Sexual behaviour and reproductive competition in male wild and domestic Norway rats

The copulatory behaviour of male wild Norway rats (Rattus norvegicus) exposed individually to females in hormone-induced oestrus is characterized by fewer mounts and intromissions per ejaculatory series, shorter ejaculation latencies, and longer ejaculatory clasps than the copulatory behaviour of domestic males. Competition between wild and domestic males tested simultaneously in pairs produced only minor changes in copulatory behaviour. The reproductive success of wild and domestic male pairs simultaneously exposed to naturally cycling females was nearly equal in both the laboratory and an outdoor enclosure. Genotype of the female had little effect on male copulatory behaviour. The copulatory behaviour of sexually naive and experienced domestic rats did not differ. However, most sexually naive wild males failed to exhibit copulatory behaviour under the test conditions employed.     

Effect of the post-weaning environment on the climbing behaviour of wild and domestic Norway rats

The climbing behaviour of wild and domestic Norway rats (Rattus norvegicus) was compared after early rearing in three post-weaning environments offering different climbing experiences. Wild rats climbed in the test apparatus even when denied early climbing experience; male domestic rats did not. Early climbing experience increased the climbing scores of both stocks but influenced the climbing proficiency of wild rats only. Treatment differences in climbing behaviour may be related to specific motor experiences gained during development and the effect of early experience on the response to a novel environment (test apparatus). Stock differences in climbing behaviour may reflect a general reduction in motor activity among domestic rats and their reduced sensitivity to stimulus change or novelty.     

The effect of the S1A-receptor agonist ipsapirone on behavior types in wild and domesticated rats]

Selective agonist of 1A subtype of serotonine receptors ipsapirone inhibited manifestation of affective kinds of aggression in wild and domesticated rats. Administration of ipsapirone (10 mg/kg) decreased the number of aggressive attacks of wild and domesticated rats in the test of shock-induced aggression and blocked manifestation of defensive reaction to the experimenter in wild rats. Neophobia in wild rats decreased under the influence of ipsapirone. At the same time ipsapirone did not change mouse-killing behaviour either in wild or in domesticated rats. Probably, 5-HT1A receptors the aggressive regulate reaction, which are parts of the complex of defensive behaviour of the wild animals.     

Species specific behavioural patterns (digging and swimming) and reaction to novel objects in wild type, Wistar, Sprague-Dawley and Brown Norway rats

Background

The purpose of the present study was to analyse species-specific forms of behaviour (digging and swimming) and response to novelty in laboratory rats and their wild type counterparts at a very early stage of laboratorization. Three behavioural phenomena were taken into account: burrowing, spontaneous swimming, and neophobic behaviour.

Principal Findings

Wild-type rats and three strains of laboratory rats were involved in experiments: Warsaw-Wild-Captive-Pisula-Stryjek (WWCPS), Wistar, Sprague-Dawley, and Brown Norway rats were compared in spontaneous swimming test, while WWCPS and Wistar rats were studied in burrowing and neophobia experiments. Wild rats were found to be faster at building tunnels than Wistar rats and at constructing more complex burrow systems. The experiment on neophobia showed that Wistar rats exhibited less neophobic responses and were more often trapped. WWCPS rats showed highly neophobic behaviour and were rarely trapped in this experiment. The experiment on swimming showed that WWCPS rats showed more complex water tank related activity than their laboratory counterparts. They swam and explored under surface environment.

Conclusions

The three experiments showed profound behavioural differences in quasi-natural forms of behaviour between wild type rats (WWCPS) and three laboratory strains frequently used in behavioural studies.     

