Understanding Demographic and Behavioral Mechanisms that Guide Responses of Neotropical Migratory Birds to Urbanization: a Simulation Approach

Although studies often report that densities of many forest birds are negatively related to urbanization, the mechanisms guiding this pattern are poorly understood. Our objective was to use a population simulation to examine the relative influence of six demographic and behavioral processes on patterns of avian abundance in urbanizing landscapes. We constructed an individual-based population simulation model representing the annual cycle of a Neotropical migratory songbird. Each simulation was performed under two landscape scenarios. The first scenario had similar proportions of high- and low-quality habitat across the urban to rural gradient. Under the first scenario, avian density was negatively related to urbanization only when rural habitats were perceived to be of higher quality than they actually were. The second landscape scenario had declining proportions of high-quality habitat as urbanization increased. Under the second scenario, each mechanism generated a negative relationship between density and urbanization. The strongest effect on density resulted when birds preferentially selected habitats in landscapes from which they fledged or were constrained from dispersing. The next strongest patterns occurred when birds directly evaluated habitat quality and accurately selected the highest-quality available territories. When birds selected habitats based on the presence of conspecifics, the density–urbanization relationship was only one-third the strength of other habitat selection mechanisms and only occurred under certain levels of population survival. Although differences in adult or nest survival in the face of random habitat selection still elicited reduced densities in urban landscapes, the relationships between urbanization and density were weaker than those produced by the conspecific attraction mechanism. Results from our study identify key predictions and areas for future research, including assessing habitat quality in urban and rural areas in order to determine if habitats in urban areas are underutilized.

Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)

The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.

Quantification of urbanization in relation to chronic diseases in developing countries : a systematic review

During and beyond the twentieth century, urbanization has represented a major demographic shift particularly in the developed world. The rapid urbanization experienced in the developing world brings increased mortality from lifestyle diseases such as cancer and cardiovascular disease. We set out to understand how urbanization has been measured in studies which examined chronic disease as an outcome. Following a pilot search of PUBMED, a full search strategy was developed to identify papers reporting the effect of urbanization in relation to chronic disease in the developing world. Full searches were conducted in MEDLINE, EMBASE, CINAHL, and GLOBAL HEALTH. Of the 868 titles identified in the initial search, nine studies met the final inclusion criteria. Five of these studies used demographic measures (such as population density) at an area level to measure urbanization. Four studies used more complicated summary measures of individual and area level data (such as distance from a city, occupation, home and land ownership) to define urbanization. The papers reviewed were limited by using simple area level summary measures (e.g., urban rural dichotomy) or having to rely on preexisting data at the individual level. Further work is needed to develop a measure of urbanization that treats urbanization as a process and which is sensitive enough to track changes in “urbanicity” and subsequent emergence of chronic disease risk factors and mortality.

Level of urbanization and noncommunicable disease risk factors in Tamil Nadu, India

Objective To investigate the poorly understood relationship between the process of urbanization and noncommunicable diseases (NCDs) through the application of a quantitative measure of urbanicity.

Methods We constructed a measure of the urban environment for seven areas using a seven-item scale based on data from the Census of India 2001 to develop an “urbanicity” scale. The scale was used in conjunction with data collected from 3705 participants in the World Health Organization’s 2003 STEPwise risk factor surveillance survey in Tamil Nadu, India, to analyse the relationship between the urban environment and major NCD risk factors. Linear and logistic regression models were constructed examining the relationship between urbanicity and chronic disease risk.

Findings
Among men, urbanicity was positively associated with smoking (odds ratio, OR: 3.54; 95% confidence interval, CI: 2.4–5.1), body mass index (OR: 7.32; 95% CI: 4.0–13.6), blood pressure (OR: 1.92; 95% CI: 1.4–2.7) and low physical activity (OR: 3.26; 95% CI: 2.5–4.3). Among women, urbanicity was positively associated with low physical activity (OR: 4.13; 95% CI: 3.0–5.7) and high body mass index (OR: 6.48; 95% CI: 4.6–9.2). In both sexes urbanicity was positively associated with the mean number of servings of fruit and vegetables consumed per day (P < 0.05).

Conclusion
Urbanicity is associated with the prevalence of several NCD risk factors in Tamil Nadu, India.

Simplification of arboreal marsupial assemblages in response to increasing urbanization

Arboreal marsupials play an essential role in ecosystem function including regulating insect and plant populations, facilitating pollen and seed dispersal and acting as a prey source for higher-order carnivores in Australian environments. Primarily, research has focused on their biology, ecology and response to disturbance in forested and urban environments. We used presence-only species distribution modelling to understand the relationship between occurrences of arboreal marsupials and eco-geographical variables, and to infer habitat suitability across an urban gradient. We used post-proportional analysis to determine whether increasing urbanization affected potential habitat for arboreal marsupials. The key eco-geographical variables that influenced disturbance intolerant species and those with moderate tolerance to disturbance were natural features such as tree cover and proximity to rivers and to riparian vegetation, whereas variables for disturbance tolerant species were anthropogenic-based (e.g., road density) but also included some natural characteristics such as proximity to riparian vegetation, elevation and tree cover. Arboreal marsupial diversity was subject to substantial change along the gradient, with potential habitat for disturbance-tolerant marsupials distributed across the complete gradient and potential habitat for less tolerant species being restricted to the natural portion of the gradient. This resulted in highly-urbanized environments being inhabited by a few generalist arboreal marsupial species. Increasing urbanization therefore leads to functional simplification of arboreal marsupial assemblages, thus impacting on the ecosystem services they provide.

Does urbanization have the potential to create an ecological trap for powerful owls (Ninox strenua)?

