Peromyscus Californicus Research Articles

Three-Dimensional Home Ranges of Cricetid Rodents

A 13-month live-trapping and tracking study conducted in a California coastal sage scrub community revealed extensive arboreal activity by three of four cricetid rodents, Reithrodontomys megalotis, Peromyscus eremicus, P. californicus and P. maniculatus (the latter essentially terrestrial). Peromyscus californicus showed the greatest height range and proportion of arboreal activity and Reithrodontomys megalotis the lowest height range with an intermediate proportion of arboreal activity. Peromyscus eremicus resembled P. californicus in height and distribution of arboreal records. Arboreal activity of P. californicus was affected by shrub branch dimensions including height, diameter, and angle. Concentration of arboreal activity by R. megalotis on the shrubs Lotus scoparius and Eriogonum fasciculatum and P. californicus on Salvia apiana was directly related to the importance of those shrubs as food and insect availability on the shrubs. Home range volumes calculated from area determinations and arboreal records suggest that spatial niches of these climbing species are considerably larger than previously believed. This could be an important means of avoiding overlap between potential competitors in the rodent community.

Effects of vaginal-cervical stimulation in seven species of muroid rodents

Six species of muroid rodents (Peromyscus californicus, P. eremicus, P. gossypinus, Mesocricetus auratus, Rattus norvegicus and R. rattus) were given artificlal vaginal-cervical stimulation in an attempt to induce pseudopregnancy. Some females of each species became pseudopregnant, but it was not clear that stimulation patterns mimicking the copulatory patterns of conspecific males were more effective than other patterns of stimulation. In the non-domesticated species (Peromyscus and R. rattus) a few females responded to a variety of stimulus conditions, and no species differences in responsiveness among the wild species were evident. The established laboratory rodents (R. norvegicus, M. auratusy were markedly more responsive to artificial stimulation, suggesting possible effects of domestication on fecundity and reactions to handling- Microtus ochrogaster, an induced ovulator, ovulated in response to vaginal-cervical stimulation only if one intromission from a male was also provided. No other differences in the responses of reflex and spontaneous ovulators were apparent.

Compulsory Regime and Control of Environment in Animal Behaviour Iii. Light Level Preferences of Small Noctural Mammals

Compulsory Regime and Control of Environment in Animal Behaviour Iii. Light Level Preferences of Small Noctural Mammals

Tolerance of Peromyscus to the feeding of Triatoma (Hemiptera: Reduviidae).

Wood (1943, Amer. J. Trop. Med. 23 : 315–20; 1947, Bull. S. Calif. Acad. Sci. 46 : 144–55) reported survival of Peromyscus after feedings of from 10 to 255 Triatoma over various time periods. Some examples cited included a 35-g male Peromyscus californicus , experimentally infected with Trypanosoma cruzi , which survived feedings of 82 1st-instar Triatoma protracta protracta ; a 45-g female P. californicus fed 149 Triatoma , including 44 1st-instar T. gerstaeckeri and 34 1st-instar, 53 2nd- and 3rd-instar and 18 female T. p. protracta ; and a 20.5-g male P. crinitus which survived feedings of 80 1st-instar T. p. protracta .

Temporary Occupancy of a Coastal Sage Scrub Community by a Seasonal Immigrant, the California Mouse (Peromyscus californicus)

Temporary Occupancy of a Coastal Sage Scrub Community by a Seasonal Immigrant, the California Mouse (Peromyscus californicus)

Food hoarding in muroid rodents

The hoarding of food pellets was studied in 72 adult male muroid rodents of ten species; Mesocricetus auratus, Microtus ochrogaster, Microtus pennsylvanicus, Microtus montanus, Peromyscus californicus, P. eremicus, P. gossypinus, P. leucopus, Sigmodon hispidus, and Meriones unguiculatus. Seven Oryzomys palutris were also studied. Microtus and hamsters were the only species to show any appreciable hoarding. Six species were tested for the hoarding of sunflower seeds and corn kernels. Data were consistent with those on the hoarding of food pellets. Although information is incomplete, the ease of eliciting hoarding behavior in the laboratory appears roughly correlated with the tendency to hoard in the natural habitat. No other ecological correlates were apparent.

Paternal behavior in the california mouse, Peromyscus californicus

Parental behavior was observed in Peromyscus californicus parasiticus that had been live trapped as adults and bred in the laboratory. Both male and female parents spent more time in the nest with their pups when their mate had left the nest or had been removed from the cage. Both parents gathered and cared for scattered pups equally readily. These data are interpreted as indicating that male P. californicus participate in the care of their pups.

