Wood mouse feeding effort and decision-making when encountering a restricted unknown food source

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Animals making foraging decisions must balance the energy gained, the time invested, and the influence of key environmental factors. In our work, we examined the effect of predation risk cues and experience on feeding efforts when a novel food resource was made available. To achieve this, we live-trapped wood mouse Apodemus sylvaticus in Monte de Valdelatas (Madrid), where 80 Sherman traps were set in four plots. Traps were subjected to two food-access difficulties in treatments consisting of three consecutive nights: open plastic bottles (easy) and closed bottles (difficult), both using corn as bait. To simulate predation risk, we set fox faeces in half of the traps in each plot. We also considered moonlight (medium/low) as an indirect predation risk cue. We analysed whether bottles had been bitten by mice and the gnawed area of each bottle was measured. Our results indicated that food access difficulty, experience, and predation risk determined mice feeding decisions and efforts. The ability of mice to adapt feeding effort when a new food source is available was demonstrated because a higher proportion of closed bottles exhibited bite marks and the gnawed area was bigger. Moreover, mouse experience was determinant in the use of this new resource since recaptured mice gnawed broader orifices in the bottles and the gnawed area increased each time an individual was recaptured. Additionally, direct predation risk cues prompted mice to bite the bottles whereas the effect of different moon phases varied among the food access treatments. This study provides direct evidence of formidable efficacy of wild mice to exploit a new nutrient resource while considering crucial environmental factors that shape the decision-making procedur

Respuesta comportamental y de estrés fisiológico a factores ambientales y humanos en diferentes especies de micromamíferos: implicaciones para su conservación