Landscape transformation associated with urbanization is one of the most damaging and pervasive impacts humans have on natural ecosystems. The response of species to increasing urbanization has become a major focus of research globally. Powerful owls ( Ninox strenua) are a top-order predator the have been shown to reside in urban environments, but increasing urbanization has also been demonstrated to significantly reduce available habitat. In this paper we use species distribution models established for key food and nesting resources of powerful owls across an urban-forest gradient to constrain habitat predictions from a previously developed powerful owl species distribution model. This multi-criteria decision analysis (MCDA) approach allowed us to investigate the impacts of urbanization on potential powerful owl habitat when challenged with food and nesting requirements. As powerful owls only use tree cavities for nesting we propose that the cue for settlement in an area is associated with the presence of habitat and food and as such breeding requirements may be disconnected from settlement requirements.Our results demonstrate that incorporation of a general prey resource (at least one group of arboreal marsupials) as a cue for settlement does not reduce the amount of available habitat for powerful owls substantially. Further constraining the model with a tree cavity resource, however, leads to a substantial reduction in powerful owl habitat in the urban and urban fringe environments. If a diverse prey resource (two or more groups of arboreal marsupials) is used as the cue for settlement, this sees a substantial reduction in available habitat in urban environments. Incorporation of tree cavities into this model does not reduce the available habitat for powerful owls substantially.We propose that powerful owls do not need a diverse prey base for survival, and that breeding resources are unlikely to be a cue for settlement. As such, we argue in this paper that increasing urbanization has the potential to create an ecological trap for powerful owls as there is a significant difference between habitat capable of supporting powerful owls, and habitat in which owls can breed.Management of powerful owls in urban environments will be difficult, but this research highlights the potential for the use of nest boxes to enhance the breeding activities in increasingly urbanized environments. Replacement of this critical resource may be able to reverse any potential ecological trap that is occurring. © 2014 Elsevier Ltd.

Sex-biased space-use response to urbanization in an endemic urban adapter

Urbanization impacts on the composition and distribution of wildlife. The tawny frogmouth (Podargus strigoides) is an endemic, nocturnal bird species widespread throughout Australia with recent research highlighting high densities within urban environments. The aim of this study was to investigate homerange size and land-use in response to a gradient of urbanization by determining (a) the key land-use types influencing home-range size and location in the urban landscape (b) whether urbanization impacts on home-range size; and (c) whether the response to urbanization is gender specific. Twelve birds, seven male and five female were radio-tracked within a study zone located in Melbourne, Australia. We used minimum convex polygons (MCP) 95% and 50% fixed-kernel isopleths to calculate home-range size and areas of core use within each home-range. In both the landscape and core areas of their home-range, birds positioned their home-range in areas with more trees, avoiding impervious surfaces and utilizing grassed areas. Male mean kernel home-range was 17.65 ± 4.35 ha and female 6.55 ± 1.40 ha. Male home-ranges contained higher levels of impervious surfaces than females. Modelling demonstrated that as urbanization intensified the home-range size of males increased whereas female home-ranges remained static in size. This research identifies land-use selection and highlights the possibility that spatial behaviour in the species is sex-biased in response to a gradient of urbanization. © 2014 Elsevier B.V.

Nutritional psychiatry research: an emerging discipline and its intersection with global urbanization, environmental challenges and the evolutionary mismatch

In 21st-century public health, rapid urbanization and mental health disorders are a growing global concern. The relationship between diet, brain function and the risk of mental disorders has been the subject of intense research in recent years. In this review, we examine some of the potential socioeconomic and environmental challenges detracting from the traditional dietary patterns that might otherwise support positive mental health. In the context of urban expansion, climate change, cultural and technological changes and the global industrialization and ultraprocessing of food, findings related to nutrition and mental health are connected to some of the most pressing issues of our time. The research is also of relevance to matters of biophysiological anthropology. We explore some aspects of a potential evolutionary mismatch between our ancestral past (Paleolithic, Neolithic) and the contemporary nutritional environment. Changes related to dietary acid load, advanced glycation end products and microbiota (via dietary choices and cooking practices) may be of relevance to depression, anxiety and other mental disorders. In particular, the results of emerging studies demonstrate the importance of prenatal and early childhood dietary practices within the developmental origins of health and disease concept. There is still much work to be done before these population studies and their mirrored advances in bench research can provide translation to clinical medicine and public health policy. However, the clear message is that in the midst of a looming global epidemic, we ignore nutrition at our peril.

Hydrologic response of a tropical watershed to urbanization

 Urbanization has profound influence on the hydrologic response of landscapes. Urban transformation affects the storages and processes that determine the generation of hydrologic fluxes. It also changes the time-scales associated with hydrologic processes. Shifts in hydrologic response of the watershed unit due to urban transformation may be more complex than the simple linear mixing (weighted sum) of responses from the urbanized and non-urbanized fractions of the landscape. This may especially be the case for tropical watersheds where the precipitation forcing of the watershed is frequent and intense - interacting with the shifting time-scales and changing storages with increasing urbanization. In this study, a fully distributed hydrological model (MOBIDIC) that captures hydrologic dynamics during storms and interstorms is applied in order to characterize the potentially nonlinear response of a tropical watershed to urban transformation. Indices that quantify the departures from linear response are introduced and used to test the effects of urbanization on different hydrologic processes and fluxes in a mixed (urban and non-urban) watershed. The tropical Kranji watershed in Singapore is used in this study. Fortunately two sub-watersheds within Kranji that have streamflow gaging stations are well-suited for the calibration of the model. One sub-watershed is nearly fully urbanized and another is pristine (non-urban). As a result the contrasting components (urban and non-urban) can be calibrated in the model. The simulation system is then used to assess the hydrologic response due to changing levels of urbanization. For some fluxes and storages, the hydrologic response due to changing urban fraction cannot be simply predicted from a linear mixing model.