Contributions of paternal care to the growth and development of the young in Peromyscus californicus

Because parental care is pronounced in male Peromyscus californicus parasiticus , experiments were performed in search of a reproductive advantage associated with such behavior. With the mother always in the cage, pups were heavier until they were about 22 days old if the father was also in the cage. When the mother was removed for 12 hr each day pups developed faster if the father was caged with them than if he had been removed immediately after the pups were born. At a given stage of development, the weights of these pups were the same whether or not they were being raised with their father. Early weaned pups were more likely to survive weaning if caged with their father. In the absence of the mother, pups caged with their father had higher body temperatures than pups without their father. This supports the hypothesis that the effect of the male parent on growth and development of the pups was due to his keeping them warm. The possible significance of this for mice in the wild state is discussed.

Factors Influencing the Local Distribution of Peromyscus californicus in Northern California

Abstract Factors influencing the local distribution of Peromyscus californicus in northern California were investigated. Analysis of stomach contents and laboratory feeding experiments indicated that seeds of Umbellularia californica are a dietary staple. Rates of water consumption of P. californicus were compared in the laboratory with those of P. truei, which shares a similar habitat. An association of P. californicus with the large surface dens of Neotoma fuscipes was found. The restricted geographic distribution of P. californicus may be attributable in part to an interaction of ecological factors associated with the California laurel complex.

Maximum oxygen consumption and heat loss facilitation in small homeotherms by He-O2.

ROSENMANN, MARIO, AND PETER MORRISON. Maximum oxygen consumption and heat loss facilitation in small homeotherms by He-02 . Am. J. Physiol. 226(3) : 490495. 1974.-The high thermal conductance of an 80% He-20y0 02 atmosphere was used to elicit maximum metabolism (Mmax) in moderate cold in species ranging from 7-g pygmy mice (Baiomys taylori) to 250-g white rats, including redpolls (Acanthis J?ammea), two vesper mice (Calomys d&la, C. callosus), tundra voles (Microtus oeconomus), and four strains of Mus musculus. Values slightly exceeded those in similar animals using other methods to confirm the low metabolic ratio (Mmax/M, in) in rodents (4-8 X). Submaximal values at higher temperatures defined thermal conductance in He-02 and air. In different species the ratios of these conductances ranged from 1.4 to 2.6, differences which relate to the extent and quality of the respective insulation. M,,, was obtained at 13-70°C warmer in He-02 than required in air for the same metabolic effort. Avoidance of low-temperature technology and freezing injury, elimination of treadmills and training in running, prompt attainment of M,,., (3-10 min after He-02 exposure), and obviation of shaving or wetting procedures are advantages of the present technique.

Copulatory behavior of california mice (Peromyscus californicus).

17 male-female pairs of California mice (Peromyscus californicus) were observed in a total of 60 tests of copulatory behavior, each continued to a satiety criterion of 30 min with no copulations. California mice showed a pattern with no functional lock, intra-vaginal thrusting, ejaculation possible on single insertions, and multiple ejaculations. The mean ejaculation frequency was 1.7. It is suggested that the evolution of copulatory behavior in hystricomorph and myomorph rodents has been less divergent than had been earlier proposed.

Time Patterns of Peromyscus Activity and Their Correlations with Weather

The activity of Peromyscus maniculatus in an Ontario forest and Peromyscus truei and Peromyscus californicus in California chaparral was observed directly and monitored electronically. The activity of all three species outside the burrow was pulsed through the night, with different individuals not in tight synchrony and a depression in overall activity in the middle of the night. Activity of P. californicus was similar to that of P. truei , but P. californicus had in addition a pronounced burst of activity before dawn. As summer progressed, the amount of activity of P. maniculatus diminished and was compressed into the early part of the night. Wind and moonlight had no strong effect upon activity within a night. From night to night, P. truei had conspicuous fluctuations in total nightly activity (at a period of about 4 days), the entire population usually being in synchrony. Night-to-night fluctuations in P. californicus activity were in phase with those of P. truei . Night-to-night fluctuations in vole tracks in Quebec (unpublished data from R. Bider) had low correlations with P. maniculatus tracks in the same area. Night-to-night fluctuations in P. truei activity had a positive correlation with barometric pressure and a negative correlation with low pressure weather variables (humidity, temperature). There was no correlation with wind or cloud cover. None of the weather variables had a strong periodicity at 4 days, but P. truei activity was in phase with the 4-day-component of barometric pressure, out of phase with temperature, and leading humidity. The evidence suggested that sundown temperature was the key variable. Fluctuations in tracks of P. maniculatus (Quebec) had similar properties, except they were in-phase with low pressure weather variables. Vole tracks ( Microtus pennsylvanicus and Clethrionomys gapperi ) showed the same periodicities as weather and were tightly correlated with weather.