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de BiologíaWild animal populations are continuously subjected to periodic disturbances by environmental and anthropogenic causes. Thereby, in this doctoral thesis, we carried out different investigations to study the behavioural and physiological stress responses of several small mammal species to different environmental and human factors. Behavioral responses to predation risk, interspecific competition and human disturbances were analyzed by live trapping. For analyzing the correspondent physiological stress responses, fresh faeces of individuals captured were collected during each experimental situation and the quantification of faecal corticosterone metabolites (FCM) as indicator of the adrenal activity was performed in the laboratory by an enzyme immunoassay. Results showed that wood mice (Apodemus sylvaticus) individuals responded to predation risk situations by recognizing and avoiding their main known predators in the study areas (they did not respond to the faecal odour of an unknown one) and also avoiding increased moonlight. Besides, foraging activity and food intake vary in relation to the risky situations but no physiological stress response was found due to the increase in predation risk. In relation to the interspecific competition with wild ungulates, Algerian mice (Mus spretus) abundances were higher inside areas where ungulates were not present being habitat selection influenced by greater vegetation cover. Increased FCM levels inside areas without ungulates were due to the higher mice abundance whereas in the grazed areas depended on the higher soil compaction caused by ungulates. Finally, we studied whether human disturbances through agricultural practices and motorways affected small mammal populations. We found a smaller number of common voles (Microtus arvalis) inhabiting inside crops, additionally, individuals captured inside crops showed higher FCM concentrations. In relation to the motorway, wood mice living closer to the motorway showed the highest FCM levels. Based on these results, we can conclude that small mammals generally respond by altering their behaviour when facing daily environmental or human disturbances. However, only interspecific competition with ungulates and human disturbance evoked physiological stress reactions whereas predation risk factors did not evoke such responses, suggesting that maybe these cues are not enough reliable to experience physiological stress responses since prey species daily face the risk of predation and therefore such continuous responses could be costly and pathological for individuals. All the behavioural and physiological stress responses studied also depended on individual characteristics (e.g. sex, age and breeding condition) probably based on previous experience and the balance of costs-benefits in each particular situation at a given place and time. Since small mammals are good indicators of environmental impacts and they play an important role either as seed dispersers or as a major resource for many predators, hence, understanding how they cope with diverse difficulties could be crucial for developing effective management and conservation strategies in these and other free-ranging species.Las poblaciones animales en estado natural se encuentran sometidas a perturbaciones periódicas debido a causas ambientales y humanas. Por tanto, en esta tesis doctoral, hemos llevado a cabo distintas investigaciones para estudiar las respuestas comportamentales y de estrés fisiológico en varias especies de micromamíferos a diferentes factores ambientales y humanos. Las respuestas comportamentales al riesgo de depredación, competencia interespecífica y perturbaciones humanas se analizaron mediante trampeos de vivo. Para analizar las respuestas de estrés fisiológico, se recolectaron heces frescas de los individuos capturados durante cada situación experimental y la cuantificación de metabolitos de corticosterona fecal (MCF) como indicador de la actividad adrenal se realizó en el laboratorio mediante enzimoinmunoensayos. Los resultados mostraron que el ratón de campo (Apodemus sylvaticus) respondía al riesgo de depredación reconociendo y evitando a sus principales depredadores conocidos en las áreas de estudio (no respondiendo al olor fecal de un depredador desconocido) y evitando también entrar en las trampas los días de mayor iluminación lunar. Además, la búsqueda e ingesta de alimento varió en relación a las distintas situaciones de riesgo pero no se encontraron respuestas de estrés fisiológico debido al aumento del riesgo de depredación. En relación a la competencia con ungulados salvajes, las abundancias de ratón moruno (Mus spretus) fueron mayores dentro de las áreas donde los ungulados no estaban presentes y la selección de hábitat estuvo relacionada con una mayor cobertura vegetal. El incremento en los niveles de MCF dentro de las áreas sin ungulados estuvo asociado a las mayores abundancias de ratón mientras que en las áreas con ungulados se relacionó con el incremento en la compactación del suelo causada por los ungulados. Finalmente, estudiamos si las perturbaciones humanas a través de las prácticas agrícolas y las autopistas afectaban a las poblaciones de micromamíferos. El número de capturas de topillo común (Microtus arvalis) dentro de los cultivos fue menor, además, aquellos individuos capturados en los cultivos mostraron mayores niveles de MCF. Respecto a las autopistas, los ratones de campo que vivían más cerca de la autopista mostraron concentraciones de MCF mayores. En base a estos resultados, podemos concluir que frente a las perturbaciones ambientales y humanas, los micromamíferos responden alterando su comportamiento. Sin embargo, sólo la competencia con ungulados silvestres y las perturbaciones humanas causaron respuestas de estrés fisiológico mientras que el riesgo de depredación no produjo tal respuesta, sugiriendo que quizás éstas señales no son suficientes para activar la respuesta de estrés fisiológico ya que las presas están diariamente sometidas a riesgo de depredación y por tanto estas respuestas serían muy costosas y patológicas para los individuos. Todas las respuestas comportamentales y de estrés fisiológico estudiadas también dependieron de las características individuales (p.e. sexo, edad y estado reproductor) probablemente basadas en la experiencia previa y el balance de los costes-beneficios en cada situación particular, en un lugar y momento determinados. Dado que los micromamíferos son buenos indicadores de los impactos ambientales y que tienen un papel importante tanto como dispersores de semillas así como por ser un recurso para muchos depredadores, comprender cómo pueden verse afectados ante diversas dificultades puede ser crucial para desarrollar planes de gestión y estrategias de conservación efectivas en éstas y otras especies

Non-invasive monitoring of adrenocortical activity in three sympatric desert gerbil species

The study of the endocrine status can be useful to understand wildlife responses to the changing environment. Here, we validated an enzyme immunoassay (EIA) to non-invasively monitor adrenocortical activity by measuring fecal corticosterone metabolites (FCM) in three sympatric gerbil species (Gerbillus andersoni, G. gerbillus and G. pyramidum) from the Northwestern Negev Desert’s sands (Israel). Animals included into treatment groups were injected with adrenocorticotropic hormone (ACTH) to stimulate adrenocortical activity, while control groups received a saline solution. Feces were collected at different intervals and FCM were quantified by an EIA. Basal FCM levels were similar in the three species. The ACTH effect was evidenced, but the time of FCM peak concentrations appearance differed between the species (6–24 h post-injection). Furthermore, FCM peak values were observed sooner in G. andersoni females than in males (6 h and 18 h post-injection, respectively). G. andersoni and G. gerbillus males in control groups also increased FCM levels (18 h and 48 h post-injection, respectively). Despite the small sample sizes, our results confirmed the EIA suitability for analyzing FCM in these species as a reliable indicator of the adrenocortical activity. This study also revealed that close species, and individuals within a species, can respond differently to the same stressor

