With 3.5 persons per square kilometre, Canada is one of the countries with the lowest population densities in the world. Census metropolitan areas (CMAs) with the highest population densities—Toronto (866), Montréal (854), Vancouver (735), Kitchener (546), Hamilton (505), and Victoria (475)—were located close to United States border.

Estimated number of persons by quarter of a year and by year, Canada, provinces and territories.

AbstractCities can have profound impacts on ecosystems, yet our understanding of these impacts is currently limited. First, the effects of socioeconomic dimensions of human society are often overlooked. Second, correlative analyses are common, limiting our causal understanding of mechanisms. Third, most research has focused on terrestrial systems, ignoring aquatic systems that also provide important ecosystem services. Here we compare the effects of human population density and low-income prevalence on the macroinvertebrate communities and ecosystem processes within water-filled artificial tree holes. We hypothesized that these human demographic variables would affect tree holes in different ways via changes in temperature, water nutrients, and the local tree hole environment. We recruited community scientists across Greater Vancouver (Canada) to provide host trees and tend 50 tree holes over 14 weeks of colonization. We quantified tree hole ecosystems in terms of aquatic invertebrates, litter decomposition, and chlorophyll-a. We compiled potential explanatory variables from field measurements, satellite images, or census databases. Using structural equation models, we showed that invertebrate abundance was affected by low-income prevalence but not human population density. This was driven by cosmopolitan species of Ceratopogonidae (Diptera) with known associations to anthropogenic containers. Invertebrate diversity and abundance were also affected by environmental factors, such as temperature, elevation, water nutrients, litter quantity, and exposure. By contrast, invertebrate biomass, chlorophyll-a, and litter decomposition were not affected by any measured variables. In summary, this study shows that some urban ecosystems can be largely unaffected by human population density. Our study also demonstrates the potential of using artificial tree holes as a standardized, replicated habitat for studying urbanization. Finally, by combining community science and urban ecology, we were able to involve our local community in this pandemic research pivot. This abstract is quoted from the original article "Insects in the city: Determinants of a contained aquatic microecosystem across an urbanized landscape" in Ecology (2023) by DS Srivastava et al. MethodsThese methods are quoted in abbreviated form from the original article [please also see README.md file for details on each script and data file, including description of every variable]: We installed 73 artificial tree holes (hereafter tree holes) throughout Greater Vancouver, specifically the cities of Vancouver, Abbottsford, Burnaby, Chilliwack, Delta, Maple Ridge, New Westminster, North Vancouver, Port Moody, Richmond, Surrey, and West Vancouver. We constructed artificial tree holes from black plastic buckets (950 ml, height: 12.2cm, diameter:11.5cm). Near the rim, we drilled 1-cm holes for water overflow and covered these with 1mm mesh to prevent loss of insects and litter (Figure 2a). We attached each tree hole to a deciduous tree with a cable tie, about 1.3 m above ground, before adding leaf litter and bottled spring water. The leaf litter consisted of dried (60°C for two days) and pre-weighed Acer macrophyllum (Sapindaceae) leaves collected in November 2020, both loose (2.50 g) and in a 0.5 mm mesh leaf bag (0.200 g). We filled each tree hole with ~750 ml spring water (Western FamilyTM). Community scientists were instructed to monitor water level in the tree holes during the experiment, topping up tree holes when they became half-empty with extra bottles of water (same brand) that we provided. We also added an iButtonTM temperature logger (Maxim Integrated, San Jose, CA, USA; models DS1921G, DS1921Z, and DS1922L) wrapped in ParafilmTM (Beemis Company, Neenah, WI, USA) and programmed it to collect data every hour for 85 days. We added a small stick to assist ovipositing insects to perch or pupating insects to emerge. We installed all tree holes 21–28 March 2021. We visited all tree holes 17–30 May 2021, to collect data on water chemistry (pH, chlorophyll-a concentration), light availability (canopy cover), potential oviposition cues (host tree diameter, nearby standing water), and potential source populations (distance to water bodies). We measured water pH directly using a calibrated OaktonⓇ pH 450 pH meter. To estimate chlorophyll-a concentration, we extracted 25 mL of water, filtered it through a glass microfiber (0.7 μm) filter, and froze the filters. In the lab, we extracted chlorophyll-a on filters with 90%-acetone. We used a Trilogy Laboratory Fluorometer (Turner Designs, San Jose, CA, USA) to determine chlorophyll-a concentration following Wasmund et al. (2006). To measure canopy cover, we took a photograph directly up by placing a smartphone flat on the tree hole and then used ImageJTM to differentiate open sky from any obstructing cover. We searched within 30m of tree holes for sources of persistent standing water, such as buckets, birdbaths,...