A new species of Euschoengastia (Acarina: Trombiculidae) from western North america, and the status of E. californica (Ewing).

Euschoengastia ambocalis , n. sp., holotype from San Diego County, California, off host Peromyscus californicus , is proposed for the species previously called E. californica (Ewing, 1925). Schongastia californica Ewing, 1925, is herein designated a nomen dubium .

Supraoptic nuclei of rodents adapted for mesic and xeric environments: numbers of cells, multiple nucleoli, and their distributions.

AbstractQuantitative comparisons were made between the supraoptic nuclei (SON) of rodents from mesic and xeric habitats. Laboratory rats, Rattus norvegicus, mesically adapted, were compared with xerically adapted gerbils, Meriones unguiculatus, and kangaroo rats, Dipodomys merriami and Dipodomys spectabilis. As a close genetic control, California deer mice, Peromyscus californicus (mesic), were compared with cactus mice, Peromyscus eremicus (xeric), of the same subgenus. Measures were obtained separately for anterior (Soa) and tuberal (Sot) subdivisions of SON in each species; these measurements included numbers of cells, cell size and, following the discovery of multiple nucleoli in many cells, the proportion of cells showing 1, 2, 3, and 4 or more nucleoli. In mesic species, Sot had fewer cells than Soa; in all but one (D. spectabilis) of the xeric species, the two subdivisions had equal numbers of cells. Cell size was related to body size rather than adaptation. All xeric species showed higher proportions (20 to 60%) of cells with multiple nucleoli than did corresponding mesic species (0 to 20%). Adaptation to environments requiring conservation of body water is correlated with larger numbers of SON cells with multiple nucleoli; relatively larger numbers of cells in Sot but not in Soa; and there are no notable differences in size of cells between mesic‐ and xeric‐adapted species. The suggestion that number of nucleoli is realated to a SON cell's production of antidiuretic hormone is supported by other cytological studies.

Adrenal steroid biosynthesis by different species of mouselike rodents

Adrenals from voles ( Microtus agrestis), deer mice ( Peromyscus californicus and Peromyscus erimicus) and albino mice ( Mus musculus) incubated in Krebs-Ringer bicarbonate medium formed corticosterone as major endogenous end product in vitro and no cortisol was detected. These rodents belong to the superfamily Muroidea. Adrenals from pocket mice ( Perognathus baileyi and Perognathus penicillatus pricei), of the superfamily Geomyoidea, formed cortisol as a major end product from endogenous sources and no corticosterone or only traces, and the total output of ultraviolet-absorbing steroids by these glands in the presence of ACTH was much lower than that obtained with the adrenals of the Muroidea. The adrenals from Perognathus baileyi also formed cortisol as a major end product from radioactive substrates, but not corticosterone, while the predominant conversion product obtained with vole and albino mouse adrenals was corticosterone, and cortisol was either not found or present in minimal amounts. Cortisol was, further, not recovered when adrenals from 2- to 3-week-old male albino mice were incubated in plasma. Evidence for the endogenous formation of aldosterone and 18-hydroxycorticosterone was obtained in all the species, and the identity of these compounds was established when they were present as radioactive conversion products. The adrenals of Perognathus baileyi converted radioactive progesterone to aldosterone in amounts equaling the conversion to cortisol.

Plasma corticosteroid response to stress in four species of wild mice.

