Rat Burrows Research Articles

Stability of kangaroo rat burrows in the Sonoran Desert: Evidence of biocementation

Kangaroo rats (Dipodomys deserti) construct complex burrow systems in loose desert sand that survive temperature and relative humidity fluctuations and storms. Animals that burrow in desert sand typically burrow in compacted sand, near plant roots, or when the soil is unsaturated. However, these processes are insufficient to explain tunnel stability of kangaroo rats. Our goal is to understand how kangaroo rat burrows remain stable in loose desert sand, intending to translate this knowledge to geotechnical engineering. A kangaroo rat habitat in the dunes of The Sonoran Desert, AZ, was selected for the study. Dynamic cone penetrometer tests performed at active, abandoned, and no-burrow sites demonstrated that the animals prefer loose sand for burrow construction. Soil samples collected from the burrows' ceilings, subsurface, and surface were characterized. Brazilian tensile strength test results showed that burrow soil has approximately 3 times greater tensile strength than the rest at dry state, which indicates increased interparticle attractive stress in burrow ceilings due to biocementation. Laboratory experiments, scanning electron microscopy, and confocal microscopy images showed that fungal and microbial biofilms provided 17 kPa increase in interparticle attractive stress at less than 1% biomass concentration, indicating potential to be used in soil improvement applications.

Hematological and biochemical profiles, infection and habitat quality in an urban rat population.

Host condition is key in understanding disease dynamics. In an urban population of Rattus norvegicus, we aimed to assess whether infection of Leptospira interrogans and helminths was associated with patterns of host hematological and hormone-biochemical stress-related conditions. Rat kidney imprints and urine were used to identify and quantify L. interrogans, and feces samples for helminth eggs and corticosterone metabolites. Blood samples were taken for complete blood counts and specific biochemicals in rats' sera. Principal Component Analyses were performed to check whether rats would be grouped according to health profiles. We obtained hematological and hormone-biochemical data from 95 and 61 rats, respectively. Hematological PCA revealed distinct rat groups: typical (T), eosinophil deficient (Eos-D), eosinophil- and monocyte- deficient (EM-D) and monocyte deficient with high immature neutrophils (Mon-D). No association between L. interrogans or helminths and rat health profiles was observed, except with Trichiuridae, which mean intensity was significantly higher when all deficient groups were pooled together compared to the T-group. The poorest condition group was found in areas with fewer rat burrows than the T-group, indicating EM-D had a reduced ability to occupy "good" quality habitats. In natural populations, hematological profiles may reflect host's overall condition, instead of responses to specific infections.

Urban Rats ( Rattus norvegicus ) through a One Health Lens: Social and Ecological Factors Promote Opportunities for Urban Leptospirosis in Rats, Dogs, and People

Abstract Living in cities creates One Health challenges because urban environments can promote pathogen transmission in wildlife and human-wildlife interactions with commensal species such as rats. In this study, we examined social and ecological processes that lead to an elevated risk of leptospirosis, a fatal rat-associated disease transmitted through Leptospira interrogans bacteria in urine. We examined rat and human factors associated with (1) human exposure to rat urine in the home environment, (2) the presence of rats carrying L. interrogans on the block, and (3) environmental conditions associated with rat infection. We surveyed residents and trapped rats on the same 16 blocks in four neighbourhoods in Chicago. Survey respondents were more likely to observe rat urine in their homes if they had lower incomes. Blocks where rats were carrying L. interrogans had higher rat abundance and respondents with higher incomes, who reported dogs dying from leptospirosis, children playing in yards with rat waste, flooded yards, and gardens with rat burrows. Rats were more likely to be infected with L. interrogans if they were trapped on a block with more accessible garbage and if they were older. Our results highlight that rat presence alone does not determine the risk of close contact with rat-associated pathogens; socio-economics can affect an individual’s ability to exclude animals from living spaces. In addition, improved waste management may help mitigate disease risks for humans, wildlife, and domestic animals. We also discuss opportunities for public education about rat-associated zoonoses and lessons learned about meaningful community engagement in One Health work. Information © The Authors 2024

Ectoparasites of some wild rodents /shrews captured from Scrub typhus reported areas in Tamil Nadu, India

