Sustainable Agriculture: Nutritional Benefits of Wheat–Soybean and Maize–Sunflower Associations for Hibernation and Reproduction of Endangered Common Hamsters

Farmland species face many threats, including habitat loss and malnutrition during key periods of their life cycle. This is aggravated in conventionally managed monocultures, leading to nutrient deficiencies that impair the survival and reproduction of farmland wildlife. For instance, protein deficiencies in wheat or vitamin B3 deficiency in maize reduce by up to 87% the reproductive success of the critically endangered common hamster (Cricetus cricetus), a flagship species of European farmlands. It is urgent to identify and implement agricultural practices that can overcome these deficiencies and help restoring hamsters’ reproductive success. As part of a conservation program to diversify farming habitats in collaboration with farmers, we tested whether associations between wheat or maize and three supplemental crops (soybean, sunflower and fodder radish) supported hamsters’ performance during hibernation and reproduction. We observed that maize–sunflower, maize–radish and wheat–soybean associations minimized hamsters’ body mass loss during hibernation. The wheat–soybean association led to the highest reproductive success (N = 2 litters of 4.5 ± 0.7 pups with a 100% survival rate to weaning), followed by maize–sunflower and maize–radish. These crop associations offer promising opportunities to overcome nutritional deficiencies caused by cereal monocultures. Their agronomic potential should promote their implementation on a large scale and benefit farmland biodiversity beyond the common hamster.

Preliminary Assumptions for Identification of the Common Hamster (Cricetus cricetus) as a Service Provider in the Agricultural Ecosystem

The common hamster is a critically endangered species, but it is also perceived as a pest. Searching for an economic reason for its protection can be an argument to prevent its extinction. The purpose of this paper is to reveal the identification services provided by hamsters in the agricultural ecosystem and the determination of their correlation with human welfare. We propose the methods that can be applied for this purpose, and we check if the knowledge of the species is sufficient in order to use available methods for estimating the value of the services. The common hamster is a provider of supporting, regulating, and cultural services. Estimating their value is difficult because (1) available knowledge on the species’ ecology requires an update, in many aspects, due to changes to agricultural practices that have taken place since the 1970s (e.g., assessment of actual losses to cereal, vegetable, or root crops), and also extending by context, enabling the economic valuation of services (e.g., determination of impact range on various habitat components); it is also necessary to identify the correlations between profits and losses caused by this species; (2) there is a low level of public knowledge on the presence of hamsters and their role in the ecosystem. Education, primarily for consumers, followed by the promotion of hamsters as an umbrella and key species for agricultural areas, may result in the development of cultural services, which will increase the economic value of the services provided by hamsters.

Predation and survival in reintroduced populations of the Common hamster Cricetus cricetus in the Netherlands

European populations of Common hamster (Cricetus cricetus) have dramatically declined in the last decades, and in many EU countries, the species is on the brink of extinction. In the Netherlands, a research and reintroduction program was started in three areas with hamster-friendly management to reverse the decline of the species. Since 2002, more than 800 captive-bred and wild-born hamsters were monitored using implant radiotransmitters to quantify survival rates and discover the main causes of death after release compared to those of wild individuals. Individuals with a transmitter were regularly checked at their burrow. Predation by foxes, birds of prey, and small mustelids was the most important cause of mortality of this medium-sized rodent, while crop type and harvest regime were also likely to be important drivers as they influenced survival rates through the presence or absence of protective cover. The fitted weekly survival model showed that male hamsters had much lower survival rates during the active season than females, which corresponds with the ‘risky male hypothesis’. Survival rates of females appeared too low to keep populations at a stable level. To establish a viable population, more optimal environmental conditions for both survival and reproduction of the hamsters are necessary. Using electric fences around fields with hamsters significantly increased the survival of females. However, hamster conservationists need to consider not just subadult and adult survival rates, but also habitat connectivity, weather effects on reproduction, and alternative agricultural practices on a landscape scale.

Findings of the common hamster (Cricetus cricetus) in Kharkiv Oblast, Ukraine

The article considers the change in the state of the common hamster from a widespread to a rare species in Ukraine. In 1994, it was listed in the Red Book of Ukraine. The most significant changes in the status of hamsters in the last 100 years in Kharkiv Oblast had occurred in 1982 to 2006. Isolated finds of this species in 2020 show its presence. Two actual finds from one location near Kharkiv are described. The species was found in areas not involved in intensive agricultural production. The population decline and range contraction can be explained by excessive ploughing of agricultural lands. This reduces the prospects of the species' survival.

Monitoring of the Cricetus cricetus L. population in the Upper Pobuzhzhia region

The research was carried out in Letychiv Raion of Khmelnytsky Oblast during 2003–2017. In 2016–2020, the population of the common hamster was monitored near the village of Holoskiv. During the research, we recorded 15 hamster encounters and finds of 220 burrows: 15 burrows near the village of Rusanivtsi and 205 burrows around the village of Holoskiv. 163 burrows were found directly at the monitoring site. The density of burrows in gardens ranges from 1.03 burrows / ha to 2.39 burrows / ha, and in large fields — 0.025–0.02 burrows / ha. Most burrows are located on fields of alfalfa (32.3 %) and winter wheat (25.9 %).

Species composition, diversity, and the abundance of arthropods inhabiting burrows of the common hamster (Cricetus cricetusL.)

The is insufficient knowledge of arthropod communities occurring in specific microhabitats. In this study, we characterize the arthropod assemblages inhabiting burrows of the common hamster (Cricetus cricetusL.) and factors that determine their diversity and abundance. We tested the following hypotheses: (1) arthropod assemblages are associated with a particular dominant vegetation occurring in the vicinity of burrows; (2) a correlation exists between fine-scale geographic distances among burrows and assemblage dissimilarity; and (3) the type of trap influences the sampling success of captured arthropods. We found 73 morphospecies belonging to 16 families in 109 burrows, most of which were in the families Staphylinidae (Coleoptera) and Parasitidae (Arachnida: Acari: Mesostigmata). The most abundant families were Staphylinidae, Cryptophagidae (Coleoptera), Parasitidae, and Macrochelidae (Mesostigmata) (78.89%). Among the identified species, we foundAleochara irmgardis(Staphylinidae) andPoecilochirus sexclavatus(Parasitidae) which had not yet been reported in Poland, and several other rare species. Meat-baited traps captured 64.34% more individuals, which were more diverse and species-rich than the non-baited control traps, but the former was more selective for saprophages, necrophages, and coprophages. The burrows located in areas overgrown by triticale (a hybrid of wheat and rye) were inhabited by 69.86% of the identified arthropod species, and these also had the highest abundance (64.07%) in comparison with other habitats. However, differences in sample size biased our results toward and overestimate arthropods associated with this vegetation. This study underlines that the species composition detected in burrows was affected by the methods used and hamster preferences for a specific habitat rather than the geographic proximity of the burrows. More extensive sampling across multiple habitats will be necessary to confirm our findings.