Genetical aspects of hormonal modification of the stress reactivity. II. Modification in early ontogenesis of the stress reactivity of adult gray rats selected for behavior toward man

Inherited and modificational changes of the stress reactivity in two outbreed stocks of wild Norway rats trapped in nature and selected for behaviour were studied. During 18 generations the rats of one stock were selected for the lack of defensive behaviour in the glove test (tame), while in another stock the aggressiveness was maintained by the selection (aggressive). Interstock differences in the brain noradrenaline mechanisms were observed. The emotional stress reactivity of the tame animals was decreased, in comparison with the aggressive ones. Definitive stress reactivity of adult rats was modified by injections of hydrocortisone to their mothers on the 16 and 18 days of gestation. Hormonal treatment changed noradrenaline mechanisms and decreased the reaction to emotional stressor in aggressive rats. The modified level of the stress reactivity of aggressive rats was similar to the definitive level of the tame ones. Hormonal treatment did not modify stress reactivity in tame rats. Thus, the phenotype only emerging in aggressive rats, as a result of hormonal modification, is the inherited norm of the tame animals. However, due to rat selection for the lack of defensive behaviour towards the man, high corticosteroid level in the blood of pregnant females, an external developmental factor, in respect to the fetus, loses regulatory function during the development of the neuroendocrine mechanisms of the stress reaction.     

Mass-rearing and sterilisation alter mating behaviour of male Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

Abstract  The effects of domestication and irradiation on the mating behaviour of males of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) were investigated by caging wild, laboratory-domesticated and sterile (laboratory-domesticated, gamma-irradiated) males with wild females. Mating behaviour of mass-reared males was different from that of wild males, although behaviour of wild and sterile males was similar. Mass-reared males engaged in mounting of other males much more frequently than wild and sterile males, and began calling significantly earlier before darkness. Unnatural selection pressures imposed in mass-rearing conditions may explain these changes in mass-reared male behaviour. Male calling did not appear to be associated with female choice of mating partners, although this does not exclude the possibility that calling is a cue used by females to discriminate among mating partners. Despite differences in behaviour, frequency of successful copulations and mating success were similar among wild, mass-reared and sterile males.     

Change in certain forms of aggressive behavior and the concentration of monoamines in the brain during selection of wild rats for taming

Norway rats have been selected during 20 generations by the absence of aggressive reaction to man (tamed rats). From 7 up to 20th generations of selection, different forms of aggressive behaviour (reaction to glove, intermale, shock-induced aggression and predatory aggression) were studied, and the level of noradrenaline, serotonin and its metabolite 5-hydroxyindoleacetic acid was determined in the brain. In the absence of aggressive reaction to glove in tamed rats, the shock-induced aggression considerably decreased while the predatory aggressiveness (mouse-killing behaviour) and intermale aggressiveness did not change. Beginning from 15-16th generation of selection, a higher level of the 5-hydroxyindoleacetic acid in the hypothalamus was established, in the 20th generation an increased content of serotonin was revealed in the hypothalamus and the midbrain. In some generations of selection an increased level of noradrenaline in the hypothalamus in comparison to wild rats was observed. A conclusion is made that the selection of animals by taming unequally influences different kinds of aggressiveness and is accompanied by inherited consolidated reorganization of the monoamine brain systems.     

Response to novel object in Wistar and wild-type (WWCPS) rats

Laboratory rats react to a novel object with a rapid redirection of exploratory behaviour towards the source of the novelty and a subsequent decline of this neotic preference with repeated object exposure. Studies with wild Rattus norvegicus have shown that a novel object in a familiar cage results in avoidance reactions (neophobia) in those animals, but it is also well established that the wild R. norvegicus show strong aversive reactivity to a variety of high intensity stimuli. In this study we aimed to create low-stress conditions enabling the comparison of spontaneous exploratory behaviour directed at a novel object in male (age = 80 days) “wild-type” WWCPS rats (n = 21; fourth generation bred in captivity) and Wistar (n = 24) rats. The study involved repeated placing of individual animals in the experimental chamber for 15 (6 min) trials on consecutive days. On the 11th day the novel object was introduced. Animals were tested in darkness and without human presence. Under these conditions neither WWCPS nor Wistar have shown behavioural signs of high emotional arousal, both lines have shown comparable general levels of experimental cage exploration and the positive new object exploratory reaction was observed only in Wistar rats.     

