4 - Estimating Productivity John R. Skalski; Kristen E. Ryding; Joshua J. Millspaugh
Wildlife Demography,
2005
Book Chapter
This chapter presents productivity estimators based on the analysis of juvenile and adult count data. These direct counts are appropriate for species in which juveniles are readily differentiated ...from adults at time of the survey. These direct counts also rely on the ability to observe relatively large numbers of individuals with equal probabilities of detection. Productivity estimates can also be derived from litter or brood counts. Change-in-ratio methods provide a convenient means to estimate productivity. Sample size charts should be considered, or sample size calculations performed before any serious attempts are made to use the ratio methods. In the case of open populations in which adult survival changes over the course of the study, attention to the nature of the productivity parameter being estimated is important. Auxiliary studies to estimate juvenile sex ratios or adult survival may be necessary to insure valid estimates of productivity. The inability to properly classify individual animals to sex or age category can also impact study performance. However, effective sample size is reduced, and sampling precision is degraded. A much more troublesome case exists if the probabilities of nonclassification differ between the sex or age categories. Variance expressions are derived for each of the indirect techniques, and precision curves are presented as guides to sample size calculations.
Sex ratios are among the most basic of demographic parameters and provide an indication of both the relative survival of females and males and the future breeding potential of a population. The ...observed sex ratio is a consequence of natural selection on the sexes and any anthropogenic effects of harvest. This allows wildlife managers to regulate animal harvests to maintain desired sex ratios. Conversely, by monitoring sex ratios, wildlife managers can assess how harvest regulations may influence the relative mortality rates of the male and female segments of a population. This chapter addresses two general approaches to estimating sex ratios. The most general approach uses direct field observations to estimate the population sex ratio. Finite sampling methods are used to estimate these ratios under a variety of scenarios. Choosing among these methods should begin with the structure and nature of the population under investigation. Species that form aggregates or herds need to be surveyed differently than populations of solitary individuals. Cluster sampling techniques are therefore presented. Unequal probabilities of detection are possible when making visual counts of animals. This consideration is important when probabilities of detecting animal aggregations of different sizes are expected to be a function of group size. The advantage of direct estimation methods for calculating sex ratios is that no assumption is required about the dynamics of the population being studied. Instead, adherence to the principles of probabilistic sampling is all that is needed to ensure reliable estimation of population sex ratios.
An array of methods is available to investigators to estimate the finite and instantaneous rates of population change. Different statistical approaches may need to be used to estimate intrinsic and ...realized rates of population change. Some methods are better suited for estimating one parameter or the other. Similarly, some analytical approaches are better for estimating the annual or finite rate of population change, other methods are better suited for estimating the instantaneous rate of change. These methods are generally based on geometric or exponential growth assumptions. The intrinsic rates of change are estimated by these exponential-based growth models when a population is indeed in the exponential growth phase. Alternatively, when a population is experiencing density-dependent growth, the exponential-based methods can only be used to estimate the realized rate of change over short periods of time. Nevertheless, the assumption of exponential growth will eventually be violated. In situations in which a series of abundance surveys exist during density-dependent growth, the ratio method can be expected to provide a better measure of average performance than exponential regression-based methods.
Population dynamics is concerned with changes in abundance, as well as the factors that influence those changes. This chapter considers population growth of age- and stage-structured populations and ...how knowledge of age- or stage-specific rates can help guide management activities. The chapter provides an overview of population harvest theory, and discusses the concepts of the annual surplus model, sustained yield harvesting, and additive and compensatory mortality. Density-independent factors affect population growth rates irrespective of population size. The simplest form of a Leslie matrix model is a one-sex, density-independent projection model. The model projects the number of females by age class through time. The chapter uses harvest-related data as the basis for demographic assessments. The ability to estimate harvest mortality and partition total mortality into component sources is important in understanding the dynamics of exploited populations. Demographic stochasticity, environmental stochasticity, time lags, delayed density dependence, inverse density dependence, and removals will influence population size and number of animals recruited into the population. The effect of these factors on population growth will depend on population abundance and resilience, which is related to its capacity to increase, quality of the habitat, and effects of harvest on demographic rates.
Schiff base formation, transaldimination, and reaction with aminothiols are important reactions which occur on the surface of pyridoxal-P-requiring enzymes. As a first step in assessing the role of ...the protein in these reactions, models for these reactions were studied in the absence of enzyme at 25 degrees, gamma/2 0.28. The reaction of 6-aminocaproic acid with pyridoxal-P to form the Schiff base N6-(P-pyridoxylidene)-aminocaproic acid was studied as a model for formation of Schiff base on the holoenzyme...
Epidemiologic studies following the Czernobyl accident were performed in region Kraków, including Kraków, Nowy Sacz and Kielce district. 1426 males and 2495 females were selected according to the ...random sample on the whole population of Kraków and Nowy Sacz, as well as in some selected areas in Swietokrzyski Mountains, and in Kielcecity. The aim of the study was to assess the results of the prophylaxis with Kalium iodine after the radiation and the incidence of the goiter in the population. It was stated, that 19.2% of the population in Kraków district, 16.9% in Nowy Sacz and 20% in Kielce received the prophylactic dosis of K.J. 80% took mainly the Lugol solution, between May, the 1st and 5th, 1986. Among 18 of person showing side effects like gastrointestinal disturbances, 16 were of female sex. Goiter incidence according to WHO classification was 50.7%, 67.3% and 49.9% in Kraków, Nowy Sacz and Kielce respectively. The difference between the incidence of goiter in males and females was 1:3. In women it was rather Ist and IInd degree of goiter, in men OB and Ist. Nodules of thyroid gland in the rural region of Kraków, Nowy Sacz and Kielce were seen in women in 10.8%, 1.7%, add 12.3% consecutively. Hormonal studies i.e T3, T4, TSH serum concentration showed normal results in all groups studied. TSH concentration was the highest in the group OB. The microsomal and antithyroglobulin antibodies level was the same independently on the prophylactic dosis of Lugol solution. The high incidence of thyroid diseases not related to the accident was observed.
The systematic position of C. paxi is discussed on the basis of two type specimens deposited in the zoological museum of Humboldt University in Berlin. The specimens were compared with Schellenberg's ...description and with adult and juvenile specimens of C. subterraneus . C. paxi is redescribed and a diagnostic comparison of C. paxi and C. subterraneus is given.
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