Human population increase and anthropogenic land-use changes are impacting biodiversity globally. Information on their impacts on urban wildlife is becoming increasingly apparent. Despite an increasing trend in urban wildlife studies, a systematic assessment of mammalian small carnivores in urban areas is lacking. We evaluated urban studies in international peer-reviewed journals using a systematic review process. We assessed urban wildlife publications from 1970–2021 to quantify trends over time regarding the taxonomic family and geographical focus of publications across the globe. Urban small carnivore studies have increased progressively through the decades, with 87.2% of all studies conducted in the last 20 years. Geographically, we found that small carnivore studies were disproportionately conducted, with 77.0% of all studies taking place in either North America (46.5%) or Europe (30.5%). Furthermore, the United States of America (39.8%) and the United Kingdom (11.4%) contributed to 51.2% of all studies focused on small carnivores. We found seven carnivore families represented in urban studies, consisting of 76 species. Two canid species, Vulpes vulpes (21.9%) and Canis latrans (16.9%), accounted for 38.8% of all studies conducted on urban small carnivores. The majority of studies took place in mixed or urban areas (79.8%), with suburban and exurban zones explored to a lesser extent (16.6%). Animal behaviour was the most studied scientific topic (24.6%), with the least being species conservation (0.3%). Critical gaps persist in the research of small mammalian carnivores, particularly in rapidly urbanising areas of Asia, Africa, and South America. While the field of urban ecology will certainly continue to advance, we urge future research to adopt a multi-disciplinary stance that explores the landscape transitional zones, from the periphery of the urban core (sub-urban, peri-urban, and exurban) into natural systems; or urban mosaic landscapes with natural and managed green spaces as refugia. The importance of urban fringe and margin areas for small carnivores remains largely unclear.

We carried out a comprehensive literature search to quantify the available research on urban mammalian small carnivores. We compiled data from only international peer-reviewed published journals. Article titles were found using the Google Scholar and Web of Science online search engine databases using the search phrase “"Urban Mammal" OR "Urban Carnivore" AND Mammal” with the following keyword "*" notation: mammal, carnivore, urban, suburban, city, periurban, exurban, residential. In Scopus, articles were found using the search phrase TITLE-ABS-KEY (urban)) AND ((mammal)) AND (carnivore) AND PUBYEAR AFT 1970, following with OR function with different types of urban areas (suburban, city, periurban, exurban, and residential). The search timeframe was limited between 1970 and the end of 2021. Literature resources included in the analysis were only those with a fully accessible abstract. Publications were incorporated in the review if they represented wildlife-based research (non-domestic animals) located in areas of urban landscapes (non-agricultural), and therefore, feral domestic dogs (Canis lupus familiaris) and cats (Felis catus) were excluded from this review. Review papers were included in the analyses, while editorials, letters, comments, and book reviews were excluded (Magle et al., 2012; Collins et al., 2021).

For the Web of Science, Google Scholar, and Scopus outputs, the results were refined by countries belonging to major global regions (Africa, Asia, Europe, North America, Oceania, and South America). The Web of Science search was further refined by using the Web of Science Core Collection. Additionally, we performed an additional Web of Science Core Collection search with the combination of specific families of mammalian small carnivores, namely Canidae, Felidae, Herpestidae, Mephitidae, Mustelidae, Procyonidae, and Viverridae with the "*" notation. Journal articles were subsequently separated by species of interest and tabulated by global region and country where the study was performed. Additional studies were incorporated into the final summary table by referral.

Furthermore, publications were evaluated for their primary research topics. The classification process was not limited to a single research topic and could comprise multiple topics. The 11 primary research topics were: 1. Animal behaviour: spatial movement (dispersal, home range, habitat), intraspecific interactions (mating and conflicts), alterations in activities and diet; 2. Community ecology: interspecific interactions between two or more species; 3. Conservation: studies focused on endangered or threatened species; 4. Genetics: population genetics; 5. Human dimension: citizen science and survey questionnaires; 6. Human–wildlife conflict: wildlife attacks, economic damage, domestic pet interactions, vehicle collisions; 7. Invasion ecology: studies on an invasive species; 8. Population ecology: demographic levels and population change; 9. Wildlife diseases: zoonotic and wildlife diseases, parasites and transmission; 10. Wildlife management: population control, baiting methods and sterilisation; and 11. Wildlife toxicology: anthropogenically derived blood toxins, poisons and heavy metals. Lastly, we categorised the land-use types in which the studies were conducted. Study sites were classified according to the level of development based on terms used in the abstract, title and/or keywords (urban, suburban, exurban/peri-urban and unknown) (Magle et al., 2012; Collins et al., 2021). We also added the category of mixed land-use type, which were studies that encompassed multiple degrees of urban development. Studies that occurred along an urban land-use gradient overlapping with natural areas were not excluded. We collated all these data and used descriptive statistics to show trends.