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Following the expansion of agriculture in the Neolithic period, the common hamster has spread throughout Europe, and occurred abundantly until the recent past. However, in the last 45 years, populations declined markedly, partly attributable to urbanization and to major changes in agricultural practices. As a result, the species has been considered endangered at international levels as well as in most European countries. At the same time, the species has established populations in large Central and Eastern-European cities such as Vienna (Austria), Simferopol (Ukraine) and Nalchik (Russia), where it inhabits green spaces such as parks, gardens, embankments and buffer strips. In an attempt to reveal factors enabling hamsters to cope with urban environments, we reviewed historical data and habitat conditions of several urban hamster populations. We suggest that supplemental food resources and reduced predation pressure were the main factors promoting urban occurrence of common hamsters in the last 30 years. Its notable adaptability may be associated with higher stress resilience, ecological opportunism, polyphagy and higher fertility compared to species Unauthenticated Download Date | 5/13/18 9:19 AM 114 NATALIA -YU. relying on non-urban habitats. The phenomenon of synurbization implies coexistence of wildlife and our urban civilization, but at the same time conflicting interests in conservation and urban development. Thus, the common hamster might serve as a model species for efficient mitigation and compensation concepts in urbanism and spatial planning.

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The Common hamster (Cricetus cricetus) has been intensively colonizing cities during the last decades. Changes in the burrow numbers and their distribution over an area might be important indicators of the population status for the Common hamster in an urban environment. In this study, we consider the character of the burrow distribution on the experimental plot (2.2 ha) situated in the park of Simferopol City, Russian Federation. The brushwood and tree vegetation on this plot had been previously mapped in detail. Hamster burrows were put on the map once a quarter during a year. The peak of burrowing activity is shown to be in November. Interestingly, the ground activity of hamsters continued even in the coldest month (January) of the year but the number of used burrows was very low. The squares where both trees and burrows were present (by average annual indicators) was met significantly more frequently than burrows in the tree-free squares (P = 0.02; χ 2 = 5.2) but this was not the case for the winter and spring seasons. We assume that the connection of burrows with arboreous vegetation facilitates digging, ensures better protection from predators and is a food source. All these factors ensure favorable conditions for the high abundance of the Common hamster in the urban environment.

Traditionally, urbanization has been seen as a negative phenomenon for biota. However, changes in the environmental parameters induced by urbanization might be favorable for some species. Over the past half‐century, the common hamster has actively populated cities, establishing populations in some European, Russian and Kazakhstan cities. Based on integrative methods, we investigated free‐range common hamsters inhabiting Simferopol from 2015 to 2018 to reveal possible adaptations to the urbanized environment across several parameters, including lifespan, hibernation period, reproductive activity and body mass. Results show that in urban areas, the common hamster demonstrates an extremely short hibernation period compared to other localities, possibly due to enhanced food resources from urban forestry (walnuts, locus and hazelnut), allowing the species to start breeding very early (February) and finish as late as October. We present the first evidence of polyandry for this species: mating of receptive females with several males and subsequent confirmation of multiple paternity. Despite high reproductive potential, the lifespan of the common hamster in urban conditions is generally very short (less than 1 year). We speculate that in the process of synurbization, the common hamster's innate plasticity across many life history traits permits it to successfully colonize throughout a wide range of habitats, with the ability to form novel adaptations to urban environments.