Dynamics of a Socially and Spatially Structured Giraffe Population in a Human-Natural Landscape

Sociality involves a constant trade-off between fitness benefits and costs of living in groups, and this trade-off can be influenced by the social and ecological environment in which individuals live. In this PhD I explored socioecological factors underlying the social and spatial population structure and dynamics of a large tropical herbivore with a highly fission-fusion social system, the giraffe (Giraffa camelopardalis). Using a dataset of more than 3,000 uniquely identified individuals collected over a period of 8 years in the coupled human-natural Tarangire Ecosystem of northern Tanzania, I (1) investigated natural and anthropogenic factors as mechanisms of giraffe grouping dynamics, social structure, space use, and vital rates; (2) quantified fitness consequences of social behaviours of adult female giraffes in relation to the influence of their physical environment; and (3) compared social versus spatial dispersal of subadult female and male giraffes. I used capture-mark-recapture techniques to estimate survival rates while accounting for imperfect detection, and social network analysis to derive network- and individual-level social metrics and to delineate discrete communities of socially associated adult female giraffes within a larger contiguous metapopulation. Natural and anthropogenic factors included vegetation types and preferred plant forage species, natural predation, and distance to traditional (bomas) and modern human settlements (towns). I found that grouping patterns of giraffes were influenced by food availability, predation risk, and presence of humans, with particular requirements for mothers with calves (chapter 1). I parsed the metapopulation into 14 distinct, modular yet overlapping communities of socially associated adult female giraffes, with 11 communities large enough to test hypotheses explaining variation in social structure (chapter 2). Adult females in communities closer to bomas had weaker relationship strengths among all members of the community and more exclusive relationships with fewer other females, suggesting that the presence of humans disrupted their social structure. In an examination of social versus ecological drivers of variation in reproduction and survival among 10 of the communities, I showed demographic rates were correlated with vegetation and proximity to humans, as communities with more dense bushlands had lower calf survival while those closer to human settlements had higher reproductive rates (chapter 3). Adult female survival did not differ among communities (chapter 3), but more gregarious females (being in larger groups) and females with higher betweenness (associated with more groups) had higher survival (chapter 4). Survival of adult females is improved by being well-integrated into their larger social community through having weaker bonds with many others rather than by forming stronger and highly stable bonds with just a few individuals. This suggests that the disruption of social structure close to bomas as evidenced in chapter 2 could have demographic consequences, although proximity to bomas did not influence adult female survival as much as their level of sociability (chapter 4). In chapter 5, I investigated patterns of natal dispersal, and found that while most young males dispersed into new social communities far from where they were first detected as calves, many shifted into new communities that were close to their natal areas. In contrast, few young females dispersed, but those that did disperse rarely shifted into a new social community. Instead females moved spatially while remaining within their natal community, further demonstrating the importance of maintaining social ties, from calf to adulthood, across their community of associates. Human presence influenced space use of adults, as adult females living closer to densely populated towns had significantly larger home ranges, but no such relationship was evident with bomas, indicating a difference in anthropogenic impact on movements of giraffes between traditional versus modern human lifestyles (chapter 6). My research indicates that social associations among individuals in addition to ecological conditions are likely to be important for population persistence, and should be considered when developing and implementing conservation measures for giraffes such as land-use plans and translocations

A multi-method approach to delineate and validate migratory corridors

Context: Managers are faced with numerous methods for delineating wildlife movement corridors, and often must make decisions with limited data. Delineated corridors should be robust to different data and models. Objectives: We present a multi-method approach for delineating and validating wildlife corridors using multiple data sources, which can be used conserve landscape connectivity. We used this approach to delineate and validate migration corridors for wildebeest (Connochaetes taurinus) in the Tarangire Ecosystem of northern Tanzania. Methods: We used two types of locational data (distance sampling detections and GPS collar locations), and three modeling methods (negative binomial regression, logistic regression, and Maxent), to generate resource selection functions (RSFs) and define resistance surfaces. We compared two corridor detection algorithms (cost-distance and circuit theory), to delineate corridors. We validated corridors by comparing random and wildebeest locations that fell within corridors, and cross-validated by data type. Results: Both data types produced similar RSFs. Wildebeest consistently selected migration habitat in flatter terrain farther from human settlements. Validation indicated three of the combinations of data type, modeling, and corridor detection algorithms (detection data with Maxent modeling, GPS collar data with logistic regression modeling, and GPS collar data with Maxent modeling, all using cost-distance) far outperformed the other seven. We merged the predictive corridors from these three data-method combinations to reveal habitat with highest probability of use. Conclusions: The use of multiple methods ensures that planning is able to prioritize conservation of migration corridors based on all available information

