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The first three papers in the Loess and Bee-eaters series sought to establish links between the nesting of bee-eater birds (family Meropidae) and the occurrence of loess deposits. For the European bee-eater there is a close and fairly obvious relationship; for the Carmine bee-eater nesting in the 15 N band of Africa more assumptions and adjustments have to be made, and for the Blue-cheeked bee-eater nesting in the Indus region the relationship is becoming vague and more speculative. The trend continues with the Australian bee-eater- the rainbowbird ( Merops ornatus ). We lack precise maps of loess distribution in Australia and there is an equal lack of detailed and accurate maps of the distribution of rainbowbird nesting. Loess in Australia is elusive; the maps of Kriger and Scheidig show little detail and are essentially contradictory. If the deterministic theory of loess deposit formation were applied, it would suggest that loess should be found in the region where Pleistocene cold-phase mountain glaciers occurred. In the last glacial phase there was very little glacial occurrence in Australia; probably a limited region near Mount Kosciuszko. This places some glacial activity in the extreme southeast of the country. This agrees, more or less, with the data on the Kriger map. Fry has mapped the breeding zones of the rainbowbird and they are concentrated in the southeast and southwest. The maps are not precise but there does seem to be indications of co-existence of bee-eater nests and loessic regions. This is not the clearcut relationship which has been observed with the European bee-eater but it is suggestive. The ill-defined loess/dust regions and the poorly demarcated nesting zones of the rainbowbird do seem to be coincident. Better mapping is urgently required for loess in Australia, and nesting zones of M. ornatus . It may be that dust rather than loess is the ground material to be observed in Australia. There are still problems of integrating the dust and loess concepts, but mapping of dust deposits does produce some coincidence with rainbowbird nesting. The region of Vertisol occurrence appears to be a barrier to the spread of rainbowbird nesting. [ABSTRACT FROM AUTHOR]

Part 3 of the study of loess ground and bee-eater birds concerns birds and ground in the north-western part of the Indian Sub-continent. Three species of bee-eaters are considered, relative to the Indus region: the Green bee-eater, the Blue-cheeked bee-eater and the European bee-eater. Loess in the Indus region is considered via the deterministic approach to loess deposit formation; the P events occur in the mountains of the western part of High Asia, particles are formed by the action of mountain glaciers. Major T actions involve the five rivers of the region which carry loess material into the Punjab plains. Subsequent T actions deliver loess material to local deposits, which provide nesting grounds for bee-eaters. To some extent the bee-eaters define the loess. The Green bee-eater is small (16–18 cm long) and lives over all of India and Pakistan-nesting ground is available everywhere. The larger bee-eaters (European and Blue-cheeked: (25 cm)) are more constrained by ground properties-they require the ideal properties of loess ground (an ideal positioning relative to the Heneberg compromise) for nesting, and thus tend to define loess extent. Soil mechanics requires that more exact stress conditions are achieved when a relatively large nest tunnel is being constructed. [ABSTRACT FROM AUTHOR]