Information Acquisition and Sociality Among Migratory Birds

Information use is a key feature of adaptive behavior: the better informed an individual, the better it is able to adjust its behavior to meet the demands of a variable world. Therefore, most animals attempt to reduce environmental uncertainty by gathering information when it is available. However, tracking unpredictable ecological factors may carry costs as individuals invest valuable time and energy in the process of information acquisition. Social learning (i.e., use of social information inadvertently produced by other individuals) enables the individual to gain rapid and more complete assessment of its novel environment. This process may be particularly important for animals under time and energetic constraints, such as migrating birds that land at unfamiliar stopover sites to replenish depleted energy stores. Migration is an ideal context in which to examine how animals respond to multiple, simultaneous constraints (informational, time and energetic) because a successful migration depends on making appropriate decisions quickly under novel circumstances. In this dissertation, I investigate the mechanisms of information acquisition in the context of migration with particular attention to social learning. My research was organized around the following questions: (a) When are long-term spatial memories encoded during the life of a first-year migratory songbird? (b) Is the seasonally high degree of sociality observed during migration an indication of the increased value and use of social information in a stopover setting? (c) Can social learning speed up the familiarization process with a novel foraging environment? (d) Does the degree of social information use vary between seasons? I found evidence of relatively low investment in long-term spatial memory formation during migration in free living migratory thrushes. However, social affiliation reduced the novelty response in captive migrants and sped up the acquisition of a novel foraging technique. Interestingly, birds in migratory disposition were slower on a social learning task than birds in non-migratory condition. Finally, as indicated by the change in flocking propensity and space use, the value and use of social information seemed to decline over the course of the stopover period. These findings suggest that social learning plays an important role in the decision-making process during migration

High-resolution GPS tracking reveals sex differences in migratory behaviour and stopover habitat use in the lesser black-backed gull Larus fuscus

Sex-, size-or age-dependent variation in migration strategies in birds is generally expected to reflect differences in competitive abilities. Theoretical and empirical studies thereby focus on differences in wintering areas, by which individuals may benefit from avoiding food competition during winter or ensuring an early return and access to prime nesting sites in spring. Here, we use GPS tracking to assess sex-and size-related variation in the spatial behaviour of adult Lesser Black-backed Gulls (Larus fuscus) throughout their annual cycle. We did not find sex-or size-dependent differences in wintering area or the timing of spring migration. Instead, sexual differences occurred prior to, and during, autumn migration, when females strongly focussed on agricultural areas. Females exhibited a more protracted autumn migration strategy, hence spent more time on stopover sites and arrived 15 days later at their wintering areas, than males. This shift in habitat use and protracted autumn migration coincided with the timing of moult, which overlaps with chick rearing and migration. Our results suggest that this overlap between energy-demanding activities may lead females to perform a more prolonged autumn migration, which results in spatiotemporal differences in foraging habitat use between the sexes

Food discovery is associated with different reliance on social learning and lower cognitive flexibility across environments in a food-caching bird

Social learning is a primary mechanism for information acquisition in social species. Despite many benefits, social learning may be disadvantageous when independent learning is more efficient. For example, searching independently may be more advantageous when food sources are ephemeral and unpredictable. Individual differences in cognitive abilities can also be expected to influence social information use. Specifically, better spatial memory can make a given environment more predictable for an individual by allowing it to better track food sources. We investigated how resident food-caching chickadees discovered multiple novel food sources in both harsher, less predictable high elevation and milder, more predictable low elevation winter environments. Chickadees at high elevation were faster at discovering multiple novel food sources and discovered more food sources than birds at low elevation. While birds at both elevations used social information, the contribution of social learning to food discovery was significantly lower at high elevation. At both elevations, chickadees with better spatial cognitive flexibility were slower at discovering food sources, likely because birds with lower spatial cognitive flexibility are worse at tracking natural resources and therefore spend more time exploring. Overall, our study supported the prediction that harsh environments should favour less reliance on social learning

Privacy-preserving human mobility and activity modelling

The exponential proliferation of digital trends and worldwide responses to the COVID-19 pandemic thrust the world into digitalization and interconnectedness, pushing increasingly new technologies/devices/applications into the market. More and more intimate data of users are collected for positive analysis purposes of improving living well-being but shared with/without the user's consent, emphasizing the importance of making human mobility and activity models inclusive, private, and fair. In this thesis, I develop and implement advanced methods/algorithms to model human mobility and activity in terms of temporal-context dynamics, multi-occupancy impacts, privacy protection, and fair analysis. The following research questions have been thoroughly investigated: i) whether the temporal information integrated into the deep learning networks can improve the prediction accuracy in both predicting the next activity and its timing; ii) how is the trade-off between cost and performance when optimizing the sensor network for multiple-occupancy smart homes; iii) whether the malicious purposes such as user re-identification in human mobility modelling could be mitigated by adversarial learning; iv) whether the fairness implications of mobility models and whether privacy-preserving techniques perform equally for different groups of users. To answer these research questions, I develop different architectures to model human activity and mobility. I first clarify the temporal-context dynamics in human activity modelling and achieve better prediction accuracy by appropriately using the temporal information. I then design a framework MoSen to simulate the interaction dynamics among residents and intelligent environments and generate an effective sensor network strategy. To relieve users' privacy concerns, I design Mo-PAE and show that the privacy of mobility traces attains decent protection at the marginal utility cost. Last but not least, I investigate the relations between fairness and privacy and conclude that while the privacy-aware model guarantees group fairness, it violates the individual fairness criteria.Open Acces