Effect of local climate anomalies on giraffe survival

With the rapid pace of global warming, there is an urgent need to understand survival responses to climate, particularly for large mammals that are already experiencing population declines associated with anthropogenic pressures such as poaching and habitat loss. We tested hypotheses about the interactive effects of local climatic anomalies (variations around a long-term mean) and proximity to edge of protected area boundaries on seasonal adult and juvenile survival in a population of 2,385 individually identified giraffes monitored over 8 years in the Tarangire Ecosystem of northern Tanzania. Temperature anomalies were positively correlated with seasonal survival of adult giraffes, suggesting these megaherbivores are adapted to hot conditions. Higher seasonal rainfall anomalies were negatively correlated with both juvenile and adult survival, and greater vegetation greenness was associated with lower adult survival. During seasons of anomalously high rainfall and vegetation greenness, higher parasite and disease abundance, poorer-quality nutrition in forage, and higher predation risk may all play a role in lowering giraffe survival. Furthermore, climate-associated reduction in survival was most pronounced during the short rainy season for adult giraffes living closer to the edge of protected areas, indicating that the influence of climate anomalies may be exacerbated by anthropogenic edge effects such as poaching or livestock keeping. Precipitation in East Africa is projected to increase substantially, with a greater proportion of rain falling during heavy events in the short rainy season, which may threaten persistence of giraffes in one of Earth’s most important landscapes for large mammals

Density, sex ratio, and space use in the gray-tailed vole, Microtus canicaudus

Female and male mammals have different behavioral strategies for maximizing their reproductive success. Pregnancy and lactation obligate female mammals to provide greater parental investment than males; thus, females compete with each other for food and space to rear their offspring, while male mammals compete with each other for female mates. Therefore, natural selection should favor any behavior among females that increases their access to food and space to rear successful offspring and any behavior among males that increases their access to females. In two enclosure experiments, the gray-tailed vole, Microtus canicaudus, was used as a model species to study (1) the relative influence of male competition versus access to females on space use by males and (2) facultative sex-ratio adjustment at the population level in response to low and high population densities, skewed adult sex ratios, and season. Home-range sizes of male voles did not appear to expand beyond an overlap with about five members of either sex. Intrasexual competition with 3-4 males and/or overlap with five females appear to set the upper limits to home-range size. Space use by males is influenced by intrasexual competition and by access to females with an upper limit of overlap with either sex. Additionally, facultative sex-ratio adjustment in response to changing population densities and skewing adult sex ratios did not occur, but a seasonal effect was detected with significantly more males produced in autumn than in spring. Under the conditions of this experimental study, I was not able to measure sex ratios of individual litters, but if any sex-ratio adjustment occurred in response to densities and adult sex ratios, it was not detectable at the population level

A New Forest Fire Paradigm: The Need for High-Severity Fires

Forest fires, particularly those that burn at mixed and high severity (collectively called ‘severe’), have been traditionally perceived as catastrophic events, directing public attention and immense forest management budgets toward fire prevention and suppression. These fires may indeed be catastrophic when measured by losses of human lives and property. However, severe fires in wildland areas are both natural and necessary to maintain the integrity of dynamic, disturbance-adapted forest systems. We propose a change in the current paradigm—which holds that severe forest fires are always harmful—to a new one that embraces their ecological necessity

ACCOMMODATING MIXED-SEVERITY FIRE TO RESTORE AND MAINTAIN ECOSYSTEM INTEGRITY WITH A FOCUS ON THE SIERRA NEVADA OF CALIFORNIA, USA