ABSTRACT Scrub typhus cases have been reported in Madurai, but very little is known about the distributionpatterns of ectoparasites on rodents and shrews in the Madurai district. To determine the chigger vectors of scrub typhus, Rattus rattus, R. norvegicus, Mus musculus, and Suncus murinus were collected from these areas and the prevalence and mean intensity were calculated as 40% & 14.8 ± 3.9 for chiggers. Mites were collected from burrow soil samples. The chiggers Leptotrombidium deliense and Schoengastiella ligula, both known as vectors for the transmission of Orientia tsutsugamushi in India, were recorded in this study. In addition, Rhipicephalus sanguineus ticks, a putative vector of Indian tick typhus and canine ehrlichiosis, and the oriental rat flea Xenopsylla cheopis, a known vector of the plague pathogen Yersinia pestis, were also reported. They have high zoonotic potential and have been implicated in the transmission of the aforementioned emerging zoonotic diseases. Parapathi is a typical scrub typhus village with lots of rat burrows found around many houses and many reported scrub typhus cases. Rodents and shrews collected from these areas harboured vectors of medical and veterinary importance and act as endemic reservoir for transmitting zoonotic diseases which requires urgent attention for its control. http://www. zoobank.org/urn:lsid:zoobank.org:pub:5EFDD3BC-B9BA-4595-A02E-8AAEB4E7D755

Epidemiology of Talaromycosis (Penicilliosis) Marneffei in India: An Update

Talaromycosis marneffei (Penicilliosis marneffei) caused by a thermally dimorphic fungus, Talaromyces (Penicillium) marneffei is emerging as an important systemic opportunistic mycosis in HIV infected patients in several countries in Southeast Asia and in northeast India. This study presents an update on epidemiological and clinical aspects of talaromycosis marneffiei in India. A thorough search of literature was done in Medline, PubMed, and Google Scholar, for accessing relevant data. Fifty-three cases of this disease have originated from the Manipur State. Several cases have been reported from Assam, a few are also known from Meghalaya, Mizoram, Nagaland, Sikkim, Delhi and Maharashtra. Clinical manifestations of disseminated infection in AIDS patients are fever, anemia, weight loss, weakness, lymphadenopathy, hepatosplenomegaly, respiratory signs, and characteristic skin lesions. The bamboo rat (Cannomys badius) has been found to be a natural host of Talaromyces (Penicillium) marneffei in Manipur. It is noteworthy that one of the ten T. marneffei isolates from bamboo rats shared the genotype with a human isolate from that area providing evidence for common source of infection for the rats and humans and host to host transmission. Natural reservoir of T. marneffei has not been established, though it has been demonstrated that the fungus can survive in sterile soil for several weeks, but only for a few days in unsterile soil. There is need for comprehensive investigation of T. marneffei infection in humans, and for occurrence of the fungus in bamboo rats and in soils of the rat burrows in India employing conventional and molecular techniques.

Thermal ecology of the federally endangered blunt-nosed leopard lizard (Gambelia sila).

Recognizing how climate change will impact populations can aid in making decisions about approaches for conservation of endangered species. The blunt-nosed leopard lizard (Gambelia sila) is a federally endangered species that, despite protection, remains in extremely arid, hot areas and may be at risk of extirpation due to climate change. We collected data on the field-active body temperatures, preferred body temperatures and upper thermal tolerance of G. sila. We then described available thermal habitat using biophysical models, which allowed us to (i) describe patterns in lizard body temperatures, microhabitat temperatures and lizard microhabitat use; (ii) quantify the lizards' thermoregulatory accuracy; (iii) calculate the number of hours they are currently thermally restricted in microhabitat use; (iv) project how the number of restricted hours will change in the future as ambient temperatures rise; and (v) assess the importance of giant kangaroo rat burrows and shade-providing shrubs in the current and projected future thermal ecology of G. sila. Lizards maintained fairly consistent daytime body temperatures over the course of the active season, and use of burrows and shrubs increased as the season progressed and ambient temperatures rose. During the hottest part of the year, lizards shuttled among kangaroo rat burrows, shrubs, and open habitat to maintain body temperatures below their upper thermal tolerance, but, occasionally, higher than their preferred body temperature range. Lizards are restricted from staying in the open habitat for 75% of daylight hours and are forced to seek refuge under shrubs or burrows to avoid surpassing their upper thermal threshold. After applying climatic projections of 1 and 2°C increases to 2018 ambient temperatures, G. sila will lose additional hours of activity time that could compound stressors faced by this population, potentially leading to extirpation.

