1. Longitudinal records of prey selection by 10 adult female sea otters on the Monterey Peninsula, California, from 1983 to 1990 demonstrate extreme inter-individual variation in diet. Variation in ...prey availability cannot explain these differences as the data were obtained from a common spatial-temporal area. 2. Individual dietary patterns persisted throughout our study, thus indicating that they are life-long characteristics. 3. Individual dietary patterns in sea otters appear to be transmitted along matrilines, probably by way of learning during the period of mother-young association. 4. Efficient utilization of different prey types probably requires radically different sensory/motor skills, each of which is difficult to acquire and all of which may exceed the learning and performance capacities of any single individual. This would explain the absence of generalists and inertia against switching, but not the existence of alternative specialists. 5. Such individual variation might arise in a constant environment from frequency-dependent effects, whereby the relative benefit of a given prey specialization depends on the number of other individuals utilizing that prey. Additionally, many of the sea otter's prey fluctuate substantially in abundance through time. This temporal variation, in conjunction with matrilineal transmission of foraging skills, may act to mediate the temporal dynamics of prey specializations. 6. Regardless of the exact cause, such extreme individual variation in diet has broad ramifications for population and community ecology. 7. The published literature indicates that similar patterns occur in many other species.
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Vocalizations of the California sea otter (Enhydra lutris nereis) were recorded from wild and captive adults and young and analyzed spectrographically. Parameters measured from the sonagrams included ...fundamental frequency, duration, maximum frequency, intercall interval, and the location and amplitude of energy peaks. We identified 10 basic vocal categories, one of which consisted of graded signals. The contexts for each call, when known or suspected, are described. Discriminant analysis of the spectrographic parameters for the scream call showed significant differences among individuals for adult females and young. Using only the parameters quantified, each call was assigned correctly to the individual that produced it with 80% accuracy for mothers and 75% for young, thus, indicating that the potential exists for individual vocal recognition in the sea otter. The sea otter's vocal repertoire is similar in complexity to that of certain pinnipeds, but may be less complex than that of several species of social cetaceans and primates. In general, the sea otter's vocal patterns have characteristics thought to be most suitable for short-range communication among familiar individuals.
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Following commercial exploitation in the eighteenth and nineteenth centuries, sea otter (Enhydra lutris) populations in Alaska, British Columbia, and Washington recovered at 17-20% a year, yet the ...California population increased at only 5% a year. This slow rate of increase is perplexing, given that unoccupied and apparently favorable habitats occur throughout the sea otter's California range, and higher growth rates occurred among northern sea otter populations. Better knowledge of the demography of the California population is important in understanding these disparate population growth rates. We studied the reproductive biology and behavior of 53 tagged female sea otters from 1985 to 1991 in Monterey Bay, California. During the study, 136 pups were born to these females. Observations of each female enabled us to determine exact or estimated pup birth dates, which we used to calculate lengths of gestation, pup dependency, and reproductive cycle. Seasonal trends in pupping, in the proportion of adult females with pups, and in pup separations from their mothers were relatively uniform throughout the year. The average interval between separation from pup and subsequent birth was 198 days, the interbirth interval was 407 days, and estimated birth rate was 0.90/year for all adult females. For females that pupped annually (did not lose undetected newborns), the average interbirth interval was 342 days, given an estimated birth rate of 1.07/year. Length of the reproductive cycle increased with increasing length of prior pup dependency. However, the interval between separation from pup and subsequent birth was delayed among females that prematurely lost their pups. The average length of dependency for pups that survived to weaning was 166 days, but ranged from 120 to 280 days. The maximum preweaning survival rate was 0.60-0.65, less than values measured or inferred for some Alaskan populations. Most pups that did not survive to weaning were lost within a month of birth. The probability of successfully weaning pups and the length of dependency increased (P = 0.077) with mothers' ages, thus indicating that reproductive success may increase among females with greater mothering experience. The high preweaning pup mortality we observed probably accounts for much of the relatively slow growth rate of the California sea otter population.