Ratón de campo – Apodemus sylvaticus (Linnaeus, 1758)

Mamíferos - Orden Rodentia - Familia Muridae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/.A comprehensive review of the natural history of the Wood Mouse Apodemus sylvaticus in Spain.Peer reviewe

Topillo campesino – Microtus arvalis (Pallas, 1779)

Mamíferos - Orden Rodentia - Familia Arvicolidae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/.A comprehensive review of the natural history of the Common Vole Microtus arvalis in Spain.Peer reviewe

Are motorways potential stressors of roadside wood mice (Apodemus sylvaticus) populations?

Linear infrastructures represent one of the most important human impacts on natural habitats and exert several effects on mammal populations. Motorways are recognized as a major cause of habitat fragmentation and degradation and of biodiversity loss. However, it is unknown whether motorways lead to increased physiological stress reactions in wild animal populations. We analysed faecal corticosterone metabolites (FCM) in wild populations of wood mice (Apodemus sylvaticus) living in a well-preserved Mediterranean agro-pastoral woodland at different distances (verge, 500 m and 1000 m) from the AP-51 motorway in Spain. Wood mice were captured with Sherman live traps, and fresh faecal samples from 424 individuals were collected and analyzed in the laboratory. The quantification of FCM was performed by a 5a-pregnane-3b,11b, 21-triol-20-one enzyme immunoassay. Results showed that females had higher FCM levels than males, and these levels were higher in breeding females. In addition, FCM levels were positively correlated with body weight of individuals. Wood mice captured where cattle were present showed higher FCM levels than individuals living where cattle were not detected. FCM levels were higher in non-breeding individuals living close to the motorway compared with FCM levels in those individuals captured further from the motorway. This is the first study showing evidence of the motorways' impact on physiological stress reactions in wild wood mice populations. Understanding how free-living animals are influenced by human interventions could help to understand other subtle changes observed in wild animal populations. Since mice are used world-wide as research models these results could open new perspectives testing human influence on the natural environment and trade-offs of species in degraded ecosystemsThis research has been funded by the projects: CENIT-OASIS supported by CDTI of the Spanish Ministry of Science and Innovation, REMEDINAL-2 S-2009/AMB/1783 and CCG10-UAM/AMB-5325 (Comunidad de Madrid together with the European Social Fund and Universidad Autónoma de Madrid). A. Navarro-Castilla was supported by a FPU grant from the Ministerio de Educación y Ciencia of Spai

Wild Ungulates Constitute the Basis of the Diet of the Iberian Wolf in a Recently Recolonized Area: Wild Boar and Roe Deer as Key Species for Its Conservation

The Iberian wolf (Canis lupus signatus) is recolonizing historical distribution areas after decades of absence. As in other human-dominated landscapes, finding a balance to protect this species by favoring recolonization and mitigating human–wildlife conflicts is a challenge. Since wolves are often generalist opportunistic predators, we studied their diet composition in central Spain to evaluate the consumption of domestic ungulates and provide reliable data that could help local authorities to deal with the current wolf–cattle ranchers conflict and coexistence. Diet composition (% prey occurrence, % prey ingested biomass) was analyzed through the identification of prey hairs present in 671 scats collected between 2017 and 2021. The wolves fed more on wild ungulates (82% occurrence) than domestic ones (18%). Wild boar (Sus scrofa, 44% occurrence) and roe deer (Capreolus capreolus, 35%) were the most consumed prey. The wolves positively selected these two species. The wolves’ diets varied between seasons, years, and forest regions, but a diet based on wild ungulates predominated over domestic ones. Food niche breadth showed variations depending on seasons and years. Preserving the availability and diversity of wild ungulates may favor reducing livestock attacks and would be an achievable goal that would help to conserve this species and reduce conservation conflictsFinancial support was provided by Consejería de Medio Ambiente, Administración Local y Ordenación del Territorio de la Comunidad de Madrid and Sierra de Guadarrama National Park (projects: 10/329633.9/18, 10/122964.9/19, 10/180884.9/19; contracts: 2020/0112, 2020/0169, 2020/0379, 2020/0528, 2021/0138

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio