822 
Birds of Celebes: Ardeidae. 
The Eeef Heron occurs under two forms, one slate-colour, the other white. 
By some authors these are believed to be two distinct species, by others they 
are held to be of one species which is dichomatic. Slate-coloured adults and 
white adults of both sexes are known; also slate-coloured young and white young. 
Piebald intermediate examples are often observed; and slate-coloured and pure 
white birds are frequently seen paired. In habits the birds are similar, and 
they live together; but Hume and Davison in the Andaman and Nicobar 
Islands found that tlie white bird was (the rule with albinos?) much the shyer 
and more difficult to shoot of the two. The white form is much less plentiful 
than the dark, but it seems to occur everywhere with it, even in New Zealand 
(d IX.), where it has been supposed to be absent. The view that there is only 
one species with strong tendencies to albinism is the more probable one; in 
the allied species Ardea gidaris of Africa, India and Ceylon, A. coerulea and 
A. rufa of America closely similar conditions occur, as pointed out by Finsch 
& Hartlaub, Stejneger, Legge, and Baird, Brewer and Ridgway. Such 
questions must be studied in the haunts of the birds; from the museum they 
cannot be ansAvered. 
Another matter which is likely to cause perplexity is the supposed existence 
of local races. The Reef Heron is known to breed in many localities (Australia, 
Tasmania, New Zealand, Fiji, Andamans, Arrakan) , and it may perhaps be station- 
ary in some localities ; it is, however, according to Mr. Whitehead (20), a migrant 
in North Borneo, which means, of course, that it moves in some other spots. The 
Arrakan and Nicobar birds were separated by Blyth as Demiegretta concolor, but on 
grounds subsequently shoAvn by Hume to be invalid; more recently Stejneger 
named those inhabiting the Loochoo Islands and Corean Strait H. ringeri. Without 
material from all parts it is difficult to form an opinion on this question, to- 
wards solving Avhich vol. XXVI of the Catalogue of Birds should go far, and 
in that Avork Sharpe does not admit D. ringeri as a species. 
The Reef Heron seems to have its closest affinities with the Indo-African 
A, gularis (Bose) in Avhich the white of the throat extends over the submalar 
region and much farther doAvn the throat, and, as Legge points out, it is 
longer in the leg and has much more of the tibia bare of feathers. The albino- 
form of D. sacra is likely to be mistaken at first sight for a Avhite Heron of 
the genus Herodias; it may best be distinguished by its short tarsus, except from 
II. eulophotes in which, however, the first primary is the longest and the wing 
is shorter than in sacra. The bill of Demiegretta is peculiar; it is unserrated, 
stouter than in Herodias, not tapering to a sharp point, but of fairly even width 
for ^4 of its length, the cutting edges meeting at the tip, but not quite meeting 
for the terminal third behind it ^ — a condition also seen in Anastomus and Esacus 
magnirostris, for instance, and a result, perhaps, of laying hold of rough objects, 
such as crabs, coarse-shelled molluscs, etc., on the sea-shore which the birds 
haunt. The toes of Demiegretta are stout, being covered Avith unusually thick 
transverse scales. 
