(1388) Micropternus brachyurus williamsoni * Kloss.
THE SIAM RUFOUS WOODPECKER.
Micropternus brachyurus williamsoni, Fauna B. I., Birds, 2nd. ed. vol. iv, p. 62.
Omitting the area occupied by Sundevall’s squameigularis, we may define the area of this form as from South of Pegu to the extreme South of Tenasserim and Siam from Bangkok, or Samkok to the South of Peninsular Siam. If, as some systematists still think, williamsoni of Kloss is the same as squameigularis, the former name will become a synonym of the latter.
The eggs of this Woodpecker have been taken only by Hopwood and Herbert, and the former’s brief note, given me with eggs, agrees completely with the fuller account given by Herbert, except that the ants’ nest from which they were taken was built on a bamboo. Herbert, when sending me two clutches of eggs, wrote as follows:— “I was fortunate in obtaining the nest of this most interesting bird on two occasions, and I think it was most probable that both nests belonged to the same pair of birds. My reasons for thinking this are that the second nest was taken a fortnight after the first from a place very near by and, considering that the Rufous Woodpecker had seldom been seen in the Bansakai gardens, which I was in the habit of visiting regularly, it would have been a curious coincidence for one pair to follow another in such quick succession.
“The first was discovered on a mango sapling, at a height of about 10 feet from the ground. The collector noticed the circular hole in the ants’ nest when he was going his rounds, and shook the sapling, which frightened the bird from the nest. He probably shook it rather violently, as the stem was not thicker than his wrist, and gave the bird a bad fright, for it deserted the nest, I visited the place later in the day and, as the bird had not returned, I took the three eggs, which I found to be in an early stage of incubation.
“The second was in a similar ants’ nest on one of the shade trees for the Betel-vines, at about the same height from the ground and some 200 yards away from the other sapling. In this case the bird was successfully snared as it left the nest, being taken by means of a noose tied to the end of a fishing-rod. The snare was suspended in front of the entrance and then a kick on the tree accomplished the desired result. The bird, a male, was caught about an hour before sunset, and the skin is now in the British Museum.
* I at first considered this to be a synonym of burmanicus Hume (Proc. As. Soe. Beng. 1870, p. 70), but on re-examination of the fine material in the British Museum I came to the conclusion that burmanicus was, on the whole, much nearer phoeoceps, the Northern form. Nor was I able to define any area in which burmanicus could be considered a stable form, as over all Pegu the birds vary so greatly individually that it is impossible to refer them to any definite race.
The nest was made by excavating a cavity in the globular¬shaped nest of the tree-ant. These ants’ neats are built round a fork on the stem of a sapling, and measure 10 inches to a foot in diameter. The material is exceedingly hard and so stands up bo the work of the Woodpecker without cracking or breaking away too freely, and in both cases the bird made use of the fork of the tree for the entrance. The neats were partially occupied by the ants whilst the birds were sitting and remains of the ants were found in the stomach of the bird which was caught, while many heads were still attached to the tail-feathers. It will be seen therefore that tills Woodpecker attacks a ‘live' ants’ nest in its most perfect condition, just in the same way as Sauropatis does with the neat of the large black ant,
“The eggs are slightly elongated ovals, fine in texture but with a mat surface, and in that respect unlike any other Woodpecker’s eggs that I have seen. The shell is very hard. It is translucent, and not only are the contents visible, but if water is injected into the empty shell the amount can clearly be seen.
“Three eggs were found in each of the above nests.”
Hopwood’s and Herbert’s eggs, now all in my collection, are alike in character, and are really very extraordinary. Herbert’s description is excellent and applies to almost all eggs of Woodpeckers which are deposited in holes made in ants’ nests. I say almost all because in very rare cases one comes on eggs which are not quite so transparent, though equally strong and thin shelled. It cannot be the action of formic acid on the shells after deposition that causes this curious condition, for eggs laid a few minutes and others- incubated several days have the same texture. The birds themselves, however, live very largely on these and other ants, and their diet may quite possibly have some effect on the eggs they lay. Another curious point is this : if we placed eggs other than those of the Woodpecker among a similar assembly of ants, they would in very quick time work their way into the eggs and extract every atom of their contents. Yet they seem never to attack the eggs or young of this Woodpecker, nor, I believe, do the Woodpeckers regularly eat the ants belonging to the nest in which they are breeding. If they did it would not take many days, or even hours, for two- Woodpeckers to clear out a whole nest of its living ants, the pupae soon following the ants, I have found ants’ nests in which young Woodpeckers have been reared to maturity and, when they have finally left, the nest is still as full of ants as when the entrance to the nest-hole was commenced. It is true that occasionally the birds have been found sitting on eggs or young in deserted, or partially occupied, ants’ nests, but such eases are exceptional and possibly due to a mistake on the part of the bird. It must be remembered that if all these curious papier-mache black nests of the ants were examined whenever seen probably about two out of three would be found to be deserted by the ants, yet not one Wood¬pecker’s nest-hole in ten is to be found drilled in such nests.
These points, though raised here, refer equally to all those Wood¬peckers who make their nest-holes in ants’ nests, and need not be alluded to again. I have personally seen many hundreds of the ants’ nests, which are, so I am told, made by Crematogaster ants of various species. They look like large cellular balls of black papier mache and measure anything from 8 inches to 2 feet in diameter, and are built in trees and bamboos at any height from the ground between 7 and 70 feet, but most often between 10 and 30 feet. The ants arc exceptionally vicious and, when taking eggs, unless the nests are first smoked, one gets badly bitten, the hands often swelling considerably and remaining so for some days. The whole affair seems to be on a par with the cases we know of in which the Laggar Falcon, though living mainly on Doves, yet never molests the same birds when breeding within a few yards of him.
The breeding season is probably January to March, Herbert having taken two clutches, one in January and one in February, while Hopwood took one in March.
The number of eggs laid seems to be three normally, two occasionally.
Eleven eggs average 27.1 x 19.5 mm. : maxima 29.8 x 20.8 and 28.0 x 21.0 mm. ; minima 25.6 x 19.5 and 27.0 x 18.7 mm.
1388. Micropternus brachyurus williamsoni
(1388) Micropternus brachyurus williamsoni * Kloss.