Perception of predation risk by African giant pouched rats (Cricetomys sp. nov) is higher in forest-edge microhabitats

How rodents perceive predation risk may alter their seed foraging behaviour and therefore potentially influence the recruitment of tree species. In this study we used two methods to investigate the effect of predation risk on habitat use by the African giant pouched rat (Cricetomys sp. nov) in Ngel Nyaki forest reserve, Nigeria. The first method was ‘giving up density’ (GUD), an index of perceived risk of predation at an artificial food patch, and the second was the ‘spool-and-line’ approach, whereby unravelling spools attached to rodent bodies are used to trace their tracks. For our GUD experiment, we chose four major sites in the forest; two representative of core habitat and two at the forest edge. Additionally, three characteristic microsites were used in the GUD experiment: dense understory, open understory and near-burrows. We hypothesised that GUDs would be lower on every succeeding observation day as rats learn to use the food patches, higher GUDs would be observed in the forest edges and open microsites, and rats would show preference for the microhabitats with least exposure to potential predators. In support of our first hypothesis, we found that GUDs were highest on the first experimental nights of every session. We also found that GUDs in the forest edges were higher than GUDs in the forest core. Lower GUDs were observed close to the rat burrows and in dense understory microsites, even though these differences were not statistically significant. Tracking of rat movements using the spool-and-line method overall revealed an even use across microhabitats, with a weak preference for those with logs, dense understory or exposed ground. Overall, our results suggest that vegetation density on a microhabitat scale has little or no effect on the perception of predation risk by African giant pouched rats.

Rat Damage Assessment and Evaluation of some Methods of Control for Rattus rattus on Date Palm and Orange Trees in New Reclaimd Land.

Rodent damage assayed in date palm and orange trees in different locations at El- Wady El- Gadid Governorate (El-Kharga, El-Dakhla, Gharb El-Mawhob and El–Farafra) as new reclaimed lands. In addition, two control methods were studied i.e. chemical control (zinc phosphide and diphacinone anticoagulant bait) and mechanical control (Aluminum sheet rolled around the trees, clean around the trees by rake, the weeds around the trees were removed, demolition of rat burrows by axe and muslin covered the date). Results showed the damage percentages were 37.06 % in El- Kharga, 45.63 % in El-Dakhla, 0.57% in Gharb El-Mawhob and 4.75% in El- Farafra for date palm. While the damage percentages in sweet orange were 28.16% in El-Kharga, 44.08% in El-Dakhla, 4.78% in Gharb El-Mawhob and 9.14% in El-Farafra. In case of bitter oranges damage percentage were 18.61, 28.28, 4.12 and 4.15 % in El-Kharga, El-Dakhla, Gharb El-Mawhob and El–Farafra, respectively. The results of chemical control showed that diphacinone bait was more effective than zinc phosphide. Whereas, zinc phosphide gave 72.43%, while diphacinone achived 89.26 % population reduction of rats in date palm. Concerning orange trees, it was 69.30 and 86.79 % population reduction of rats. Regarding the mechanical methods, the damage percent in date palm declined to zero percentage after using aluminum sheets around palm stem, clean around the palm, remove the weeds and demolition of rat burrows in date palm. While, in case of using the muslin cover, percentage the damage not decreased in date palm. The average damage percentage after using the chemical and mechanical control on date palm in El- Dakhla were 1.39, 1.80 and 0.00 % by zinc phosphide, diphacinone and aluminum sheets, respectively. In conclusion, mechanical control of rats on palm was better than the chemical methods to protect the environment from the impact of rodenticides especially in new reclaimed land.

Soil preference in blind mole rats in an area of supposed sympatric speciation: do they choose the fertile or the familiar?