Existing fire policy encourages the maintenance of ecosystem integrity in fire management, yet this is difficult to implement on lands managed for competing economic, human safety, and air quality concerns. We discuss a fire management approach in the mid-elevations of the Sierra Nevada, California, USA, that may exemplify similar challenges in other fire-adapted regions of the western USA. We also discuss how managing for pyrodiversity through mixed-severity fires can promote ecosystem integrity in Sierran mixed conifer and ponderosa pine (Pinus ponderosa Laws) forests. To illustrate, we show how coarse-filter (landscape-level) and complementary fine-filter (species-level) approaches can enhance forest management and conservation biology objectives as related to wildfire management. At the coarse-filter level, pyrodiverse mixed-severity fires provide landscape heterogeneity. Species and ecosystem characteristics associated with pyrodiversity can be maintained or enhanced by accommodating moderately severe fires, which hasten restoration by recreating a complex vegetation mosaic otherwise at risk from suppression. At the fine-filter level, managers can select focal species and species of conservation concern based on the degree to which those species depend on fire and accommodate their specific conservation needs. The black-backed woodpecker (Picoides arcticus [Swainson, 1832]) is an ideal focal species for monitoring the ecological integrity of forests restored through mixed-severity fire, and the California spotted owl (Strix occidentalis occidentalis [Xantus de Vesey, 1860]) is a species of conservation concern that uses post-fire habitat mosaics and is particularly vulnerable to logging. We suggest a comprehensive approach that integrates wildland fire for ecosystem integrity and species viability with strategic deployment of fire suppression and ecologically based restoration of pyrodiverse landscapes. Our approach would accomplish fire management goals while simultaneously maintaining biodiversity

Occupancy of California Spotted Owl sites following a large fire in the

ABSTRACT High-severity forest fire often is presumed to adversely affect the occupancy of territories by California Spotted Owls (Strix occidentalis occidentalis) because these owls are associated with mature and old-growth forests. We used single-season, multi-state occupancy statistics to estimate site occupancy probability for Spotted Owls at 45 historically occupied sites during the breeding season immediately following the 2013 Rim Fire, which was one of the largest forest fires on record in California. We quantified how occupancy probability was influenced by the amount of high-severity fire occurring in mature forested habitat within Protected Activity Centers (PACs). The model-averaged estimate of site-occupancy probability for at least a single owl was 0.922 (6SE ¼ 0.073), which was higher than other published occupancy probability estimates for this subspecies in either burned or long-unburned sites in the Sierra Nevada. Mean site-occupancy probability for pairs was 0.866 (60.093), and most sites (33) were occupied by pairs. The amount of high-severity fire in the PAC did not affect pair occupancy. Occupancy probability by at least a single bird was negatively correlated with the amount of high severity fire in the PAC but remained .0.89 in 100% high-severity burned PACs. These data add to observations that California Spotted Owls continue to use post-fire landscapes, even when the fires were large and where large areas burned at high severity, suggesting that owls are not generally negatively impacted by high-severity fire. Based on this and other studies of Spotted Owls, fire, and logging, we suggest land managers consider burned forest within and surrounding PACs as potentially suitable California Spotted Owl foraging habitat when planning and implementing management activities, and we recommend against logging burned forest within at least 1.5 km of nests or roosts for the conservation and recovery of this declining subspecies. Keywords: California Spotted Owl, Strix occidentalis occidentalis, occupancy, forest fire Ocupación de sitios de Strix occidentalis occidentalis luego de un gran incendio en la Sierra Nevada, California RESUMEN Generalmente se supone que los incendios forestales de alta severidad afectan la ocupación de los territorios de Strix occidentalis occidentalis debido a que estos búhos se asocian con bosques maduros y primarios. Usamos estadísticos multiestado de ocupación de una temporada para estimar la probabilidad de ocupación de un sitio por S. occidentalis en 45 sitios históricamente ocupados, durante la temporada reproductiva que siguió inmediatamente al incendio Rim de 2013, uno de los incendios forestales más grandes registrados en California. Cuantificamos cómo la probabilidad de ocupación se vio influenciada por la cantidad de incendios de alta severidad en bosques maduros dentro de Centros de Actividad Protegida (PAC, por sus siglas en inglés). El estimado promedio de los modelos de probabilidad de ocupación de sitios para al menos un individuo fue de 0.922 (6EE ¼ 0.073), lo que es mayor que otras probabilidades de ocupación estimadas para esta subespecie en sitios con o sin incendios recientes en la Sierra Nevada. La probabilidad promedio de ocupación de sitios para parejas fue de 0.866 (60.093), y la mayoría de los sitios (33) fueron ocupados por parejas. La cantidad de incendios de alta severidad en los PAC no afectó la ocupación de las parejas. La probabilidad de ocupación por al menos un individuo se correlacionó negativamente con la cantidad de incendios de alta severidad en los PAC, pero permaneció mayor a 0.89 en el 100% de los PAC severamente incendiados. Estos datos complementan las observaciones de que S. o. occidentalis sigue usando los paisajes incendiados, aún cuando los incendios fueron grandes y donde grandes áreas se incendiaron con alta severidad, lo que sugiere que los búhos generalmente no sufren un impacto negativo por los incendios de alta severidad. Basados en este y otros estudios sobre S. occidentalis, incendios y tala de bosques, sugerimos que los administradores de la tierra consideren los bosques incendiados dentro y alrededor de los PAC como hábitats de alimentación potencialmente apropiados para S. o. occidentalis durante la planeación e implementación de las actividades de manejo. No recomendamos la tala de los bosques incendiados en un radio Q 2015 Cooper Ornithological Society