The temporal pattern of stressinduced elevation of plasma 11-hydroxycorticosteroid concentrations was studied in 4 species of wild mice. There were highly significant differences among Mus musculus, Peromyscus boylii, Peromyscus californicus and Perognathus baileyi. The first 3 species attained plasma corticosterone concentrations markedly greater than those seen in laboratory rodents. Perognathus baileyi mice did not demonstrate an elevation of 11-hydroxycorticosteroids following exposure to a variety of stressors. Corticosterone was the principal corticosteroid found in the circulating plasma of Mus musculus, P. boylii and P. californicus; significant concentrations of corticosterone, cortisol, 11-deoxycorticosterone and 17α-hydroxy-lldeoxycorticosterone were found in Perognathus. Significant differences in adrenal weight/body weight ratios were also found among the 4 species (Endocrinology 84: 676, 1969)

Piroplasms (Protozoa: Sarcodina) of Wild Mammals in California1

Piroplasms were found in the blood of Neotoma lepida, Peromyscus californicus, Microtus californicus, Spermophilus beecheyi and Sylvilagus audubonii during wildlife disease surveys in Southern California. Although naturally infected animals appeared healthy, splenectomy of naturally or experimentally infected animals invariably resulted in severe parasitemias and anemias, often terminating fatally. Limited attempts to infect different mammal species were made with varying success. All of the piroplasms were indistinguishable morphologically and were considered to belong to the same species: Babesia microti (Franca, 1912).

The Intraspecific Social Behavior of Some Cricetine Rodents of the Genus Peromyscus

A three-compartment territorial cage was employed in studying the intraspecific social behavior of Peromyscus californicus, P. eremicus, P. crinitus, and P. maniculatus. Two pairs of mice of the same species were allowed to interact for one week following a period of separa- tion from each other in the end compartments. All species showed similar forms of agonistic behavior patterns. The closely related P. eremicus and P. californicus employed a modified fighting technique involving an attack leap, scuffle, and avoidance leap. The females of P. crinitus and P. californicus showed a pronounced nest site attachment and defense. Agonistic behavior with the exception of nest defense was confined almost entirely to the males. The aggressivity of P. eremicus was the least pro- nounced. Peromyscus crinitus males showed the most agonistic behavior, and P. californicus and P. maniculatus were intermediate. Pair associa- tions in the territorial boxes were prolonged for P. californicus and, to a lesser extent, for P. crinitus. The other two species showed a weak pair bonding.

Linearity of Home Ranges of California Mice and Other Animals

Linearity of Home Ranges of California Mice and Other Animals

Studies On the Behavior of Peromyscus Maniculat Us Gambelii and Peromyscus Californicus Parasiticus

Peromyscus californicus parasiticus and Peromyscus maniculatus gambelii which inhabit the same macro-environment near Berkeley, California, were the subjects of an analysis of adult behavior patterns. Daily activities of single individuals were observed. Encounters between two animals were staged to determine the basic behavior patterns employed by each species in its intraspecific social behavior. After the various postures had been identified, their frequencies in encounters were found to be influenced by several factors. (1) The sex of the animal under observation. Males exhibit more aggressive patterns and initiate more grooming than do females. (2) The locus of the encounter. An animal introduced into a strange cage exhibits more submission and flight behavior than does the resident. (3) The sex of the animal encountered. A resident male will usually attack another male, but displays upright postures and grooming in response to an introduced female. (4) The physiological condition of the animals participating in the encounter. The chief variables here include the estrous cycle of the females and the breeding condition of the males. In male-male encounters the descended testes are associated with prolonged chases, and aggressive behavior with little grooming. In encounters between males during the non-breeding season, there is less chasing and more mutual grooming. The more complex aspects of social behavior were studied by two other methods: (1) Pairs were observed in order to determine the sexual behavior patterns and the subsequent behavior between the adults and the young. (2) Pairs were established in adjoining cages with removable doors. The pairs were kept separate for two weeks, and then the doors were removed and the subsequent behavior noted. By combining these laboratory data with the field data from several other workers, a picture of the social organization within these two species was constructed. It appears that P. californicus is more strongly territorial, since paired males and females defend the nest site; however, californicus employs a fighting technique involving jumping and avoidance and also exhibits a specific mewing cry which appears to inhibit aggressive behavior of another individual. These patterns may account for the ability of californicus to form bisexual groups of adults with little injury to the participants. P. maniculatus pairs differ in that the female does not defend the nest against intruders unless she is parturient. In the confines of a cage male maniculatus will fight until serious injuries occur. P. californicus with its lower reproductive potential. longer development time for the young, and complex nest, has a more rigid nest defense system and more rigid behavioral controls to regulate aggressive tendencies within the family group. P. maniculatus with its rapid growth rate. larger reproductive potential. and simple nest, has a less rigid social organization and nest site attachment when compared to californicus.