_Butors Leguat_, Relation du Voyage (1708).
_Ardea megacephala_ Milne-Edwards, Ann. Sci. Nat. (5) XIX, 1874, p. 10.
Leguat's description, here translated, is as follows:--"We had Bitterns as
big and as fat as capons. They are tamer and more easily caught than the
'gelinotes.'" He also says, "The lizards often serve as prey for the birds,
especially for the Bitterns. When we shook them down from the branches with
a pole, these birds ran up and gobbled them down in front of us, in spite
of all we could do to prevent them; and even if we only pretended to do so
they came in the same manner and always followed us about."
Milne-Edwards remarks, among other notes, that "This bird is not a true
Bittern, but its head is so large and its feet so short that it is easy to
understand that Leguat should have called it so."
The bony structure of the head is remarkable on account of its massive and
thick proportions; the skull itself is strongly enlarged posteriorly, and
the temporal fossae are bordered by very pronounced ridges, especially
those on the occipital region. The upper side of the skull is hardly
convex, and the interorbital region is large, but only slightly depressed
along its middle line. The bill is stout, almost straight, a good deal
enlarged at its base and rounded beneath. The nostrils are large and
preceded by a large groove, which extends very far towards the tip.
It is impossible to confound this skull with that of any Bittern, the
latter having the beak relatively slender and only barely exceeding the
skull in length. These also have the skull much constricted at the temporal
region. The fossil skull from Rodriguez therefore presents characters
essentially those of a Heron, but differs from all known species in its
massive appearance. In the Grey, Purple and Goliath Herons, as well as in
the Egrettes, the head is narrower, more elongated, the bill less conical
and less strong. In _Ardea atricollis_, now inhabiting Madagascar, the beak
much resembles that of our extinct species, but it is longer and less
enlarged at the base. The interorbital area is much wider, while on the
other hand the hinder portion of the skull is narrower and more elongated,
which gives to the skull a totally different aspect.
The feet relatively to the head are extremely short, and from this I
conclude that we know no species of Heron which can be compared to that of
Rodriguez. Nevertheless, the tarso-metatarsus presents all the characters
{112} of _Ardea_, and is far removed from that of _Botaurus_. The tibia is
big and short; it surpasses in length the tarso-metatarsus by about a
third, as is usual in the Herons; but the femur on the contrary is strongly
developed, being quite as large as in the _Ardea cinerea_; which shows us
that the body of this creature was of large size, and that the reduction in
size of the feet had only taken place at their extremities.
The sternum is puny and small as compared with the creature's size. It is
clearly that of a bird not furnished with powerful wings, and is even much
less elongated than in the Bittern, but the coracoidal bones are very long
and slender. The wings also were short and feeble, the humerus being hardly
as big as in _Butorides atricapilla_. It is conspicuously slenderer and
shorter than in the Bittern. The main body of the bone is slightly curved
on the outside, and the lower articular condyle is large and flattened. I
have not been able to examine any bone of the "manus," but the metacarpal
bone shows exactly the same proportions for the wing as does the humerus,
as it also barely reaches the size of that of _Butorides atricapilla_. The
measurements are as follows:--
_Skull._
Total length 154 mm.
Length of upper mandible 94 "
Width of upper mandible at base 22 "
Width of interorbital region 22 "
Space between the mastoid apophyses 40 "
Width of skull at level of postorbital apophyses 40 "
Length of lower mandible 147 "
_Tarso-metatarsus._
Total length 95-162 mm.
Width at proximal extremity 14 "
Width at distal extremity 13.5-14 "
Width of shaft 6.2-7 "
_Tibio-tarsus._
Total length 140-210 mm.
Width at distal extremity 12-13 "
Width at proximal extremity 13-14 "
Width of shaft 6-6.5 "
{113}
_Femur._
Total length 90-92 mm.
Width of distal extremity 15-16 "
Width of proximal extremity 14-16 "
Width of shaft 6.2-7 "
_Sternum._
Total length 64-88 mm.
Width in front 35-48 "
Width behind costal facets 26-36 "
Width at posterior border 27-35 "
_Coracoidals._
Total length 59-67 mm.
Width at lower extremity 17-18 "
_Humerus._
Total length 118-180 mm.
Width of proximal extremity 20-27 "
Width of distal extremity 16.5-24 "
Width of shaft 7-11 "
_Metacarpals._
Total length 62-98 mm.
Width of proximal extremity 12-17 "
Width of distal extremity 7-11 " "
The anonymous author of the manuscript "Rélation de l'île Rodrigue" (see
Ann. Sci. Nat. (6) II p. 133 et seq. 1875) about the year 1830 mentions
this bird as follows:--"There are not a few Bitterns which are birds which
only fly a very little, and run uncommonly well when they are chased. They
are of the size of an Egret and something like them."
Habitat: Rodriguez Island.