5. SOME NOTES RESULTING FROM A HOLIDAY TRIP THROUGH EAST GRIQUALAND

The study investigated the bird species diversity associated with vegetation communities found on a single mountain slope in the Usuthu Gorge Community Conservation Area, northern KwaZulu-Natal. Thirteen sample sites were surveyed on a monthly basis for 12 months. Over this period, 279 birds and 55 species were recorded, of which the Dark-capped Bulbul Pycnonotus tricolor was the most abundant. The Rattling Cisticola Cisticola chiniana was the indicator species in the highest community, Open Bushveld, which is characterised by grassland and bush patches. The White-bellied Sunbird Cinnyris talatala was an indicator in the second-lowest community, Dense Bushveld–Woodland, which is characterised by steep slopes and thickets. In Wooded Grassland, located between the above two communities, the highest beta diversity (species turnover) was recorded and this outcome was probably caused by large areas covered by rocks that compelled woodland birds to move through this community. Contrary to expectation, the gamma diversity per vegetation community increased with elevation from 18 to 33 species in Dense Bushveld–Woodland, Wooded Grassland and Open Bushveld. A future study should measure bird species diversity on larger elevational gradients, i.e. slopes from 500 to 3 000 m above sea level, which also include more distinct vegetation communities.     

The Heart and Physical Exercise

Cardiac hypertrophy and extreme bradycardia occur in the highly trained endurance athlete, but not in those with lesser degrees of training. Several longevity studies in athletes fail to show any beneficial effects of athletic training confined to the college years. The invaluable British studies relating physical activity of various occupations to coronary disease show that while exercise does not prevent coronary atherosclerosis, it may reduce the incidence of large and fatal infarctions and of complete coronary obstructions. Various American studies have not confirmed this beneficial effect of exercise. To be of any value in the prevention of coronary disease, exercise must be continued on into middle age. The sedentary life characteristic of western civilization is probably not a major factor in the high incidence of coronary disease.