Methods of sampling aquatic beetles in the transitional habitats at water margins

Populations of water-beetles (Hydrophiloidea) were studied during the ice-free seasons of 2 years at a lake shore near Stockholm, Sweden. They were sampled by means of an absolute quantitative method (twenty-four bottom cores/sample), extracted by Berlese-Tullgren funnels, and a relative searching method (time-catch or catch per unit effort). The sampling efficiency was tested by charging empty samples with known numbers of beetles. ‘Smaller’ species were less efficiently extracted than ‘larger’ ones. Absolute and relative population estimates of eight species were compared by means of regression analysis, the relative estimate being considered as the dependent variable. Only three statistically significant correlations were found, but a correlation always seemed to exist, and the relative estimates are considered as crude estimates. To obtain better ones when studying several species in one habitat much work is required, and then the advantages of the simple relative method disappears. The different sizes of the species were evaluated as sources of errors affecting the relative estimates. The estimates of the 'smaller’ species were more affected than the ‘larger’ ones. It is considered that relative population estimates would gain much if compared with independent absolute estimates. This seems to have been done rarely with invertebrates in aquatic habitats. Further, it is thought that behavioural extraction methods might be applied to several aquatic animal groups in eulittorals and littorals, saving much time compared with mechanical methods or hand sorting.     

INCOMPLETE SONG STROPHES IN THE CHAFFINCH FRINGILLA COELEBS L.: GENERAL INFLUENCES ON A SPECIFIC BEHAVIOURAL OUTPUT

ABSTRACT

Incomplete song strophes in free-living territorial Chaffinch males can be induced by different experimental as well as natural stimulus situations including replay of species- specific song, approaching of human beings, and aggressive encounters with con-specific males. While the first post-stimulus song strophe is shortest the following ones gradually attain their full number of elements again. The strength of this reaction differs with regard to different stimuli.     

ANNUAL CHANGES OF LEARNED BEHAVIOUR—VARIATION OF SONG PATTERN IN FREE-LIVING CHAFFINCHES,FRINGILLA COELEBS,DURING THE BREEDING SEASON

ABSTRACT

Seasonal changes of parameters of full song were studied in a free-living population of chaffinches Fringilla coelebs during one entire reproductive period. Approximately 7000 strophes sung by 14 male chaffinches were recorded and analysed by sonography and a particular oscillographic method. While the general pattern of song strophes, i.e. characteristics of elements, number and arrangement of phrases, and final flourish, remained constant throughout the reproductive period, full song varied with respect to the repetition rate of strophes, number of strophe types used, intensity of singing, duration of strophes, and percentage of incomplete strophes sung. These changes are discussed as results of learning processes, social interactions in the population, and endogenous mechanisms activating memorized information.     

MORAL EXPERTISE: A PROBLEM IN THE PROFESSIONAL ETHICS OF PROFESSIONAL ETHICISTS

Philosophers, particularly moral philosophers, are increasingly being involved in public decision-making in areas which are seen to raise ethical issues. For example, Dame Mary Warnock chaired the ‘Committee of Inquiry into Human Fertilization and Embryology’ in the UK in 1982–4; the Philosophy Department at Auckland was commissioned by the Auckland Regional Authority to report on the ethical aspects of fluoridating the public water supply in 1990; and many of us are serving on ethics committees of various sorts. Not only are philosophers actually being called on or consulted, but many of us would argue that a philosophical contribution in such areas is essential. The involvement of moral philosophers in public policy decisions raises a question of professional ethics, viz, what role should a philosopher's own moral perspective or judgements play in the advice s/he gives, or contribution s/he makes, to public decision-making on ethical issues. Like most problems in professional ethics, this prompts reflection on the nature of the profession, and in particular on the expertise we take moral philosophy to offer. It also prompts reflection on how processes of public decision making in ethically problematic areas should be understood. I explore these issues in this paper.