AbstractAnimals become adapted to different habitats, which, under some circumstances, may lead to speciation. Such speciation can possibly take place even in sympatry, as has recently been suggested in the blind mole rat Spalax galili surveyed at a microsite where two soil types of ecologically contrasting characteristics, basaltic soil and rendzina soil, abut each other. Such speciation would be possible if mole rats developed reproductive isolation, for example, by means of habitat choice. In our study, we quantified food supply and soil characteristics of 20 blind mole rat burrow systems in both soils at a new microsite and tested the mole rat's soil preference in a T‐maze. The basaltic soil was harder and heavier than the rendzina soil, and had higher density and biomass of food, which is comparable to the published data from the only other studied microsite 3.7 km apart. Mole rats preferred to burrow in their familiar soil, when the tested soils were moist. After the soils were dried, both groups of mole rats tended to burrow preferentially in the rendzina soil, nevertheless, this preference was only significant in rendzina‐soil mole rats. We propose that after the suppression of olfactory cues mole rats preferred to burrow in soil with lower energetic costs of burrowing. We suggest that soil preference by mole rats is effective mainly in moist soil that releases specific odorous cues, which coincides with mating season and natal dispersal. This preference could also play an important causative role in reproductive isolation of the two blind mole rat populations.

An invasive tree facilitates the persistence of native rodents on an over‐grazed floodplain in tropical Australia

AbstractIn an ecosystem under simultaneous threat from multiple alien species, one invader may buffer the impact of another. Our surveys on a remote floodplain in the Kimberley region of north western Australia show that invasive chinee apple trees (Ziziphus mauritiana) provide critical refuge habitat for native rodents (pale field rats, Rattus tunneyi). Feral horses (Equus caballus) have trampled most of the remaining floodplain, but are excluded from the area around each chinee apple tree by thorny foliage. Although chinee apple trees constituted <10% of trees along our transects, they represented >50% of trees that harboured rat burrows. The mean number of burrows under each chinee apple tree was twice as high as under most other tree species, and we trapped more than seven times as many rats under chinee apple trees as under other types of trees. The extensive burrow systems under chinee apple trees contained female as well as male rats, whereas we only captured males around the smaller burrow systems under other tree species. Our data suggest that this invasive tree plays a critical role in the persistence of pale field rat populations in this degraded ecosystem, and that managers should maintain these trees (despite their alien origins) at least until feral horses have been removed.

Kangaroo Rat Population Response to Seismic Surveys for Hydrocarbon Reserves

Abstract Seismic surveys are a method used to locate commercially producible deposits of crude oil and natural gas. These surveys entail generating energy waves that reflect off of subterranean strata and return to the surface where they are recorded and interpreted. In the southern San Joaquin Valley of California, a region rich in hydrocarbon deposits, the two common methods of creating these energy waves include detonating buried explosive charges (“shot-hole” method) and generating strong ground-penetrating vibrations (“vibroseis” method). However, this region also supports many species of conservation concern, including several endemic species of kangaroo rats (Dipodomys spp.). We investigated the effects of a seismic survey on kangaroo rats, including two rare species, the giant kangaroo rat Dipodomys ingens and the short-nosed kangaroo rat Dipodomys nitratoides brevinasus, to determine whether seismic survey activities reduced kangaroo rat abundance, survival, or condition. In 2011, we established 18 study plots: eight subjected to shot-holes, six subjected to vibroseis, and eight controls with no energy source activities. A live-trap grid consisting of 30 traps was established on each plot, and kangaroo rats were captured and marked for four consecutive nights during trapping sessions 1–2 wk before the seismic survey (presurvey), 1–2 wk after the survey (postsurvey), and 5 mo after the survey (long term). Based on capture rates of unique individuals, abundance was similar among shot-hole, vibroseis, and control plots in each of the trapping sessions. Based on recaptures of marked individuals from previous sessions, survival was similar among treatments. Based on mass measurements, condition was similar among treatments. We did not detect adverse impacts to kangaroo rats from a seismic survey; in part, the lack of impacts detected may have been attributable to mitigation measures implemented to avoid or reduce adverse effects. These measures included restricting vibroseis trucks to existing roads, limiting off-road vehicle activity to small tractor-mounted drilling rigs with balloon tires, and attempting to avoid all kangaroo rat burrows by at least 10 m. Similar measures are recommended for any future seismic surveys in this region and elsewhere when burrowing species of conservation concern may be present.

Habitat and Burrow System Characteristics of the Blind Mole Rat Spalax galili in an Area of Supposed Sympatric Speciation.

