Puzzle for birdophiles

[Chris Lavers <chris.lavers@nottingham.ac.uk>]

Dear birdophiles

Mark Carwardine in his *Guiness Book of Animal Records* records the
following statistics about the species density of birds in what appear to
be some non-standard biogeographic regions. He does NOT reference the
source of the original information, however. Does anyone know the
book/article from which he got the original numbers of bird species and
areas for each region?

1. Indomalayan region of India and southeast Asia through western Indonesia
= 196 species per million square kilometers. 
2. The Neotropics = 177 / mill.sq.km
3. The Australasian region of New Guinea, Australia, New Zealand and
adjacent islands = 154 / mill.sq.km
4. The Afrotropical region of sub-Saharan Africa and southern Arabia = 66 /
mill.sq.km
5. The Nearctic of North America and temperate Mexico = 34. 
6. The Palearctic of Europe, North Africa and Asia north of the Himalayas =
31 / mill.sq.km
7. Antarctic region = 3 / mill.sq.km 
8. Malagasy region of Madagascar and the western Indian Ocean islands = 328
/ mill.sq.km
9. Tropical Pacific islands = 4,894 / mill.sq.km (!)

Prize for the right answer is the knowledge that you have made at least one
person's day.

Best wishes to all
Chris