the target behaviour and extinction burst, as in previous research. Experiments 2 and 3 used the same procedures but the hens were exposed to a centre key alone (associated with one of VI 150 s (red centre key), 75 s (white centre key) or 37.5 s (pink centre key) schedule) prior to each baseline and this centre key then acted as the disruptor. Reinforcement was available on all keys in the tests. These found that the red key worked as a disruptor, and there were similar effects on persistence as in Experiment 1, regardless of the red key schedule. Experiment 4, using the same procedures but with no formal disruptor, also found the separate training gave reduced persistence of the target but not the alternative behaviour in the tests. Experiment 5 to 7 examined different disruptors (flashing light, sound, and a separate chamber), all with reinforcement continuing in tests. Target response persistence was reduced as a result of the separate training. Experiment 8 compared the effects on target persistence of separate training with the training schedule thinned prior combining and after combining. This found there was reduced target behaviour persistence when the schedules were thinned prior to being combined. Experiment 9 added a baseline with the target behaviour alone, prior to the previous procedure, and showed the same reduced target persistence even when both the target keys were initially presented alone. Experiment 10 showed the results were robust when each component was associated with a physically separate context. All experiments showed that training a target behaviour in a separate context to the alternative behaviour was successful at reducing the persistence-strengthening effects of DRA.

year: 2018

title: Molecular insights into ecosystem health: Comparative characterisation of dietary ecology and spatial biodiversity patterns through DNA metabarcoding of threatened predator species in Aotearoa New Zealand

authors: Stanners, Ashleigh

subjects: eDNA

abstract: Predator species play critical ecological roles, influencing food web dynamics, regulating prey populations, and reflecting the health of their surrounding ecosystems. In Aotearoa New Zealand, many threatened predators inhabit environments under pressure from habitat modification, invasive species, and climate change. Understanding their dietary ecology and the biodiversity of their habitats is essential for effective conservation management. Environmental DNA (eDNA) metabarcoding, which uses genetic material shed into the environment to identify taxa, offers a non-invasive and highly sensitive approach to investigating both diet and broader biodiversity patterns. My thesis aimed to compare the dietary ecology and incidental biodiversity detection of two threatened predators inhabiting contrasting ecosystems, and to evaluate how ecological context shapes the information recovered through molecular analyses.

The first analysis (Chapter 2) examined the diet of the long-tailed bat (Chalinolobus tuberculatus) across multiple roosting locations within a single plantation forest over the summer season. This was the first study of its kind at this scale for the species, generating an unprecedented molecular dataset. Metabarcoding revealed a diet dominated by arthropods from multiple insect orders, encompassing both native and introduced taxa. Differences linked to reproductive status suggested shifts in prey choice driven by energetic demands, while variation between pre- and post-harvest periods indicated sensitivity to forestry management cycles. These results highlight both the potential role of this species in regulating introduced insects and its value as a bioindicator in managed forest systems.

The second analysis (Chapter 3) investigated little blue penguins (Eudyptula minor) from an island breeding colony within a sheltered harbour, focusing on both dietary and non-diet biodiversity signals. While direct dietary resolution was limited, eDNA recovered a rich record of terrestrial and nearshore taxa, reflecting seasonal and spatial variation in colony-adjacent biodiversity. These patterns were potentially influenced by seasonal ocean productivity, prey migration, microhabitat heterogeneity, and anthropogenic disturbance, demonstrating the capacity of faecal eDNA to capture wider ecosystem information.

Together, these studies demonstrate that predator faecal metabarcoding can provide complementary insights into species ecology and environmental condition, even when direct dietary resolution is constrained. By integrating trophic and incidental biodiversity data, this research contributes molecular baselines for long-term monitoring, enables the characterisation of hard-to-study or cryptic species that are otherwise difficult to observe directly, underscores the influence of ecological context on eDNA recovery, and supports the use of non-invasive molecular tools to inform evidence-based management and the conservation of threatened species and their habitats in Aotearoa New Zealand.

