**2. Materials and Methods**

#### *2.1. Systematic Literature Review*

To review the scientific literature published about urban carnivores we followed the guidelines proposed by Haddaway et al. [65] and Lozano et al. [66]. First, we studied peerreviewed articles published in journals available on Web of Science and Scopus databases. The search was applied to the title, without selecting any date range. We considered the inclusion of the grey literature, taking into account the contribution of these additional sources for systematic reviews [67,68]. However, in our searches, we did not find these technical reports, conferences and similar publications, and so we only included scientific articles. To avoid the heterogeneity inherent to different observers, only one of the authors searched the databases, by using a search string that combined different terms related to predation and scavenging in urban environments. We conducted two different searches including the terms (urban\* OR city\*) AND (scaveng\* OR predat\*). Second, we completed our database, both in the case of urban predation and urban scavenging, by applying a "snowball" procedure, including additional articles found in the previously selected reference lists [66]. Third, we completed the dataset on predation and scavenging by including more articles found in a complementary non-systematic search, based mainly on Google Scholar.

We explored the content of the compiled articles with a two-step process. First, we screened titles and abstracts to ensure we only included articles focused on the urban predation and scavenging diet of urban wildlife. Accordingly, studies located in human dominated but non-urban sites, for example, those conducted in transformed landscapes such as agricultural areas, were excluded. Moreover, we also left out those nature reserves located in other anthropized locations with less urban development. Equally, articles focused on human scavenging in garbage dumps (picking through garbage for food scraps), and those referring to forensic science were discarded. Secondly, we read the main text of the articles to see how and to what extent urban predation/scavenging was addressed. We considered a species to be an urban predator when it was recorded in urban environments actively preying on vertebrates (including eggs) while we considered a species to be an urban scavenger when it was recorded consuming carrion (including human waste). Regarding the topic in the studies we reviewed, in our final list, we discarded those studies based on scavenger species but exploring other aspects of their biology and ecology

different from their diet, as well as non-empirical studies (i.e., reviews, conceptual papers and anecdotal short notes without detailed data to use in further analyses).

#### *2.2. Data Extraction*

From the retained articles, we extracted the following information: (i) year of publication; (ii) study site, including the biome (based on the classification used by Olson et al. [69] to define major habitat types), continent, country and city studied; (iii) population size of the city during the year of the study; (iv) sector of the city considered, classifying the articles as urban, (those conducted in the interior of the cities), and peri-urban (i.e., peripheral landfills and urban nature reserves surrounding cities, and residential neighborhoods); (v) studied taxa, at class, order and species level; (vi) richness of predator/scavenging species (this was calculated only in those studies that did not focus on the activity of a single species). Then, for each reported species, we identified (vii) the carnivore level, calculated as the proportion of diet based on vertebrates (including eggs). To calculate this, in the case of mammals and birds, we summed all dietary variables which included vertebrates, from Wilman et al. [70], (viii) average body mass of the species in grams and (ix) daily activity (mainly diurnal or nocturnal). For reptiles, we used complementary dietary bibliography [71–75]. Solely for scavengers, we included whether the study was conducted thinking specifically about scavenging or, in contrast, if this was merely an aspect within studies focused on diet in a broader sense. Additionally, when the studies were focused on scavenging, we added information regarding the origin of the carrion, to clarify whether the species was purposely fed with certain carrion for research purposes (fish heads, bird carcasses from domestic or wild animals, garbage) instead of consuming the refuse scattered in the city.
