Thomas Morrison

• Doctor of Philosophy
• Research Associate at University of Glasgow

The loss of aquatic subsidies such as spawning salmonids is known to threaten a number of terrestrial predators, but the effects on alternative prey species are poorly understood. At the heart of the Greater Yellowstone ecosystem, an invasion of lake trout has driven a dramatic decline of native cutthroat trout that migrate up the shallow tributari...

1. In migratory populations, the degree of fidelity and dispersal among seasonal ranges is an important population process with consequences for demography, management, sensitivity to habitat change and adaptation to local environmental conditions. 2. Characterizing patterns of range fidelity in ungulates, however, has remained challenging because...

Over the last two centuries overhunting, anthropogenic barriers and habitat loss have disrupted many ungulate migrations. We review the literature on ungulate migration disruptions and find that for many species the disruption of migratory routes causes a rapid population collapse. Previous research has focused on the proximal ecological factors th...

Understanding animals' habitat selection and movement behaviours relative to human activities is important for evaluating resource requirements and ensuring effective conservation management. The world's largest remaining population of Kordofan giraffe (Giraffa camelopardalis antiquorum) reside in Zakouma National Park, Chad. However, it is unclear...

COVID-19 lockdowns in early 2020 reduced human mobility, providing an opportunity to disentangle its effects on animals from those of landscape modifications. Using GPS data, we compared movements and road avoidance of 2300 terrestrial mammals (43 species) during the lockdowns to the same period in 2019. Individual responses were variable with no c...

Site fidelity—the tendency to return to previously visited locations—is widespread across taxa. Returns may be driven by several mechanisms, including memory, habitat selection, or chance; however, pattern‐based definitions group different generating mechanisms under the same label of ‘site fidelity’, often assuming memory as the main driver. We pr...

Human activities are transforming landscapes and altering the structure and functioning of ecosystems worldwide and often result in sharp contrasts between human‐dominated landscapes and adjacent natural habitats that lead to the creation of hard edges and artificial boundaries. The configuration of these boundaries could influence local biotic int...

A fundamental condition for maintaining viable populations of wildlife is to ensure that animals can access resources. In landscapes where the boundaries of protected areas encompass only a fraction of annual home ranges, animal movement is often curtailed by human activities, often with negative population consequences. In the Tarangire Ecosystem...

The ability to move is essential for animals to find mates, escape predation, and meet energy and water demands. This is especially important across grazing systems where vegetation productivity can vary drastically between seasons or years. With grasslands undergoing significant changes due to climate change and anthropogenic development, there is...

Our understanding of ungulate migration is advancing rapidly due to innovations in modern animal tracking. Herein, we review and synthesize nearly seven decades of work on migration and other long-distance movements of wild ungulates. Although it has long been appreciated that ungulates migrate to enhance access to forage, recent contributions demo...

Malignant Catarhal Fever (MCF), caused by a virus transmitted from asymptomatic wildebeest, is a lethal disease in cattle that threatens livestock-based livelihoods and food security in many areas of Africa. Many herd owners reduce transmission risks by moving cattle away from infection hot-spots, but this imposes considerable economic burdens on t...

In Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different path...

Migration of ungulates (hooved mammals) is a fundamental ecological process that promotes abundant herds, whose effects cascade up and down terrestrial food webs. Migratory ungulates provide the prey base that maintains large carnivore and scavenger populations and underpins terrestrial biodiversity (fig. S1). When ungulates move in large aggregati...

In Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different path...

While the tendency to return to previously visited locations—termed ‘site fidelity’—is common in animals, the cause of this behaviour is not well understood. One hypothesis is that site fidelity is shaped by an animal's environment, such that animals living in landscapes with predictable resources have stronger site fidelity. Site fidelity may also...

Background: Current animal tracking studies are most often based on the application of external geolocators such as GPS and radio transmitters. While these technologies provide detailed movement data, they are costly to acquire and maintain, which often restricts sample sizes. Furthermore, deploying external geolocators requires physically capturin...

Background: Current animal tracking studies are most often based on the application of external geolocators such as GPS and radio transmitters. While these technologies provide detailed movement data, they are costly to acquire and maintain, which often restricts sample sizes. Furthermore, deploying external geolocators requires physically capturi...