Behavioural changes in the African giant rat (Cricetomys gambianus Waterhouse) under domestication

A gradient of behavioural patterns was observed among the wild and the first four generations of the African giant rat. Escape reactions and agonistic behaviour were completely lost as from the second generation. Wild rats were easily tamed and those born in captivity were very social. However, being a burrowing rodent, preferring a cool environment in nature, they had a low tolerance to heat. Cannibalism was an important management problem which persisted to the fourth generation resulting in the mortality of 40% of the newly born. From the fifth generation onwards, rats became completely tame and docile. Cannibalism was reduced to less than 10% of the newly born at the fifteenth generation. At this stage, for all practical purposes the giant rat can be regarded as a domestic animal.     

A novel feeding behaviour in wild redfronted lemurs (Eulemur rufifrons): depletion of spider nests

Reports on behavioural innovations in wild primate populations as well as on their transmission are rare. Here, we report observations suggesting that redfronted lemurs (Eulemur rufifrons) invent new behaviours in the wild. We observed a novel feeding behaviour in redfronted lemurs in Kirindy Forest, western Madagascar. The feeding behaviour consisted of depletion of nests of a social spider species (Stegodyphus sp.). The behaviour was observed in only one out of four study groups, although spider nests were present in the home ranges of all four groups. The behaviour was exhibited in three different years (2009, 2011, 2012) and appears to be re-invented from time to time. Interestingly, in 2011 this behaviour was shown by four individuals and probably spread within the group. This feeding behaviour has only been observed between the middle of June and early August (i.e. the early dry season), and nests were found to be empty later on, suggesting that these nests are available as a food source only seasonally. Our observation contributes a rare case of behavioural innovations in a wild primate population.     

Social dominance in wild and domestic Norway rats (Rattus norvegicus)

Differences in the relative social dominance of wild, hybrid and domestic strains of Norway rats are observed in mixed groups (twelve animals each) housed in a large room for 13 consecutive days. Domestic subjects are dominant to wild rats in both spontaneous and competitive interactions. Hybrids are intermediate. Explanations offered for the superior dominance of the domestic strain included: (a) the lack of social inhibitions displayed by domestic rats as reflected in frequent play-motivated interactions (‘bully effect’), and (b) the larger body size of the domestic subjects. Domestic subjects are most active and interacted most frequently. Dominance behaviour does not influence nest box utilization. Dominance in spontaneous and competitive interactions is not correlated suggesting that in the rat social dominance is not a unidimensional trait.     

Do intensive drive hunts affect wild boar (Sus scrofa) spatial behaviour in Italy? Some evidences and management implications

Wild boar have been increasing in numbers all over Western Europe in the last 30 years. The species is a major pest for agriculture, but it has a high value as a game species, and in Italy, as in several other countries, it is traditionally hunted in drive hunts by hunting teams with several dogs. This hunting method can have disruptive effects on the demography and spatial behaviour of wild boar, especially family groups. We conducted a 2-year study (2003 and 2004) to determine the effects of drive hunt disturbance on the spatial behaviour of wild boar family groups in the Northern Apennines (central Italy). Twenty wild boar belonging to ten family groups were ear tagged with a radio device. We located resting sites daily and used intensive tracking sessions during drive hunts. Three seasons were determined: pre-hunting, hunting and post-hunting. A general pattern of increased spatial instability during the hunting season was shown. Resting ranges were larger, and resting sites were more interspersed. Distances between consecutive resting sites were greater during the hunting season and, especially, on hunting days. The displacement of family groups caused by drive hunts was generally short lived except for those groups that were repeatedly hunted and so abandoned their pre-hunt (native) range. During drive hunts, wild boar showed a moderate tolerance to hunting disturbance, and only family groups which were directly chased by dogs escaped or altered their behaviour. The response of wild boar to hunting disturbance seemed to be highly related to the degree of hunting pressure combined with individual variability. The impact on wild boar behaviour should be reduced, above all by avoiding repeated hunts in the same areas within a short period and by employing well-trained hounds.     

Are antipredator behaviours of hatchery Salmo salar juveniles similar to wild juveniles?

