A focus on the European hamster to illustrate how to monitor endangered species

Abstract

Agriculture intensification, marked by the generalization of crop monoculture, by the increase in plot size and by the reduction of plant diversity, has led to huge decline in wildlife in European farmlands. In such habitat, research has long been biased towards birds and invertebrates, while very few studies have investigated the effect on small mammals. Considering the European hamster, Cricetus cricetus, we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals. We suggest that only a multidisciplinary approach will allow exploration of these effects, combining experimental laboratory work on captive‐bred animals with the monitoring of wild individuals. In particular, individual energy balance has to be investigated and measured as accurately as possible, through either biochemical or bio‐logging techniques. It is, indeed, the most affected physiological trait in a changing environment, as it determines both the reproductive output and the survival of the individual. We also discuss the inconvenience of capture–release approaches for such an endangered species and emphasize the disturbance that experimental protocols could impose on the hamster.

Are All Conservation Measures for Endangered Species Legitimate? Lines of Thinking With the European Hamster

“…The impact and a cost-benefit assessment have, however, to be evaluated, including ethical considerations. Kletty et al (2019) summarized and compared the different methods available to monitor small mammals like the European hamster. Hereafter, we discuss some of them and their implications.…”

“…It is no more painful than a syringe injection, easy to use, and works for life. Another advantage of PIT-tags is that it can be combined with automated identification recorders to monitor the presence or movements (e.g., wildlife underpasses or burrows), biological parameters (i.e., coupled with a weight-watcher), or behavior (coupled with camera) of animals, without requiring their recapture (Tissier et al, 2018a;Kletty et al, 2019). Dying and ringing are other ways to gather information on the presence or behavior of specific individuals since it allows a direct or indirect (via cameras) recognition.…”

“…The use of external transmitters is also possible and does not require surgery, but it can have adverse effects on animals, like handicap (especially collars for hamsters, since they have cheek pouches), perturbation of its behavior, or survival impairment (Webster and Brooks, 1980;Theuerkauf et al, 2007;Kletty et al, 2019). Thus, if internal transmitters can be used, it seems to be a more suitable option.…”

The Role Transition of Dietary Species Richness in Modulating the Gut Microbial Assembly and Postweaning Performance of a Generalist Herbivore

“…Higher DSR can reduce the energy cost of locating food resources and provide a balanced nutrient supply for consumers, as well as act as a buffer against stochastic loss of food species under harsh natural conditions ( 8 ). Accordingly, a long-standing hypothesis in ecology holds that lower DSR can cause serious population decline and shrinkage of wildlife ( 9 ), while greater DSR is associated with a lower risk of consumer population collapse ( 10 – 12 ). Amid ongoing global changes, however, a preferable level of high DSR has often been accompanied by a parallel increase in negative effects on consumers.…”

Symposium “How to track wild animals without disturbance and subsequent bias”

“…In the next paper, R. S. Hetem et al (2019) demonstrate the use of implanted bio-loggers to document that the maintenance of homeothermy of cheetahs at high ambient temperatures may be explained by a shift from a diurnal to a crepuscular activity pattern. The last paper of this special issue by F. Kletty et al (2019) reviews all readily available tagging methods to track small rodents, including threatened species. The study shows how tracking can be used to develop an integrative approach for studying these animals, providing a better understanding of the interacting effects of extensive agricultural development and climate change on their population dynamics.We feel that we are entering a time when there is a profound change in the methods available to investigate freely ranging wild animals.…”