We examine tourism demand for an iconic ecological resource – the migration of ~1.3 million wildebeest (Connochaetes taurinus) in the Serengeti-Mara ecosystem. The wildebeest migration generates economic benefits through ecotourism, which we investigated by combining quantitative tools from spatial ecology and environmental economics with wildebees...

Wild mammals in ex-situ captivity experience substantially different environmental conditions compared to free-ranging conspecifics, e.g. in terms of diet, climatic conditions, social factors, movement space, and direct anthropogenic disturbance. Moreover, animals in captivity frequently undergo management interventions such as medical treatments w...

• Nearly 90% of the world's large herbivore diversity occurs in Africa, yet there is a striking dearth of information on the movement ecology of these organisms compared to herbivores living in higher latitude ecosystems. • The environmental context for movements of large herbivores in African savanna ecosystems has several distinguishing features....

Fire is a key driver in savannah systems and widely used as a land management tool. Intensifying human land uses are leading to rapid changes in the fire regimes, with consequences for ecosystem functioning and composition. We undertake a novel analysis describing spatial patterns in the fire regime of the Serengeti-Mara ecosystem, document multide...

Anthelmintic resistance is a threat to global food security. In order to alleviate the selection pressure for resistance and maintain drug efficacy, management strategies increasingly aim to preserve a proportion of the parasite population in ‘refugia’, unexposed to treatment. While persuasive in its logic, and widely advocated as best practice, ev...

Threats to the Serengeti Protected areas are an important tool for conserving biodiversity and ecosystem functioning. But how well do these areas withstand pressure from human activity in surrounding landscapes? Veldhuis et al. studied long-term data from the Serengeti-Mara ecosystem in East Africa. Human activities at boundary regions cause animal...

Savanna ecosystems span a diverse range of climates, edaphic conditions, and disturbance regimes, the complexity of which has stimulated long‐standing interest in the mechanisms that maintain tree–grass coexistence. One hypothesis suggests that tree establishment is strongly limited by one or several demographic bottlenecks at early stages of the t...

A central question in ecology is how to link processes that occur over different scales. The daily interactions of individual organisms ultimately determine community dynamics, population fluctuations and the functioning of entire ecosystems. Observations of these multiscale ecological processes are constrained by various technological, biological...

Restrictions on roaming Until the past century or so, the movement of wild animals was relatively unrestricted, and their travels contributed substantially to ecological processes. As humans have increasingly altered natural habitats, natural animal movements have been restricted. Tucker et al. examined GPS locations for more than 50 species. In ge...

Fire is a fundamental process in savannas and is widely used for management. Pyrodiversity, variation in local fire characteristics, has been proposed as a driver of biodiversity although empirical evidence is equivocal. Using a new measure of pyrodiversity (Hempson et al.), we undertook the first continent-wide assessment of how pyrodiversity affe...

Conservation management is strongly shaped by the interpretation of population trends. In the Serengeti ecosystem, Tanzania, aerial total counts indicate a striking increase in elephant abundance compared to all previous censuses. We developed a simple age-structured population model to guide interpretation of this reported increase, focusing on th...

Tree recruitment in savannas proceeds in multiple stages characterized by successive filters occurring at the seed and seedling stages. The “demographic bottleneck” hypothesis suggests that such filters ultimately restrict tree density and prevent trees from dominating grasses in savannas, but many of the demographic transitions underlying this ass...

Pyrodiversity, which describes fire variability over space and time, is believed to increase habitat heterogeneity and thereby promote biodiversity. However, to date there is no standardised metric for quantifying pyrodiversity, and so broad geographic patterns and drivers of pyrodiversity remain unexplored. We present the first generalizable metho...

The hyper-abundance of migratory wildlife in many ecosystems depends on maintaining access to seasonally available resources. In Eastern and Southern Africa, land-use change and a loss of connectivity have coincided with widespread declines in the abundance and geographic range of ungulate populations. Using photographic capture-mark-recapture, we...

Monitoring the fates of individuals after release in the wild is essential for building effective species recovery programs. Current conservation efforts for the endangered Wyoming Toad (Anaxyrus baxteri) are limited by the size and number of toads that can be individually marked using invasive tagging techniques. We evaluated the use of natural pa...