This study explores how antipredator behaviour of juvenile Atlantic salmon Salmo salar developed during conventional hatchery rearing of eggs from wild brood stock, compared with the behaviour of wild‐caught juveniles from the same population. Juveniles aged 1+ years were tested in two unfamiliar environments; in one S. salar were presented with simulated predator attacks and in the other they were given the opportunity to explore an open‐field arena. No difference was found in their spontaneous escape responses or ventilation rate (reflex responses) after simulated predator attacks. Hatchery‐reared juveniles were more risk‐prone in their behaviours than wild‐caught individuals. Hatchery juveniles stayed less time in association with shelter. In the open‐field arena, hatchery juveniles were more active than wild juveniles. Hatchery juveniles were also immobile for less time and spent a shorter amount of time than wild juveniles in the fringe of the open‐field arena. Salmo salar size had no effect on the observed behaviour. Overall, this study provides empirical evidence that one generation of hatchery rearing does not change reflex responses associated with threats, whereas antipredator behaviour, typically associated with prior experience, was less developed in hatchery‐reared than in wild individuals.     

The predisposition to catatonic reactions, monoamine oxidase and the delta-sleep peptide in rats]

MAO B/MAO A rations and the influence of delta-sleep inducing peptide (DSIP) on the two forms of MAO and on the predisposition to different types of catatonic reactions were compared in rats of GC strain selected from Wistar for predisposition to catalepsy, and in wild rats. In GC rats, the MAO B/MAO A ratio was increased, as compared to Wistar, in the brain stem and hemispheres, whereas in wild rats predisposed to catatonia it was increased, as compared to normal wild rats, only in the hemispheres. In GC rats, this increase of the MAO B/MAO A ratio was due to a decrease of MAO A and increase of MAO B activity, while in wild catatonic rats only due to heightened MAO B activity. Administration of DSIP abolished the susceptibility to catatonic reactions and normalized the MAO B/MAO A ratio both in GC and in wild catatonic rats. There seems to be a partial similarity of physiological mechanisms of catatonic reactions in laboratory albino and in wild rats.     

广西地区野鼠戊型肝炎病毒感染情况调查

从广西壮族自治区5个市采集256份野鼠肝脏和对应的血清211份,采用HEV抗体(HEV-Ab)酶联免疫试剂盒(双抗原夹心法)对血清样本进行抗-HEV检测,并对不同地区HEV抗体阳性率进行χ2检验。采用HEV核酸荧光PCR试剂盒对肝脏样本进行HEV核酸检测。结果显示,211份野鼠血清抗-HEV的抗体阳性率为6.6%,其中百色市的抗体阳性率最高,为14.1%,其他地区抗体阳性率均在10%以下。256份野鼠肝脏中未检测到HEV核酸。由此可见,广西壮族自治区5个市的野鼠中存在HEV感染,但其是否为HEV的自然宿主及在戊型肝炎传播中起何作用需进一步研究。     

Behavioural characteristics of wild jumping or running episodes in the double mutant spontaneously epileptic rat

Spontaneously epileptic rats (SER) are homozygous for two mutations, zitter (zi) and tremor (tm), and spontaneously exhibit both absence-like seizure and tonic convulsion. In addition, wild jumping or running episodes sometimes appear without any previous stimuli. We recorded the behaviour on a video camera and/or a vibration response apparatus to examine the behavioural characteristics. All wild jumping or running episodes appeared within 27 s after termination of tonic convulsion with a frequency of 2.1%, and the episode could be detected even in the dark by using the vibration response apparatus. A rapid increase of high motor activity around the episodes was recorded as a single peak with high amplitude by the vibration response apparatus. The wild jumping or running episode appeared in all 4 SER at 8-14 weeks of age with a variable frequency, 0-9 times in the light period and 0-6.7 times in the dark period 8 h each week. Thus, the wild jumping or running episode was found to occur not only during the light period but also during the dark period without any significant difference in frequency.     