Customer initiated service requests received by 3-1-1 Contact Centre from 2022. Service requests refer only to those call types that generate a requ​​es​​t to a City of Vancouver department to provide service.This dataset contains location information such as address or intersection where service was requested and the local area corresponding to the case (incident) location. ​Due to the volume of records, we segmented the service requests data into multiple datasets. See 3-1-1 service requests 2009-2021 dataset for records from 2009 to 2021.​ Note​The 3-1-1 case management system started collecting case service requests data on June 1, 2009. The system was upgraded on August 17, 2022. Department, Division or Call Types beginning with ZZ – OLD refers to obsolete types used in the past. Generally, another call type within the same division, or another division within the same department replaced the obsolete type. When reviewing case location data spatially, consideration should be given to the City’s urban attributes such as vegetation density, population density, age of infrastructure asset, area specific bylaws, etc. Some case types are associated with city locations.​ Data currency​Records on or after August 17, 2022 are refreshed daily. Records prior to this date are static.​ Data accuracyData are electronically extracted from the 3-1-1 case management system.Address data of some selected service request types is not disclosed to provide privacy protection.There may be addresses that do not return coordinates in the gecoding process. These records will appear in the Table view but not on the Map.​​ Websites for further informationContact the City of Vancouver​

The plate contains four maps of 10 minute rainfalls (in millimetres) for a 2 year return period, a 5 year return period, a 10 year return period and a 25 year return period. Each map has a detailed inset of the Vancouver area. These four maps were not analyzed for the mountainous parts of Canada in British Columbia and the Yukon because of the limited number of stations, the non-representative nature of the valley stations and the variability of precipitation owing to the orographic effects. From the incomplete data, it is impossible to draw accurate isolines of short duration rainfall amounts on maps of national scale. Point values for all stations west of the Rocky Mountain range and in the Yukon have been plotted for durations of less than 24 hours. For the Vancouver metropolitan area, recording rain gauges have been in operation for several years. For some of these stations point rainfall data have been plotted on inset maps. The density of climatological stations varies widely as does population density. In general, the accuracy of the analysis increases with station density. North of latitude 55 degrees North, there are only five stations. Therefore, the isoline analyses represent extrapolations beyond the station values. Whenever sufficient data were available for interpretation, isolines were drawn as solid lines. The scale of the map used for Canada dictates the use of an isoline interval of 4 millimetres.

Urban rats (Rattus spp.) are among the most ubiquitous pest species in the world. Previous research has shown that rat abundance is largely determined by features of the environment; however, the specific urban environmental factors that influence rat population density within cities have yet to be clearly identified. Additionally, there are no well described tools or methodologies for conducting an in-depth evaluation of the relationship between urban rat abundance and the environment. In this study, we developed a systematic environmental observation tool using methods borrowed from the field of systematic social observation. This tool, which employed a combination of quantitative and qualitative methodologies, was then used to identify environmental factors associated with the relative abundance of Norway rats (Rattus norvegicus) in an inner-city neighborhood of Vancouver, Canada. Using a multivariate zero-inflated negative binomial model, we found that a variety of factors, including specific land use, building condition, and amount of refuse, were related to rat presence and abundance. Qualitative data largely supported and further clarified observed statistical relationships, but also identified conflicting and unique situations not easily captured through quantitative methods. Overall, the tool helped us to better understand the relationship between features of the urban environment and relative rat abundance within our study area and may useful for studying environmental determinants of zoonotic disease prevalence/distribution among urban rat populations in the future.

The plate contains four maps of 10 minute rainfalls (in millimetres) for a 2 year return period, a 5 year return period, a 10 year return period and a 25 year return period. Each map has a detailed inset of the Vancouver area. These four maps were not analyzed for the mountainous parts of Canada in British Columbia and the Yukon because of the limited number of stations, the non-representative nature of the valley stations and the variability of precipitation owing to the orographic effects. From the incomplete data, it is impossible to draw accurate isolines of short duration rainfall amounts on maps of national scale. Point values for all stations west of the Rocky Mountain range and in the Yukon have been plotted for durations of less than 24 hours. For the Vancouver metropolitan area, recording rain gauges have been in operation for several years. For some of these stations point rainfall data have been plotted on inset maps. The density of climatological stations varies widely as does population density. In general, the accuracy of the analysis increases with station density. North of latitude 55 degrees North, there are only five stations. Therefore, the isoline analyses represent extrapolations beyond the station values. Whenever sufficient data were available for interpretation, isolines were drawn as solid lines. The scale of the map used for Canada dictates the use of an isoline interval of 4 millimetres.