Seeing spots: quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes (Giraffa camelopardalis)

Polymorphic phenotypes of mammalian coat coloration have been important to the study of genetics and evolution, but less is known about the inheritance and fitness consequences of individual variation in complex coat pattern traits such as spots and stripes. Giraffe coat markings are highly complex and variable and it has been hypothesized that variation in coat patterns most likely affects fitness by camouflaging neonates against visually hunting predators. We quantified complex coat pattern traits of wild Masai giraffes using image analysis software, determined the similarity of spot pattern traits between mother and offspring, and assessed whether variation in spot pattern traits was related to fitness as measured by juvenile survival. The methods we described could comprise a framework for objective quantification of complex mammal coat pattern traits based on photographic coat pattern data. We demonstrated that some characteristics of giraffe coat spot shape were likely to be heritable, as measured by mother-offspring regression. We found significant variation in juvenile survival among phenotypic groups of neonates defined by multivariate clustering based on spot trait measurement variables. We also found significant variation in neonatal survival associated with spot size and shape covariates. Larger spots (smaller number of spots) and irregularly shaped or rounder spots (smaller aspect ratio) were correlated with increased survival. These findings will inform investigations into developmental and genetic architecture of complex mammal coat patterns and their adaptive value

Nest Making and Oxytocin Comparably Promote Wound Healing in Isolation Reared Rats

Background: Environmental enrichment (EE) fosters attachment behavior through its effect on brain oxytocin levels in the hippocampus and other brain regions, which in turn modulate the hypothalamic-pituitary axis (HPA). Social isolation and other stressors negatively impact physical healing through their effect on the HPA. Therefore, we reasoned that: 1) provision of a rat EE (nest building with Nestlets®) would improve wound healing in rats undergoing stress due to isolation rearing and 2) that oxytocin would have a similar beneficial effect on wound healing. Methodology/Principal Findings: In the first two experiments, we provided isolation reared rats with either EE or oxytocin and compared their wound healing to group reared rats and isolation reared rats that did not receive Nestlets or oxytocin. In the third experiment, we examined the effect of Nestlets on open field locomotion and immediate early gene (IEG) expression. We found that isolation reared rats treated with Nestlets a) healed significantly better than without Nestlets, 2) healed at a similar rate to rats treated with oxytocin, 3) had decreased hyperactivity in the open field test, and 4) had normalized IEG expression in brain hippocampus. Conclusions/Significance: This study shows that when an EE strategy or oxytocin is given to isolation reared rats, the peripheral stress response, as measured by burn injury healing, is decreased. The findings indicate an association between the effect of nest making on wound healing and administration of the pro-bonding hormone oxytocin. Further elucidation of this animal model should lead to improved understanding of how EE strategies can ameliorate poor wound healing and other symptoms that result from isolation stress

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London