Mainstreaming nature-based solutions for climate resilient infrastructure in peri-urban sub-Saharan Africa

This work was conducted under the “Urban Ecolution: Predicting synergies and trade-offs of water-related ecological infrastructure for climate adaptation in peri-urban Sub-Saharan Africa'', supported through the Climate Research for Development Postdoctoral Fellowship (CR4D-19-21) implemented by the African Academy of Sciences in partnership with the UK’s Department for International Development, Weather and Climate Information Services for Africa (WISER) programme and the African Climate Policy Center of the United Nations Economic Commission for Africa. This study has also been funded in part by the African Women in Climate Change Science Fellowship supported by the African Institute of Mathematical Sciences Next Einstein Forum and the International Development Research Centre of Canada Aid, the UK’s Research and Innovation’s Global Challenges Research Fund under the Development Corridors Partnership project (ES/P011500/1), and Lincre College, University of Oxford.Despite a growing recognition of the importance of designing, rehabilitating, and maintaining green infrastructure to provide essential ecosystem services and adapt to climate change, many decision makers in sub-Saharan Africa continue to favour engineered solutions and short term economic growth at the expense of natural landscapes and longer term sustainability agendas. Existing green infrastructure is typically maintained in more affluent suburbs, inadvertently perpetuating historic inequalities. This is in part because there remains a lack of fine-grained, comparative evidence on the barriers and enablers to mainstreaming green infrastructure in peri-urban areas. Here, we developed an analytical framework based on a review of 155 studies, screened to include 29 studies in 24 countries. Results suggest eight overarching categories of interconnected barriers to green infrastructure in peri-urban areas. Using a combinatorial mixed method approach, we then surveyed households in nine settlements in drought-prone Windhoek (n=330) and seven settlements in flood-prone Dar es Salaam (n=502) and conducted key informant interviews (n=118). Peri-urban residents in Windhoek and Dar es Salaam indicated 18 forms of green infrastructure and 47 derived ecosystem services. The most frequently reported barriers were financial (40.8%), legal and institutional barriers (35.8%) followed by land use change and spatial trade-offs (33%) and finally ecosystem disservices (30.6%). The most significant barriers in Dar es Salaam were legal and institutional (22.7%) and in Windhoek were land use change and spatial trade-offs (24.4%). At the household level, the principal barrier was financial; at community and municipal levels the main barriers were related to design, performance, and maintenance; while at the national level, the main barriers were legal and institutional. Embracing institutional cultures of adaptive policymaking, equitable partnerships, co-designing futures, integrated landscape management and experimental innovation have potential to scale long term maintenance for urban green infrastructure and foster agency, creativity and more transformative relationships and outcomes.Publisher PDFPeer reviewe

Strategy-specific Differentiation in Response to Resources and Drivers of Spring Migration Phenology in Rocky Mountain Elk

Elk (Cervus canadensis) are known to exhibit high movement strategy diversity compared to other ungulate species. Most elk populations are migratory or partially migratory, presenting unique conservation and management challenges. For example, successful maintenance of multiple seasonal ranges and connectivity between them is necessary to conserve populations with migratory behaviors. Further study of the structure and maintenance of movement strategy diversity within partially migratory populations is needed to assist management and refine fundamental ecological theory. Improved understanding of the determinants of elk migratory timing is also important, with the dynamics of significant drivers likely to shift under future climate change and anthropogenic expansion. I investigated strategy-specific environmental responses in multiple Rocky Mountain elk populations and found evidence for a differentiation in resource use and selection among sympatric individuals using differing strategies. This result suggests a potential mechanism for the reduction of intraspecific competition and heightened population densities in partially migratory herds. However, the nature and strength of differentiation was found to be context dependent. I found that elk avoid human development and seasonally select for forage quantity over quality at relatively fine scales, highlighting some consistent selection responses as well. Overall, this analysis demonstrated intrapopulation response heterogeneity in partially migratory elk populations and characterized strategy-specific patterns of resource use and selection.I investigated how spring migratory timing and duration relate to spatiotemporal forage dynamics, finding that departure dates are affected by vegetative green-up along migratory corridors, while the duration of migration is influenced by the timing of green-up at the summer range. These results highlight a form of migratory plasticity, wherein migrants modulate both their departure date and the duration of their migration as a function of vegetative phenology. Additionally, I present a framework to quantify optimality of migratory movements in relation to peak forage conditions. On average, elk were found to exhibit high optimality, with interindividual variability along a gradient. My findings suggest a variety of responses to green-wave phenology, with optimality of movements differing as a function of individual and study area. This work contributes to the growing understanding of migratory plasticity as multidimensional and highlights the variability of migratory behavior within and among populations

Advanced flight control system study

The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed