The Zoologist/4th series, vol 1 (1897)/Issue 675/The Breeding Habits of the Purple Heron

by Frederick Bulstrode Lawson Whitlock

 

THE BREEDING HABITS OF THE PURPLE HERON.

By F.B. Whitlock.

 

In May of the present year I visited a certain district in France where the Purple Heron (Ardea purpurea) breeds in moderate numbers. As my experience of the nesting habits of this species differs in some respects from previously published accounts, a few notes should not prove uninteresting.

The district to which I refer should be a paradise for Herons, as numerous large ponds or meres, of one, up to many hundred acres in extent, are scattered over a wide extent of country. All, however, are not favoured as breeding-places by the Herons, and it is only in those which are covered by a dense forest of reeds and other aquatic vegetation that colonies are found.

In a mere of about one hundred acres, occupied by one vast reed bed, and where in the few open spaces round the margins I found the lovely white water-lily growing in profusion, I observed Herons rising at intervals from the thickest portion of the reeds. Having been told that a colony existed here, I determined on making a closer examination. The only plan appearing to be to wade out and force a passage into the reeds to the part to and from which the birds were passing, I naturally carefully took my bearings as I sat on the bank eating my lunch. Once amongst the reeds I could only trust to my sense of direction, as they grew to a height of seven or eight feet above the water. I was glad to find when I commenced to wade that the depth of the water rarely exceeded four feet, and that underfoot was a good firm bottom free from mud.

It was laborious work pressing through the reeds with a mass of vegetation round my waist, and a long tail trailing behind, not to speak of the hot sun overhead, and I must have travelled quite two hundred and fifty yards before putting up a Heron a little distance away to my right. Turning in the latter direction, I found, after five minutes' search, a large nest containing eggs. Further explorations revealed seven more; two of which, however, belonged to Ardea cinerea, the remainder to Ardea purpurea. The nests of both species were identical in structure, and were formed entirely of the dried stems of the surrounding reeds. They were rather shallow, but very bulky; one would have perhaps filled an ordinary clothes-basket. The foundations of the nests rested on broken-down reed-stems, and were on a level with the water. Standing by the side of one I could just comfortably get my chin over the rim of the nest. Those of A. purpurea contained 6, 6, 6, 5, 5, 5 eggs respectively; but those of the larger species, in one case, had young, perhaps a week or ten days old; and the other, three young and two unhatched eggs. This was on the 11th of May. The eggs of A. purpurea in several cases were quite fresh or nearly so, and in others incubated for perhaps a week or thereabouts. Each nest stood in a little clearing, due, as I surmised, to the materials having been gathered by the parent birds close at hand. The Purple Heron appears to be a close sitter, for on my invading the colony the owners did not rise in a body, but got up singly as I approached the nests; though on one occasion when I blew a whistle to re-assure an anxious companion on the bank, two rose very precipitately, but without any cry betokening alarm. All flew off, indeed, without any sound or protest, nor did I hear a single cry from the flock of forty or more individuals, which my companion counted, circling around some two hundred yards above the mere. Some of the latter must have gathered from the surrounding country, as I did not put up anything like this number from amongst the reeds.

In the part of France to which these notes refer the Purple Heron is much commoner than its larger ally, and I estimated that fully ninety per cent. of the Herons I observed were A. purpurea. The latter species is readily distinguishable from A. cinerea, even at a distance, by its smaller size and by its distinctly reddish appearance, due in part to the rufous colour of the scapulary plumes, and also to its chestnut under parts; whilst close at hand the black stripe down the sides of the neck in contrast with the clear grey neck of A. cinerea is very conspicuous.

Most of our recognised authorities,—Dresser, Seebohm, Yarrell, Saunders, &c,—in writing on the nesting habits of the Purple Heron, quote the account by Lieut.-Col. Irby of his visit to a colony in the south of Spain. It is interesting to learn that the latter ornithologist only found three or four eggs in each nest, in the place of five or six in rny own experience. Abundance of food may perhaps account for the greater fecundity of the Herons I came into contact with, for Dresser states that the Purple Heron is said to devour large numbers of young Green Frogs (Rana esculenta). Now these creatures abound in the large ponds before mentioned, and the Herons must have no difficulty in eating their fill throughout the nesting season. Some divergence of opinion may be noted on the dimensions of the eggs of the present species. Seebohm states that they are indistinguishable from those of A. cinerea, except that they are slightly smaller. He gives the following measurements: length 2·45 to 1·95 in. by 1·75 to 1·45 in. in breadth. Dresser states that eggs taken in Hungary varied from 24/10 × 123/40 to 210/40 × 127/40 in. The average dimensions of eggs of A. cinerea the latter author gives as 21/2 × 127/40 in. Saunders, in his 'Manual of British Birds,' states that average eggs of A. purpurea measure 2·2 × 1·5 in. These dimensions I find approximate to the sizes of the eggs I took in France; my largest specimen being equal to 2·23 in. in length by 1·62 in. in breadth, and my smallest but 1·95 × 1·47 in. An attenuated egg, however, has a length of 2·30, but a breadth of only 1·50 in.

Comparing these measurements with those of eggs of A. cinerea kindly supplied me by Mr. R.J. Ussher, who has had considerable experience with the latter species in Ireland, I think it may be laid down as a general rule that large eggs of A. purpurea in size rarely overlap those of small ones of A. cinerea. According to the above-named ornithologist, eggs of A. cinerea vary between 2·63 × 1·71 in. and 2·39 × 1·7 in. These dimensions, I may say, tally with those of eggs in my own collection.