A costly search for food in subterranean rodents resulted in various adaptations improving their foraging success under given ecological conditions. In Spalax ehrenbergi superspecies, adaptations to local ecological conditions can promote speciation, which was recently supposed to occur even in sympatry at sites where two soil types of contrasting characteristics abut each other. Quantitative description of ecological conditions in such a site has been, nevertheless, missing. We measured characteristics of food supply and soil within 16 home ranges of blind mole rats Spalax galili in an area subdivided into two parts formed by basaltic soil and pale rendzina. We also mapped nine complete mole rat burrow systems to compare burrowing patterns between the soil types. Basaltic soil had a higher food supply and was harder than rendzina even under higher moisture content and lower bulk density. Population density of mole rats was five-times lower in rendzina, possibly due to the lower food supply and higher cover of Sarcopoterium shrubs which seem to be avoided by mole rats. A combination of food supply and soil parameters probably influences burrowing patterns resulting in shorter and more complex burrow systems in basaltic soil.

Influence of kangaroo rat burrows in the spatial organization of the San Jose Island rodent community

Knowledge of the spatial distribution of rodents around kangaroo rat burrows may help us to understand the role that kangaroo rats play in the spatial organization of small desert rodent communities. In this study we analyzed the pattern of proximity between capture locations of desert rodents and burrows of Dipodomys merriami insularis, and describe the reproductive characteristics of these rodents. Captures and recaptures of individuals were carried out in an area of 79.8 ha on Isla San José in the Gulf of California, Mexico, during March to May and October to November of 2008. In order of decreasing frequency, Chaetodipus spinatus bryanti, D. m. insularis, Peromyscus fraterculus cinereus, and Neotoma bryanti bryanti were captured during both periods. The results provide evidence that the spatial distribution of these rodents around D. m. insularis burrows varies with sex and reproductive activity of the kangaroo rats. They suggest that female and male kangaroo rats have a different influence on the spatial organization of the rodent community on Isla San José. Furthermore, this study provides information that should improve our understanding of the island rodent community, and hence should help to improve conservation management of this endangered population of kangaroo rats.

Seismic communication in demon African mole rat Tachyoryctes daemon from Tanzania

We describe the production of substrate-borne vibrations in a subterranean mole rat of the genus Tachyoryctes for the first time. These signals with a supposed communication function were recorded using two approaches. Firstly, we recorded the production of spontaneous substrate-borne vibrations of individual test animals in artificial tunnels simulating a mole rat burrow system. Secondly, we recorded substrate-borne vibrations in individuals with interconnected home systems divided by a barrier. We found that Tachyoryctes produces these seismic signals by striking its head against the ceiling of the tunnel. Two types of seismic signals differing in physical parameters were identified. A slow signal (inter-pulse distance 0.12 s, inter-bout distance 3.89 s, number of pulses within each bout 9.53) was produced in both experiments, whereas a fast signal (inter-pulse distance 0.05 s, inter-bout distance 18.44 s, number of pulses within each bout 22.54) was produced mainly in close proximity to another individual. Our results indicate that fast signals are probably individually specific, because the success rate of classification according to discriminant function analysis was 70.4 % for the three tested individuals.

Isolation of Penicillium marneffei From Soil and Wild Rodents in Guangdong, SE China

Infection by Penicillium marneffei is an important emerging public health problem, especially among travelers and inhabitants in SE China and SE Asia infected with human immunodeficiency virus (HIV). In recent years, the number of patients with penicilliosis marneffei (PM) has increased rapidly in Guangdong province, SE China. However, the natural habitat and transmission mode of the etiologic agent remains unclear. In this study, wild rats (Microtus, focus Rattus and Rhizomys pruinosus) and soil samples were collected from rat burrows, populated and rural areas from November 2007 to December 2008 for fungus cultures. All isolates, suspected of being P. marneffei, were identified by gross and microscopic morphology and ITS analysis. Sixteen of 23 (about 70%) bamboo rats were P. marneffei positive, whereas none was recovered from hamsters, loirs or soil. This suggests that as of today the bamboo rat is the exclusive natural reservoir for P. marneffei. Definite evidence that rodents are a part of the infectious cycle is still lacking.

Description of two new species of mites of the family laelapidae (Acari: Mesostigmata) from rat burrow in West Bengal, India

Two new species of laelapid mites, Hypoaspis reticulatus and Pseudolaelaps splendens collected from rat burrow in West Bengal, India are described and illustrated.