text: Molecular insights into ecosystem health: Comparative characterisation of dietary ecology and spatial biodiversity patterns through DNA metabarcoding of threatened predator species in Aotearoa New Zealand Predator species play critical ecological roles, influencing food web dynamics, regulating prey populations, and reflecting the health of their surrounding ecosystems. In Aotearoa New Zealand, many threatened predators inhabit environments under pressure from habitat modification, invasive species, and climate change. Understanding their dietary ecology and the biodiversity of their habitats is essential for effective conservation management. Environmental DNA (eDNA) metabarcoding, which uses genetic material shed into the environment to identify taxa, offers a non-invasive and highly sensitive approach to investigating both diet and broader biodiversity patterns. My thesis aimed to compare the dietary ecology and incidental biodiversity detection of two threatened predators inhabiting contrasting ecosystems, and to evaluate how ecological context shapes the information recovered through molecular analyses.

The first analysis (Chapter 2) examined the diet of the long-tailed bat (Chalinolobus tuberculatus) across multiple roosting locations within a single plantation forest over the summer season. This was the first study of its kind at this scale for the species, generating an unprecedented molecular dataset. Metabarcoding revealed a diet dominated by arthropods from multiple insect orders, encompassing both native and introduced taxa. Differences linked to reproductive status suggested shifts in prey choice driven by energetic demands, while variation between pre- and post-harvest periods indicated sensitivity to forestry management cycles. These results highlight both the potential role of this species in regulating introduced insects and its value as a bioindicator in managed forest systems.

The second analysis (Chapter 3) investigated little blue penguins (Eudyptula minor) from an island breeding colony within a sheltered harbour, focusing on both dietary and non-diet biodiversity signals. While direct dietary resolution was limited, eDNA recovered a rich record of terrestrial and nearshore taxa, reflecting seasonal and spatial variation in colony-adjacent biodiversity. These patterns were potentially influenced by seasonal ocean productivity, prey migration, microhabitat heterogeneity, and anthropogenic disturbance, demonstrating the capacity of faecal eDNA to capture wider ecosystem information.

Together, these studies demonstrate that predator faecal metabarcoding can provide complementary insights into species ecology and environmental condition, even when direct dietary resolution is constrained. By integrating trophic and incidental biodiversity data, this research contributes molecular baselines for long-term monitoring, enables the characterisation of hard-to-study or cryptic species that are otherwise difficult to observe directly, underscores the influence of ecological context on eDNA recovery, and supports the use of non-invasive molecular tools to inform evidence-based management and the conservation of threatened species and their habitats in Aotearoa New Zealand.

year: 2025

title: Differential trends in the compression of mortality: Assessing the antecedents to current gaps in health expectancy in New Zealand

authors: Pool, Ian

subjects: New Zealand

abstract: Health Expectancies (HEs) for New Zealand show significant differentials between Maori and non-Maori, but also by gender and period. These differentials correlate with findings from both generation and synthetic life-tables relating to New Zealand’s epidemiologic transition. At the beginning of that transition quartile 1 (Q(1)), and Median (Med) d(x) values were close and centred at young ages; during the transition the gap became very wide; at the transition’s end the gap again narrowed. Cohort and synthetic trends in d(x), l(x), M, Qs and Meds are reviewed and linked to recent HEs. Data point to epidemic polarisation. Cohort analysis allows the evaluation of the role of past experiences on the recent HEs, and thus point to possible strategies for reducing gaps in both d(x), and HEs.

text: Differential trends in the compression of mortality: Assessing the antecedents to current gaps in health expectancy in New Zealand Health Expectancies (HEs) for New Zealand show significant differentials between Maori and non-Maori, but also by gender and period. These differentials correlate with findings from both generation and synthetic life-tables relating to New Zealand’s epidemiologic transition. At the beginning of that transition quartile 1 (Q(1)), and Median (Med) d(x) values were close and centred at young ages; during the transition the gap became very wide; at the transition’s end the gap again narrowed. Cohort and synthetic trends in d(x), l(x), M, Qs and Meds are reviewed and linked to recent HEs. Data point to epidemic polarisation. Cohort analysis allows the evaluation of the role of past experiences on the recent HEs, and thus point to possible strategies for reducing gaps in both d(x), and HEs.

year: 2009