THOMAS SCHOENER (Biological Laboratories, Harvard) has continued his 
studies of species ecology on the several Bahaman banks, In winter to spring 
1973 he visited Bimini, Abaco, and Andros, censusing plots of varying 
vegetational diversity in order to discover what the species abundance and 
population composition (age, sex) are in the main areas of these islands, 
He will use his results as a baseline for his fringing micro-island study 
planned for 1974, Tentative results are: 
1. There is an increase in species diversity (by any measure) from low 
to high vegetational complexity. 
2. Equitability is perhaps highest in the areas of highest vegetational 
density, but the number of individuals is highest in areas of intermediate to 
high complexity. 
Mangrove areas apparently show the lowest species diversity for a 
given level of vegetational complexity. 
4, Population structure varies with both overall number of individuals 
and with vegetational complexity. 
In particular, for Anolis sagrei: 
(a) In very low vegetation the ratio of males to females is very high. 
In the most complex vegetation (forest) the male-female ratio is lower. 
(b) In deep forest (with little understory) the male-female ratio is 
high, but there are few juveniles and subadults of either sex, In broken 
forest, male-female ratio is also high but there are lots of small immature 
lizards, Hence, age structure and male-female ratio are not always correlated. 
5. (a) Some individual anoles on Bimini (ca 2-3% of individuals in all 
species combined) have lived at least three years, All but one of these are 
the largest of all the lizards in the study areas. Thus age and size are 
very closely correlate 
(b) On Abaco survival is higher in the area of low population density 
(mature beach forest) than in that of high density (successional legumes). 
Population density in any year may reflect differences in food abundance, 
However, there may also be a long-term trade-off between growth and survival, 
making the two areas equally favorable. 
(c) On Abaco survival is overall less than on Bimini. There are more 
birds on Abaco and the climate is somewhat more rigorous, 
(d) On the large island of Andros the number of species of Anolis is the 
same as on Bimini but all species are smaller. There are many more species 
of birds on Andros, and it is possible that 1) greater bird predation favors 
anoles that mature at smaller sizes, or 2) reduction in food availability due 
to greater competition with birds makes the anole size optimal for feeding 
smaller, 