The tunnel structure of blind mole rats (genus Spalax) in Turkey

The structure of the tunnels and burrows of mole rats (genus Spalax) was examined in Central and Southeastern Anatolia in the years 2002–2009. There are two types of mounds: linear ones and scattered ones. While a one-layer tunnel structure is observed in nearly all parts of Turkey, we also found three-layer tunnels, which were made in soft and moist soil. The tunnels made in moist soil were deeper than the ones made in hard soil. We found that mole rats blend the soil with their urine and produce a sticky mud with a bad odour in order to strengthen the walls of the opened galleries.

Occurrence of pathogenic fungi in soil of burrows of rats and of other sites in bamboo plantations in India and Nepal

This study examined 215 samples of soil from burrows of rats, other sites in bamboo plantations in different parts of India and Nepal by dilution plating and mouse passage technique for occurrence of Penicillium marneffei and other pathogenic fungi. None of the samples including 25 collected from the burrows of a bamboo rat (Cannomys badius) known to be a carrier of P. marneffei, was positive for the fungus. Among the pathogenic fungi recovered were four isolates of Pseudallescheria boydii (including one from Nepal), two of Trichosporon asteroides, one of Scytalidium hyalinum, 23 isolates of Trichophyton mentagrophytes var. mentagrophytes (including two from Nepal), and two of Microsporum gypseum. Fourteen of the 23 isolates of T. mentagrophytes var. mentagrophytes when tested with the mating types of Arthroderma vanbreuseghemii were found to be of the '+' mating type. The frequent recovery of this dermatophyte from soils of bamboo plantations in several parts of India is remarkable. The study also demonstrates for the first time the occurrence of P. boydii and T. mentagrophytes var. mentagrophytes in Nepalese soil. Among the other fungi recovered were several isolates of species of Aspergillus, Penicillium, Paecilomyces, Fusarium, Chrysosporium, Acremonium, Rhizopus, Mucor, Geotrichum, Trichosporon and Rhodotorula.

Poor Housing Quality Increases Risk of Rodent Infestation and Lassa Fever in Refugee Camps of Sierra Leone

Lassa fever, a viral hemorrhagic fever endemic in parts of West Africa, is a severe febrile illness transmitted to humans by the rodent Mastomys natalensis. To determine risk of Lassa fever in households in Sierra Leonean refugee camps, we analyzed the spatial relationships between households with a Lassa case and focal locations of potential rodent habitats. Quality and hygiene factors of households were assessed to determine possible risk factors for household rodent infestation and occurrence of Lassa fever. The odds to have a rat burrow were higher in case houses than in control houses (OR 24, 95% CI 6.0-93). Case houses scored significantly worse in the quality of housing and external hygiene. These findings suggest that risk of Lassa fever in refugee camps depends on individual housing quality and the hygiene of the immediate surrounding environment.

The burrow system of the African ice rat Otomys sloggetti robertsi

We studied the architecture of the burrow system of the African ice rat Otomys sloggetti robertsi, a non–hibernating, diurnal murid rodent endemic to the sub–alpine and alpine regions of the southern African Drakensberg and Maluti mountains. In our study site we found ice rat burrows in two substrates (organic and mineral soils). The structure of the burrow system was similar in both soil types, comprising several interlinking tunnels, numerous burrow entrances and 1–2 nest chambers. However, the surface area of the burrow systems in organic soils was larger, the tunnels were deeper, and some of the systems contained two levels, all of which was contrary to our assumption that digging would be more difficult in the compact organic soils. Ice rats occur in colonies of up to 17 individuals, and the collected efforts of several individuals are required for constructing complex burrow systems. The burrow structure is similar to those of two arid–adapted relatives, Parotomys brantsii and Parotomys littledalei, suggesting that the burrow architecture among these three taxa may reflect the similar functions of burrows in extreme environments. For ice rats, burrows could provide a suitable microhabitat in which to escape adverse environmental conditions, particularly during winter. Moreover, ice rat burrows contained far fewer nest chambers than those of both Parotomys species, indicating that members in a colony share nest chambers, thereby facilitating huddling. Finally, the extensive interlinking tunnels may provide underground routes to aboveground feeding sites, thereby reducing exposure to adverse conditions.