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To investigate whether psychosocial factors (i.e., depression, anxiety, and well-being) moderated educational gradients in interleukin-6 (IL-6) levels using data from the Survey of Midlife ...Development in the U.S. (MIDUS). The influences of educational attainment and psychosocial factors on IL-6 in middle aged and older adults were also examined.
Telephone interviews and mail surveys were utilized to collect educational attainment and psychosocial information from respondents (N = 1028). Respondents also participated in an overnight clinic visit, during which health information and a fasting blood sample were obtained.
Serum levels of IL-6.
Greater educational attainment predicted lower levels of IL-6 independent of age and gender, although this effect was attenuated after taking health behaviors, body mass index, waist-to-hip ratio, and chronic illnesses into account. Psychological well-being interacted with education to predict IL-6, such that for those with less education, higher well-being was associated with lower levels of IL-6.
The findings indicate a strong association between education and inflammation, which can be further moderated by psychosocial factors. The health benefits associated with psychological well-being were particularly evident for individuals with low educational attainment.
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A combined cohort of 8,884 North American, 2,893 British and 1,574 Nordic subjects with Wilms tumor (WT) diagnosed before 15 years of age during 1960–2004 was established to determine the risk of ...secondary malignant neoplasms (SMN). After 169,641 person‐years (PY) of observation through 2005, 174 solid tumors (exclusive of basal cell carcinomas) and 28 leukemias were ascertained in 195 subjects. Median survival time after a solid SMN diagnosis 5 years or more from WT was 11 years; it was 10 months for all leukemia. Age‐specific incidence of secondary solid tumors increased from approximately 1 case per 1,000 PY at age 15 to 5 cases per 1,000 PY at age 40. The cumulative incidence of solid tumors at age 40 for subjects who survived free of SMNs to age 15 was 6.7%. Leukemia risk, by contrast, was highest during the first 5 years after WT diagnosis. Standardized incidence ratios (SIRs) for solid tumors and leukemias were 5.1 and 5.0, respectively. Results for solid tumors for the 3 geographic areas were remarkably consistent; statistical tests for differences in incidence rates and SIRs were all negative. Age‐specific incidence rates and SIRs for solid tumors were lower for patients whose WT was diagnosed after 1980, although the trends with decade of diagnosis were not statistically significant. Incidence rates and SIRs for leukemia were highest among those diagnosed after 1990 (p‐trend = 0.003). These trends may reflect the decreasing use of radiation therapy and increasing intensity of chemotherapy in modern protocols for treatment of WT.
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Alloparental care and adoption of young, aparently altruistic and reproductively costly behaviors, have been reported in over 120 mammalian and 150 avian species. Members of these taxonomically and ...ecologically diverse species often share similar behavioral and sociecological strategies in parental care, and may practice strikingly convergent forms of allopareting, such as "babysitting" behavior. Individuals that care for alien young may acquire selective advantages associated with increased inclusive fitness, parental experience, reciprocal altruis, and exploitation of fostered young. In many cases, environmental constraints, such as scare breeding resources of food sources requiring cooperative foraging strategies, appear to influence the occurrence of allopareting and adoption. In addition, proximate factors incorporating "reproductive errors" may be involved in some instances of fostering, Often, several selective benefits, along with various environmental pressures or reproductives mistakes may collectively promote the evolution of alloparental care and adoption. Fostering behaviors have been reported especially often in animals characterized by one or more of the following reproductive or social features, most of which are typical of K-selected species: (1) production of single offspring; (2) prolonged or energetically intensive parental investment; (3) limited lifetime reproductve output; (4) smal groups with tight kinship bonds; (5) highly social or cooperative group structure; and (6) young that are raised in high-density breeding colonies.