Growth and social interactions of wild and sea-ranched brown trout and their hybrids

A laboratory study of the social behaviour and growth performance of juvenile brown trout Salmo trutta of wild and sea-ranched origin and their crosses, indicated that the social behaviour of wild and sea-ranched fish differed. Male and female parents seemed to have a different impact on the juveniles. The category having wild mother and sea-ranched father were less aggressive, less active in general, but active in feeding, and therefore had higher growth rates. This pattern arose despite that the feeding rate and the motivation to first get a food item when food was provided did not differ between the groups of fish. Wild fish tended to be most aggressive. If sea-ranched and wild fish have different intrinsic (genetically based) 'life styles', the crosses between wild and sea-ranched fish indicate that there is likelihood for an introgression of genes adapted to hatchery environment into the genetics of wild conspecifics. This is particularly serious when hatchery-reared fish invades wild populations over many years.     

Neophobia and its effect on the macro-structure and micro-structure of feeding in wild brown rats (Rattus norvegicus)

The effect of neophobia (fear of novelty) on feeding behaviour was examined in two groups of captive wild rats fed ad libitum. Different individuals employed different feeding patterns in response to novelty despite the absence of social and ecological constraints. The prevalent feeding pattern was to delay eating from a novel bowl several nights after it was introduced and, in general, novel food was sampled towards the end of a night. Systematic relationships (prandial correlations) were revealed in the meal pattern data which were consistent with the prediction that post-prandial correlations (controlled regular feeding bouts) are more likely in predictable environments. A large proportion of the individuals exhibited no prandial relationships which correlated with high levels of neophobia supporting the hypothesis that highly neophobic individuals are less able to regulate their feeding in the presence of novelty.     

Behavioural responses of cattle to shared foraging with wild herbivores in an East African rangeland

We assessed whether prior foraging by wild herbivores affected foraging behaviour of cattle in Laikipia rangeland, Kenya, during February 2001, August 2001 and February 2002. The study compared cattle bite rate, step rate and bites per step in plots exclusively accessible to cattle and those accessible to cattle and large wild herbivores. During February 2001 when conditions were dry, cattle bite rate was 18–19% lower, step rate 25–26% higher, and bites per step 36% lower in plots shared by cattle and wildlife compared to those exclusively accessible to cattle. Differences in these measured foraging behaviour parameters were strongly correlated with reductions in herbage cover in plots accessible to wild herbivores. Plot differences in herbage cover and the measured foraging behaviour parameters were not significant in the subsequent trials when conditions were wet, suggesting that wild herbivore impacts reported here are short-term within season and dependent on weather conditions (and plant productivity). With reduced herbaceous plant cover in wildlife grazed realms in the dry season, cattle respond with increased travel and reductions in bite rate and bites per step, suggesting that wild herbivores can seasonally affect foraging behaviour of cattle. It remains to be demonstrated whether or not these altered behaviours of cattle affect weight gains or other measures of performance.     

Swimming behaviour and dispersal patterns of headstarted loggerhead turtles Caretta caretta

Swimming behaviour and dispersal patterns were studied in headstarted loggerhead turtles Caretta caretta which were released at three different sites on the Caribbean island of Curaçao (Netherlands Antilles) and at one site on the neighbouring island of Klein Curaçao, after 1–2.5 yrs of captivity. Turtles were tagged and followed up to a distance of 6125 m offshore, using a boat with a Global Positioning Unit. The released turtles reverted to typical hatchling behaviour and showed an offshore migration almost perpendicular to the coastline. No significant differences were found in directional swimming among the four sites. The turtles swam almost continuously about 30 cm under the water surface; their mean overall swimming speed was higher than in adult wild loggerheads suggesting a 'frenzy'-like swimming stage. The turtles exhibited diving behaviour, and the dive frequency and duration was comparable to that of similar-sized (wild) turtles. The present study demonstrates that upon release the headstarted loggerheads behave naturally and show dispersal patterns similar to wild hatchling turtles. The fact that the released turtles were still able to show offshore directional swimming suggests that the headstarting did not affect their short-term orientation abilities.