Generalizations about the drivers of tree demography in tropical savannas continue to prove difficult because of the complex and dynamic interactions involved, and because multi‐year data sets spanning meaningful gradients in potential drivers are lacking. Overstorey trees play disproportionate roles in the long‐term dynamics and functioning of sav...

Tree size distributions are the outcome of demographic processes and disturbance events, and size distribution analysis provides a useful tool for understanding pattern and process in tree population dynamics. Demographic bottleneck mechanisms such as fire “traps” are important for driving tree cover dynamics in savanna systems, and bottlenecks mig...

Questions What is the pattern of compositional similarity for woody plants across the demographic bottleneck (i.e. canopy trees >2 m vs understorey trees <2 m) commonly observed in savannas? Does compositional similarity between woody plants in the canopy and understorey change across environmental gradients, and if so, which resource or disturbanc...

Surprisingly little is known about the spatial dimensions of most tropical ungulate migrations, including that of wildebeest Connochaetes taurinus, a species famous for long-distance movements. Using non-invasive photographic identification of 834 adult wildebeest from 8,530 images collected over 4 years we characterize patterns of migratory connec...

Background/Question/Methods In plant communities characterized by high productivity and high species turnover, such as many C4 savannahs, identifying the relative influence of biotic and abiotic controls is challenging because of the number and interactivity of different controlling agents. African savanna elephants (Loxodonta africana africana)...

Despite recognition that nearly one-third of the 6300 amphibian species are threatened with extinction, our understanding of the general ecology and population status of many amphibians is relatively poor. A widely-used method for monitoring amphibians involves injecting captured individuals with unique combinations of colored visible implant elast...

Wdump scores to capture history R code. (TXT)

Wild-ID confirmed matches to capture history R code. (TXT)

Impermeable barriers to migration can greatly constrain the set of possible routes and ranges used by migrating animals. For ungulates, however, many forms of development are semi‐permeable, and making informed management decisions about their potential impacts to the persistence of migration routes is difficult because our knowledge of how semi‐pe...

1. Photographic mark–recapture is a cost-effective, non-invasive way to study populations. However, to efficiently apply photographic mark–recapture to large populations, computer software is needed for image manipulation and pattern matching. 2. We created an open-source application for the storage, pattern extraction and pattern matching of digit...

Background/Question/Methods Many ungulate species experience highly variable recruitment rates from year to year, often due to environmental conditions or increased predation on young. The restoration and range expansion of large predators (namely wolves and grizzly bears) in the Western United States over the last 15 years has coincided with wid...

Background/Question/Methods Life history theory predicts a tradeoff between current reproductive effort and future survival and reproduction. In ungulates, few studies have detected strong reproductive costs in terms of future reproduction, and fewer still have observed survival costs. However, reproductive trade-offs have rarely (if ever) been s...

1. For many species, noninvasive photographic identification offers a powerful and cost–effective method for estimating demographic parameters and testing ecological hypotheses in large populations. However, this technique is prone to misidentification errors that can severely bias capture–recapture estimates. 2. We present a simple ad hoc data con...

Background/Question/Methods - Photographic mark-recapture is a cost-effective, non-invasive way to study populations. However, to effectively apply photographic mark-recapture to large populations, computer software is needed for efficient image manipulation and pattern matching. This talk describes a new software package and its application to gir...

Background/Question/Methods Site fidelity to breeding habitat shapes the spatial structure of migratory populations and constrains its capacity to respond to heterogeneity and change in the landscape. Because population structure defines both management units and evolutionarily significant units, site fidelity can be a critical aspect of migrator...

Background/Question/Methods Recent advances in computer vision technology have expanded the opportunity for using photographic identification within large-scale mark-recapture studies. Photo-identification relies on variation in natural marking patterns to ‘mark’ and re-identify individuals from photographs. However, error in the photo matching pro...

Socioecological models of the evolution of female-bonded societies predict a relation between resource distribution and the nature of female affiliative and dominance relationships. Species that mainly rely on abundant, widely distributed resources, like African savanna elephants, are predicted to have unresolved dominance hierarchies and poorly di...

The availability of a population of mostly known-age African elephants Loxodonta africana from Amboseli National Park, Kenya, provided a unique opportunity to assess the use of dung bolus diameter for estimating age. A predictive equation for estimating dung bolus diameters from elephants of known age was derived and was found to follow the typical...