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The evolution of fostering behavior, parental care directed toward another's young, has been the focus of much recent interest. During a five-year study of northern elephant seals (Mirounga ...angustirostris) at Año Nuevo, California, we recorded the frequency of mother-pup separation, reunion, and adoption of orphaned pups in crowded and low-density breeding areas. While most females nursed their own pup exclusively until it was weaned, many females, especially young mothers (age 3-5 years), were unable to raise a pup successfully. In the crowded main breeding harem on Año Nuevo Island, 24 to 57 percent of the pups born each year were separated from their mothers from 1977 to 1980. Mother-pup separation and pup mortality were associated with the following inter-related factors: 1) female density; 2) weather and tidal conditions; 3) topographical features of the breeding areas (i.e., degree of exposure to high tides and surf); and 4) the proportion of young, maternally inexperienced females pupping in a particular area. Most mother-pup separations were caused directly by 1) adult males moving through the harem; 2) pups wandering from their mothers; 3) female aggression; and 4) inclement weather. Most of the separations, as well as adoptions, occurred when pups were quite young. Mother-pup recognition appeared to be based on a combination of acoustic, visual, and olfactory cues, and most mother-pup reunions were effected by the female rather than her pup. On the main island breeding area, 572 orphans were marked. Of these, five percent relocated their mother, 27 percent were adopted or frequently cared for by foster mothers, and 68 percent were not adopted, or rarely fostered. The survival of an orphan was clearly contingent on the amount of care it received; most orphans which were not nursed or protected by females died before reaching 6 weeks of age. Frequently, an adopted orphan's foster mother was in the stage of lactation which corresponded closely to that of its own mother. The most common fostering event involved females that had lost their own pup and adopted a single orphan. Other pupless females attempted to steal a pup, cared for a pup while it was still with its mother, adopted a weaned pup, adopted two pups, or indiscriminately nursed any orphaned pup that approached. Some females kept their own pup in addition to fostering in alien pup. Most foster mothers were young and had little or no previous maternal experience. The formation of large, high-density breeding rookeries, due to a scarcity of suitable breeding sites, results in frequent mother-pup separations, especially during inclement weather and tidal conditions. Many opportunities for adoptive behavior are therefore presented, because of the great number of orphans and pupless females. Increased maternal experience appears to be a benefit associated with adoption. Some instances of fostering behavior may also be based on "reproductive errors" on the part of the foster mother.
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Elephant seals, Mirounga angustirostris, are exceptional mammals in that females fast entirely during nursing while their pups may quadruple in weight over the 28-day suckling period. Obviously, all ...water and nutrients for both pup and mother must be derived from the females' body reserves. Thus one might anticipate changes in milk composition during nursing which reflect the physiological requirements of both parent and offspring. Milk samples were taken from 20 females in the field at known times in their respective nursing cycles during the 1976-77 breeding season on Año Nuevo Island, California. The milk was analyzed for: percent H₂O, percent protein, percent fat, fatty acid composition, and the presence of reducing sugars. During the first 21 days of lactation, fat and water content of milk changed with mirror-image kinetics; fat rising from approximately 15% to a plateau of approximately 55%, while water content fell from approximately 75% to a constant level of approximately 35%. Plateau values persisted until weaning. Protein content remained fairly constant during lactation, comprising 5%-12% of milk by weight. Fatty acid composition of milk lipids varied little throughout nursing; 16:0, 18: 1, and 20:1 species accounting for ≥70% of total lipid. In all samples reducing sugars were below the detectable limit (0.25%). These results must reflect strong selection pressure for short, intense, and highly efficient nursing regimes in species which fast during lactation, as compared with conventional mammalian nursing strategies.
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Geophysical surveys were conducted in the Pima mining district by
students from the University of Arizona. The surveys were concentrated
along section B-B' from Cooper (1973). The objectives of
this ...survey included: teaching geophysical techniques, mapping
regional structure along this profile, and determining which geophysical
techniques were most useful for regional .mapping in this
area. Controlled source audio-frequency magnetotelluric (CSAMT)
surveys successfully mapped depth to basement along this profile.
Seismic refraction surveys were not able to map depth to basement.
Either the depth to basement was beyond the range of the
arrays used in this experiment or there is insufficient contrast
in the velocity between the basement and the overlying rocks. A
test of the seismic reflection method was carried out using a
walk-away noise spread. Possible reflections from basement were
noted but were not sufficiently diagnostic to be routinely use able.
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